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Anatomy and Physiology > Chapter 17 > Flashcards

Chapter 17 Flashcards

1
Q

What are the general functions of skeletal muscle?

A
  • movement
  • heat production
  • posture
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2
Q

What functional characteristics are unique to skeletal muscles?

A
  • excitability
  • contractility
  • extensibility
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3
Q

What are the unique characteristics of muscle cells?

A
  • sarcolemma
  • sarcoplasm
  • sarcoplasmic reticulum
  • multinucleated
  • many mitochondria
  • t-tubules
  • myofibrils
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4
Q

What is a t-tubule? Function?

A
  • an inward extension of the sarcolemma

- conduct impulses from the surface of the sarcolemma

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5
Q

What is a triad? Purpose?

A
  • the sarcoplasmic reticulum butting up on either side of the t tubule
  • allows the electrical impulse traveling along at tubule to stimulate the membranes of adjacent sacs of sarcoplasmic reticulum
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6
Q

What is a sarcomere?

A
  • segment of myofibril

- one group of contractile units

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7
Q

What are the different portions of a sarcomere?

A
  • z discs
  • a band
  • i band
  • h zone
  • m line
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8
Q

What portions of a sarcomere change during contraction?

A
  • h zone

- i band

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9
Q

What kinds of proteins make up a myofibril? Function? Where are they found?

A
  • Contractile: myosin and actin
  • Regulatory: tropomyosin and troponin
  • Structural: titin and dystrophin
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10
Q

What is the general mechanism of contraction?

A

-myosin heads attach to and walk along the thin filaments at both ends of the sarcomere

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11
Q

How is contraction initiated?

A
  • nerve impulses reach the end of a motor neuron
  • ach stimulates receptors
  • Ca+ is released and binds to troponin
  • troponin causes tropomyosin to shift
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12
Q

What is the contraction cycle?

A
  • ATP hydrolysis
  • Formation of cross-bridges
  • Power stroke
  • Detachment of myosin from actin
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13
Q

What are the steps to relaxation?

A
  • sarcoplasmic reticulum begins pumping Ca+ into sacs

- tropomyosin moves back into place

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14
Q

How does the muscle generate ATP while contracting?

A
  • creatine phosphate
  • anaerobic cellular respiration
  • aerobic cellular respiration
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15
Q

What is muscle fatigue?

A

-inability of a muscle to maintain force of contraction after prolonged activity

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16
Q

What factors contribute to muscle fatigue?

A
  • inadequate release of calcium ions
  • insufficient amounts of ATP: depletion of creatine phosphate, oxygen, glycogen, and buildup of lactic acid and ADP
  • failure of the motor neuron to release enough ACH
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17
Q

Why does heavy breathing occur after exercise?

A
  • it restores muscle cells to their resting level
  • convert lactic acid into glycogen
  • used to synthesize creatine phosphate and ATP
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18
Q

What is the graded strength potential?

A

-strength of a muscle depends on certain variables

19
Q

What is strength dependent on?

A
  • nutrient and oxygen availability
  • the size of the motor unit
  • the rate at which nerve impulses arrive
  • the amount of stretch before contraction
  • amount of load imposed on a mucle
20
Q

What is a motor unit?

A

-a motor neuron and the muscle fibers it stimulates

21
Q

How does the motor unit affect precise movements?

A

-the fewer the number of fibers supplied by a motor neuron, the more precise movements

22
Q

How does the motor unit affect strength?

A

-the larger the motor unit, the more powerful the force

23
Q

What is a twitch contraction?

A

-the brief contraction of the muscle fibers in a motor unit in response to an action potential

24
Q

What are the phases of a twitch contraction? What is occurring during each phase?

A
  • latent: delay between stimulus and contraction
  • contraction
  • relaxation
25
Q

What is treppe?

A

-the gradual, steplike increase in the strength of contraction that is observed in a series of twitch contractions

26
Q

How and why does treppe affect strength?

A
  • muscle contracts more forcefully after it has contracted a few times
  • Ca+ diffused easier, more actin-myosin reactions, and more calcium available because it has not been reabsorbed yet
27
Q

What is tetanus?

A

-smooth, sustained contractions

28
Q

What is the difference between incomplete and complete tetanus?

A
  • incomplete is hilly

- complete is constant

29
Q

How does sarcomere length affect strength and tension?

A

-if the sarcomeres are too short or too long then they will not be strong

30
Q

How does load affect strength and tension?

A

-an increased load threatens to stretch the muscle beyond the setpoint

31
Q

What happens if you pass the maximum sustainable level of load on a muscle?

A

-golgi tendon organs take over and force the muscle to relax

32
Q

What is muscle tone? Why is it important?

A
  • tonic contraction
  • a continual, partial contraction of a muscle organ
  • important for posture and keeping muscles firm
33
Q

What types of contractions are there?

A
  • isotonic: same tension

- isometric: same length

34
Q

What types of skeletal muscle fibers are there?

A
  • red

- white

35
Q

Which skeletal muscle fibers are red? White? Larger? Smaller?

A
  • red: more mitochondria and supplied by more blood capillaries; small; slow oxidative fibers
  • white: low myoglobin; large; fast glycolytic fibers
36
Q

What type of ATP producing reaction do muscle fibers use?

A

-cellular respiration

37
Q

Which muscle fibers fatigue quickly? Slowly?

A
  • quickly: white

- slowly: red

38
Q

Which muscle fibers are used for long periods of time? Short bursts of energy?

A
  • long: red

- short: white

39
Q

Which types of muscle fibers are determined genetically?

A

-the ratio of fast glycolytic to slow oxidative

40
Q

What is the anatomy of cardiac muscle?

A
  • contains myofibrils/sarcomeres
  • muscle cells branch
  • muscle cells have intercalated disks
  • many mitochondria
41
Q

What is unique about cardiac muscle?

A
  • self exciting

- produces rhythmic contractions on its own

42
Q

What is the anatomy of smooth muscle?

A
  • involuntary
  • action potentials are spread through the muscle fibers via gap junctions
  • fibers are stimulated by neurotransmitters, hormones, or autorhythmic signals
43
Q

What is unique to smooth muscle? Location?

A
  • thick and thin filaments are not arranged in orderly sarcomeres
  • single unit and multi-unit
  • vessels, hollow organs, airways, hair follicles, pupil, lens of eye

Anatomy and Physiology (19 decks)

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