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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
Q

Coiled protein
In relaxed muscle, ____ blocks the myosin attachment sites on actin
Regulatory protein in thin filaments

A

Tropomyosin

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26
Q

Bind sarcomeres together
Maintain alignment of sarcomere
N, M, C

A

Nebulin
Myomesin
C proteins

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27
Q

Structural protein that links thin filaments to integral proteins of sarcolemma which are then anchored to the extracellular matrix

A

Dystrophin

28
Q

Muscle-destroying diseases
Most common type = Duchenne muscular dystrophy

A

Muscular dystrophy

29
Q

Sarcolemma of DMD tears easily, allowing for entry of excess calcium which damages contractile fibers
Disease progresses from extremities upwards

A

Duchenne Muscular Dystrophy

30
Q

Nervous system stimulates muscle fiber, myosin heads are allowed to bind to binding sites on actin
Causes sliding (contraction) to begin

A

Cross bridges

31
Q

Activation of cross bridges to generate force
Ends when cross bridges are inactive

A

Contraction

32
Q

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

A

Sliding filament model of contraction

33
Q

Thin and thick filaments overlap only at ends of A band

A

Relaxed state

34
Q

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:

A

Contracted state

35
Q

Network of smooth endoplasmic reticulum tubules surrounding each myofibril
Regulates intracellular Ca2+ levels
Runs longitudinally
Terminal cisterns: Thicker areas with lots of calcium

A

Sarcoplasmic reticulum (SR)

36
Q

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

A

T tubules

37
Q

Area formed from terminal cisterns of two sarcoplasmic reticulums and a T tubule

A

Triad

38
Q

Events at neuromuscular junction
Muscle fiber excitation (shortening and developing tension)
Excitation-Contraction coupling
Cross bridge cycling

A

Skeletal muscle contraction

39
Q

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

A

Cross Bridge Cycling

40
Q

Myosin heads bind to active sites of actin, forming ____

A

Cross bridges

41
Q

Part one of CBC
Myosin binds to actin

A

Cross bridge formation

42
Q

Part two of CBC
ADP and P are released, myosin head pivots and bends, changing shape
Pulls filament toward M line

A

Power stroke

43
Q

Part three of CBC
Cross bridge breaks

A

Cross bridge detachment

44
Q

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

A

Cocking myosin head

45
Q
  1. Activation by brain
  2. Transmission down spinal cord
  3. Motor neurons activate muscle
A

Muscle movement process

46
Q

Electrical signals that are created by a depolarizing current
Occurs along the cell membrane in adjacent sarcolemma
Short term

A

Action potential

47
Q

Open by chemical messengers binding such as neurotransmitters
Ex. ACh

A

Chemically gated ion channels

48
Q

Open or close in response to voltage changes
Ex. K+ channels

A

Voltage-gated channels

49
Q

Stimulate skeletal muscles

A

Somatic motor neurons

50
Q

Long, threadlike extensions of motor neurons

A

Axon

51
Q

Region where motor neuron hovers over skeletal muscle
Contains: axon terminal, synaptic cleft, junctional folds

A

Neuromuscular junction

52
Q

End of axon

A

Axon terminal

53
Q

Gel-filled space separating muscle fiber and axon terminal

A

Synaptic cleft

54
Q

Membrane pockets filled with neurotransmitters and stored in axon terminal
Commonly holding acetylcholine

A

Synaptic vesicles

55
Q

ACh broken down into ____

A

Acetylcholinesterase

56
Q

Infoldings of sarcolemma, containing ACh receptors (ion channels)

A

Junctional folds

57
Q

Flip in polarity; (Inside + Outside -)
Na+ rushes into muscle fiber, K+ rushes out

A

Depolarization

58
Q

Difference in electrical potential between inside and outside of membrane
Resting sarcolemma is polarized (Inside - Outside +)

A

Membrane potential

59
Q

Local depolarization occurring at the neuromuscular junction

A

End plate potential (EPP)

60
Q

Restoring sarcolemma to its initial polarized state (- inside, + outside)

A

Repolarization

61
Q

Muscle fiber cannot be stimulated for a specific amount of time, until repolarization is complete

A

Refractory period

62
Q

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

A

Excitation-contraction (EC) coupling

63
Q

T-tubule proteins change shape –> calcium release channels in SR –> release calcium into cytoplasm

A

Part of EC coupling

64
Q

Tropomyosin blocks actin binding site, Ca2+ levels low

A

End of muscle contraction

65
Q

3-4 hours after death, muscles stiffen
Intracellular calcium levels increase because ATP is no longer being synthesized

A

Rigor mortis

A and P I (18 decks)

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