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Anatomy > Muscles 3 > Flashcards

Muscles 3 Flashcards

1
Q

Tension produced in individual muscle fibers can vary due to?

A
  • length-tension relationship

- frequency of stimulation

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2
Q

Tension produced by entire muscle can vary even more widely due to?

A
  • number of muscle cells receiving nerve stimulation, commanding them to contract
  • muscle cells are grouped in motor units
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3
Q

all the muscle fibers innervated by?

A

one motor neuron

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4
Q

Amount of tension produced in a muscle determined by?

A

number of motor units activated

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5
Q

What kind of motor unit summation for sustained contractions?

A

asynchronous motor unit summation

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6
Q

Small motor unit

A

precise control

-one motor neuron innervates a small number of muscle fibers

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7
Q

large motor unit

A

gross movement control

-one motor neuron innervates a large number of muscle fibers

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8
Q

muscle tone is caused by?

A
  • resting tension in skeletal muscle
  • Some motor units are always active; tense and firm the muscle
  • active motor units are constantly changing, muscle tone is not produced by a specific subset of motor units
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9
Q

Muscle tone functions

A
  • stabilizes bones and joints

- greater resting muscle tone causes higher resting rate of metabolism

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10
Q

Isotonic contraction

A

tension rises, length of muscle changes

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11
Q

Concentric contraction

A

muscle tension exceeds resistance and muscle shortens

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12
Q

Eccentric contraction

A

peak tension developed is less than the resistance, muscle elongates

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13
Q

physiology of isometric contractions

A
  • tension produced never exceeds resistance
  • individual muscle fibers shorten until internal connective tissues and tendons are taut
  • cannot shorten further bc tension doesn’t exceed resistance
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14
Q

lengthening a muscle

A
  • no active mechanism for muscle fiber elongation

- muscle cell doesn’t cause itself to length after contraction process ends

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15
Q

how does a muscle return to resting length?

A
  • recoil in elastic components in connective tissue
  • contraction of opposing muscle groups
  • gravity
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16
Q

How long to high energy molecules in the muscle last and what are they?

A

~15 sec once contraction begins, of ATP and creatine phosphate (CP)

17
Q

Creatine Phosphate reserves

A
  • muscle cell makes more ATP than needed; extra ATP transfers high energy phosphate to creatine for storage
  • CP reserves releases stored energy to convert ADP to ATP when ATP is needed
18
Q

Cellular respiraton

A

uses O2 and releases CO2

  • occurs in mitochondria
  • citric acid cycle
  • electron transport chain
19
Q

citric acid cycle

A

CO2 is produced

20
Q

Electron transport chain

A
  • ATP synthesis

- O2 is used

21
Q

Resting muscle fibers rely o what to generate ATP?

A

Aerobic metabolism of fatty acids

22
Q

how is aerobic metabolism of FA used to generate ATP?

A
  • FA absorbed from circulation
  • broken down to 2 C units of acetyl CoA which enter into the CAC
  • Excess ATP used to store glucose into glycogen, create creatine phosphate
23
Q

explain pyruvate metabolism

A

Anaerobic

-insufficient oxygen converts pyruvate to lactic acid

24
Q

What does conversion of pyruvate to lactic acid do to cofactors

A

Recycles cofactors needed by glycolysis enzymes

25
Q

what happens in resting muscle metabolism?

A

fatty acids to mitochondria to produce atp

26
Q

what happens in moderately active muscle metabolism

A

still functions aerobically, glucose and fatty acids are catabolized, ATP produces is used to power contraction

27
Q

What happens in peak activity muscle metabolism?

A

ATP is produced through glycolysis with lactic acid as a by-product. Mitochondrial activity provides 1/3 of the ATP consumed.

28
Q

Advantage of anaerobic metabolism

A

produces ATP rapidly at an O2 deficit

29
Q

Disadvantage of anaerobic metabolism

A

inefficient use of glucose

-lactic acid lowers intracellular pH

30
Q

When does the recovery period starts?

A

immediately after activity ends

31
Q

What is oxygen debt?

A
  • excess post-exercise oxygen consumption
  • more intense exercise=larger O2 debt
  • amt of O2 req. during resting period needed to get rid of lactic acid and restore creatine phosphate reserves
32
Q

What happens during the recovery period?

A
  • oxygen debt
  • rebuild ATP and creatine phosphate levels
  • recycle lactic acid to make pyruvate
  • rebuild glycogen reserves
33
Q

Fatigued muscle

A

a muscle that can no longer perform at required level of activity

34
Q

causes of fatigue

A
  • exhaustion of energy resources
  • build up of lactic acid and lowering of pH
  • psychological fatigue

Anatomy (12 decks)

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