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MHS1102 - Anatomy and physiology 2 > lecture 1 - muscle physiology > Flashcards

lecture 1 - muscle physiology Flashcards

1
Q

what are the universal characteristics of muscles

A

excitability, conductivity, contractility, extensibility, elasticity

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2
Q

excitability

A

responsiveness to chemical signals, stretch and electrical charges across plasma membrane

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3
Q

conductivity

A

electrical excitation initiates wave of excitation that travels along muscle fibre

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4
Q

contractility

A

shortens when stimulated

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5
Q

extensibility

A

capable of being stretched between contractions

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6
Q

elasticity

A

returns to original rest length after being stretched

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7
Q

features of skeletal muscles

A

voluntary, striated

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8
Q

voluntary action

A

usually subject to conscious control

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9
Q

striated

A

alternating light and dark bands due to internal contractile proteins

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10
Q

muscle

A

contractile organ, usually attached to bone by way of tendons

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11
Q

fascicle

A

bundle of muscle fibres

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12
Q

muscle fibre

A

single muscle cell

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13
Q

myoblasts

A

stem cells fuse and form muscle fibres early in development

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14
Q

satellite cells

A

unspecialised myoblasts between muscle fibre and endomysium

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15
Q

what is the role of satellite cells

A

regeneration of damaged skeletal muscle tissue

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16
Q

sarcoplasmic reticulum

A

smooth ER that forms a network around each myofibril

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17
Q

terminal cisterns

A

dilated end-sacs of SR that cross muscle fibre from one side to the other

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18
Q

T tubules

A

tubular infoldings of sarcolemma which penetrate through cell and emerge on other side

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19
Q

Triad

A

a T tubule and two terminal cisterns associated with it

20
Q

when does muscle contraction begin

A

stored calcium is released into sarcoplasm

21
Q

functional muscle units

A

sarcomeres

22
Q

sarcomere

A

segment from Z line to Z disc

23
Q

H band

A

thick filaments at the centre of the sarcomere

24
Q

I bands

A

thin filaments

25
Q

function sarcomeres

A
  1. stabilise the position of thin and thick filaments
  2. proteins that regulate interactions between thin and thick filaments
26
Q

M line

A

proteins that connect neighbouring thick filaments

27
Q

H band

A

region either side of M line

28
Q

A band

A

thin and thick filaments overlap

29
Q

fibrous actin

A

two intertwined strands

30
Q

tropomyosin

A

actin binding protein

31
Q

troponin

A

small, calcium binding protein on each tropmyosin molecule

32
Q

what occurs when skeletal muscles contract

A
  1. sarcomere shorten
  2. H bands and I bands get smaller
  3. zones of overlap get larger
  4. Z lines move closer together as thick and thin filaments slide past each other
  5. A band remains constant
  6. sliding occurs in all sarcomeres in myofibril
  7. myofibril gets shorter
  8. muscle gets shorter
  9. tension is produced
33
Q

somatic motor fibres

A

axons that lead to skeletal muscles

34
Q

somatic motor neurons

A

nerve cell whose cell bodies lie in brainstem and spinal cord

35
Q

motor unit

A

one nerve fibre and all muscle fibres innervated by it

36
Q

characteristics of muscle fibres in a motor unit

A
  1. dispersed throughout muscle
  2. contract in unison
  3. produce weak contraction over wide area
  4. able to sustain long term contraction
  5. requires contraction of several motor units at once
37
Q

synapse

A

where nerve fibre meets target cell

38
Q

neuromuscular junction

A

when target cell meets a muscle fibre

39
Q

axon terminal

A

swollen end of nerve fibre

40
Q

synaptic cleft

A

gap between axon terminal and sarcolemma

41
Q

basal lamina

A

thin layer of collagen and glycoprotein separating schwann cell and muscle cell from surrounding tissues

42
Q

tetanus (lockjaw)

A

form of spastic paralysis caused by toxin Clostridium tetani

43
Q

flaccid paralysis

A

muscles are limp and cannot contract

44
Q

Botulism

A

food poisining caused by a neuromuscular toxin secreted by the bacterium Clostridium botulinium

45
Q

What are the four major phases of contraction and relaxation

A
  1. excitation - nerve action potentials lead to muscle action potentials
  2. excitation-contraction coupling - events that link action potentials on sarcolemma to activation of myofilaments
  3. contraction - muscle fibre develops tension and may shorten
  4. relaxation - stimulation ends
46
Q

length- tension relationship - amount of tension generated by muscle a muscle depends on how stretched or shortened it was before it was stimulated

A

MHS1102 - Anatomy and physiology 2 (3 decks)

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