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BIO 201 > Muscle Physiology > Flashcards

Muscle Physiology Flashcards

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1
Q

How many skeletal muscles are in the human body?

A

600

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2
Q

What are the functions of skeletal muscle?

A

Movement
Stability
control of body openings/passages
generates heat

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3
Q
  1. Muscle produce up to ____ of one’s body heat.
A

85%

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4
Q
  1. What determines the origin and insertion of a muscle?
A

Origin: remains relatively fixed during muscle contraction,
Insertion: attachment site that moves towards the origin during muscle contraction

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5
Q
  1. Name the 5 characteristics of muscle tissue.
A

Excitability
Conductivity
Contractibility
Extensibility
Elasticity

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6
Q
  1. What makes up the striations of skeletal muscle? Which bands are associated with dark and light?
A

Sarcomeres make up striations
A-Band makes up dark
I-Band makes up light

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7
Q
  1. What is a sarcomere?
A

Z-Disk to Z-Disk
or
Basic function unit of muscle

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8
Q
  1. What is the function of z-disc?
A

acts as an anchor for actin filaments

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9
Q
  1. What is the sliding filament theory? Do the thick or thin filaments change length during contraction?
A

thin filaments slide past the thick filaments, causing the sarcomere to shorten and the muscle to contract
Neither change in length

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10
Q
  1. Which bands of the sarcomere change size during contraction?
A

I band and the H zone of the sarcomere decrease in size while the A band remains constant in size.

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11
Q
  1. What 2 proteins are considered contractile proteins? Regulatory proteins?
A

Contractile: Actin and Myosin
Regulatory: Troponin and Tropomyosin

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12
Q
  1. What are the components of the thin filament? Thick filament?
A

Thin: Actin, Tropomyosin, and Troponin
Thick: Myosin

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13
Q
  1. Sarcoplasmic reticulum is the main storage site for what ion?
A

Calcium

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14
Q
  1. What makes up the Triad? What part of the triad does the AP go down into?
A

A T-tubule and two terminal cisternae
The action potential goes down the T-tubule

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15
Q
  1. What is the function of dystrophin? What happens if there are genetic defects to this protein?
A

-maintaining the structural integrity of muscle cells.
helps anchor the actin filaments of the muscle fiber to the sarcolemma
-absence of functional dystrophin leads to progressive muscle weakness, wasting, and eventual loss of muscle function.

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16
Q
  1. Is muscular dystrophy more common in males or females?
A

males

17
Q
  1. What is considered a motor unit? What is the difference between small and large?
A

single motor neuron and all the muscle fibers it innervates
Small: muscles that require fine control and precision
large: muscles that require more force

18
Q
  1. What histologically does muscle tissue look like when contracted and at rest?
A

Contracted: muscle to appear darker under the microscope
At Rest: gives the muscle a striated appearance

19
Q
  1. What is rigor mortis? What is the main cause of this stiffness? How long does it last?
A
  • occurs after death where the muscles become stiff and difficult to move
  • due to the depletion of ATP in the muscle fibers, required for the separation of the myosin and actin filaments during muscle relaxation.
  • begins within 2-6 hours after death and peaks around 12 hours, lasting for approximately 24-48
20
Q
  1. What prevents Ach from escaping the neuromuscular junction? What breaks down Ach at the neuromuscular junction?
A

-Synaptic cleft: narrow space between the motor neuron terminal and the muscle fiber
-Acetylcholinesterase (AChE): breaks down Ach into acetyl and choline.

21
Q
  1. What is the role of the junctional folds at the neuromuscular junction?
A

increase surface area

22
Q
  1. What two things can cause flaccid paralysis? What are their mechanisms?
A
  • Curare and Botulism
  • preventing the release of acetylcholine or by blocking the receptors for acetylcholine causing for immobile
23
Q
  1. What two things can cause spastic paralysis? What are their mechanisms?
A
  • Insect Venom and tetanus
  • leads to excessive muscle activity and spasticity
24
Q
  1. During excitation-contraction coupling, what happens at the neuromuscular junction?
A
  • End plate potential
  • Action potential
  • T-tubules
  • Ca is released
  • contraction
  • Ca is pumped back to SR
25
Q
  1. What are the two roles of Ca++ during excitation contraction coupling?
A
  • increases the concentration of Ca++ in the sarcoplasm of the muscle fiber
  • conformational change in tropomyosin, which exposes the binding sites on actin molecules for the myosin heads.
26
Q
  1. How does contraction stop and relaxation occur?
A

occurs when the action potential that triggered the release of calcium from the sarcoplasmic reticulum stops

27
Q
  1. Explain the length tension relationship in the muscle.
A

the amount of tension a muscle can generate is dependent on the length of the muscle fiber at the time of contraction.

28
Q
  1. What two things does temporal summation cause?
A
  • Increased force of muscle contraction
  • Increased frequency of muscle contraction
29
Q
  1. Describe the 4 different types of muscle stimulation.
A
  • Twitch contraction: single, brief contraction
  • Summation: Repeated stimulation of a muscle fiber
  • Tetanus: sustained contraction of a muscle fibe
  • Recruitment: increasing the number of motor units
30
Q
  1. What is the difference between isometric and isotonic?
A

Isometric: muscle generates tension without changing its length
Isotonic: the muscle generates tension while changing its length

31
Q
  1. What is the difference between concentric an eccentric?
A

Concentric: muscle shortens while generating tension (Upward curl)
Eccentric: muscle lengthens while generating tension
(Downward motion)

32
Q
  1. When would the muscle use anaerobic fermentation? Aerobic respiration?
A

Anaerobic Ferm: short-term, high-intensity demand for energy, such as during intense exercise
Aerobic Res: sustained, low-intensity demand for energy, such as during moderate exercise

33
Q
  1. Know the difference between fast-twitch and slow-twitch muscle fibers. Which process is aerobic and which is anaerobic? What types of activities recruit each?
A

Fast-twitch: contract more quickly and with greater force, rely on anaerobic (weightlifting)
Slow-twitch: contract more slowly and with less force, rely on aerobic (running)

34
Q
  1. How is cardiac muscle stimulated to contract? Smooth muscle?
A

Cardiac: by an electrical signal from the sinoatrial (SA) node, which is located in the right atrium of the heart.

Smooth: neurotransmitters, hormones, and changes in the local environment (such as stretch or pH).

35
Q
  1. How does cardiac muscle get its ATP?
A

through aerobic respiration using oxygen and glucose

36
Q
  1. Why is smooth muscle smooth? Where does it get its calcium?
A

-smooth because it lacks striations, which are present in skeletal and cardiac muscles.
-gets its calcium from both extracellular and intracellular sources

37
Q
  1. What is the difference between slow twitch fibers, fast-twitch oxidative glycolytic fibers, and fast-twitch fibers? What energy pathways do each use? What gives rise to their colors? Which has the greatest force production? Which has greatest fatigue resistance?
A

Slow-twitch: aerobic respiration generates ATP and has a large number of mitochondria and myoglobin, a reddish appearance. (greatest fatigue resistance)

Fast-twitch oxidative glycolytic fibers: aerobic respiration and glycolysis to generate ATP, a moderate number of mitochondria and myoglobin, pink appearance

Fast-twitch: anaerobic glycolysis to generate ATP and fewer mitochondria and myoglobin, white in appearance. ( Greatest force production)

38
Q
  1. Why do muscles fatigue?
A
  • accumulation of lactic acid
  • depletion of energy stores (ATP)
  • decrease in calcium ion availability
39
Q
  1. During excitation-contraction coupling.
    What neurotransmitter is involved?
A

AHc

BIO 201 (3 decks)

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