Term
|
Definition
| what are the three types of muscle tissue? |
|
|
Term
|
Definition
| skeletal and smooth muscle cells are elongated and for this reason are called __ |
|
|
Term
|
Definition
| what prefixes are in reference to muscle? |
|
|
Term
|
Definition
| __ is packaged into the skeletal muscles |
|
|
Term
|
Definition
| organs that attach to and cover the bony skeleton |
|
|
Term
|
Definition
| skeletal muscle tissue is attached to __ and __ |
|
|
Term
|
Definition
| skeletal muscle fibers are the __ muscle cells |
|
|
Term
|
Definition
| skeletal muscle have obvious stripes called __ |
|
|
Term
|
Definition
| although it is often activated by reflexes, skeletal muscle is called _ because it is the only type subject to conscious control |
|
|
Term
|
Definition
| skeletal muscle is responsible for overall body __ |
|
|
Term
|
Definition
| skeletal muscle can contract rapidly, but it tires __ and must rest after short periods of activity |
|
|
Term
|
Definition
| skeletal muscle can exert tremendous __ |
|
|
Term
|
Definition
| occurs only in the heart, where it constitutes the bulk of the heart walls |
|
|
Term
|
Definition
| like skeletal muscle cells, cardiac muscle cells are __ |
|
|
Term
| not voluntary (involuntary) |
|
Definition
| unlike skeletal muscle cells, cardiac muscle is __ |
|
|
Term
|
Definition
| cardiac muscle usually contracts at a fairly steady __ set by the heart's pacemaker, but neural controls allow the heart to speed up for brief periods |
|
|
Term
|
Definition
| found in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passages |
|
|
Term
| to force fluids and other substances through internal body channels |
|
Definition
| what is the role of smooth muscle tissue? |
|
|
Term
| no striations (not striated) |
|
Definition
| smooth muscle cells like skeletal muscle cells are elongated "fibers," but smooth muscle has __ |
|
|
Term
voluntary control
involuntary |
|
Definition
| like cardiac muscle, smooth muscle is not subject to __, so it is __ |
|
|
Term
|
Definition
| contractions of smooth muscle fibers are __ and __ |
|
|
Term
excitability
(responsiveness)
(irritability) |
|
Definition
| __ is the ability to receive and respond to a stimulus, that is, any change in the environment either inside or outside the body |
|
|
Term
|
Definition
| in the case of muscle, the stimulus is usually a __ |
|
|
Term
|
Definition
| __ body location: attached to bones or (some facial muscles) to skin |
|
|
Term
|
Definition
| __ body location: walls of the heart |
|
|
Term
|
Definition
| __ body location: single-unit muscle in walls of hollow visceral organs (other than the heart); multiunit muscle in intrinsic eye muscles, airways, large arteries |
|
|
Term
|
Definition
| __ cell shape and appearance: single, fusiform, uninucleate; no strations |
|
|
Term
|
Definition
| __ cell shape and appearance: single, very long, cylindrical, multinucleate cells with obvious striations |
|
|
Term
|
Definition
| __ cell shape and appearance: branching chains of cells; uni- or binucleate; striations |
|
|
Term
| the response (conductivity) |
|
Definition
| __ is generation of an electrical impulse that passes along the plasma membrane of the muscle cell and causes the cell to contract |
|
|
Term
|
Definition
| __ is the ability to shorten forcibly when adequately stimulated |
|
|
Term
|
Definition
| this ability sets muscle apart from all other tissue types |
|
|
Term
|
Definition
| __ is the ability to be stretched or extended |
|
|
Term
|
Definition
| muscle cells __ when contracting, but they can be stretched, even beyond their resting length, when relaxed |
|
|
Term
|
Definition
| __ is the ability of a muscle cell to recoil and resume its resting length after being stretched |
|
|
Term
1. excitability (responsiveness or irritability)
2. contractility
3. extensibility
4. elasticity |
|
Definition
| what are the special characteristics of muscle tissue? |
|
|
Term
1. produces movement (bones or fluid movement --> ex: blood)
2. maintains posture and body position
3. stabilizes joints
4. generates heat (especially skeletal muscle) |
|
Definition
| what are the important functions that muscle preforms for the body? |
|
|
Term
|
Definition
| just about all movements of the human body and its parts result from __ |
|
|
Term
|
Definition
| __ muscles are responsible for all locomotion and manipulation |
|
|
Term
|
Definition
| even as muscles pull on bones to cause movements, they __ and __ the joints of the skeleton |
|
|
Term
|
Definition
| muscles generate __ as they contract |
|
|
Term
|
Definition
| the heat that muscles generate is important in maintaining normal __ |
|
|
Term
|
Definition
| skeletal muscle accounts for at least __ of body mass |
|
|
Term
|
Definition
| __ muscle is the muscle type most responsible for generating heat |
|
|
Term
|
Definition
| skeletal muscles protect the more fragile internal organs (the viscera) by __ them |
|
|
Term
valves
dilates
constricts
arrector pili |
|
Definition
| smooth muscle also forms __ to regulate the passage of substances through internal body openings, __ and __ the pupils of your eyes, and forms the __ muscles attached to hair follicles |
|
|
Term
|
Definition
| each __ is a discrete organ, made up of several kinds of tissues. skeletal muscle fibers predominate, but blood vessels, nerve fibers, and substantial amounts of connective tissue are also present |
|
|
Term
| one artery, one nerve, and one or more veins |
|
Definition
| Each muscle is served by __ |
|
|
Term
|
Definition
| cardiac and smooth muscle tissues can contract in the absence of __ |
|
|
Term
|
Definition
| each skeletal muscle fiber is supplied with a __ that controls its activity |
|
|
Term
|
Definition
| skeletal muscle has a rich __ supply |
|
|
Term
|
Definition
| contracting muscle fibers use huge amounts of energy and require more or less continuous delivery of __ and __ via the arteries |
|
|
Term
|
Definition
| muscle cells also give off large amounts of metabolic wastes that must be removed through __ if contraction is to remain efficient |
|
|
Term
|
Definition
| __, the smallest of the body's blood vessels, are long and winding and have numerous cross-links, features that accommodate changes in muscle length |
|
|
Term
|
Definition
| muscle capillaries __ when the muscle is stretched and __ when the muscle contracts |
|
|
Term
| connective tissue sheaths |
|
Definition
| in an intact muscle, the individual muscle fibers are wrapped and held together by several different __ |
|
|
Term
|
Definition
| together these connective tissue sheaths support each cell and reinforce the muscle as a whole, preventing the bulging muscles from __ during exceptionally strong contractions |
|
|
Term
1. epimysium
2. perimysium and fascicles
3. endomysium |
|
Definition
| what are the three types of connective tissue sheaths of skeletal muscle? |
|
|
Term
|
Definition
| an "overcoat" of dense irregular connective tissue that surrounds the whole muscle |
|
|
Term
|
Definition
| sometimes the __ blends with the deep fascia that lies between neighboring muscles or the superficial fascia deep to the skin |
|
|
Term
|
Definition
| within each skeletal muscle, the muscle fibers are grouped into __ that resemble bundles of sticks |
|
|
Term
|
Definition
| surrounding each fascicle is a layer of fibrous connective tissue called __ |
|
|
Term
|
Definition
| the __ is a whispy sheath of connective tissue that surrounds each individual muscle fiber. it consists of fine areolar connective tissue |
|
|
Term
|
Definition
| connective tissue sheath of skeletal muscle that is dense regular connective tissue, surrounding the entire muscle |
|
|
Term
|
Definition
| connective tissue sheath of skeletal muscle that is fibrous connective tissue, surrounding the fascicles (groups of muscle fibers) |
|
|
Term
|
Definition
| connective tissue sheath of skeletal muscle that is fine areolar connective tissue, surrounding each muscle fiber |
|
|
Term
|
Definition
| the epimysium, perimysium and fascicles, and endomysium connective tissue sheaths are __ with one another as well as with the tendons that join muscles to bones |
|
|
Term
|
Definition
| when muscle fibers contract, they pull on the connective tissue sheaths, which in turn transmit the pulling force to the __ to be moved |
|
|
Term
muscle tissue
blood vessels
nerve fibers |
|
Definition
| the connective tissue sheaths contribute somewhat to the natural elasticity of __, and also provide entry and exit routes for the __ and __ that serve the muscle |
|
|
Term
|
Definition
| most skeletal muscles span joints and are attached to bones (or other structures) in at least two places, and that when a muscle contracts, the movable bone, the muscle's __, moves toward the immovable or less movable bone, the muscle's __ |
|
|
Term
|
Definition
| in the muscles of the limbs, the origin typically lies __ to the insertion |
|
|
Term
|
Definition
| muscle attachments, whether origin or insertion, may be __ or __ |
|
|
Term
|
Definition
| in __ muscle attachments, the epimysium of the muscle is fused to the periosteum of a bone or perichondrium of a cartilage |
|
|
Term
|
Definition
| in __ muscle attachments, the muscle's connective tissue wrappings extend beyond the muscle either as a ropelike tendon or as a sheetlike aponeurosis |
|
|
Term
|
Definition
| in indirect muscle attachments, the tendon or aponeurosis anchors the muscle to the __ covering of a skeletal element (bone or cartilage) or to the __ of other muscles |
|
|
Term
|
Definition
| __ attachments are much more common because of their durability and small size |
|
|
Term
|
Definition
| __ are mostly tough collagen fibers which can withstand the abrasion of rough bony projections that would tear apart the more delicate muscle tissues |
|
|
Term
|
Definition
| a __ consists of hundreds to thousands of muscle cells, plus connective tissue wrappings, blood vessels, and nerve fibers. it is covered externally by the epimysium |
|
|
Term
|
Definition
| a __ is a discrete bundle of muscle cells, segregated from the rest of the muscle by a connective tissue sheath. is is surrounded by a perimysium |
|
|
Term
|
Definition
| a __ is an elongated multinucleate cell; it has a banded (striated) appearance. it is surrounded by endomysium |
|
|
Term
|
Definition
| each skeletal muscle fiber is a long cylindrical cell with multiple oval nuclei just beneath its __ or plasma membrane. skeletal muscle fibers are huge cells. |
|
|
Term
|
Definition
| the skeletal muscle fiber's diameter typically ranges from __ to __ and their length is up to __ long |
|
|
Term
|
Definition
| __ is the cytoplasm of a muscle cell |
|
|
Term
|
Definition
| sarcoplasm, the cytoplasm of a muscle cell contains unusually large amounts of __ and __ |
|
|
Term
|
Definition
| granules of stored glycogen that provide glucose during periods of muscle cell activity |
|
|
Term
|
Definition
| a red pigment that stores oxygen |
|
|
Term
| myofibrils, the sarcoplasmic reticulum, and T tubules |
|
Definition
| what organelles are highly modified in muscle fibers? |
|
|
Term
|
Definition
| skeletal muscle fibers have multiple peripheral __ and many __ |
|
|
Term
|
Definition
| each muscle fiber contains many rodlike myofibrils that run __ to its length |
|
|
Term
|
Definition
| the myofibrils, each __ in diameter, are so densely packed in the fiber that mitochondria and other organelles appear to be squeezed between them |
|
|
Term
|
Definition
| hundreds to thousands of myofibrils are in a single muscle fiber, depending on its size, and they account for about __ of cellular volume |
|
|
Term
|
Definition
| __ is a complex organelle composed of bundles of myofilaments |
|
|
Term
|
Definition
| __ are rodlike contractile elements that occupy most of the muscle cell volume. composed of sarcomeres arranged end to end, they appear banded |
|
|
Term
|
Definition
| bands of adjacent myofibrils are __ |
|
|
Term
|
Definition
| myofibrils contain the contractile elements of skeletal muscle cells, the __ |
|
|
Term
|
Definition
| the sacromeres contain even smaller rodlike structures called __ |
|
|
Term
|
Definition
| a __ is a segment of a myofibril |
|
|
Term
|
Definition
| a __ is the contractile unit, composed of myofilaments made up of contractile proteins |
|
|
Term
dark A bands
light I bands |
|
Definition
| myofibrils exhibit striations ; perfectly aligned repeating series of __ and __ |
|
|
Term
|
Definition
| what are the two types of contractile myofilaments? |
|
|
Term
thick myofilaments
thin myofilaments |
|
Definition
| the __ contain bundled myosin molecules; the __ contain actin molecules (plus other proteins) |
|
|
Term
|
Definition
| the sliding of the thin myofilaments past the thick myofilaments produces __ |
|
|
Term
|
Definition
| __ filaments maintain the organization of the A band and provide for elastic recoil when muscle contraction ends |
|
|
Term
|
Definition
| __, a repeating series of dark and light bands, are evident along the length of each myofibril |
|
|
Term
|
Definition
| in an intact muscle fiber, the dark __ and light __ are nearly perfectly aligned with one another, giving the cell as a whole its striated appearance |
|
|
Term
|
Definition
| a dark A band has a lighter region in its midsection called the __, where filaments do not overlap |
|
|
Term
|
Definition
| each H zone is bisected vertically by a dark line called the __ formed by molecules of the protein myomesin |
|
|
Term
|
Definition
| the light I bands also have a midline interruption, a darker area called the __ |
|
|
Term
|
Definition
| a __ is the smallest contractile unit of a muscle fiber - the functional unit of skeletal muscle |
|
|
Term
|
Definition
| the sarcomere averages __ long |
|
|
Term
|
Definition
| a __ is the region of a myofibril between two successive Z discs |
|
|
Term
|
Definition
| a sarcomere contains an __ flanked by half an __ at each end |
|
|
Term
| end-to-end (like boxcars in a train) |
|
Definition
| within each myofibril, the sarcomeres are aligned __ |
|
|
Term
|
Definition
| __ are composed of thick and thin myofilaments made of contractile proteins |
|
|
Term
|
Definition
| if we examine the banding pattern of a myofibril at the molecular level, we see that it arises from an orderly arrangement of two types of even smaller structures, the __ or __, within the sarcomeres |
|
|
Term
|
Definition
| proteins __ and __ play a role in motility and shape changes in virtually every cell in the body |
|
|
Term
|
Definition
| the central __ containing myosin extend the entire length of the A band |
|
|
Term
|
Definition
| the more lateral __ containing actin extend across the I band and partway into the A band |
|
|
Term
|
Definition
| the __, a coin-shaped sheet composed largely of the protein alpha-actinin, anchors the thin filaments and connects myofibrils to one another |
|
|
Term
|
Definition
| __ extending from the Z disc connect each myofibril to the next throughout the width of the muscle cell |
|
|
Term
|
Definition
| the H zone of the A band appears less dense because the __ do not extend into this region |
|
|
Term
|
Definition
| the M line in the center of the H zone is slightly darker because of the presence there of fine protein strands that hold adjacent __ together |
|
|
Term
|
Definition
| the myofilaments are connected to the sarcolemma and held in register at the __ and the __ |
|
|
Term
thin filaments
thick filaments |
|
Definition
| in the outer edge of the A band, each thick filament is actually surrounded by a hexagonal arrangement of six __, and each thin filament is enclosed by three __ |
|
|
Term
|
Definition
| __ depends on the myosin- and actin-containing myofilaments |
|
|
Term
|
Definition
| __ = line of protein myomesin that holds adjacent thick filaments together |
|
|
Term
|
Definition
| thick filaments are composed primarily of the protein __ |
|
|
Term
|
Definition
| each __ molecule consists of two heavy and four light polypeptide chains, and has a rodlike tail attached by a flexible hinge to two globular heads |
|
|
Term
|
Definition
| the myosin molecules tail consists of two intertwined helical __ |
|
|
Term
|
Definition
| the globular heads of a myosin molecule are each associated with two __ and are the 'business end' of myosin |
|
|
Term
|
Definition
| the 2 light polypeptide chains in a myosin molecules head link the thick and thin filaments together, forming __, and swivel around their point of attachment during contraction |
|
|
Term
|
Definition
| the cross bridges formed during contraction in a myosin molecules head act as motors to generate the __ developed by a contracting muscle cell |
|
|
Term
|
Definition
| each thick filament contains about __ myosin molecules bundled together with their __ forming the central part of the thick filament and their __ facing outward and at each end |
|
|
Term
|
Definition
| a myosin molecules head contains binding sites for __ of thin filaments and binding sites for __ |
|
|
Term
|
Definition
| a myosin molecules head contains __ enzymes that split ATP to generate energy for muscle contraction |
|
|
Term
|
Definition
| because of the structure of how myosin molecules make thick filaments, the central portion of a thick filament (in the H zone) is __, but its ends are __ with a staggered array of myosin heads |
|
|
Term
|
Definition
| the thin filaments are composed chiefly of the protein __ |
|
|
Term
|
Definition
| actin has kidney-shaped polypeptide subunits called __ or __, which bear the active sites to which the myosin heads attach during contraction |
|
|
Term
|
Definition
| in the thin filaments, G actin subunits are polymerized into long actin filaments called __ or __ |
|
|
Term
|
Definition
| the backbone of each thin filament appears to be formed by two intertwined __ |
|
|
Term
|
Definition
| the ultrastructure of thin filament is a twisted double strand of fibrous protein __ |
|
|
Term
|
Definition
| several regulatory proteins are also present in thin filaments, like __ and __ |
|
|
Term
|
Definition
| polypeptide strands of __, a rodshaped protein, spiral about the actin core and help stiffen and stabilize it. |
|
|
Term
|
Definition
| successive tropomyosin molecules are arranged end-to-end along the actin filaments, and in a __ muscle fiber, tropomyosin molecules block myosin-binding sites on actin so that they myosin heads on the thick filaments cannot bind to the thin filaments |
|
|
Term
|
Definition
| the other major protein in thin filaments is __, a globular three-polypeptide complex. |
|
|
Term
|
Definition
| one of troponin's polypeptides __ is an inhibitory subunit that binds to actin |
|
|
Term
|
Definition
| one of troponin's polypeptides __ binds to tropomyosin and helps position it on actin |
|
|
Term
|
Definition
| one of troponin's polypeptides __ binds calcium ions |
|
|
Term
|
Definition
| both __ and __ help control the myosin-actin interactions involved in contraction |
|
|
Term
|
Definition
| in the center of the sarcomere, the thick filaments lack myosin __. |
|
|
Term
|
Definition
| myosin heads are present only in areas of __ overlap |
|
|
Term
|
Definition
| each __ consists of many myosin molecules whose heads protrude at opposite ends of the filament |
|
|
Term
|
Definition
| a __ consists of two strands of actin subunits twisted into a helix plus two types of regulatory proteins (troponin and tropomyosin) |
|
|
Term
|
Definition
| the elastic filament is composed of the giant protein __, which extends from the Z disc to the thick filament, and then runs within the thick filament (forming its core) to attach to the M line |
|
|
Term
| elastic filament (made of protien titin) |
|
Definition
| the __ holds the thick filaments in place, thus maintaining the organization of the A band, and helps the muscle cell to spring back into shape after being stretched |
|
|
Term
|
Definition
| __ does not resist stretching in the ordinary range of extension, but it stiffens as it uncoils, helping the muscle to resist excessive stretching, which might pull the sarcomeres apart |
|
|
Term
|
Definition
| another important structural protein is __, which links the thin filaments to the integral proteins of the sarcolemma |
|
|
Term
nebulin
myomesin
C proteins |
|
Definition
| other proteins that act to bind filaments or sarcomeres together and maintain their alignment include __, __, and __ |
|
|
Term
the sarcoplasmic reticulum
T tubules |
|
Definition
| skeletal muscle fibers contain two sets of intracellular tubules that participate in regulation of muscle contration: 1. __ and 2.__ |
|
|
Term
| sarcoplasmic reticulum (SR) |
|
Definition
| an elaborate smooth endoplasmic reticulum. its interconnecting tubules surround each myofibril |
|
|
Term
|
Definition
| most of the tubules of the sarcoplasmic reticulum (SR) run longitudinally along the myofibril communicating at the __ |
|
|
Term
|
Definition
| other tubules of the sarcoplasmic reticulum (SR) called __ form larger, perpendicular cross channels at the A band - I band junctions and they always occur in pairs |
|
|
Term
mitochondria
glycogen granules |
|
Definition
| closely associated with the sarcoplasmic reticulum (SR) are large numbers of __ and __, both involved in producing the energy used during contraction |
|
|
Term
|
Definition
| the major role of the sarcoplasmic reticulum (SR) is to regulate intracellular levels of __ |
|
|
Term
|
Definition
| the sarcoplasmic reticulum (SR) stores calcium and releases it on demand when the muscle fiber is stimulated to __ |
|
|
Term
|
Definition
| __ provide the final "go" signal for contraction |
|
|
Term
|
Definition
| at each A band - I band junction, the sarcolemma of the muscle cell protrudes deep into the cell interior, forming an elongated tube called the __ |
|
|
Term
|
Definition
| the __ tremendously increase the muscle fiber's surface area |
|
|
Term
|
Definition
| T tubules are continuous with the __ |
|
|
Term
|
Definition
| along its length, each T tubule runs between the paired terminal cisternae of the sarcoplasmic reticulum (SR), forming __, successive groupings of the three membranous structures (terminal cisterna, T tubule, and terminal cisterna). |
|
|
Term
|
Definition
| as they pass from one myofibril to the next, the T tubules also encircle each __ |
|
|
Term
|
Definition
| T tubules associate with the paired terminal cisternae to form triads that encircle each __ |
|
|
Term
|
Definition
| muscle contraction is ultimately controlled by nerve-initiated electrical impulses that travel along the sarcolemma. because the __ are continuous of the sarcolemma, they conduct impulses to the deepest regions of the muscle cell and to every sarcomere. these impulses signal for the release of calcium from the adjacent terminal cisternae |
|
|
Term
|
Definition
| __ ensure that every myofibril in the muscle fiber contracts at virtually the same time |
|
|
Term
|
Definition
| __ conduct impulses deep into muscle fiber |
|
|
Term
voltage sensors
foot proteins |
|
Definition
| Integral proteins protrude into the intermembrane space from T tubule and SR cisternae membranes. the protruding integral proteins of the T tubule act as __. Those of the SR, called __, form gated channels through which Ca^2+ can be released from the SR cisternae |
|
|
Term
|
Definition
| the activation of myosin's cross bridges, which are the force-generating sites (generation of force) |
|
|
Term
|
Definition
| __ does not necessarily cause shortening of the fiber |
|
|
Term
|
Definition
| __ occurs if and when the tension generated by the cross bridges on the thin filaments exceeds the forces opposing shortening and pulls the thin filaments toward the M line |
|
|
Term
|
Definition
| __ ends when the cross bridges become inactive and the tension declines, inducing relaxation of the muscle fiber |
|
|
Term
| sliding filament model of contraction |
|
Definition
| the __ states that during contraction the thin filaments slide past the thick filaments so that the actin and myosin filaments overlap to a greater degree |
|
|
Term
|
Definition
| in a __ muscle fiber, the thick and thin filaments overlap only slightly at the ends of the A band |
|
|
Term
|
Definition
| when muscle fibers are stimulated by the nervous system, the myosin heads on the thick filaments latch onto myosin-binding sites on actin in the __, and the sliding begins |
|
|
Term
|
Definition
| During contraction, myosin heads bind to actin, detach, and bind again, to propel the thin filaments toward the __ |
|
|
Term
|
Definition
| as a muscle cell shortens, the I bands shorten, the distance between successive Z discs is reduced, the H zones disappear, and the contiguous A bands move closer together but do not change in __ |
|
|
Term
|
Definition
| As H zones shorten and disappear, sarcomeres shorten, muscle cells shorten, and the whole muscle __ |
|
|
Term
1. it must be activated
2. it must have an action potential
3. it must have a rise in intracellular calcium ion levels |
|
Definition
| what are the requirements for a skeletal muscle fiber to contract? |
|
|
Term
|
Definition
| the first thing for a skeletal muscle fiber to contract is that it must be __, that is, stimulated by a nerve ending so that a change in membrane potential occurs |
|
|
Term
|
Definition
| the second thing for a skeletal muscle fiber to contract is that it must generate and propagate an electrical current, called an __, along its sarcolemma |
|
|
Term
|
Definition
| the third thing for a skeletal muscle fiber to contract is that there must be a short-lived rise in intracellular __ levels, which is the final trigger for contraction to occur |
|
|
Term
|
Definition
| step 1 for a skeletal muscle fiber to contract, the activation step, occurs at the __ and sets the stage for the events that follow |
|
|
Term
| excitation-contraction coupling |
|
Definition
| steps two and three for a skeletal muscle fiber to contract, which link the electrical signal to contraction are called __ |
|
|
Term
| somatic motor neurons or motor neurons OR the somatic (voluntary) nervous system |
|
Definition
| the nerve cells that activate skeletal muscle fibers are called __ |
|
|
Term
|
Definition
| somatic motor neurons "reside" in the __ |
|
|
Term
|
Definition
| the somatic motor neurons have long threadlike extensions called __ that travel from the central nervous system via nerves to skeletal muscles |
|
|
Term
|
Definition
| each axons forms several branches as it enters a __ |
|
|
Term
|
Definition
| each axons ending gives off several short, curling branches that collectively form an elliptical __ with a single muscle fiber |
|
|
Term
|
Definition
| as a rule, each muscle fiber has only one neuromuscular junction, located approximately __ along its length |
|
|
Term
|
Definition
| the axon terminal and the muscle fiber are exceedingly close, but they remain separated by a space, the __, which is filled with a gel-like extracellular substance rich in glycoproteins and collagen fibers |
|
|
Term
|
Definition
| within the moundlike axon terminal are __, small membranous sacs containing the neurotransmitter acetylcholine or ACh |
|
|
Term
|
Definition
| the trough-like part of the muscle fiber's sarcolemma that helps form the neuromuscular junction is highly folded. these junctional folds provide a large surface area for the millions of __ located there |
|
|
Term
axonal endings
synaptic cleft
junctional folds of the sarcolemma |
|
Definition
| what all does the neuromuscular junction include? |
|
|
Term
| when a nerve impulse reaches the end of an axon, the axon terminal releases ACh into the synaptic cleft. ACh diffuses across the cleft and attaches the ACh receptors on the sarcolemma of the muscle fiber, which triggers electrical events that ultimately cause action potential generation |
|
Definition
| how does a motor neuron stimulate a skeletal muscle fiber? |
|
|
Term
|
Definition
| after ACh binds to the ACh receptors, its effects are quickly terminated by its enzymatic breakdown to its building blocks, __ and __ |
|
|
Term
|
Definition
| what enzyme breaks down ACh into acetic acid and choline after it binds to the ACh receptors? |
|
|
Term
|
Definition
| an enzyme located in the synaptic cleft |
|
|
Term
|
Definition
| when the enzyme acetylcholinesterase breaks down ACh, the removal of ACh prevents continued (and most likely undesirable) __ in the absence of additional nervous system stimulation |
|
|
Term
|
Definition
| Electrical events lead to the generation of an __ |
|
|
Term
|
Definition
| a disease characterized by drooping upper eyelids, difficulty swallowing and talking, and generalized muscle weakness, involves a shortage of ACh receptors |
|
|
Term
|
Definition
| like the plasma membranes of all cells, a resting sacrolemma is __. that is, a voltmeter would show there is a potential difference (voltage) across the membrane and the inside is negative relative to the outer membrane face |
|
|
Term
|
Definition
| the __ is the result of a predictable sequence of electrical charges that once initiated occurs along the entire surface of the sarcolemma |
|
|
Term
1. local depolarization and generation of an end plate potential
2. generation and propagation of the action potential
3. repolarization |
|
Definition
| what are the three steps in generation of an action potential? |
|
|
Term
Na+ and K+
(step 1 of generation of an action potential - local depolarization and generation of an end plate potential) |
|
Definition
| in step 1 in generation of an action potential, binding of ACh molecules to ACh receptors at the neuromuscular junction opens chemically (ligand) gated ion channels that allow __ and __ to pass |
|
|
Term
depolarization
(step 1 of generation of an action potential - local depolarization and generation of an end plate potential) |
|
Definition
| because more Na+ diffuses in that K+ diffuses out, a transient charge in membrane potential occurs as the interior of the sarcolemma become slightly less negative, an event called __ |
|
|
Term
end plate potential
(step 2 in generation of an action potential - generation and propagation of the action potential) |
|
Definition
| in step 2 of generation of an actoin potential, inital depolarization is a local electrical event called an __, but it ignites the action potential that spreads in all directions from the neuromuscular junction across the sarcolemma |
|
|
Term
sodium channels
(step 2 in generation of an action potential - generation and propagation of the action potential) |
|
Definition
| after the action potential spreads in all directions, local depolarization (end plate potential) then spreads to adjacent membrane areas and opens voltage-gated __ there |
|
|
Term
threshold
(step 2 in generation of an action potential - generation and propagation of the action potential) |
|
Definition
| after local depolarization spreads to adjacent membrane areas and opens voltage-gated sodium channels, Na+ enters, following its electrochemical gradient, and once a certain membrane voltage, referred to as __, is reached, action potential is generated (initiated). |
|
|
Term
propagated
(step 2 in generation of an action potential - generation and propagation of the action potential) |
|
Definition
| after an action potential is initiated, the action potential is __ (moved along the length of the sarcolemma) as the local depolarization wave spreads to adjacent areas of the sarcolemma and opens voltage-gated sodium channels there. Again, Na+ diffuses into the cell following its electrochemical gradient. |
|
|
Term
repolarization
(step 3 in generation of an action potential - repolarization) |
|
Definition
| in step three of generation of an action potential the sarcolemma is restored to its inital polarized state during __ |
|
|
Term
permeability
(step 3 in generation of an action potential - repolarization) |
|
Definition
| the repolarization wave, like the depolarization wave, is a consequence of changes in membrane __ |
|
|
Term
close
open
(step 3 in generation of an action potential - repolarization) |
|
Definition
| in repolarization of the sarcolemma in step 3 of generation of an action potential, Na+ channels __ and voltage-gated K+ channels __ |
|
|
Term
negatively
(step 3 in generation of an action potential - repolarization) |
|
Definition
| since the potassium ion concentration is substantially higher inside the cell than in the extracellular fluid in repolarization of the sarcolemma in step 3 of generation of an action potential, K+ diffuses rapidly out of the muscle fiber, restoring __ charge conditions inside |
|
|
Term
| Step 1 - Local depolarization and generation of an end plate potential |
|
Definition
-ACh binding opens chemically (ligand) gated ion channels
-Simultaneous diffusion of Na+ (inward) and K+ (outward)
-More Na+ diffuses, so the interior of the sarcolemma becomes less negative
-Local depolarization – end plate potential
at what step in generation of an action potential does this occur? |
|
|
Term
| step 2 - generation and propagation of the action potential |
|
Definition
-End plate potential spreads to adjacent membrane areas
-Voltage-gated Na+ channels open
-Na+ influx decreases the membrane voltage toward a critical threshold
-If threshold is reached, an action potential is generated
-Local depolarization wave continues to spread, changing the permeability of the sarcolemma
-Voltage-regulated Na+ channels open in the adjacent patch, causing it to depolarize to threshold
at what step in generation of an action potential does this occur? |
|
|
Term
|
Definition
-Na+ channels close and voltage-gated K+ channels open
-K+ efflux rapidly restores the resting polarity
-Fiber cannot be stimulated and is in a refractory period until repolarization is complete
-Ionic conditions of the resting state are restored by the Na+-K+ pump
at what step in generation of an action potential does this occur? |
|
|
Term
|
Definition
| during repolarization, a muscle fiber is said to be in a __ because the cell cannot be stimulated again until repolarization is complete |
|
|
Term
|
Definition
| repolarization restores only the __ of the resting (polarized) state. |
|
|
Term
|
Definition
| the ATP-dependent Na+ - K+ pump restores the __ of the resting state, but hundreds of action potentials can occur before ionic imbalances interfere with contractile activity |
|
|
Term
|
Definition
| once initiated, the action potential is __, and it ultimately results in contraction of the muscle fiber |
|
|
Term
|
Definition
| although the action potential itself is very brief, only 1-2 milliseconds (ms), the contraction phase of a muscle fiber may persist for 100 ms or more and far outlasts the __ event that triggers it |
|
|
Term
| excitation-contraction (E-C) coupling |
|
Definition
| __ is the sequencing of events by which transmission of an action potential along the sarcolemma leads to the sliding of myofilaments |
|
|
Term
|
Definition
| the events of excitation-contraction coupling occur during the __, between action potential initiation and the beginning of mechanical activity (contraction). |
|
|
Term
|
Definition
| the electrical signal does not act directly on the myofilaments, but instead causes the rise in intracellular __ ion concentration that allows the filaments to slide |
|
|
Term
|
Definition
| action potential is propagated along sarcomere to __ |
|
|
Term
|
Definition
| voltage-sensitive proteins stimulate __ release from sarcoplasmic reticulum which is necessary for contraction |
|
|
Term
1. process initiated when the nerve impulse reaches the neuron terminal and open voltage-gated calcium channels in the axonal membrane. calcium entry triggers release of ACh into the synaptic cleft.
2. release ACh binds to ACh receptors in the sarcolemma, opening chemically gated Na+ - K+ channels. greater influx of Na+ causes a local voltage change (the end plate potential)
3. local depolarization opens voltage-gated sodium channels in the neighboring region of the sarcolemma. this allows more sodium to enter, which further depolarizes the sarcolemma, resulting in action potential generation and propagation.
4. transmission of an action potential along the T tubules changes the shape of voltage-sensative proteins in the T tubules, which in turn stimulate sarcoplasmic reticulum calcium release channels to release Ca^2+ into the cytosol |
|
Definition
| in summary, the process in initiating muscle contraction involves activation of what four sets of ion channels? |
|
|
Term
1. action potential is propagated along the sarcolemma and down the T tubules
2. calcium ions are released
3. calcium binds to troponin and removes the blocking action of tropomyosin
4. contraction begins |
|
Definition
| what are the steps in excitation-contraction coupling? |
|
|
Term
|
Definition
| cross bridge formation, (attachment of myosin heads to actin) requires __ |
|
|
Term
|
Definition
| when intracellular calcium levels are __, the muscle cell is relaxed, and the active (myosin-blocking) sites on actin are physically blocked by tropomyosin molecules so myosin heads cannot attach to actin |
|
|
Term
|
Definition
| as intracellular levels of Ca2+ rise, the ions bind to regulatory sites on __ |
|
|
Term
calcium ions
shape
tropomyosin |
|
Definition
| to activate its group of seven actins, a troponin must bind two __, change __, and then roll __ into the groove of the actin helix, away from the myosin-binding sites |
|
|
Term
|
Definition
| the tropomyosin "blockade" is removed when sufficient __ is present |
|
|
Term
|
Definition
| once binding sites on __ are exposed, the events of the cross bridge cycle occur in rapid succession |
|
|
Term
calcium signal
adequate ATP |
|
Definition
| sliding of thin filaments continues as long as the __ and __ are present |
|
|
Term
|
Definition
| at __ intracellular Ca2+ concentrations, Ca2+ binds to troponin, troponin changes shape and moves tropomyosin away from active sites, and events of the cross bridge cycle occur |
|
|
Term
sarcoplasmic reticulum
shape
contraction |
|
Definition
| when nervous stimulation ceases, Ca2+ is pumped back into the __, troponin again changes __, actin's myosin-binding sites are again covered by tropomyosin, and the __ ends and the muscle fibers relax |
|
|
Term
|
Definition
| when the cross bridge cycle is back where it started, the myosin head is in its upright high-energy configuration, ready to take another "step" and attach to an actin site farther along the __ |
|
|
Term
|
Definition
| thin filaments cannot slide backward as the cross bridge cycle repeats again and again because some __ are always in contact with actin |
|
|
Term
|
Definition
| contracting muscles shorten by 30-35% of their total resting length, so each myosin cross bridge attaches and detaches __ during a single contraction |
|
|
Term
|
Definition
| except for the brief period following muscle cell excitation, calcium ion concentrations in the cytosol are kept almost __ |
|
|
Term
| because ATP is the cell's energy souce, and its hydrolysis yields inorganic phosphate. this inorganic phosphate would combine with calcium ions to form hydroxyapatite crystals, the stony-hard salts found in bone matrix, is calcium ion concentrations were always high. such calcified muscle cells would die |
|
Definition
| why are calcium ion concentration kep low except for the brief period following muscle cell excitation? |
|
|
Term
|
Definition
| __ - high-energy myosin head attaches to thin filament |
|
|
Term
|
Definition
| __ - myosin head pivots and pulls thin filament toward M line |
|
|
Term
|
Definition
| __ - ATP attaches to myosin head and the cross bridge detaches |
|
|
Term
| “Cocking” of the myosin head |
|
Definition
| __ - energy from hydrolysis of ATP cocks the myosin head into the high-energy state |
|
|
Term
|
Definition
| the principles governing contraction of a single muscle fiber and of a skeletal muscle consisting of a large number of fibers are __ |
|
|
Term
| Same principles apply to contraction of a single fiber and a whole muscle |
|
Definition
| __ principles apply to contraction of a single fiber and a whole muscle |
|
|
Term
|
Definition
| the force exerted by a contracting muscle on an object is called __ |
|
|
Term
|
Definition
| the opposing force exerted on the muscle by the weight of the object to be moved is called the __ |
|
|
Term
|
Definition
| Contraction produces __, the force exerted on the load or object to be moved |
|
|
Term
|
Definition
| a contracting muscle does not always __ and __ the load |
|
|
Term
|
Definition
| if muscle tension develops but the load is not moved, the contraction is called __ |
|
|
Term
|
Definition
| if the muscle tension developed overcomes the load and muscle shortening occurs, the contraction is __ |
|
|
Term
| increasing muscle tension |
|
Definition
| __ is measured for isometric contractions |
|
|
Term
| amount of muscle shortening (distance in millimeters) |
|
Definition
| __ is measured for isotonic contractions |
|
|
Term
|
Definition
| __: no shortening; muscle tension increases but does not exceed the load |
|
|
Term
|
Definition
| __: muscle shortens because muscle tension exceeds the load |
|
|
Term
|
Definition
| a skeletal muscle contracts with varying __ and for different periods of __ in response to stimuli of varying frequencies and intensities. |
|
|
Term
|
Definition
| Force and duration of contraction vary in response to stimuli of different __ and __ |
|
|
Term
|
Definition
| each muscle is served by at least one __ and each of these contains axons (fibrous extensions) of up to hundreds of motor neurons |
|
|
Term
|
Definition
| a __ consists of a motor neuron and all (four to several hundred) the muscle fibers it supplies |
|
|
Term
|
Definition
| when a motor neuron fires (transmits an action potential), all the muscle fibers it innervates __ |
|
|
Term
|
Definition
| muscles that exert fine control (such as those controlling the fingers and eyes) have __ motor units |
|
|
Term
|
Definition
| large, weight-bearing muscles, whose movements are less precise (such as hip muscles), have __ motor units |
|
|
Term
|
Definition
| the muscle fibers in a single motor unit are not __ but are __ throughout the muscle |
|
|
Term
|
Definition
| stimulation of a single motor unit causes a weak contraction of the __ muscle |
|
|
Term
|
Definition
| motor units in a muscle usually contract __ which helps to prevent fatigue |
|
|
Term
|
Definition
| in investigating muscle contraction in the lab the muscle is attached to an apparatus that produces a __, a graphic recording of contractile activity. the line recording the activity is called a __ |
|
|
Term
|
Definition
| the response of a motor unit to a single action potential of its motor neuron is called a __. the muscle fibers contract quickly and then relax |
|
|
Term
1. latent period
2. period of contraction
3. period of relaxation |
|
Definition
| every twitch myogram has three distinct phases, what are they? |
|
|
Term
latent period
(first phase in twitch myogram) |
|
Definition
| the __ is the first few milliseconds following stimulation when excitation-contraction coupling is ocurring. during this period, muscle tension is beginning to increase but no response is seen on the myogram |
|
|
Term
period of contraction
(2nd phase of twitch myogram) |
|
Definition
| the __ is when cross bridges are active, from the onset to the peak of tension development, and the myogram tracing rises to a peak. this period lasts 10-100ms. if the tension (pull) become great enough to overcome the resistance of a load, the muscle shortens. |
|
|
Term
period of relaxation
(3rd phase of twitch myogram) |
|
Definition
| the period of contraction is followed by the __. this final phase, lasting 10-100ms, is initiated by reentry of Ca2+ into the sarcoplasmic reticulum. because contractile force is declining, muscle tension decreases to zero and the tracing returns to the baseline. if the muscle shortened during contraction, it now returns to its initial length. |
|
|
Term
|
Definition
| a muscle contracts __ than it relaxes |
|
|
Term
metabolic properties
enzymes |
|
Definition
| Different strength and duration of twitches are due to variations in __ and __ between muscles |
|
|
Term
|
Definition
| healthy muscle contractions are relatively __ and vary in strength as different demands are placed on them |
|
|
Term
skeletal movement
graded muscle responses |
|
Definition
| the strength variations of muscle contractions are needed for proper control of __ and are referred to as __ |
|
|
Term
1. by changing the frequency of stimulation
2. by changing the strength of stimulation |
|
Definition
| in general, muscle contraction can be graded in what two ways? |
|
|
Term
|
Definition
| the nervous system achieves greater muscular force by __ the firing rate of motor neurons |
|
|
Term
|
Definition
| a single stimulus results in a single contractile response - a __ |
|
|
Term
|
Definition
| if two identical stimuli (electrical shocks or nerve impulses) are delivered to a muscle in rapid succession, the second twitch will be stronger than the first. on a myogram the second twitch will appear to ride on the shoulders of the first. this phenomenon, called __ or __, occurs because the second contraction occurs before the muscle has completely relaxed |
|
|
Term
unfused
incomplete tetanus |
|
Definition
| if the stimulus strength is held constant and the muscle is stimulated at an increasingly faster rate, the relaxation time between the twitches becomes shorter and shorter, the concentration of Ca2+ in the cytosol higher and higher, and the degree of wave summation greater and greater, progressing to a sustained but quivering contraction reffered to as __ or __ |
|
|
Term
|
Definition
| if stimulation continually increases, muscle tension increases until a maximal tension is reached. at this point all evidence of muscle relaxation disappears and the contractions fuse into a smooth, sustained contraction plateau called __ or __ |
|
|
Term
|
Definition
| in the real world, __ tetanus happens infrequently |
|
|
Term
|
Definition
| prolonged tetanus inevitably leads to __, a situation in which the muscle is unable to contract and its tension drops to zero |
|
|
Term
recruitment
multiple motor unit summation |
|
Definition
| the force of contraction is controlled more precisely by __, also called __, which brings more and more muscle fibers into action |
|
|
Term
|
Definition
| stimuli that produce no observable contractions are called __ |
|
|
Term
|
Definition
| the stimulus at which the first observable contraction occurs is called the __ |
|
|
Term
|
Definition
| the __ is the strongest stimulus that produces increased contractile force. it represents the point at which all the muscle's motor units are recruited |
|
|
Term
|
Definition
| the recruitment process is not random. instead it is dictated by the __. in any muscle, motor units with the smallest muscle fibers are controlled by small, highly excitable motor neurons, and these motor units tend to be activated first. as motor units with larger and larger muscle fibers begin to be excited, contractile strength increases |
|
|
Term
|
Definition
| although all the motor units of a muscle may be recruited simultaneously to produce an exceptionally strong contraction, motor units are more commonly activated __ in the body |
|
|
Term
|
Definition
| skeletal muscles are described as voluntary, but even relaxed muscles are almost always slightly contracted, a phenomenon called __ |
|
|
Term
|
Definition
| __ is due to spinal reflexes that activate first one group of motor units and then another in response to activation of stretch receptors in the muscles |
|
|
Term
|
Definition
| muscle tone does not produce __ movements |
|
|
Term
firm
healthy
ready to respond |
|
Definition
| muscle tone keeps the muscles __, __, and __ to stimulation |
|
|
Term
|
Definition
| skeletal muscle tone also helps stabilize __ and maintain __ |
|
|
Term
|
Definition
| In __, muscle length changes and moves the load |
|
|
Term
|
Definition
| what are the two types of isotonic contractions? |
|
|
Term
|
Definition
| __ are an isotonic contractions in which the muscle shortens and does work |
|
|
Term
|
Definition
| __ are isotonic contractions in which the muscle generates force as it lengthens |
|
|
Term
|
Definition
| eccentric contractions are about __ more forceful than concentric ones at the same load and more often cause delayed-onset muscle soreness |
|
|
Term
|
Definition
| eccentric contractions put the body in position to contract __ |
|
|
Term
|
Definition
| all __ and __ activities involve both concentric contractions and eccentric contractions |
|
|
Term
|
Definition
| in __ contractions, tension may build to the muscle's peak tension-producing capacity, but the muscle neither shortens nor lengthens |
|
|
Term
|
Definition
| __ contractions occur when a muscle attempts to move a load that is greater than the force (tension) the muscle is able to develop |
|
|
Term
|
Definition
| muscles contract isometrically when they act primarily to maintain upright __ or to hold __ in stationary positions while movements occur at other joints |
|
|
Term
|
Definition
| electrochemical and mechanical events occurring within a muscle are __ in both isotonic and isometric contractions |
|
|
Term
|
Definition
| in __ contractions, the thin filaments are sliding |
|
|
Term
|
Definition
| in __ contractions, the cross bridges are generating force but are not moving the thin filaments, so there is no change in the banding pattern from that of the resting state |
|
|
Term
|
Definition
| __ contraction = on stimulation, muscle develops enough tension (force) to lift the load (weight). once the resistance is overcome, the muscle shortens, and the tension remains constant for the rest of the contraction |
|
|
Term
|
Definition
| __ contraction = muscle is attached to a weight that exceeds the muscle's peak tension-developing capabilities. when stimulated, the tension increases to the muscle's peak tension-developing capability, but the muscle does not shorten |
|
|
Term
|
Definition
| __ is the only source used directly for contractile activities |
|
|
Term
| as a muscle contracts, ATP supplies the energy for cross bridge movement and detachment and for operation of the calcium pump in the sarcoplasmic reticulum |
|
Definition
| how does the body provide the energy needed for contraction? |
|
|
Term
|
Definition
| muscles store very limited reserves of ATP. they store __ worth at most, just enough to get you going |
|
|
Term
|
Definition
| because ATP is the only energy source used directly for contractile activities, it must be __ as fast as it is broken down is contraction is to continue |
|
|
Term
1. direct phosphorylation of ADP by creatine phosphate (CP)
2. the anaerobic pathway called glycolysis, which converts glucose to lactic acid
3. aerobic respiration |
|
Definition
| after ATP is hydrolyzed to ADP and inorganic phosphate in muscle fibers, it is regenerated within a fraction of a second by one or more of the three pathways for regenerating ATP during muscle activity. what are the three pathways? |
|
|
Term
glycolysis
aerobic respiration |
|
Definition
| all body cells use __ and __ to produce ATP |
|
|
Term
|
Definition
| __ - a unique high-energy molecule stored in muscles that is used to regenerate ATP while the metabolic pathways are adjusting to a sudden higher demand for ATP |
|
|
Term
|
Definition
| the result of coupling creatine phosphate (CP) with ADP is almost instant transfer of energy and a phosphate group from CP to ADP to form __ |
|
|
Term
|
Definition
| creatine phosphate (CP) + ADP yields __ with the help of the enzyme creatine kinase |
|
|
Term
|
Definition
| muscle cells store __ to __ times as much CP as ATP |
|
|
Term
|
Definition
| the CP-ADP reaction, catalyzed by the enzyme __, is so efficient that the amount of ATP in muscle cells changes very little during the initial period of contraction |
|
|
Term
|
Definition
| together, stored ATP and CP provide maximum muscle power for __ seconds - long enough to energize a 100-meter dash (slightly longer is the activity is less vigorous) |
|
|
Term
|
Definition
| the reaction of CP + ADP --> creatine + ATP is __ |
|
|
Term
|
Definition
| to keep CP readily available, CP reserves are replenished during periods of __ or __ |
|
|
Term
direct phosphorylation
aerobic respiration |
|
Definition
| the fastest pathway for regenerating ATP during muscle activity is __ and the slowest pathway is __ |
|
|
Term
| direct phosphorylation for regenerating ATP during muscle activity |
|
Definition
| __ = coupled reaction of creatine phosphate (CP) and ADP |
|
|
Term
|
Definition
| what is the energy source in direct phosphorylation for regenerating ATP during muscle activity? |
|
|
Term
|
Definition
| how much oxygen is used in direct phosphorylation for regenerating ATP during muscle activity? |
|
|
Term
| 1 ATP per creatine phosphate (CP), and creatine |
|
Definition
| what is the product of direct phosphorylation for regenerating ATP during muscle activity? |
|
|
Term
|
Definition
| what is the duration of energy provision for direct phosphorylation for regenerating ATP during muscle activity? |
|
|
Term
|
Definition
| as stored ATP and CP are exhausted, more ATP is generated by breakdown (catabolism) of __ obtained from the blood or of glycogen stored in the muscle |
|
|
Term
|
Definition
| the initial phase of glucose breakdown is __ ("sugar splitting") |
|
|
Term
|
Definition
| the anaerobic pathway: glycolysis and lactic acid formation, occurs in both the presence and the absence of __ |
|
|
Term
|
Definition
| the glycolysis and lactic acid pathway for regenerating ATP during muscle activity is an __ pathway |
|
|
Term
|
Definition
| during glycolysis, glucose is broken down to two __ molecules, releasing enough energy to form small amounts of ATP |
|
|
Term
|
Definition
| in anaerobic conditions, most of the pyruvic acid produced during glycolysis is converted into __ |
|
|
Term
|
Definition
| __ = energy-yielding conversion of glucose to lactic acid in various tissues, notably muscle, when sufficient oxygen is not available |
|
|
Term
|
Definition
| most of the lactic acid formed during anaerobic glycolysis diffuses out of the muscles into the __ and is gone from the muscle tissue within 30 minutes after exercise stops |
|
|
Term
|
Definition
| when lactic acid is in the bloodstream, the lactic acid is picked up by the __, __, or __ cells which can use it as an energy source |
|
|
Term
pyruvic acid
glucose
glycogen |
|
Definition
| liver cells can reconvert lactic acid to __ or __ and release it back into the bloodstream for muscle use, or convert it to __ for storage |
|
|
Term
|
Definition
| the anaerobic pathway harvests only about __ as much ATP from each glucose molecule as the aerobic pathway, but it produces ATP about __ times faster |
|
|
Term
|
Definition
| when large amounts of ATP are needed for moderate periods (30-40 seconds) of strenuous muscle activity, __ can provide most of the ATP needed as long as the required fuels and enzymes are available |
|
|
Term
|
Definition
| together, stored ATP and CP and the glycolysis-lactic acid pathway can support strenuous muscle activity for nearly a __ |
|
|
Term
|
Definition
| when muscles contract vigorously and contractile activity reaches about __ of the maximum possible, the bulging muscles compress the blood vessels within them, impairing blood flow and oxygen delivery |
|
|
Term
| anaerobic pathway for regenerating ATP during muscle activity |
|
Definition
| __ = glycolysis and lactic acid formation |
|
|
Term
|
Definition
| what is the energy source for the anaerobic pathway for regenerating ATP during muscle activity? |
|
|
Term
|
Definition
| how much oxygen is used in the anaerobic pathway for regenerating ATP during muscle activity? |
|
|
Term
| 2 ATP per glucose ; lactic acid |
|
Definition
| what are the products of the anaerobic pathway for regenerating ATP during muscle activity? |
|
|
Term
| 60 seconds, or slightly more |
|
Definition
| what is the duration of energy provision for the anaerobic pathway for regenerating ATP during muscle activity? |
|
|
Term
|
Definition
| during rest and light to moderate exercise, even if prolonged, __ of the ATP used for muscle activity comes from aerobic respiration |
|
|
Term
|
Definition
| __ occurs in the mitochondria, requires oxygen, and involves a sequence of chemical reactions in which the bonds of fuel molecules are broken and the energy released is used to make ATP |
|
|
Term
|
Definition
| during aerobic respiration, the pyruvic acid produced during glycolysis enters the mitochondria and reacts with oxygen to produce more __ |
|
|
Term
|
Definition
| during aerobic respiration, which includes glycolysis and the reactions that take place in the mitochondria, glucose is broken down entirely, yielding __, __, and large amounts of __ as the final products |
|
|
Term
| direct phosphorylation of ADP by Creatine Phosphate |
|
Definition
| creatine phosphate + ADP --> creatine + ATP |
|
|
Term
|
Definition
| Glucose + oxygen --> carbon dioxide + water + ATP |
|
|
Term
|
Definition
| the carbon dioxide released during aerobic respiration diffuses out of the muscle tissue into the blood and is removed from the body by the __ |
|
|
Term
glycogen
(aerobic respiration) |
|
Definition
| as exercise begins, muscle __ provides most of the fuel |
|
|
Term
glucose
pyruvic acid
free fatty acids |
|
Definition
| shortly after exercise begins, bloodborne __, __ from glycolysis, and __ are the major sources of fuels |
|
|
Term
|
Definition
| aerobic respiration provides a high yield of ATP about __ ATP per glucose, but it is __ because of its many steps and it requires continuous delivery of oxygen and nutrient fuels to keep it going |
|
|
Term
| aerobic pathway for regenerating ATP during muscle activity |
|
Definition
| __ = aerobic cellular respiration |
|
|
Term
| glucose; pyruvic acid; free fatty acids from adipose tissue; amino acids from protein catabolism |
|
Definition
| what is the energy source for the aerobic pathway for regenerating ATP during muscle activity? |
|
|
Term
|
Definition
| what is the oxygen use in the aerobic pathway for regenerating ATP during muscle activity? |
|
|
Term
| 32 ATP per glucose; CO2; H2O |
|
Definition
| what are the products of the aerobic pathway for regenerating ATP during muscle activity? |
|
|
Term
|
Definition
| what is the duration of energy provision for the aerobic pathway for regenerating ATP during muscle activity? |
|
|
Term
-ATP stored in muscles is used first
-ATP is formed from creatine phosphate and ADP
-Glycogen stored in muscles is broken down to glucose, which is oxidized to generate ATP |
|
Definition
| short duration exercise: 6 seconds = __; 10 seconds = __; 30-40 seconds & end of exercise = __ |
|
|
Term
| ATP is generated by breakdown of several nutrient energy fuels by aerobic pathway. this pathway uses oxygen released from myoglobin or delivered in the blood by hemoglobin. when it ends, the oxygen deficit is paid back |
|
Definition
| prolonged-duration exercise: hours = __ |
|
|
Term
| as long as it has enough oxygen, a muscle cell will form ATP by the aerobic pathway |
|
Definition
| which pathways predominate during exercise? |
|
|
Term
|
Definition
| when ATP demands are within the capacity of the aerobic pathway, light to moderate muscular activity can continue for several __ in well-conditioned individuals |
|
|
Term
|
Definition
| when exercise demands begin to exceed the ability of the muscle cells to carry out the necessary reactions quickly enough, __ begins to contribute more and more of the total ATP generated |
|
|
Term
|
Definition
| the length of time a muscle can continue to contract using aerobic pathways is called __ |
|
|
Term
|
Definition
| the point at which muscle metabolism converts to anaerobic glycolysis is called __ |
|
|
Term
|
Definition
| activities that require a surge of power but last only a few seconds, such as weight lifting, diving, and sprinting, rely entirely on __ |
|
|
Term
|
Definition
| the more on-and-off or burst-like activities of tennis, soccer, and a 100-meter swim appear to be fueled almost entirely by __ |
|
|
Term
|
Definition
| prolonged activities such as marathon runs and jogging, where endurance rather than power is the goal, depend mainly on __ |
|
|
Term
|
Definition
| levels of __ and __ don't change much during prolonged exercise because ATP is generated at the same rate as it is used |
|
|
Term
|
Definition
| __ is a state of physiological inability to contract even though the muscle still may be receiving stimuli |
|
|
Term
excitation-contraction coupling
neuromuscular junction |
|
Definition
| most experimental evidence indicates that fatigue is due to a problem in __ or, in rare cases, problems at the __ |
|
|
Term
|
Definition
| availability of ATP declines during contraction, but normally it is unusual for a muscle to totally run out of ATP. so ATP, is not a __ factor in moderate exercise |
|
|
Term
|
Definition
| a total lack of ATP results in __, states of continuous contraction because the cross bridges are unable to detach (not unlike what happens in rigor mortis) |
|
|
Term
|
Definition
| as action potentials are transmitted, potassium is lost from the muscle cells, and the Na+-K+ pumps are inadequate to reverse the ionic imbalances quickly, so K+ accumulates in the fluids of the T tubules. this ionic change disturbs the membrane potential of the muscle cells and halts Ca2+ release from the sarcoplasmic reticulum. this in means that the muscles cannot contract, so it causes __ |
|
|
Term
|
Definition
| in short duration exercise, an accumulation of inorganic phosphate from CP and ATP breakdown may interfere with calcium release from the sarcoplasmic reticulum or alternatively with the release of inorganic phosphate from myosin and thus hamper myosin's power strokes. both cause __, the physiological inability to contract |
|
|
Term
|
Definition
| __ seems to be more important in provoking psychological fatigue rather than physiological fatigue. it has also recently been shown to counteract high K+ levels, which do lead to muscle fatigue. |
|
|
Term
| excitation-contraction (E-C) coupling |
|
Definition
| intense exercise of short duration produces muscle fatigue rapidly via ionic imbalances (K+, Ca2+, inorganic phosphate) that interfere with __, but recovery is also rapid |
|
|
Term
|
Definition
| the slow developing fatigue of prolonged low intensity exercise may require several __ for complete recovery |
|
|
Term
|
Definition
| __ exercise damages the sarcoplasmic reticulum, interfering with Ca2+ regulation and release, and therefore with muscle activation. which causes muscle fatigue |
|
|
Term
-oxygen reserves must be replenished
-the accumulated lactic acid must be reconverted to pyruvic acid
-glycogen stores must be replaced
-ATP and creatine phosphate reserves must be resynthesized
-the liver must convert any lactic acid persisting in blood to glucose of glycogen |
|
Definition
| what has to happen for a muscle to return to its resting state? |
|
|
Term
|
Definition
| __ = the extra amount of oxygen that the body must take in for the replenishment of oxygen reserves, glycogen stores, ATP and CP reserves, and conversion of lactic acid to pyruvic acid in the muscle |
|
|
Term
|
Definition
| the oxygen deficit represents the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount __. all anaerobic sources of ATP used during muscle activity contribute to this deficit as well. |
|
|
Term
|
Definition
| only about __ of the energy released during muscle contraction is converted to useful work. |
|
|
Term
|
Definition
| the energy released during muscle contraction that isn't converted to useful work is given off as __, which has to be dealt with if body homeostasis is to be maintained |
|
|
Term
sweating
radiation of heat from the skin surface |
|
Definition
| heat buildup in the body is prevented from reaching dangerous levels by several homeostatic processes, including __ and __ |
|
|
Term
|
Definition
| __ represents the opposite side of homeostatic balance, in which muscle contractions are used to produce more heat |
|
|
Term
1. the number of muscle fibers stimulated (recruitment)
2. the relative size of the fibers
3. the frequency of stimulation
4. the degree of muscle stretch |
|
Definition
| the force of muscle contraction is affected by what? |
|
|
Term
muscle force
(number of muscle fibers stimulated affects the force of muscle contraction) |
|
Definition
| the more motor units that are recruited, the greater the __ |
|
|
Term
strength
(size of muscle fibers affects the force of muscle contraction) |
|
Definition
| the bulkier the muscle (the greater its cross-sectional area), the more tension it can develop and the greater its __ |
|
|
Term
hypertrophy
(size of muscle fibers affects the force of muscle contraction) |
|
Definition
| regular resistance exercise increases muscle force by causing muscle cells to __, or increase in size |
|
|
Term
|
Definition
| as a muscle begins to contract, the force generated by the cross bridges - the __ - stretches the connective tissue sheaths (noncontractile components) |
|
|
Term
|
Definition
| as a muscle contracts the connective tissue sheaths (noncontractile components) become taut and transfer their tension, called the __, to the load (muscle insertion) |
|
|
Term
| noncontractile components |
|
Definition
| when the contraction ends, the recoiling of the __ helps to return the muscle to its resting length |
|
|
Term
|
Definition
| time is required to take up slack and stretch the noncontractile components, and while this is happening, the internal tension is already __ |
|
|
Term
|
Definition
| in brief twitch contractions, the external tension is always __ than the internal tension |
|
|
Term
|
Definition
| when a muscle is stimulated rapidly, contractions are summed, becoming stronger and more vigorous and ultimately producing __ |
|
|
Term
|
Definition
| during tetanic contractions more time is available to stretch the noncontractile components, and external tension approaches the internal tension. so the more rapidly a muscle is stimulated, the greater the __ it exerts |
|
|
Term
| noncontractile components |
|
Definition
| higher frequency of stimulation allows time for more effective transfer of tension to __ |
|
|
Term
|
Definition
| the optimal operating length for muscle fibers is the length at which they can generate maximum __ |
|
|
Term
| length-tension relationship |
|
Definition
| within a sarcomere, the ideal __ occurs when a muscle is slightly stretched and the thin and thick filaments overlap optimally, because this relationship permits sliding along nearly the entire length of the thin filaments |
|
|
Term
|
Definition
| if a muscle fiber is stretched so much that the thin and thick filaments do not overlap, the myosin heads have nothing to attach to and cannot generate __ |
|
|
Term
|
Definition
| if the sarcomeres are so compressed and cramped that the Z discs abut the thick myofilaments, and the thin filaments touch and interfere with one another, little or no further __ can occur |
|
|
Term
|
Definition
| if you stretch a muscle to various extents and then stimulate it tetanically, the active tension the muscle can generate varies with __ |
|
|
Term
|
Definition
| a severely stretch muscle (say one over 180% of its optimal length) cannot develop __ |
|
|
Term
| force generation (or shortening) |
|
Definition
| at 75% of a muscle's resting length, __ is limited because the actin myofilaments in its sarcomeres overlap and the thick filaments run into the Z discs, restricting further shortening |
|
|
Term
|
Definition
| length-tension relationships of sarcomeres in skeletal muscles: maximum force is generated when the muscle is between __ of its optimal resting length. increases and decreases beyond this optimal range result in decreased force and inability to generate tension |
|
|
Term
|
Definition
| in the body, skeletal muscles are maintained near their optimal operating length by the way they are attached to __. the __ normally prevent the bone movements that would stretch attached muscles beyond their optimal range |
|
|
Term
|
Definition
| muscles vary in how __ they can contract and in how __ they can continue to contract before they fatigue |
|
|
Term
muscle fiber type
load
recruitment |
|
Definition
| how fast a muscle can contract and how long a muscle can continue to contract is influenced by __, __, and __ |
|
|
Term
|
Definition
| on the basis of speed of shortening, or contraction, there are __ and __ |
|
|
Term
myosin ATPases split ATP
electrical |
|
Definition
| the difference in the speed of shortening, or contraction, which determines if it is slow fiber or fast fiber, reflects how fast their __, and on the pattern of __ activity of their motor neurons |
|
|
Term
cytosol
sarcoplasmic reticulum (SR) |
|
Definition
| duration of contraction also varies with fiber type and depends on how quickly Ca2+ is moved from the __ into the __ |
|
|
Term
oxidative fibers
glycolytic fibers |
|
Definition
| the cells that rely mostly on they oxygen-using areobic pathways for ATP generation are __, and those that rely more on anaerobic glycolysis are __ |
|
|
Term
slow oxidative (SO) fibers
fast oxidative (FO) fibers
fast glycolytic (FG) fibers |
|
Definition
| what are the three types of skeletal muscle cells/fibers? |
|
|
Term
1. speed of contraction
2. metabolic pathways for ATP synthesis (the major pathways for forming ATP) |
|
Definition
| muscle fiber type is classified according to what two characteristics? |
|
|
Term
slow
(because its myosin ATPases are slow) |
|
Definition
| slow oxidative fibers have a __ speed of contraction |
|
|
Term
|
Definition
| slow oxidative fibers have __ myosin ATPase activity |
|
|
Term
aerobic
(because it depends on oxygen delivery) |
|
Definition
| slow oxidative fibers primary pathway for ATP synthesis is __ |
|
|
Term
high
(because it uses an aerobic pathway and needs a lot of oxygen and myoglobin stores O2 and aids diffusion of O2 through the cell) |
|
Definition
| slow oxidative fibers myoglobin content is __ |
|
|
Term
low
(because it doesn't use glycolysis for its ATP pathway) |
|
Definition
| slow oxidative fibers glycogen stores is __ |
|
|
Term
slow (fatigue-resistant)
(because fatigue resistance is typical of fibers that depend on aerobic metabolism) |
|
Definition
| slow oxidative fibers rate of fatigue is __ |
|
|
Term
endurance-type activites (ex: running a marathon)
(because a thin cell can contain only a limited number of myofibrils, it has little power and so it is best suited for low power activities(one that don't use a lot of force)) |
|
Definition
| activites best suited for slow oxidative fibers is __ |
|
|
Term
red
(because of the abundance of myoglobin, muscle's oxygen-binding pigment that stores O2 reserves in the cell and aids diffusion of O2 through the cell) |
|
Definition
| a slow oxidative fibers color is __ |
|
|
Term
small
(this makes it thin, which makes sense because a large amount of cytoplasm impedes diffusion of O2 and nutrients from the blood and since this fiber is uses an aerobic pathway is needs to be thin for a high diffusion of O2) |
|
Definition
| a slow oxidative fibers diameter is __ |
|
|
Term
many
(because mitochondria are the actual sites of oxygen use and because it uses an aerobic pathway) |
|
Definition
| a slow oxidative fiber has __ mitochondria |
|
|
Term
many
(because it uses an aerobic pathway, it needs a high oxygen supply and a high capillary supply is higher to deliver bloodborne O2) |
|
Definition
| a slow oxidative fiber has __ capillaries |
|
|
Term
fast
(because of fast myosin ATPases) |
|
Definition
| fast glycolytic fibers have a __ speed of contraction |
|
|
Term
|
Definition
| fast glycolytic fibers have a __ myosin ATPase activity |
|
|
Term
anaerobic glycolysis
(because it does not use oxygen) |
|
Definition
| fast glycolytic fibers primary pathway for ATP synthesis is __ |
|
|
Term
low
(because it does not depend on oxygen for ATP so it doesn't need as much myoglobin) |
|
Definition
| fast glycolytic fibers myoglobin content is __ |
|
|
Term
high
(because it uses glycogen for fuel rather than on blood-delivered nutrients) |
|
Definition
| fast glycolytic fibers glycogen stores is __ |
|
|
Term
fast (fatigable)
(because glycogen reserves are short-lived and lactic acid accumulates quickly, making it a fatigable fiber) |
|
Definition
| fast glycolytic fibers rate of fatigue is __ |
|
|
Term
short-term intense or powerful movements (ex: hitting a baseball)
(because it uses an anaerobic pathway is energy doesn't last for a very long time) |
|
Definition
| activities best suited for fast glycolytic fibers is __ |
|
|
Term
white (pale)
(because it has few mitochondria, little myoglobin, and low capillary density) |
|
Definition
| a fast glycolytic fibers color is __ |
|
|
Term
large
(because it has a large diameter, it has plentiful contractile myofilaments that allow it to contract powerfully before it "poops out" |
|
Definition
| a fast glycolytic fibers diameter is __ |
|
|
Term
few
(because it doesn't need oxygen) |
|
Definition
| a fast glycolytic fiber has __ mitochondria |
|
|
Term
few
(because it doesn't need oxygen) |
|
Definition
| a fast glycolytic fiber has __ capillaries |
|
|
Term
fast
(because its myosin ATPases are fast) |
|
Definition
| fast oxidative fibers have a __ speed of contraction |
|
|
Term
|
Definition
| fast oxidative fibers have __ myosin ATPase activity |
|
|
Term
| aerobic (some anaerobic glycolysis) |
|
Definition
| fast oxidative fibers primary pathway for ATP synthesis is __ |
|
|
Term
|
Definition
| fast oxidative fibers myoglobin content is __ |
|
|
Term
|
Definition
| fast oxidative fibers glycogen stores is __ |
|
|
Term
| intermediate (moderately fatigue-resistant) |
|
Definition
| fast oxidative fibers rate of fatigue is __ |
|
|
Term
|
Definition
| a fast oxidative fibers color is __ |
|
|
Term
|
Definition
| a fast oxidative fibers diameter is __ |
|
|
Term
|
Definition
| a fast oxidative fiber has __ mitochondria |
|
|
Term
|
Definition
| a fast oxidative fiber has __ capillaries |
|
|
Term
contractile speeds
fatigue resistance |
|
Definition
| some muscles have a predominance of one fiber type, but most contain a mixture of fiber types, which gives them a range of __ and __ |
|
|
Term
|
Definition
| all muscle fibers in a particular motor unit are of __ |
|
|
Term
|
Definition
| because muscles are attached to bones, they are always pitted against some __ when they contract |
|
|
Term
|
Definition
| a greater load results in a __ latent period, a __ contraction, and a __ duration of contraction |
|
|
Term
|
Definition
| if the load exceeds the muscle's maximum tension, the speed of shortening is __ and the concentration is __ |
|
|
Term
|
Definition
| the more motor units that are contracting, the __ and more __ the contraction |
|
|
Term
|
Definition
| when used actively or strenuously, muscles may increase in __ or __ or become more efficient and fatigue resistant |
|
|
Term
|
Definition
| muscle inactivity always leads to muscle __ and __ |
|
|
Term
| aerobic or endurance exercise |
|
Definition
| __ results in several recognizable changes in skeletal muscles. there is an increase in the number of capillaries surrounding the muscle fibers, and in the number of mitochondria within them, and the fibers synthesize more myoglobin |
|
|
Term
|
Definition
| aerobic (endurance) exercise leading to increased muscle cappilaries, number of mitochondria, and myoglobin synthesis occurs in all fiber types, but are most dramatic in __, which depend primarily on aerobic pathways |
|
|
Term
endurance
strength
fatigue resistance |
|
Definition
| aerobic (endurance) exercise leading to increased muscle cappilaries, number of mitochondria, and myoglobin synthesis also results in more efficient muscle metabolism and in greater __, __, and __ |
|
|
Term
|
Definition
| regular endurance exercise may convert fast glycolytic fibers into __ |
|
|
Term
|
Definition
| the moderately weak but sustained muscle activity require for endurance exercise does not promote significant skeletal muscle __, even though the exercise may go on for hours |
|
|
Term
| resistance exercise (typically under anaerobic conditions) |
|
Definition
| muscle hypertrophy results mainly from high-intensity __ such as weight lifting or isometric exercise, in which the muscles are pitted against high-resistance or immovable forces |
|
|
Term
|
Definition
| the increased muscle bulk largely reflects increases in the size of __ muscle fibers (particularly the fast glycolytic variety) rather than an increased number of muscle fibers |
|
|
Term
mitochondria
myofilaments
glycogen stores
connective tissue |
|
Definition
| resistance exercise (typically anaerobic) results in increased __, __, __, and __ in the muscle fiber |
|
|
Term
|
Definition
| fast oxidative fibers can be shifted to __ fibers in response to resistance exercise |
|
|
Term
|
Definition
| when muscle training is not balanced, individuals can become __, which means they lack flexibility, have a generally awkward stance, and are unable to make full use of their muscles |
|
|
Term
|
Definition
| __ - forcing a muscle to work hard promotes increased muscle strength and endurance, and as muscles adapt to the increased demands, they must be overloaded even more to produce further gains |
|
|
Term
|
Definition
| doing too much too soon, or ignoring the warning signs of muscle or joint pain, increases the risk of __ that may prevent future sports activity, or even lead to lifetime disability |
|
|
Term
| disuse atrophy (degeneration and loss of mass) |
|
Definition
| complete immobilization due to enforced bed rest or loss of neural stimulation results in __, which begins almost as soon as the muscles are immobilized |
|
|
Term
|
Definition
| except for the heart, the muscle in the walls of all the body's hollow organs is almost entirely __ muscle |
|
|
Term
|
Definition
| smooth muscle fibers are __ shaped cells of variable size, with __ centrally located nucleus |
|
|
Term
| connective tissue sheaths |
|
Definition
| smooth muscle lacks the coarse __ seen in skeletal muscle |
|
|
Term
|
Definition
| a small amount of fine connective tissue (endomysium), secreted by the smooth muscles themselves and containing blood vessels and nerves is found __ smooth muscle fibers |
|
|
Term
longitudinal layer
circular layer |
|
Definition
| two sheets of smooth muscle are present, what are they? |
|
|
Term
|
Definition
| in the __ layer of smooth muscle, the muscle fibers run parallel to the long axis of the organ. when the muscle contracts, the organ dilates and shortens |
|
|
Term
|
Definition
| in the __ layer of smooth muscle, the fibers run around the circumference of the organ. contraction of this layer constricts the lumen (cavity) of the organ and causes the organ to elongate |
|
|
Term
|
Definition
| alternating contraction and relaxation of the longitudinal layer and circular layer of smooth muscle mixes substances in the lumen and squeezes them through the organ's internal pathway. this propulsive action is called __ |
|
|
Term
|
Definition
| in smooth muscle, the innervating nerve fibers, which are part of the autonomic (involuntary) nervous system, have numerous bulbous swellings called __. |
|
|
Term
|
Definition
| the varicosities release neurotransmitter into a wide synaptic cleft in the general area of the smooth muscle cells. such junctions are called __ |
|
|
Term
|
Definition
| the __ of smooth muscle fibers is much less developed than that of skeletal muscle and lacks a specific pattern relative to the myofilaments |
|
|
Term
|
Definition
| the sarcolemma of the smooth muscle fiber has multiple __, pouchlike infoldings that squester bits of extracellular fluid containing a high concentration of Ca2+ close to the membrane |
|
|
Term
sarcomeres
myofibrils
T tubules |
|
Definition
| a smooth muscle fiber has no __, __, or __ |
|
|
Term
|
Definition
| in contrast to the skeletal muscle fiber which does not depend on extracellular Ca2+ for excitation-contraction coupling, a smooth muscle fiber gets its calcium that triggers contraction through calcium channels directly from the __ |
|
|
Term
|
Definition
| in smooth muscle fibers, thick filaments are __ but have myosin heads along their entire length |
|
|
Term
|
Definition
| the ratio of thick to thin filaments in smooth muscle (1:13) is much __ than in skeletal muscle (1:2) |
|
|
Term
|
Definition
| in smooth muscle fibers there is no _ complex in thin filaments. instead a protein called calmodulin acts as the calcium-binding site |
|
|
Term
|
Definition
| in smooth muscle fibers thick and thin filaments are arranged __ |
|
|
Term
|
Definition
| myofilaments in smooth muscle are __ arranged, causing smooth muscle to contract in a corkscrew manner |
|
|
Term
|
Definition
| smooth muscle fibers contain a lattice-like arrangement of noncontractile __ that resist tension |
|
|
Term
|
Definition
| smooth muscle fibers intermediate filaments attach at regular intervals to cytoplasmic structures called __, which are also tethered to the sarcolemma and act as anchoring points for thin filaments and therefore correspond to Z discs of skeletal muscle |
|
|
Term
|
Definition
| in most cases, adjacent smooth muscle fibers exhibit __, __ contrations, the whole sheet responding to stimulus in unison |
|
|
Term
|
Definition
| smooth muscle cells are electrically coupled by __, which allow smooth muscles to transmit action potentials from fiber to fiber |
|
|
Term
|
Definition
| some smooth muscle fibers in the stomach and small intestine are __ cells and, once excited, they act as "drummers" to set the contractile pace for the entire muscle sheet |
|
|
Term
|
Definition
| pacemaker cells have fluctuating membrane potentials and are self-excitatory, that is, they _ spontaneously in the absence of external stimuli |
|
|
Term
1. actin and myosin interact by the sliding filament mechanism
2. the final trigger for contraction is a rise in the intracellular calcium ion level
3. the sliding process is energized by ATP |
|
Definition
| contraction in smooth muscle is like that in skeletal muscle in what ways? |
|
|
Term
|
Definition
| rate and intensity of contraction of smooth muscle may be modified by __ and __ stimuli |
|
|
Term
sarcoplasmic reticulum
extracellular space |
|
Definition
| the final trigger for contraction of smooth muscle is a rise in intracellular Ca2+, the Ca2+ is obtained from the __ and __ |
|
|
Term
myosin kinase
myosin light chain kinase |
|
Definition
| by binding Ca2+ to calmodulin, the calmodulin in turn interacts with a kinase enzyme called __ or __ which phosphorylates the myosin, activating it and cross bridges interact with actin |
|
|
Term
|
Definition
| smooth muscle relaxes when intracellular __ levels drop |
|
|
Term
|
Definition
| the contraction of smooth muscle is very energy efficient which means __ ATPases |
|
|
Term
|
Definition
| in contraction of smooth muscle, myofilaments may maintain a latch state for __ contractions |
|
|
Term
Ca2+
sarcoplasmic reticulum
extracellular fluid
dephosphorylation |
|
Definition
| relaxation of smooth muscle requires __ detachments from calmodulin, active transport of Ca2+ into __ and __, and __ of myosin to reduce myosin ATPase activity |
|
|
Term
nerves
hormones
local chemical changes |
|
Definition
| the contraction of smooth muscle can be regulated by __, __, or __ |
|
|
Term
| graded (local electrical signals) |
|
Definition
| in some cases the activation of smooth muscle by a neural stimulus is identical to that in skeletal muscle: an action potential is generated by neurotransmitter binding, and is coupled to a rise in calcium ions in the cytosol. however, some types of smooth muscle respond to neural stimulation with __ potentials only |
|
|
Term
neurostransmitter
receptor |
|
Definition
| in neural regulation of smooth muscle contraction, response depends on the __ released and the type of __ molecules |
|
|
Term
|
Definition
| not all smooth muscle activation results from neural signals. some smooth muscle layers have no nerve supply at all. instead, they depolarize spontaneously or in response to chemical stimuli that bind to G protein-linked receptors. others respond to both __ and __ stimuli |
|
|
Term
|
Definition
| chemical factors that cause smooth muscle contraction or relaxation without an action potential are done by __ or __ Ca2+ entry into the sarcoplasm |
|
|
Term
| stress-relaxation response |
|
Definition
| stretching of smooth muscle also provokes contraction, which automatically moves substances along an internal tract. however, the increased tension persists only briefly, and soon the muscle adapts to its new length and relaxes, while still retaining the ability to contract on demand. this __ allows a hollow organ to fill or expand slowly to accommodate a greater volume without promoting strong contractions that would expel its contents |
|
|
Term
|
Definition
| smooth muscle __ much more than skeletal muscle and generates more __ than skeletal muscles to a comparable extent. |
|
|
Term
|
Definition
| in smooth muscle, the lack of sarcomeres and the irregular, overlapping arrangement of smooth muscle filaments allow them to generate considerable __, even when they are substantially stretched |
|
|
Term
|
Definition
| smooth muscle can contract when it is anywhere from __ to __ its resting length, which allows hollow organs to tolerate tremendous changes in volume without becoming flabby when they empty |
|
|
Term
|
Definition
| besides being able to hypertrophy (increase in cell size), which is common to all muscle cells, certain smooth muscle fibers can __ and __ their numbers |
|
|
Term
1. fiber arrangement and organization
2. innervation
3. responsiveness to various stimuli |
|
Definition
| the smooth muscle in different body organs varies substantially how? |
|
|
Term
|
Definition
| smooth muscle is usually categorized into what two major types? |
|
|
Term
single-unit smooth muscle
visceral muscle |
|
Definition
| __ commonly called __ because it is in the walls of all hollow organs except the heart, is far more common |
|
|
Term
| opposing (longitudinal and circular) |
|
Definition
| the cells of a single-unit smooth muscle are arranged in __ sheets |
|
|
Term
|
Definition
| the cells of a single-unit smooth muscle are innervated by __ and often exhibit rhythmic spontaneous action potentials |
|
|
Term
|
Definition
| the cells of a single-unit smooth muscle are electrically coupled by __ and so contract as a unit (for this reason recruitment is not an option in smooth muscle) |
|
|
Term
|
Definition
| the cells of a single-unit smooth muscle respond to various __ stimuli |
|
|
Term
|
Definition
| the smooth muscles in large airways to the lungs and in large arteries, the arrector pilli muscles attached to hair follicles, and the internal eye muscles that adjust pupil size and allow the eye to focus are all examples of __ |
|
|
Term
|
Definition
| in multiunit smooth muscle __ are rare, and spontaneous synchronous depolarizations are infrequent |
|
|
Term
|
Definition
| multiunit smooth muscle consists of muscle fibers that are structurally __ of one another |
|
|
Term
|
Definition
| multiunit smooth muscle is richly supplied with __, each of which forms a motor unit with a number of muscle fibers |
|
|
Term
|
Definition
| multiunit smooth muscle responds to __ stimulation with graded contractions that involve recruitment |
|
|
Term
|
Definition
| multinit smooth muscle is innervated by the __ division of the nervous system and is also responsive to hormonal controls |
|
|
Term
|
Definition
| all three types of muscle tissue develop from embryonic mesoderm cells called __ |
|
|
Term
|
Definition
| Multinucleated skeletal muscle cells form by __ |
|
|
Term
|
Definition
| Growth factor __ stimulates clustering of ACh receptors at neuromuscular junctions |
|
|
Term
|
Definition
| Cardiac and smooth muscle myoblasts develop __ |
|
|
Term
|
Definition
| Cardiac and skeletal muscle become amitotic, but can __ |
|
|
Term
|
Definition
| Myoblast-like skeletal muscle satellite cells have limited __ ability |
|
|
Term
|
Definition
| Injured heart muscle is mostly replaced by __ |
|
|
Term
|
Definition
| Smooth muscle regenerates throughout __ |
|
|
Term
|
Definition
| Muscular development reflects __ coordination |
|
|
Term
|
Definition
| Development occurs __ to __, and __ to __ |
|
|
Term
|
Definition
| Peak natural neural control occurs by __ |
|
|
Term
|
Definition
| __ and __ can improve neuromuscular control |
|
|
Term
|
Definition
| Female skeletal muscle makes up __ of body mass |
|
|
Term
|
Definition
| Male skeletal muscle makes up __ of body mass, primarily due to testosterone |
|
|
Term
|
Definition
| Body strength per unit muscle mass is the __ in both sexes |
|
|
Term
|
Definition
| With age, connective tissue __ and muscle fibers __ |
|
|
Term
|
Definition
| By age __, loss of muscle mass (sarcopenia) begins |
|
|
Term
|
Definition
| Regular exercise reverses __ |
|
|
Term
|
Definition
| __ may block distal arteries, leading to intermittent claudication and severe pain in leg muscles |
|
|
Term
|
Definition
| __ refers to a group of inherited muscle-destroying diseases that generally appear during childhood. the muscles enlarge due to fat and connective tissue deposits. the muscle fibers atrophy and degenerate |
|
|
Term
| duchenne muscular dystrophy (DMD) |
|
Definition
| the most common and severe type of muscular dystrophy is __ |
|
|
Term
| duchenne muscular dystrophy (DMD) |
|
Definition
| Inherited, sex-linked, carried by females and expressed in males (1/3500) as lack of dystrophin |
|
|
Term
| duchenne muscular dystrophy (DMD) |
|
Definition
| Victims become clumsy and fall frequently; usually die of respiratory failure in their 20s |
|
|
Term
| duchenne muscular dystrophy (DMD) |
|
Definition
| No cure, but viral gene therapy or infusion of stem cells with correct dystrophin genes show promise |
|
|
