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A and P I > Chapter 9 > Flashcards

Chapter 9 Flashcards

Muscle Tissue and Physiology

1
Q

Nearly half of body’s mass
Can transform chemical energy into directed mechanical energy
3 types: skeletal, cardiac, smooth

A

Muscle tissue

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2
Q

Packaged into skeletal muscles
Voluntary muscle (consciously controlled)
Contract rapidly, tire easily, powerful
Made of nerve blood supply, connective tissue sheaths, attachments
KEY WORDS: skeletal, striated, voluntary

A

Skeletal muscle tissue

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3
Q

Longest of all muscle, have striations

A

Skeletal muscle fibers

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4
Q

Found only in heart
Striated
Involuntary (not controlled consciously)
KEY WORDS: cardiac, striated, involuntary

A

Cardiac muscle tissue

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5
Q

Found in walls of hollow organs
Not striated
Involuntary
KEY WORDS: visceral, nonstriated, involuntary

A

Smooth muscle tissue

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6
Q

Excitable - receive and respond to stimuli
Contractible - shorten forcefully
Extensibility - stretched
Elasticity - recoil to resting strength

A

4 Main Muscle Characteristics:

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7
Q
  1. Produce movement
  2. Maintain posture
  3. Stabilize joints
  4. Generate heat when they contract
A

Skeletal muscle functions

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8
Q

Dense irregular connective tissue surrounding entire muscle; may blend with fascia
Outermost tissue sheath

A

Epimysium

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9
Q

Fibrous connective tissue surrounding fascicles
Middle tissue sheath

A

Perimysium

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10
Q

Fine areolar connective tissue surrounding each muscle fiber
Most internal tissue sheath

A

Endomysium

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11
Q

Epimysium fused to periosteum of bone or perichondrium of cartilage

A

Direct attachement

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12
Q

Connective tissue wrappings extend beyond muscle as ropelike tendon or sheetlike aponeurosis

A

Indirect attachment

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13
Q

Long, cylindrical cells that contain multiple nuclei
Sarcolemma - muscle fiber membrane
Sarcoplasm - muscle fiber cytoplasm
Contains glycosomes and myoglobin
Modified organelles: myofibrils, S.R., T tubules

A

Muscle fiber

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14
Q

Densely packed, rod-like elements that run length of muscle fiber
Features: striations, sarcomeres, myofilaments

A

Myofibrils

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15
Q

Stripes formed from repeating series of dark and light bands along length of each myofibril
A bands = dark regions
I bands = light regions

A

Striations

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16
Q

Lighter region in middle of dark A band
Intersected by “M” zone vertically

A

H zone

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17
Q

Sheet of proteins on midline of light I band
Zigzag pattern

A

Z disc

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18
Q

Smallest contractile unit (functional unit) of muscle fiber
Consists of area between Z discs
Contains whole A band, 1/2 I band
Align with one another along myofibril

A

Sarcomere

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19
Q

Thick and thin filaments within sarcomere
2 types: Actin and Myosin

A

Myofilaments

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20
Q

Extend length of A band
Connected at M line
Myosin band

A

Thick filaments

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21
Q

2 Heavy polypeptide chains intertwined

A

Myosin tails

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22
Q

4 Light polypeptide chains combined
Contain actin and ATP binding sites

A

Myosin globular heads

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23
Q

Extend across I band and partway in A band
Anchored to Z disc
Composed of actin (G actin and F actin)

A

Thin filaments

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24
Q

Complex of three molecules attached to tropomyosin
Found in groove between actin filaments
Regulatory protein in thin filaments

A

Troponin

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25
Coiled protein In relaxed muscle, ____ blocks the myosin attachment sites on actin Regulatory protein in thin filaments
Tropomyosin
26
Bind sarcomeres together Maintain alignment of sarcomere N, M, C
Nebulin Myomesin C proteins
27
Structural protein that links thin filaments to integral proteins of sarcolemma which are then anchored to the extracellular matrix
Dystrophin
28
Muscle-destroying diseases Most common type = Duchenne muscular dystrophy
Muscular dystrophy
29
Sarcolemma of DMD tears easily, allowing for entry of excess calcium which damages contractile fibers Disease progresses from extremities upwards
Duchenne Muscular Dystrophy
30
Nervous system stimulates muscle fiber, myosin heads are allowed to bind to binding sites on actin Causes sliding (contraction) to begin
Cross bridges
31
Activation of cross bridges to generate force Ends when cross bridges are inactive
Contraction
32
Cross bridges attachments form and break several times During contraction, thin filaments slide past thick filaments, causing actin and myosin to overlap more No change in length
Sliding filament model of contraction
33
Thin and thick filaments overlap only at ends of A band
Relaxed state
34
Z discs are pulled towards M line (Z discs get closer) I bands shorten H zones disappear A bands move closer to each other Myofibril state:
Contracted state
35
Network of smooth endoplasmic reticulum tubules surrounding each myofibril Regulates intracellular Ca2+ levels Runs longitudinally Terminal cisterns: Thicker areas with lots of calcium
Sarcoplasmic reticulum (SR)
36
Tubes formed by protrusion of sarcolemma deep into cell interior Lumen continuous with extracellular space Tubules penetrate cell's interior at each A-I band junction between terminal cisterns Increase muscle fiber's surface area
T tubules
37
Area formed from terminal cisterns of two sarcoplasmic reticulums and a T tubule
Triad
38
Events at neuromuscular junction Muscle fiber excitation (shortening and developing tension) Excitation-Contraction coupling Cross bridge cycling
Skeletal muscle contraction
39
Low Ca2+ = Tropomyosin blocks active sites on actin; Myosin heads cannot attach to actin High Ca2+ = Ca2+ binds to troponin; Troponin changes shape and moves tropomyosin away from myosin-binding sites; Myosin heads allowed to bind to actin, forming bridge Sarcomere shortening
Cross Bridge Cycling
40
Myosin heads bind to active sites of actin, forming ____
Cross bridges
41
Part one of CBC Myosin binds to actin
Cross bridge formation
42
Part two of CBC ADP and P are released, myosin head pivots and bends, changing shape Pulls filament toward M line
Power stroke
43
Part three of CBC Cross bridge breaks
Cross bridge detachment
44
Part four of CBC ATP is hydrolyzed to ADP and P Myosin head returns to high energy position Binds to new binding site on actin
Cocking myosin head
45
1. Activation by brain 2. Transmission down spinal cord 3. Motor neurons activate muscle
Muscle movement process
46
Electrical signals that are created by a depolarizing current Occurs along the cell membrane in adjacent sarcolemma Short term
Action potential
47
Open by chemical messengers binding such as neurotransmitters Ex. ACh
Chemically gated ion channels
48
Open or close in response to voltage changes Ex. K+ channels
Voltage-gated channels
49
Stimulate skeletal muscles
Somatic motor neurons
50
Long, threadlike extensions of motor neurons
Axon
51
Region where motor neuron hovers over skeletal muscle Contains: axon terminal, synaptic cleft, junctional folds
Neuromuscular junction
52
End of axon
Axon terminal
53
Gel-filled space separating muscle fiber and axon terminal
Synaptic cleft
54
Membrane pockets filled with neurotransmitters and stored in axon terminal Commonly holding acetylcholine
Synaptic vesicles
55
ACh broken down into ____
Acetylcholinesterase
56
Infoldings of sarcolemma, containing ACh receptors (ion channels)
Junctional folds
57
Flip in polarity; (Inside + Outside -) Na+ rushes into muscle fiber, K+ rushes out
Depolarization
58
Difference in electrical potential between inside and outside of membrane Resting sarcolemma is polarized (Inside - Outside +)
Membrane potential
59
Local depolarization occurring at the neuromuscular junction
End plate potential (EPP)
60
Restoring sarcolemma to its initial polarized state (- inside, + outside)
Repolarization
61
Muscle fiber cannot be stimulated for a specific amount of time, until repolarization is complete
Refractory period
62
Events that transmit AP along sarcolemma (excitation) are coupled to sliding myofilaments (contraction) AP is propagated along sarcolemma and down into T-tubules AP is very brief
Excitation-contraction (EC) coupling
63
T-tubule proteins change shape --> calcium release channels in SR --> release calcium into cytoplasm
Part of EC coupling
64
Tropomyosin blocks actin binding site, Ca2+ levels low
End of muscle contraction
65
3-4 hours after death, muscles stiffen Intracellular calcium levels increase because ATP is no longer being synthesized
Rigor mortis

A and P I (18 decks)

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