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ML 125 Physiology/Pathology Exam 2
Exam 2 Muscular System Notes/Handouts
131
Physiology
Undergraduate 2
02/17/2014

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Term
Which muscle type is: striated and involuntary
Definition
cardiac
Term
Which muscle type is: spindle-shaped fibers
Definition
visceral/smooth
Term
Which muscle type is: multinucleated and cylindrical
Definition
skeletal
Term
Which muscle type is: found in blood vessels
Definition
visceral/smooth
Term
Which muscle type is: found in the heart
Definition
cardiac
Term
more movable attachment of a muscle
Definition
insertion
Term
covering around an individual muscle fiber
Definition
endomysium
Term
protein in thick myofilaments
Definition
myosin
Term
bundle of fibers surrounded by perimyseum
Definition
fasciculus
Term
less movable attachment of a muscle
Definition
origin
Term
broad, flat sheet of tendon
Definition
aponeurosis
Term
cell membrane of a muscle cell
Definition
sarcolemma
Term
protein in thin myofilaments
Definition
actin
Term
unit of muscle between Z lines
Definition
sarcomere
Term
type of myofilament in the I band
Definition
thin/actin
Term
Muscle fibers must me stimulated before they can contract, therefore they have an abundant _____.
Definition
nerve supply
Term
The blood supply delivers _____ and _____ for contraction.
Definition
oxygen; nutrients
Term
First event of muscle contraction:
Definition
nerve impulse reaches axon terminal
Term
Second event of muscle contraction:
Definition
acetylcholine (ACh)is released into synaptic cleft
Term
Third event of muscle contraction:
Definition
acetylcholine (ACh) reacts with receptors on sarcolemma
Term
Fourth event of muscle contraction:
Definition
impulse travels into the T-tubules
Term
Fifth event of muscle contraction:
Definition
calcium ions are released from the sarcoplasmic reticulum
Term
Sixth event of muscle contraction:
Definition
calcium reacts with troponin and exposes binding sites on actin
Term
Seventh event of muscle contraction:
Definition
energized myosin heads attach to actin
Term
Eighth event of muscle contraction:
Definition
power stroke pulls actin toward center of A band
Term
minimum stimulus that causes contraction
Definition
threshold
Term
principle by which muscle fibers contract
Definition
all-or-none
Term
stimulus insufficient to cause contraction
Definition
subthreshold
Term
single neuron and muscle fibers it stimulates
Definition
motor unit
Term
increases contraction strength in a muscle
Definition
summation
Term
sustained contraction due to rapid stiumuli
Definition
tetany
Term
staircase effect due to partial muscle contraction
Definition
treppe
Term
continued state of partial muscle contraction
Definition
tone
Term
muscle contraction with constant tension
Definition
isotonic
Term
muscle contraction with changing tension
Definition
isometric
Term
immediate source of energy for contraction
Definition
ATP
Term
stored in muscle to regenerate ATP
Definition
creatine phosphate
Term
molecule that stores oxygen in muscle
Definition
myoglobin
Term
acid that accumulates with lack of oxygen
Definition
lactic acid
Term
products of aerobic breakdown of pyruvic acid
Definition
CO2 + H20 + energy (ATP)
Term
the immediate (initial source) of energy is
Definition
ATP
Term
stored ATP is depleted in _____ in working muscles
Definition
6 seconds
Term
high energy compound stored in muscles
Definition
creatine phosphate
Term
creatine phosphate + ADP ->
Definition
creatine + ATP
Term
muscles store enough creatine phosphate to regenerate ATP for sustained contraction of _____
Definition
10 seconds
Term
when muscles are actively contracting for extended periods of time, _____ and _____ become primary energy sources
Definition
fatty acids; glucose
Term
glucose is stored in muscles as
Definition
glycogen
Term
more ATP is produced from the metabolism of _____ and _____
Definition
glucose and fatty acids
Term
fatty acids (or glucose) + O2 -->
Definition
CO2 + H20 + ATP
Term
which pathway produces 20x more ATP?
Definition
aerobic
Term
which pathway produces ATP 2 1/2x faster?
Definition
anaerobic
Term
vigorous activity over long periods of time, _____ and blood cannot deliver enough _____ to maintain aerobic respiration
Definition
myoglobin; O2
Term
what is metabolized anaerobically to produce lactic acid and a small amount of ATP?
Definition
glucose
Term
glucose -->
Definition
lactic acid + ATP
Term
_____ accumulates, causing a burning sensation
Definition
lactic acid
Term
lactic acid diffuses out of the muscle --> _____ --> _____
Definition
bloodstream; liver
Term
when O2 is available, the liver will convert lactic acid to _____ (storage form of _____)
Definition
glycogen; glucose
Term
muscle metabolism: resting muscle
Definition
fatty acids are catabolized; the ATP produced is used to build energy reserves of ATP, creatine phosphate, and glycogen
Term
muscle metabolism: moderate activity
Definition
glucose and fatty acids are catabolized; the ATP produced is used to power contraction
Term
muscle metabolism: peak activity
Definition
most ATP is produced through glycolysis, with lactic acid as a by-product
Term
key steps in the initiation of a contraction: 1
Definition
at the neuromuscular junction, ACh released by the synaptic terminal binds to receptors on the sarcolemma
Term
key steps in the initiation of a contraction: 2
Definition
the resulting change in the membrane potential of the muscle fiber leads to the production of an action potential that spreads across the entire surface along the T tubules
Term
key steps in the initiation of a contraction: 3
Definition
the sarcoplasmic reticulum releases stored calcium ions, increasing the calcium concentration of the sarcoplasm in and around the sarcomeres
Term
key steps in the initiation of a contraction: 4
Definition
calcium ions bind to troponin, resulting in the movement of tropomyosin and the exposure of active sites on the thin (actin) filaments; myosin cross bridges form when myosin heads bind to active sites
Term
key steps in the initiation of a contraction: 5
Definition
repeated cycle of cross-bridge binding, pivoting, and detachment occur, powered by the breakdown of ATP; these events produce filament sliding, and the muscle fiber shortens
Term
this process continues for a brief period, until: 6
Definition
action potential generation ceases as ACh is broken down by acetylcholinesterase
Term
this process continues for a brief period, until: 7
Definition
the sarcoplasmic reticulum reabsorbs calcium ions, and the concentration of calcium ions in the sarcoplasmic reticulum declines
Term
this process continues for a brief period, until: 8
Definition
when calcium ion concentrations approach normal resting levels, the troponin and tropomyosin molecules return to their normal positions; these changes cover the active sides and prevent further cross-bridge interaction
Term
this process continues for a brief period, until: 9
Definition
without cross-bridge interactions, further sliding cannot take place and the contraction will end
Term
this process continues for a brief period, until: 10
Definition
muscle relaxation occurs, and the muscle returns passively toward resting length
Term
thousands of elongated, cylindrical fiber cells that lie parallel to one another
Definition
myofibers
Term
plasma membrane covering myofibers and surrounding sarcoplasma
Definition
sarcolemma
Term
cell cytoplasm; contains many nuclei lying close to sarcolemma
Definition
sarcoplasma
Term
cylindrical structures that compose myofibers; run the partial length of the sarcolemma; consist of two kinds of smaller structures called thin myofilaments and thick myofilaments
Definition
myofibrils
Term
high energy enzyme molecules; can break down and be sued to convert ADP to ATP
Definition
phosphocreatines
Term
network of membranes; stores Ca+
Definition
sarcoplasmic reticulum
Term
extensions of the sarcolemma that open to the outside of the fiber
Definition
transverse tubules / T tubules
Term
compartments of arranged myofilaments
Definition
sarcomeres
Term
Z lines
Definition
separates each sarcomere
Term
A band
Definition
length of thick myofilaments
Term
I band
Definition
composed of thin myofilaments
Term
dark bands
Definition
thick myofilaments
Term
light bands
Definition
thin myofilaments
Term
actin
Definition
light bands / thin myofilaments
Term
myosin
Definition
dark bands / thick myofilaments
Term
anchored to the Z lines and project in both directions, composed mostly of actin
Definition
thin myofilaments
Term
each actin molecule contains a myosin-binding site; also contains protein molecules _____ and _____
Definition
tropomyosin; troponin
Term
are not anchored to Z lines
Definition
thick myofilaments
Term
protein molecule shaped like a golf club
Definition
myosin
Term
the heads of myosin form cross-bridges and contain an _____-binding site and an _____-binding site
Definition
actin; ATP
Term
ATP + ATPase -->
Definition
ADP + P + energy
Term
needs O2
Definition
aerobic
Term
absence of O2
Definition
anaerobic
Term
_____ releases Ca++
Definition
sarcoplasmic reticulum
Term
_____ alters permeability of sarcolemma, allowing _____ movement (depolarizes end plate membrane)
Definition
acetylcholine; Na+/K+
Term
_____ binds to myosin
Definition
Ca++
Term
_____ inactivates ACh
Definition
acetylcholinesterase
Term
the amount of O2 needed to convert lactic acid into CO2 and H2O; is paid back by rapid breathing after exercise
Definition
oxygen debt
Term
spasm
Definition
involuntary, sudden contraction (stomach, eye twitch, etc)
Term
cramp
Definition
a muscle spasm without relaxation; due to lack to ATP which is needed to move Ca++ back to sarcoplasmic reticulum
Term
twitch
Definition
rapid, jerky contraction (1-2 seconds) of a muscle in response to single stimulus
Term
tetany
Definition
muscle in total (intermittent or continuous) contraction
Term
tetanus
Definition
sustained contraction produces by a series of very rapid stimuli to a muscle
Term
convulsion
Definition
violent, involuntary, tetanic contractions occurring in a series in skeletal muscles
Term
what gives muscle its brownish color?
Definition
myoglobin (due to similar properties of Hgb in blood)
Term
treppe
Definition
the gradual increase in the amount of contraction by a muscle caused by rapid, repeated stimuli of the same strength (but not at a fast enough rate to produce tetanus)
Term
isotonic contraction
Definition
muscle contraction in which tension on the muscle remains constant, but the muscle shortens and pulls on another structure to produce movement
Term
isometric contraction
Definition
a muscle contraction in which tension on the muscle increases, but there is minimal muscle shortening so that no movement is produced
Term
muscle tone
Definition
a sustained, partial contraction of portions of a skeletal muscle in response to activation of stretch receptors (essential for maintaining posture)
Term
muscle spindles
Definition
receptors in the muscle that monitor degree of tone
Term
flaccid
Definition
muscles with less than normal tone
Term
atrophy
Definition
wasting away of muscles due to loss of myofibrils
Term
muscular hypertrophy
Definition
reverse of atrophy; increase in diameters of muscle fibers due to increased production of myofibrils
Term
atria
Definition
muscular walls and partition of upper chambers
Term
ventricles
Definition
muscular walls and partition of lower chambers
Term
intercalated discs
Definition
separate fibers in a network; an irregular, transverse thickening of the sarcolemma, they strengthen cardiac muscle tissue and aid in nerve impulse conduction from on muscle fiber to another
Term
refractory period (cardiac)
Definition
allows heart to relax between beats
Term
skeletal muscle has _____ refractory period than cardiac muscle
Definition
shorter
Term
myogram
Definition
record of contractions
Term
wave summation
Definition
the increased strength of a contraction resulting from the application of a second stimulus before the muscle has completely relaxed after a previous stimulus
Term
fibrillation
Definition
irregular twitching of individual muscle fibers, or small groups of fibers, preventing effective action by an organ or muscle
Term
(smooth muscle tissue) smaller or larger than skeletal muscle fibers?
Definition
smaller
Term
(smooth muscle tissue) cell shape
Definition
widest at midpoint and tapered at both ends with centrally located nucleus
Term
(smooth muscle tissue) sarcoplasm contains thick myofilaments that are (longer/shorter) than skeletal
Definition
longer
Term
(smooth muscle tissue) thick and thin myofilaments are not arranged as orderly as in skeletal muscle tissue so there are no _____
Definition
A or I bands or sarcomeres
Term
(smooth muscle tissue) intermediate filaments
Definition
are attached to dense bodies which have characteristics similar to Z lines; bundles of intermediate filaments stretch from one dense body to another
Term
(smooth muscle tissue) sliding filament mechanism
Definition
thick and thin myofilaments during contraction produces tension that is transmitted to intermediate filaments; these in turn pull the dense bodies (attached to sarcolemma) causing a lengthwise shortening of muscle fiber
Term
(smooth muscle tissue) caveolae
Definition
a less well-developed sarcoplasmic reticulum than skeletal, though to function like a transverse tubule and carry nerve impulses to fibers
Term
(smooth muscle tissue) contraction
Definition
lasts 5-500 times longer than skeletal; can also undergo sustained, long-term done (steady contraction of G.I. tract, arteriole walls that have steady pressure on blood, and in bladder with steady pressure in urine)
Term
(smooth muscle tissue) stress-relaxation
Definition
fibers are stretched and initially develop increased tension, however the is an almost immediate decrease of the tension; this permits smooth muscle to accommodate great changes in size while still retaining the ability to contact effectively (walls of stomach, intestines, bladder)
Term
(smooth muscle tissue) contract in response to _____
Definition
nerve impulses, hormones, local factors
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