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Flashcards in Physiology Deck (119)
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1

name the physiological functions of skeletal muscle

posture

movement/ respiratory movements

heat production

contributor to whole body metabolism

2

skeletal muscle is striated/non striated and voluntary/ non voluntary

striated and voluntary

3

which nerves innervate skeletal muscle?

somatic nervous system

4

skeletal muscle has _______ initaion of contraction

neurogenic

5

what is the transmitter at the neuromuscular junction of skeletal muscle

Ach

6

skeletal muscle fibres are organised into what?

motor units- single alpha motor neuron

7

muscles that allow for precise movements will have fewer/greater motor fibres per unit than for power?

fewer

8

sort into levels of organisation 1. muscle fibre 2. sarcomere 3. myofibril 4. actin/filamin 5. whole muscle

4. actin/filamin 2. sarcomeres 3. myofibrils 1. muscle fibre 5. whole muscle

9

define functional unit

smallest component capable of performing all the functions of that organ

10

sarcomere is found between what two lines?

Z lines

11

what are the four zones of the sarcomere

A- band

H- zone

M- line

I- band

12

describe the A- band

thick filaments with portions of thin filamwetns that overlap in both ends of thick filaments

13

describe the H- zone

lighter area of the A-band where thin filaments dotn reach

14

describe the M-line

extends vertically down A-band within the centre of H-zone

15

describe I-band

remaining portion of thin filaments that don't project in A-band

16

muscle contraction is caused by what?

actin filaments sliding on myosin filaments

17

force generation of muscle depends on what?

ATP- dependant interaction

18

in skeletal muscle fibres Ca2+ is released from where?

lateral sacs of the sarcoplasmic reticulum

19

the surface action potential of skeletal muscle spreads down what?

the transverse (T)- tubules (extensions of the surface membrane)

20

what allows simultaneous contraction of muscle fibres?

motor units

21

stimulating more motor units to achieve a stronger contraction is known as what?

motor unit recruitment

22

asynchronous motor unit recruitment during submaximal contractions helps prevent what?

muscle fatigue

23

tension developed by each contracting muscle fibre depends on what two things?

frequency of stimulation and summation of contractions

length of muscle fibre

24

the action potential in skeletal muscle is longer than the duration of the resulting twitch true/false

false- the AP is shorter

25

describe single twitch in skeletal muscle

the muscle fibre has completely relaxed before being restimulated

26

with single twitch the second twitch is the same/greater magnitude than the first twitch

same magnitude

27

what happens if a muscle fibre is restimulated before it has completely relaxed?

the second twitch is added to the first resulting in twitch summation

28

what is tetanus?

when a muscle fibre is stimulated so rapidly it doesn't have time to relax between stimuli- maximal sustained contraction

29

what type of muscle cannot be tetanised and why?

cardiac muscle- long refractory period

30

when is maximal tetanic contraction achieved?

when the muscle is at its optimal length before the onset of contraction