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Biology AP > Chapter 39: Motor Mechanisms and Behaviours > Flashcards

Chapter 39: Motor Mechanisms and Behaviours Flashcards

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1
Q

what is muscle activity a response to?

A

input from the nervous system

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2
Q

is muscle contraction a passive or active process?

A

active

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3
Q

is muscle relaxation a passive or active process?

A

passive

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4
Q

what is a vertebrate skeletal muscle?

A

moves bones and the body and is characterized by a hierarchy of smaller and smaller units

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5
Q

what does a skeletal muscle consist of?

A

a bundle of long fibers, each a single cell, running parallel to the length of a muscle

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6
Q

what is each muscle fiber made of?

A

bundle of smaller myofibrils

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7
Q

what did myofibrils contain?

A

thick and thin filaments

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8
Q

what is the skeletal muscle also called? why?

A

striated muscle because the regular arrangement of myofibrils creates a pattern of light and dark bands

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9
Q

what is the functional unit of a muscle?

A

a sarcomere. it is bordered by Z-lines (any of the dark thin bands across a striated muscle fiber that mark the junction of actin filaments in adjacent sarcomeres)

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10
Q

what does muscle contraction rely on?

A

interactions between protein structures

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11
Q

what do the thin filaments consist of?

A

2 strands of actin

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12
Q

what do thick filaments consist of?

A

staggered arrays of myosin molecules

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13
Q

what are filaments?

A

proteins that cause movement (motor proteins)

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14
Q

what is the model called that explains how muscles contract?

A

sliding-filament model

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15
Q

what does the sliding-filament model say?

A

filaments slide past each other longitudinally, causing an overlap between thin and thick filaments. the head of a myosin molecule binds to an actin filament, forming a cross bridge, and pulling the thin filament toward the centre of the sarcomere (Z-line comes closer)

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16
Q

what is the sliding of filaments reliant on?

A

interactions between actin and myosin

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17
Q

what do muscle contractions require?

A

repeated cycles of binding and release

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18
Q

how is the ATP needed to sustain muscle contraction made?

A

glycolysis and aerobic respiration

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19
Q

does the filament ever change shape?

A

no, only the closeness of the Z-lines

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20
Q

what binds to actin stands when the fiber is at rest?

A

tropomyosin and troponin complex

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21
Q

what are tropomyosin and troponin complex

A

additional proteins that bind to actin stands when a muscle fiber is at rest

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22
Q

what must happen to the myosin binding sites before it can be contracted?

A

it must be uncovered

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23
Q

how are the myosin binding sites exposed?

A

Ca 2+ bind to the troponin complex. this moves the troponin and the tropomyosin.

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24
Q

what needs to be present for a contraction to occur?

A

high concentration of Ca 2+

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25
Q

when does a muscle stop contracting?

A

when there is a low concentration of Ca 2+

26
Q

where does Ca 2+ come from?

A

it is controlled by the brain

27
Q

what makes actin and myosin unbind?

A

ATP

28
Q

what are graded contractions?

A

the extent and strength of contraction can be voluntarily altered

29
Q

what mechanisms does the nervous system use to produce graded contractions?

A

varying the number of fibers that contract. varying the rate at which fibers are stimulated.

30
Q

what does a motor unit consist of?

A

a single motor neuron and the muscle fibers it controls

31
Q

what send a message to the muscle to contract?

A

multiple neurons

32
Q

what is action potential?

A

sudden, fast, transitory, and propagating change of the resting membrane potential. property called excitability.

33
Q

what does the recruitment of multiple motor neurons result in?

A

stronger contracts. this allows for a variation in contraction strength

34
Q

what is a twitch a result of?

A

a single action potential in a motor neuron

35
Q

what is tetanus?

A

is a state of smooth and sustained contraction produced when motor neurons deliver a volley of action potentials

36
Q

what are the types of skeletal muscle fibers?

A

slow oxidative, fast oxidative, and fast glycolytic

37
Q

what is the contraction speed in slow oxidative?

A

slow

38
Q

what is the contraction speed in fast oxidative?

A

fast

39
Q

what is the contraction speed in fast glycolytic?

A

fast

40
Q

what is the major ATP source in slow oxidative?

A

aerobic respiration

41
Q

what is the major ATP source in fast oxidative?

A

aerobic respiration

42
Q

what is the major ATP source in fast glycolytic?

A

glycolysis

43
Q

what is the rate of fatigue for slow oxidative?

A

slow

44
Q

what is the rate of fatigue for fast oxidative?

A

intermediate

45
Q

what is the rate of fatigue for fast glycolytic?

A

fast

46
Q

how many mitochondria in slow oxidative?

A

many

47
Q

how many mitochondria in fast oxidative?

A

many

48
Q

how many mitochondria in fast glycolytic?

A

few

49
Q

what is the myoglobin content in slow oxidative?

A

high (red muscle)

50
Q

what is the myoglobin content in fast oxidative?

A

high (red muscle)

51
Q

what is the myoglobin content in fast glycolytic?

A

low (white muscle)

52
Q

how do oxidative and glycolytic fibers differentiate?

A

what their energy source is

53
Q

what is myoglobin?

A

a protein that binds O2 more tightly than hemoglobin does

54
Q

how does fast twitch and slow twitch fibers differ?

A

their speed of contraction

55
Q

what is a slow twitch fiber?

A

they contract more slowly but sustain longer contractions. all slow-twitch fibers are oxidative

56
Q

what is a fast twitch fiber?

A

they contract more rapidly but sustain shorter contractions. fast twitch fibers can be either oxidative or glycolytic

57
Q

what are characteristics of the cardiac muscle?

A

found only in the heart. consists of striated cells and Z-lines. striated cells are electrically connected by intercalated discs. they are involuntary. cardiac muscle gain can generate action potentials without neural input

58
Q

what are intercalated discs?

A

found between myocardial cells of the heart. help bond muscle cells together and transmit signals between cells

59
Q

what are characteristics of smooth muscle?

A

found mainly in the walls of hollow organs such as those of the digestive tract. not striated. contractions are relatively slow. contractions may be initiated by the muscle itself without the brain. involuntary. contractions may also be caused by a stimulation from neurons in the autonomic nervous system

60
Q

what are skeletal muscles attached in?

A

antagonistic pairs

61
Q

what happens if one muscle in the pair contracts?

A

the other relaxes

62
Q

what does the skeleton do?

A

provides a rigid structure to which muscles attach. helps with support, protection, and movement

Biology AP (13 decks)

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