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Z A&P Chapters 7-9 > Lecture #15 Chapter 9 > Flashcards

Lecture #15 Chapter 9 Flashcards

1
Q

What type of neurotransmitter does skeletal muscle respond to?

A

Acetylcholine (ACh)

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2
Q

What is the motor end plate?

A

A specialized part of a muscle fiber membrane at a neuromuscular junction

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3
Q

What are the four steps in nervous control of contraction?

A
  1. An action potential travels down a the length of a motor neuron causing the release of ACh
  2. ACh bind to ACh receptors on the motor end plate
  3. This result in changes in membrane permeability to Na+ and K+ ions which generate muscle impulse (action potential)
  4. This impulse causes sarcoplasmic reticulum to release stored Ca++ ions which cause the muscle to contract
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4
Q

What is the excitation-contraction coupling?

A

The connection between stimulation of a muscle fiber and contraction

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5
Q

What happens during muscle relaxation?

A

Ca++ ions stored in SR, troponin-tropomyosin complexes cover binding sites of actin filaments

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6
Q

What are the five steps that occur upon muscle stimulation?

A
  1. Muscle impulses stimulate the SR to release Ca++ ions into the cytosol
  2. Ca++ bind to troponin causing it to change shape
  3. Tropomyosin protein then become altered
  4. Binding site on actin is now exposed
  5. Myosin head find action resulting in cross-bridge formation
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7
Q

What is the sliding filament model?

A

Where sarcomere shorten and the thick and thin filaments slide past one another

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8
Q

What part of the sarcomere shorten when a muscle contracts?

A

H zones and I bands narrow

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9
Q

What do two Z lines do when a muscle contracts?

A

They move closer together

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10
Q

What is cross-bridge formation?

A

Myosin heads attaching to actin binding-site

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11
Q

What is the powerstroke?

A

When the myosin cross-bridge pulls thin filaments toward the center of the sarcomere (M line) and ADP and Phosphate are released

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12
Q

What breaks the actin/myosin cross-bridge?

A

ATP

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13
Q

What causes the myosin heads to cock?

A

ATP breaks into ADP and Phosphate

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14
Q

What are the 4 steps in muscle relaxation?

A
  1. Acetylcholinesterase decomposes ACh in the synapse (muscle impulses stop causing the stimulus of the sarcolemma to stop)
  2. The Ca++ pump sequesters calcium ions back into the SR
  3. Troponin-tyopomyosin complexes conceal actin binding sites once again (Cross-bride formation is prevented)
  4. The muscle fiber relaxes
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15
Q

What are the tree energy sources availabe for muscle contraction?

A

-ATP (available in small amounts only)
-Creatine phosphate (Enables muscle cells to regenerate ATP for ADP via phosphate transfer)
-Cellular respiration (via mitochondria)

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16
Q

What is creatine phospahte?

A

A molecule in muscle that stores energy

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17
Q

What is ATP?

A

Adenosine triphosphate

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18
Q

What are the two types of cellular respiration?

A

Anaerobic phase and aerobic phase

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19
Q

What happens in the anaerobic phase or cellular respiration?

A

Glycolysis, which occurs in the cytoplasm, produces 2 ATP per glucose sugar

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20
Q

What is glycolysis?

A

The energy releasing breakdown of glucose into 2 pyruvic acid and 2 ATP

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21
Q

What happens in the aerobic phase of cellular respiration?

A

Citric acid cycle + electron transport chain, which occurs in the mitochondria, produce a large of ATP

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22
Q

What is the citric acid cycle?

A

A series of chemical reaction that oxidizes certain molecules (Krebs cycle)

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23
Q

What is the electron transport chain?

A

Series of chemical reaction that high energy electrons from glycolysis and the citric acid cycle and form water and ATP

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24
Q

What is myoglobin?

A

An oxygen storing pigment in muscle tissue

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25
Q

What is oxygen debt?

A

The amount of oxygen muscle cells require after physical exercise to restore levels of glucose, ATP, and creatine phosphate

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26
Q

What is anaerobic/lactic acid threshold?

A

Shift in metabolism from aerobic to anaerobic during strenuous muscle activity when insufficient O2 is available

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27
Q

What is muscle fatigue?

A

The inability to contract muscle

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28
Q

What are the four common causes of muscle fatigue?

A

-Decreased blood flow
-Ion imbalances across the sarcolemma
-Loss of desire to continue exercise
-Accumulation of lactic acid (iffy)

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29
Q

What is a muscle cramp?

A

Sustained, involuntary contraction

30
Q

What causes muscle cramps?

A

Changes in electrolyte concentrations in extracellular fluids near muscle

31
Q

What is the threshold stimulus?

A

The minimum strength of stimulus required for a muscle to contract (when reached is causes an action potential)

32
Q

What is an action potential?

A

The sequence of electrical changes in a nerve or muscle cells exposed to a stimulus that exceeds threshold

33
Q

What is a twitch?

A

A single contraction of a muscle fiber followed by relaxation

The contractile response to a single impulse

34
Q

WHat are the three periods of a twitch?

A

-Latent
-Contraction
-Relaxation

35
Q

What is one thing that can determine the force a muscle can generate?

A

The length of the muscle fiber before stimulation

36
Q

Why do stretched muscle fibers generate less force?

A

Due to myosin head being unable to reach actin binding sites

37
Q

Why do shortened muscle fibers develop less force?

A

Due to the physical restriction of sarcomeres become further compressed

38
Q

What is summation?

A

The process of combining the force generated by individual muscle fiber twitches

Increased force of contraction by skeletal muscle fibers when a twitch occurs before the previous twitch relaxes

39
Q

What is a motor unit?

A

Motor neuron + all of the muscle fibers it controls

40
Q

A whole muscle consists of ______ motor units?

A

Many

41
Q

A large number of fibers within a motor unit provide ____ movements?

A

Coarse

42
Q

A small number of muscle fibers within a motor unit provide ____ movements?

A

Precise

43
Q

What is recruitment?

A

An increase in the number of motor units becoming activated which helps to produce additional force

44
Q

During sustained contractions what type of motor units are recruited first?

A

Smaller motor units

45
Q

During sustained contraction what type of motor units are recruited later?

A

Larger motor units

46
Q

Isotonic contraction?

A

Muscle contracts and changes length, equal force

47
Q

Concentric contraction?

A

Shortening contraction

48
Q

Eccentric contraction?

A

Lengthening contraction

49
Q

Isometric contraction?

A

Muscle contracts but does not change length, change in force

50
Q

5 Facts about slow-twitch fibers?

A

-Type I
-resistant to fatigue
-Slower to contract
-Stimulated by aerobic exercise
-High myoglobin (red)

51
Q

5 Facts about fast-twitch, fatigue-resistant fibers?

A

-Type IIA
-Quicker to contract than type I
-Resistant to fatigue
-Stimulated by forceful exercise
-High myoglobin (red)

52
Q

4 Facts about fast-twitch, glycolytic fibers?

A

-Type IIB
-Contract rapidly
-Susceptible to fatigue
-Low myoglobin (white)

53
Q

Time frame when each energy system is used?

A

1-6sec stored ATP
10sec creatine phosphate
30-40sec anaerobic pathway
Hours aerobic pathway

54
Q

6 characteristics of smooth muscles?

A

-Short, elongated fibers with tapered ends
-Centrally located nuclei
-Myofilaments randomly organized
-No striations
-No transverse tubules
-SR not fully developed

55
Q

Two types of smooth muscles?

A

Multi-unit and visceral

56
Q

Where can multi-unit smooth muscles be found?

A

Iris (eye) and walls of blood vessels

57
Q

2 characteristics of multi-unit smooth muscles?

A

Less organized cells where each fiber functions independently

58
Q

Where can visceral smooth muscle be found?

A

In the walls of most hollow organs

59
Q

What is the characteristic of visceral smooth muscle?

A

Sheets of spindle-shaped muscle fibers function as a unit to contract with rhythmicity

60
Q

What does smooth muscle have in place of troponin?

A

Calmodulin

61
Q

What two neurotransmitters work in smooth muscles?

A

ACh and norepinephrine (NE)

62
Q

Differences in contraction rate and fatigue between smooth and skeletal muscles?

A

Smooth muscles contract slower and are more resistant to fatigue

63
Q

What are characteristics of caridac muscle?

A

-Joined via intercalated discs
-Fibers branch but have single nucleus
-Contract together as a unit (syncytium)
-Self-exciting; rhythmic
-Longer refractory periods than skeletal muscle
-No sustained/tetanic contractions

64
Q

What two things are the action of a muscle dependent on?

A

The type of joint and the way the muscle is attached on either side of the joint

65
Q

4 basic components of levers?

A

-Rigid bar/rod (bones)
-Fulcrum/pivot point (joint)
-Resistance (weight)
-Force (muscles)

66
Q

Organization of first class lever?

A

Resistance-fulcrum-force

67
Q

Organization of second class lever?

A

Fulcrum-resistance-force

68
Q

Organization of third class lever?

A

Resistance-force-fulcrum

69
Q

Agonist?

A

Prime mover-the muscle that causes movement at a joint

70
Q

Extensor muscles?

A

Extend the joint and increase joint angle

71
Q

Flexor muscles?

A

Decrease joint angle

72
Q

6 cells and 5 stages of muscle repair?

A

Quiescent satellite cell
-Activation
Activated satellite cell
-Proliferation
Myogenic progenitor (myoblast)
-Differentiation
Myocyte
-Fusion
Myotube
-Maturation
Myofiber

Z A&P Chapters 7-9 (5 decks)

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