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1. MSK > Physiology > Flashcards

Physiology Flashcards

1
Q

What do motor units contain?

A

a single aplha neuron and all of the muscle fibres it innervates

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2
Q

What initiates skeletal muscle contraction?

A

neurogenic

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3
Q

What links excitation and contraction in skeletal muscle?

A

Ca from sarcoplasmic reticulum

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4
Q

Is a neuromuscular junction present in skeletal muscle or cardiac muscle?

A

Skeletal

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5
Q

What initiates cardiac muscle contraction?

A

myogenic - pacemaker potential

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6
Q

Are gap junctions present in cardiac or skeletal muscle?

A

cardiac

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7
Q

What links excitation in cardiac muscle?

A

Ca from the ECF and sarcoplasmic reticulum

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8
Q

What is the transmitter at neuromuscular junctions?

A

acetylcholine

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9
Q

what are myofibrils?

A

alternating sections of myosin and actin, arranged into sacromeres

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10
Q

What is the functional unit of muscle?

A

sarcomeres

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11
Q

What are the zones of sacromeres?

A

A band, H zone, M line, I band

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12
Q

Where is a sacromere found/where does it span?

A

between two z lines

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13
Q

What is the A band?

A

thick filaments with thin portions that overlap at the end

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14
Q

What is the H zone?

A

light area in the middle of the A band

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15
Q

What is the M line?

A

extends vertically down the H zone and the A band

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16
Q

What is the I band?

A

remaining portion of filament that does not project into the A band

17
Q

What happens when a surface action potential is reached?

A

Ca is released from the lateral sacs of the SR, when the action potential spreads down the transverse T tubules
this causes cross bridge formation - actin and myosin

18
Q

What does skeletal muscle contraction depend on?

A

number of muscle fibres contracting

tension developed by each muscle fibre

19
Q

What is twitch summation?

A

muscle stimulated once = twitch

stimulated again before it can relax = greater tension twitch

20
Q

What is a muscles optimal length?

A

point where maximal tension is achieved - its resting length

i.e. point of optimal overlap of thick filament and thin filament cross bridge

21
Q

Describe isoTonic contraction?

A

FIXED POSTION

Tension constant, length changes

22
Q

Describe isometric contraction?

A

MOVEMENT

Tension changes, length constant

23
Q

Describe slow oxidative type 1 muscle fibres?

A

RED

used for prolonged, low work aerobic activities - walking

24
Q

Describe fast oxidative type 2a muscle fibres?

A

WHITE

use aerobic and anaerobic metabolism and are useful in prolonged moderate work - jogging

25
Q

Describe fast oxidative type 2b muscle fibres?

A

WHITE

use anaerobic metabolism and are useful in short term, high intensity activities

26
Q

What is the stretch reflex?

A

A negative feedback mechanism that resists passive change in muscle length to maintain the optimal length of muscle

27
Q

What is the receptor for the stretch reflex?

A

muscle spindle

28
Q

What is the effector for the stretch reflex?

A

increased firing in afferent neurones

29
Q

What are extrafusal fibres?

A

ordinary muscle fibres

30
Q

What are intrafusal fibrers?

A

muscle spindles - specialised muscle fibres

31
Q

What are muscle spindles supplied by?

A

gamma motor neurones

32
Q

What is the action of muscle spindles when muscle is stretched?

A

increased discharge from sensory endings

33
Q

What is the role of gamma motor neurones?

A

ajust the level of tension in muscle spindles to maintain their sensitivity when the muscles shorten during contraction

34
Q

What does electromyography measure?

A

detects the presence of muscular activity, frequencey and amplitude of muscle fibres

1. MSK (36 decks)

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