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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
What is treppe?
-the gradual, steplike increase in the strength of contraction that is observed in a series of twitch contractions
26
How and why does treppe affect strength?
- 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
What is tetanus?
-smooth, sustained contractions
28
What is the difference between incomplete and complete tetanus?
- incomplete is hilly | - complete is constant
29
How does sarcomere length affect strength and tension?
-if the sarcomeres are too short or too long then they will not be strong
30
How does load affect strength and tension?
-an increased load threatens to stretch the muscle beyond the setpoint
31
What happens if you pass the maximum sustainable level of load on a muscle?
-golgi tendon organs take over and force the muscle to relax
32
What is muscle tone? Why is it important?
- tonic contraction - a continual, partial contraction of a muscle organ - important for posture and keeping muscles firm
33
What types of contractions are there?
- isotonic: same tension | - isometric: same length
34
What types of skeletal muscle fibers are there?
- red | - white
35
Which skeletal muscle fibers are red? White? Larger? Smaller?
- red: more mitochondria and supplied by more blood capillaries; small; slow oxidative fibers - white: low myoglobin; large; fast glycolytic fibers
36
What type of ATP producing reaction do muscle fibers use?
-cellular respiration
37
Which muscle fibers fatigue quickly? Slowly?
- quickly: white | - slowly: red
38
Which muscle fibers are used for long periods of time? Short bursts of energy?
- long: red | - short: white
39
Which types of muscle fibers are determined genetically?
-the ratio of fast glycolytic to slow oxidative
40
What is the anatomy of cardiac muscle?
- contains myofibrils/sarcomeres - muscle cells branch - muscle cells have intercalated disks - many mitochondria
41
What is unique about cardiac muscle?
- self exciting | - produces rhythmic contractions on its own
42
What is the anatomy of smooth muscle?
- involuntary - action potentials are spread through the muscle fibers via gap junctions - fibers are stimulated by neurotransmitters, hormones, or autorhythmic signals
43
What is unique to smooth muscle? Location?
- 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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