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Human Anatomy & Physiology > Exam 4 - Nerve/Physiology Section > Flashcards

Exam 4 - Nerve/Physiology Section Flashcards

1
Q

What is the agonist (prime mover)?

A

The muscle that produces most of the forces during a particular joint action.

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2
Q

What is the antagonist?

A

The muscle that opposes the prime mover.

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3
Q

In some cases what does the antagonist do?

A

It relaxes to give the prime mover almost complete control over an action.

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4
Q

More often, what does the antagonist do?

A

The antagonist maintains some tension on a joint and thus limits the speed or range of the prime mover, preventing excess movement, joint injury or inappropriate actions.

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5
Q

What is the synergist?

A

The muscle that aids the prime mover. Two or more synergists acting on a joint can produce more power than a single larger muscle.

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6
Q

What is the structure of smooth muscle concerning intercalated discs?

A

No intercalated disc.

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7
Q

Where is smooth muscle located?

A

Walls of viscera (stomach, intestines, uterus, and urinary bladder), and blood vessels, iris of eye, and arrector muscle of hair follicles.

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8
Q

What is the function of smooth muscle?

A

Propels the contents of an organ, such as driving food through the digestive tract, voiding urine and feces, and expelling infant in childbirth. By dilating or constricting the blood vessels and airways, it can modify the speed of air and blood flow, maintain blood pressure, and reroute blood from one pathway to another.

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9
Q

What type of control is smooth muscle?

A

Involuntary

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10
Q

Smooth muscle nerve supply is…

A

Autonomic

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11
Q

What is the structure of cardiac muscle concerning intercalated discs?

A

Have intercalated discs.

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12
Q

Explain intercalated discs in cardiac muscle.

A

Cardiomyocytes branch slightly so each is joined end to end with several others. These intercellular connections are called intercalated discs. Gap junctions are present in the intercalated discs.

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13
Q

Where is cardiac muscle located?

A

The heart

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14
Q

What is the function of cardiac muscle?

A
  1. Pumps blood
  2. Must contract with regular rhythm.
  3. Must function in sleep and wakefulness, without fail or need of conscious attention.
  4. Must be highly resistant to fatigue.
  5. The cardiomyocytes of a given heart chamber must contract in unison so the chamber can effectively expel blood.
  6. Each contraction must last long enough to expel blood.
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15
Q

What type of control is cardiac muscle?

A

Involuntary

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16
Q

Cardiac muscle nerve supply is…

A

Autonomic

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17
Q

What is the structure of skeletal muscle concerning intercalated discs?

A

No intercalated discs.

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18
Q

Where are skeletal muscles located?

A

Associated with the skeletal system.

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19
Q

What is the function of skeletal muscle?

A

Contract to produce movement, sustain body posture and position, maintain body temp, store nutrients, and stabilize joints.

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20
Q

What type of control is skeletal muscle?

A

Voluntary

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21
Q

What are the contractile proteins?

A

Myosin and actin

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22
Q

What is the function of contractile proteins?

A

They do the work of shortening the muscle fiber.

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23
Q

What are the regulatory proteins?

A

Tropomyosin and troponin.

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24
Q

What is the function of regulatory proteins?

A

Together, tropomyosin and troponin act like a switch to determine when the fiber can contract and when it can’t.

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25
Q

What are the structural proteins?

A

Myosin, actin, tropomyosin, and troponin.

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26
Q

What do the 4 structural proteins form?

A

They form the foundation of the basic contractile unit called the sarcomere.

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27
Q

What is ATP hydrolysis?

A

A chemical reaction where a phosphate bond is broken by water, thereby releasing energy.

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28
Q

What does ATP hydrolysis produce?

A

ADP (adenosine diphosphate), Pi (inorganic phosphate), and energy.

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29
Q

What is the function attachment of myosin to actin to form cross bridges?

A

The globular heads of myosin containing ADP and Pi bind with actin, forming cross-bridges between the myosin and actin filaments.

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30
Q

What is the power stroke?

A

Myosin releases ADP and Pi, and flexes into a bend, low-energy position, tugging the actin along with it towards the Z line.

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31
Q

The myosin head remains bound to actin until…

A

it binds with a new ATP.

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32
Q

What is the function detachment of myosin from actin?

A

The binding of a new ATP to myosin destabilizes the myosin-actin bond, breaking the cross-bridge. ATP is reformed, and it detaches the myosin head from the actin.

33
Q

What are somatic motor neurons?

A

Nerve cells whose cell bodies are in the brainstem and spinal cord.

34
Q

What do the somatic motor neurons serve?

A

They serve skeletal muscles.

35
Q

What are synaptic vesicles?

A

Spheroidal organelles in an axon terminal containing acetylcholine.

36
Q

Acetylcholine is an example of a…

A

Neurotransmitter

37
Q

What is the axon terminal?

A

The site of synaptic vesicles and neurotransmitter release; the swollen tip at the distal end of an axon.

38
Q

What are neurotransmitters?

A

The body’s chemical messengers.

39
Q

What is the synaptic end bulb (knob)?

A

The tip of the axon enlarges and becomes known as the synaptic end bulb. It is towards the end of the axon terminal, closest to the muscle fiber.

40
Q

What is a muscle fiber?

A

One skeletal muscle cell; a myofiber.

41
Q

What is a motor end plate?

A

The point where a nerve fiber meets a target cell that is a muscle fiber.

42
Q

What is a motor end plate also called?

A

Neuromuscular junction (NMJ)

43
Q

What are acetylcholine receptors?

A

Proteins incorporated in the sarcolemma across from the axon terminals.

44
Q

What is the synaptic cleft?

A

A narrow space between an axon terminal and the membrane of the postsynaptic cell.

45
Q

Where does a neurotransmitter diffuse?

A

Across a synaptic cleft.

46
Q

What is the role of creatine phosphate in regards to production of ATP in muscle fibers?

A

Aids in rapidly generating ATP.

47
Q

What is the role of myoglobin in regards to production of ATP in muscle fibers?

A

To release oxygen to produce ATP.

48
Q

What is anaerobic cellular respiration?

A

A type of respiration where oxygen is not used.

49
Q

What does anaerobic cellular respiration allow a cell to do?

A

It enables a cell to produce ATP without the need for oxygen, but the ATP yield is very limited.

50
Q

What does the process of anaerobic cellular respiration generate?

A

A toxic by-product called lactate (lactic acid).

51
Q

What is aerobic cellular respiration?

A

A type of respiration that produces far more ATP and no lactate.

52
Q

What does aerobic cellular respiration require?

A

A continual supply of oxygen.

53
Q

What are the 2 contributing factors to muscle fatigue for high intensity, short-duration exercise?

A
  1. Potassium accumulation
  2. ADP/Pi accumulation.
53
Q

What is muscle fatigue?

A

The progressive weakness and loss of contractility that results from prolonged used of the muscles.

54
Q

What are the 3 contributing factors to muscle fatigue for low intensity, long-duration exercise?

A
  1. Fuel depletion
  2. Electrolyte loss
  3. Central fatigue
55
Q

What is lactic acid?

A

Fuel for your cells during exercise.

56
Q

How is lactic acid formed and accumulated?

A

Under conditions of high energy demand, rapid fluctuations of the energy requirement and insufficient supply of oxygen.

57
Q

What is a motor unit?

A

One motor neuron and all of the skeletal muscle fibers innervated by it.

58
Q

What are small motor units for?

A

When fine control is needed.

59
Q

What are large motor units for?

A

When strength is more important than fine control.

60
Q

What is a twitch contraction?

A

When a muscle is directly stimulated with an electrode, it exhibits a quick cycle of contraction and relaxation.

61
Q

What is the latent period of a muscle twitch?

A

The interval between a stimulus and response, especially in the action of a nerve and muscle cell.

62
Q

What is the contraction period of a muscle twitch?

A

Once the elastic components are taut, the muscle begins to produce external tension and move a resisting object, or load, such as a bone or body limb.

63
Q

What is the relaxation period of a muscle twitch?

A

The sarcoplasmic reticulum begins to quickly absorb Ca2+ even before the muscle develops maximal force. As the Ca2+ levels fall, myosin releases the thin filaments and muscle tension declines.

64
Q

What is the refractory period in muscle fiber contraction?

A

A period of time after a nerve or muscle cell has responded to a stimulus in which it can’t be re-excited by a threshold stimulus.

65
Q

What are the 2 phases of the refractory period in muscle fiber contraction?

A

Absolute refractory period and relative refractory period.

66
Q

What is the absolute refractory period?

A

In which no stimulus of any strength will trigger a new action potential.

67
Q

What is the relative refractory period?

A

In which it is possible to trigger a new action potential, but only with an unusually strong stimulus.

68
Q

What is wave summation?

A

At higher stimulus frequencies, each new stimulus arrives before the previous one and generates higher tension. This phenomenon goes by wave summation because it results from one wave of contraction added to another.

69
Q

What is unfused (incomplete) tetanus?

A

Wave upon wave, each twitch reaches a higher level of tension than the one before, and the muscle relaxes only partially between stimuli. This effect produces a state of sustained fluttering contraction called incomplete tetanus.

70
Q

What is fused (complete) tetanus?

A

In the lab, an isolated muscle can be stimulated at such high frequency that the twitches fuse into a single, nonfluctuating contraction called complete tetanus.

71
Q

What is motor unit recruitment?

A

The process by which different motor units are activated to produce a given level and type of muscle contraction.

72
Q

Motor unit recruitment is…

A

Part of the way the nervous system behaves naturally to produce varying muscle contractions.

73
Q

What is muscle tone?

A

A state of continual, partial contraction of resting skeletal or smooth muscle.

74
Q

What is the importance of muscle tone?

A

It maintains optimal sarcomere length and makes the muscles ideally ready for action.

75
Q

What is isometric muscle contraction?

A

In which a muscle develops tension but doesn’t shorten.

76
Q

What is isotonic muscle contraction?

A

In which muscle maintains tension while it lengthens, allowing a muscle to relax without going suddenly limp.

77
Q

What is the length-tension relationship?

A

The tension generated by a muscle, and therefore the force of its contraction, depends on how stretched or contracted it was at the outset.

Human Anatomy & Physiology (11 decks)

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