Term
| Functions of Muscle Tissue: |
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Definition
A. Production of body movements.
B. Stabilize body position.
C. Storage and movement of substances through the body.
D. Generating Heat |
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Term
| Properties of Muscle Tissue: |
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Definition
A. Electrical Excitability - the ability to respond to stimuli
B. Contractility - the ability to contract (shorten) forciblywhen stimulated
C. Extensibility - the ability to stretch without being damaged
D. Elasticity - the ability to return to its original length andshape after contraction or extension |
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Term
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Definition
| a sheath or broad band of fibrous connective tissuethat is deep to the skin and surrounds muscles or otherorgans of the body |
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Term
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Definition
Hypodermis
- contains Adipose and Areolar C.T., vessels, nerves
- stores Triglycerides
- provides insulation
- protects underlying muscles and separates these muscles fromthe skin (i.e. provides a reduced friction surface) |
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Term
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Definition
- dense irregular connective tissue
- contains vessels and nerves
- provides a reduced friction surface for muscle movement
- layers: |
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Term
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Definition
a. Endomysium
- surrounds individual muscle fibers
b. Perimysium
- surrounds bundles of muscle fibers = Fascicle
c. Epimysium
- the outer most fascial layer
- surrounds individual muscles, ex. Trapezius |
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Term
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Definition
| Dense regular connective tissue that connectsmuscles to the periosteum of bone. |
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Term
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Definition
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Term
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Definition
1. Skeletal muscle is highly vascularized (i.e. has a good bloodsupply) to supply the needed oxygen and nutrients, and toremove waste products.
2. Skeletal muscle is innervated by motor neurons (SomaticNervous System). A single axon will usually innervateseveral muscle fibers. |
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Term
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Definition
| A motor neuron and all the muscle fibers thatit innervates. |
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Term
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Definition
| The point of contact between themotor neuron and the muscle fiber, i.e. a synapse. |
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Term
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Definition
"muscle cells"
-is a syncytium which is a group of cells that fused to formone large structure, has many nuclei
- is surrounded by endomysium |
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Term
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Definition
| - the plasma membrane that surrounds a muscle fiber |
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Term
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Definition
| - the cytoplasm of muscle fibers |
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Term
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Definition
- thread like filaments contained with in a muscle fiber
- the contractile element of muscles
- contains myofilaments |
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Term
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Definition
- surrounds myofibrils
- stores Calcium
- contains Calcium pumps that continually pump Ca++ fromaround the myofibrils back in to the SarcoplasmicReticulum |
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Term
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Definition
- move at right angles to the Sarcoplasmic Reticulum
- they are invaginations of the Sarcolemma that pass signalsto the Sarcoplasmic Reticulum |
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Term
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Definition
- move at right angles to the Sarcoplasmic Reticulum
- they are invaginations of the Sarcolemma that pass signalsto the Sarcoplasmic Reticulum |
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Term
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Definition
- the functional unit of a myofibril
- is made up of various myofilaments (proteins) |
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Term
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Definition
a. Thick filament - made from Myosin
b. Thin filaments - mostly Actin
c. Titin - a thick, elastic protein strand thatstabilizes the thick filament
d. Troponin and Tropomyosin - surround the bindingsites an Actin |
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Term
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Definition
| region that contains the thick filamentsMyosin, also known as the Dark band |
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Term
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Definition
| region that does not contain the thickfilaments (Myosin), also known as the lightband |
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Term
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Definition
| layer of protein that separate Sarcomeres |
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Term
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Definition
| line of protein that runs down the middleof the Sarcomere |
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Term
| Sequence of events associated with muscle contraction: |
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Definition
1. An Action Potential travels down the Axon towards theNeuromuscular Junction.
Note: Action Potentials will be discussed in the actionsof the Nervous System.
2. The Action Potential reaches the axon terminal and causesa synaptic vesicle to release neurotransmitter in tothe Synaptic cleft, via exocytosis
- The synaptic vesicle is neurotransmitter enclosed in alipid bilayer "packet", Acetylcholine (ACh) is theneurotransmitter for skeletal muscle contraction
p. 287 fig. 10-11
3. ACh diffuses across the synaptic cleft
4. ACh binds to a receptor on the motor end plate (i.e.the portion of the neuromuscular junction that is on themuscle)
5. ACh binding to the receptor produces an Action Potentialwhich travels along the T-tubules toward the SarcoplasmicReticulum
6. The Action Potential signals the Sarcoplasmic Reticulumto release Calcium across the myofibrils
7. Calcium binds to Troponin. Tropomyosin is attached toTroponin. When calcium binds to Troponin the Tropomyosinslides across the Thin filament (Actin). This movementexposes the Myosin binding sites that are on the Thinfilament.
p. 284 fig. 10-9
8. The Myosin heads of the Thick filament can now approximate theMyosin binding sites.
9. ATP attaches to the Myosin head. ATP is split into ADP andphosphate. This activates the Myosin head.
10. The activated Myosin head binds to the Myosin binding site.The phosphate group is released.
11. The Myosin head flexes (Power Stroke) which draws the Thinfilament towards the M line. ADP is released after theMyosin head is flexed.
12. The Myosin head remains attached to the Myosin binding siteuntil another ATP attaches to it. The Myosin head isthen released from the Myosin binding site, and becomesextended. It will then bind to another Myosin bindingsite. Steps 9, 10 and 11 are repeated until the signalfrom the neuron ceases. |
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Term
| Termination of Muscle Contraction. |
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Definition
1. Acetylcholinesterase (an enzyme that deactivates ACh) inthe Synaptic cleft continually breaks down ACh. If thesignal to release ACh into the synaptic cleft ceases, theAction Potential in the muscle will cease.
2. The Calcium pumps in the Sarcoplasmic Reticulumcontinuously pump the Ca++ around the myofibrils backinto the Sarcoplasmic Reticulum.
- With no Ca++ to bind to Troponin, the Tropomyosinslides over the Myosin binding sites. The Myosinhead now has no where to bind, thus musclecontraction ceases. |
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Term
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Definition
found in the Sarcoplasm
Creatine Kinase
ADP + Creatine Phosphate ---------------> ATP + Creatine
- provides energy for maximum muscle contraction for approx. 15 seconds |
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Term
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Definition
occurs in Sarcoplasm
- no oxygen is required
Glucose Glycolysis
or -------------------> 2 Pyruvic Acids + 2 ATP
Muscle glycogen
- provides energy for maximum muscle contraction for 30 to 40seconds
- when plenty of oxygen is available Pyruvic Acid is transported tothe Mitochondria, where the Krebs cycle occurs
- when the muscle is short of oxygen, Pyruvic Acid is converted toLactic Acid which will diffuse into the blood, as the pH ofmuscle decreases the ability of the muscle to function willalso decrease. |
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Term
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Definition
occurs in the Mitochondria
- requires oxygen (oxygen is the limiting factor)
- produces up to 36 ATP
- can get energy from the break down of Pyruvic Acid, fattyacids and amino acids
- provide energy for prolonged muscle use |
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Term
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Definition
| the inability of muscle to contract forcefullyafter prolonged activity. |
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Term
| Recovery Oxygen Consumption - |
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Definition
| the elevated use of oxygen afterexercise to replace the lost energy stores and to facilitatetissue repair after exertion |
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Term
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Definition
| - the process where an increasing number ofmotor units are activated in response to an increased load |
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Term
| Control of Muscle Tension |
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Definition
1. Key factors:
a. The amount of stretch on the muscle fibers prior tocontraction.
b. Frequency of stimulation - the number of nerve impulsesthat pass through a motor unit per second
2. Muscle tone:
- The tautness or tension that is constantly in a muscle dueto involuntary, weak stimulation of the motor units.
a. Flaccid - loss of muscle tone associated with damage tomotor neurons
2. Muscle tone:
- The tautness or tension that is constantly in a muscle dueto involuntary, weak stimulation of the motor units.
a. Flaccid - loss of muscle tone associated with damage tomotor neurons |
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Term
Control of Muscle Tension
1. Key factors: |
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Definition
a. The amount of stretch on the muscle fibers prior tocontraction.
b. Frequency of stimulation - the number of nerve impulsesthat pass through a motor unit per second |
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Term
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Definition
| The increased strength of a musclecontraction that result when nerve impulsesoccur in rapid succession. |
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Term
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Definition
| The process where anincreasing number of motor unit are activatedin response to an increased load. |
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Term
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Definition
| The period of time in which anexcitable cell (i.e. muscle or nerve cell)cannot respond to a stimulus. Different typesof muscle fibers have different refractoryperiods. |
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Term
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Definition
| - The tautness or tension that is constantly in a muscle dueto involuntary, weak stimulation of the motor units. |
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Term
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Definition
| loss of muscle tone associated with damage tomotor neurons |
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Term
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Definition
- a red fiber
- high myoglobin content, an iron containing protein thatbinds oxygen
- smallest diameter
- contains many capillaries
- has many Mitochondria (aerobic respiration)
- fibers contract slower than the other two fiber types
- resist fatigue
- found in postural muscles and in muscles involved inendurance (i.e. prolonged contraction) |
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Term
| Fast Oxidative-Glycolytic: |
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Definition
- a red fiber
- high myoglobin content
- intermediate in diameter
- contains many capillaries
- generate ATP by aerobic and anaerobic contraction
- uses ATP faster than Slow Oxidative fibers
- provides faster muscle contraction but fatigue quicker thanSlow Oxidative fibers
- associated with activities like walking and sprinting |
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Term
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Definition
- a white fiber
- low myoglobin content
- few capillaries
- few Mitochondria
- generate most ATP via glycolysis (anaerobically)
- provide strong, rapid contraction
- fatigue the quickest
- provide quick, short bursts of muscle contraction |
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Term
| Cardiac Muscle characteristics= |
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Definition
| Heart Muscle - contain Actin and Myosin filaments arranged in Sarcomeres - striated - remains contracted longer than Skeletal muscle - most of the ATP is produced by aerobic respiration - can use Lactic Acid to form ATP - Cardiac muscle contraction is stimulated from with in theHeart (Sinoatrial Node) vs. motor units - under involuntary control |
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Term
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Definition
| a thickening of the sarcolemma betweenadjacent cardiac muscle cells, contains many desmosomesand gap junctions |
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Term
Smooth Muscle characteristics |
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Definition
| - contain irregularly arranged thick and thin filaments - no striations - spindle-shaped = thicker in the middle, narrow at the ends - under involuntary control - the source of stimulation depends upon the location of themuscle, ex. local neurons, hormone, stretch, ACh - contracts slowly and remains contracted for a prolongedperiod of time |
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Term
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Definition
- most damaged muscle is replaced via fibrosis (scar tissue).
- undamaged cells will enlarge to attempt to make up for lostfunction |
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Term
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Definition
| cells located in Skeletal Muscle tissuethat can differentiate to become new muscle cells(myofibers), not enough of these cells exist to replacedamaged cells |
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Term
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Definition
| - heals via fibrosis - existing cells can enlarge to provide additional contractionstrength - recent studies have discovered stem cell that candifferentiate to become healthy cardiac muscle cells, theextent of this regeneration remains to be discovered |
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Term
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Definition
| - cells can enlarge to provide additional contraction strength - Limited regeneration capability, but much greater thanSkeletal muscle - certain smooth muscles retain the ability to undergo celldivision, ex. Myometrium of the Uterus |
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Term
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Definition
| stem cells located in capillaries and smallveins |
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Term
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Definition
- the relative number of Slow Oxidative fibers increase
- inactivity leads to fibrosing of skeletal muscle
- overall decrease of skeletal muscle |
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Term
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Definition
- an autoimmune disorder
- antibodies bind to Acetylcholine receptors, inactivatingthem
- patient develops progressive muscle weakness
- initial symptoms often develop in the muscles of the faceand neck
- if death occurs it is can be associated with paralysis ofthe respiratory muscles |
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Term
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Definition
| - a group of genetic disorders associated with degeneration ofskeletal muscle |
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