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Anatomy and Physiology 1 > Chapter 10 > Flashcards

Chapter 10 Flashcards

1
Q

what 3 layers of CT surround the muscle?

A
  1. Epimysium
  2. Perimysium
  3. Endomysium
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2
Q

Epimysium

A

dense layer of collagen fibers that covers the entire muscle

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3
Q

perimysium

A

covers bundle of muscle fibers called fascicles

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4
Q

fascicles

A

collagen + elastic fibers, blood vessels and nerves

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5
Q

Endomysium

A

surrounds muscles fibers

-contains elastic fibers, capillaries and nerves

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6
Q

Tendon

A

where endomysium, perimysium and epimysium come together

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7
Q

names for muscles cells

A
  1. muscle cell
  2. myofiber
  3. muscle fiber
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8
Q

myofibril

A

-organelle that contains myofilaments

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9
Q

myofilaments

  • consists of 2 things
  • responsible for
A
  • thick (myosin) and think (actin) filaments

- muscle contraction

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10
Q

sarcolemma

A

plasma membrane surrounding the cytoplasm

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11
Q

Sarcoplasmic reticulum

  • what is it similar to
  • what does it contain
A

Similar to smooth ER

-contains large amount of Ca++ ions

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12
Q

terminal cisternae

A

SR tubules fuse and form an expanded chamber

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13
Q

Triad

A

2 terminal cisternae and 1 T-tubule

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14
Q

T-tubule

  • definition
  • what do they form
A

narrow tubes continuous with sarcolemma

-form passage ways through the muscle cells

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15
Q

Sarcomere

  • definition
  • function
A
  • functional unit of the myofilament

- gives the appearance of striations under microscope

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16
Q

4 components of the sarcomere

A
  1. thick filaments (myosin)
  2. Thin filaments (actin)
  3. Proteins that stabilize these filaments
  4. Proteins that regulate interactions between filaments
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17
Q

in between the I band

A

Z line that connects thin filaments

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18
Q

in between the A band

A

H zone that contains think but no thin

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19
Q

Thin filament

-composed of 4 things

A
  1. Troponin
  2. Tropomyosin
  3. Actin
  4. Active site
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20
Q

Active site of thin filament

  • location
  • binds to
  • what is it covered by when resting
A
  • on actin molecules
  • myosin
  • tropomyosin
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21
Q

Thick filament

-contains

A

-head and tail

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22
Q

Sliding filament theory

A

Thin filaments slide toward center of each sarcomere along side of each thick filament

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23
Q

During contraction what happens to the length of:

  1. A band
  2. I band
  3. H zone
  4. Zone of overlap
  5. Sarcomere
A
  1. remains constant
  2. shortens
  3. shortens
  4. increases
  5. Shortens
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24
Q

4 principles governing the contraction of skeletal muscle cells

A
  1. When muscle cells contract they pull on the attached tendon
  2. Contraction occurs only when skeletal muscle fibers are activated by neurons at a neuromuscular junction
  3. Tension produced is dependent on the number of motor neurons stimulated
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25
Q

motor neurons

A

neuron and muscle fibers it stimulates

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26
Q

How does the size of the motor unit relate to movement controlled

A

Size of the motor unit relates to how well the movement is controlled

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27
Q

small motor units

  • 1 neuron stimulates
  • allows for
A

1 neuron stimulates 4-6 muscle fibers

-fine control

28
Q

Large motor units

-1 neuron stimulates

A

1000-2000 muscle fibers

29
Q

Physiology of muscle contraction

-2 things

A
  1. Control by nervous system: the events of the neuromuscular junction
  2. Excitation contraction coupling
30
Q

Events of the neuromuscular junction

-5 steps

A
  1. Electrical signal travels down the terminal branch of the motor neuron
  2. This causes Ca++ to enter the axon terminal
  3. Vesicles in axon terminal are going to move to plasma membrane, fuse and discharge contents into synaptic cleft
  4. Ach diffuses across synaptic cleft and binds to a receptor on the muscle cell sarcolemma
  5. This initiates an electrical signal along sarcolemma of muscle cell (the muscle is now excited)
31
Q

electrical signal=

A

action potential

32
Q

what are neurotransmitters made up of

A

acetylcholine

33
Q

Excitation contraction coupling

  • definition
  • 7 steps (continuation)
A
  • link between generation of an action potential in the sarcolemma and start of muscle contraction
    6. electrical impulse conducted into a T-tubule
    7. impulse is going to reach the sarcoplasmic reticulum (at the triad)
    8. Sarcoplasmic reticulum releases Ca++ into the sarcoplasm
    9. Ca++ diffuses to myofibril and binds to troponin on thin filament
    10. When Ca++ binds to troponin, troponin changes its shape (causes tropomyosin to change position)
    11. This exposes the active site on actin
    12. Myosin head binds to the active site on actin
34
Q

contraction cycle

-3 steps

A
  1. Cross bridge attachment
  2. Cross bridge rotation (pivoting)
  3. cross bridge detachment
35
Q

Cross bridge attachment

  • -what happens
  • allows for
A
  • myosin head acts as am ATPase to hydrolyze ATP to ADP + P

- binding of myosin head to active site on actin

36
Q

Cross bridge rotation

A

powerstroke occurs as ADP + P and is released from myosin head

37
Q

Cross bridge detachment

  • what binds
  • what does binding do
A
  • ATP binds myosin head

- disrupts linkage between myosin head and active site on actin

38
Q

All or none principle

A

After stimulation by a nerve, an individual muscle cell either contracts to its fullest or not at all (does not apply to the entire muscle)

39
Q

Principle of graded strength

A

strength of the contraction can range from weak to strong

40
Q

Single stimulus

A

Twitch

41
Q

twitch

A
  • response of a muscle cell to a single stimulus
    1. latent phase
    2. contraction phase
    3. Relaxation phase
42
Q

latent phase of a twitch

A

begins at stimulation - action potential spreads down sarcolemma and SR releases Ca++
-Ca++ will bind to troponin as soon as its released from SR

43
Q

contraction phase of a twitch

A

tension rises to peak (crossbridges are forming)

44
Q

relaxation phase of a twitch

A

Ca++ levels are falling and active sites are covered

45
Q

Summation

  • definition
  • produces
  • 2 types
A

Adding individual twitches together

  • graded contractions
    1. multiple motor unit summation
    2. Temporal (wave) summation
46
Q

multiple motor unit summation

A
  • increased force of contraction caused by an increase in stimulus strength
  • sub-threshold, threshold, sub-maximal, maximal stimulus
47
Q

threshold

A

minimum stimulus needed to produce a contraction

48
Q

maximal stimulus

A

Maximum stimulus without any additional force of contraction

49
Q

tension produced by skeletal muscle is determined by:

-2 things

A
  1. stimulated muscle fibers

2. total number of stimulated muscle fibers

50
Q

temporal (wave) summation

A

increased force of contraction caused by an increase in the frequency of stimulation

51
Q

tetanus

A

stimulation of a muscle at even higher frequency produces “fusion” of summation twitches

52
Q

Frequency of temporal summation

  • definition
  • what happens to the strength
A

next stimulus arrives before relaxation phase has ended

-strength of stimulus remains the same

53
Q

why does increase in the frequency of stimulation increase the force of contraction (temporal summation)?

A
  • muscle cell has not had a chance to fully relax before the next stimulus arrive
  • muscle is still partially contracted and Ca++ stores are still available from last contraction
54
Q

Treppe

  • definition
  • why?
A

If a muscle is stimulated a 2nd time immediately after the relaxation phase has ended the force of contraction will be greater than the 1st stimulus
-increased Ca++ availability (in sarcoplasm) and heat increases activity of muscle enzyme

55
Q

Muscle tone

  • definition
  • why does it occur
  • example
A
  • constant tension produced by muscles for extended periods of time
  • because some motor units are active even when whole muscle is not contracting
  • muscles that keep the back and legs straight, the head upright and the abdomen flat
56
Q

Isotonic contraction

A

muscle develops tension, overcomes resistance and object is moved

57
Q

Isometric contraction

A

Muscle develops tension, cannot overcome resistance and object is not moved

58
Q

Muscle fatigue

A
  • lack of O2
  • depletion of ATP
  • accumulation of lactic acid
  • ionic imbalances
59
Q

Fast fibers

  • definition
  • common?
  • color
  • capillary supply
  • mito
A

Rapid movements for short periods of time

  • most muscle fibers in humans
  • white
  • scarce
  • few
60
Q

Slow fibers

  • definition
  • type of muscle
  • color
  • capillary supply
  • mito
A
  • high endurance and contracts for an extended period of time
  • postural muscle
  • red
  • dense
  • many
61
Q

Oxygen debt (excess post - exercise O2 consumption)

  • definition
  • 3 examples
  • what does rapid breathing do
A
  • Amount of O2 needed to restore homeostasis in the muscle tissue
    1. ATP stores must be replenished
      1. Lactic acid that builds up during exercise must be converted to glycogen
      2. Creatine needs to be converted back to creatine phosphate
  • helps to replenish O2
62
Q

The role of creatine phosphate

  • energy sources
  • what is it used for
  • formula
A
  • ATP + creatine phosphate
  • used to produce ATP in muscle cells
  • ADP+ creatine phosphate -> creatine + ATP
63
Q

Muscle hypertrophy

A

Muscle cell enlargement in response to repeated stimulation

64
Q

Muscle Atrophy

A

Muscle cells reduce in sixe in response to a lack of stimulation

65
Q

Delayed onset muscle soreness

-3 proposed mechanisms

A
  1. small tears in muscle tissue (damaged sarcolemma) (permits the loss of enzymes and chemicals that stimulate pain receptors
  2. muscle spasm in affected muscles may cause pain
  3. tears in connective tissue and tendons of affected muscles

Anatomy and Physiology 1 (17 decks)

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