L9/10- Skeletal muscle

Question 1

function of skeletal muscle

Answer 1

• To contract and cause movement
• To keep joints stable
• Homeostasis- generate heat

Question 2

structure of skeletal muscle

Answer 2

• Each skeletal muscle fibre is made up of many single cylindrical muscle cells
• Muscle fibres are bundled together to form muscle fascicles
• An individual skeletal muscle may be made up of thousands of muscle fibres bundled together in fasicals
  o Wrapped in a connect tissue covering (fascia)

Question 3

what covers muscle fasicles

Answer 3

fascia- loose connective tissue

Question 4

connective tissue which covers skeletal muscle

Answer 4

1) epimysium
2) perimysium
3) endomysium

Question 5

1. Epimysium:

Answer 5

wraps each muscle, providing structural support, maintaining structural integrity (connective tissue). Also separates muscle from other tissues

Question 6

2. Perimysium:

Answer 6

separates muscle fascicles-organising individual muscle fibres which form muscles

Question 7

3. Endomysium:

Answer 7

inside each fascicle, each muscle fibre is encased in a thin connective tissue layer of collagen and reticular fibres. Contains nutrients to support the muscle fibre- supplied by blood vessels

Question 8

muscles are attached to bone via

Answer 8

tendons

Question 9

movement is dependent on the

Answer 9

direction of muscle fibre contraction

Question 10

point of origin

Answer 10

• is the attachment site that doesn’t move during contraction
• Usually proximal (closer to the body)

Question 11

point of insertion

Answer 11

• the attachment site that does move when the muscle contracts
• Usually distal (further away from the body)

Question 12

skeletal muscles are well supplies with blood vessels for

Answer 12

for nourishment (glucose) , oxygen delivery (for respiration- ATP) and waste removal (lactic acid).

Question 13

somatic motor neurones signal

Answer 13

fibres to contract

- nervous impulse from somatic NS

Question 14

thin muscle fibres require

Answer 14

less blood supply

Question 15

thick muscle fibres require

Answer 15

more blood supply

Question 16

three types of striated muscle

Answer 16

• slow twitch
• intermediate
• fast twitch

Question 17

what type of muscle is slow twitch

Answer 17

type 1

Question 18

what type of muscle is intermediate

Answer 18

type 2A

Question 19

type of muscle is fast twitch

Answer 19

type 2B

Question 20

what type of respiration does slow twitch (T1) muscle do

Answer 20

aerobic

Question 21

what type of respiration does fast twitch (T2A) muscle do?

Answer 21

anaerobic

Question 22

what type of respiration does intermediate muscle do?

Answer 22

aerobic

Question 23

slow twitch features

Answer 23

o Rich capillary supply
o Fatty acids- lots of ATP/CO2
o Aerobic- lots of myoglobin to provide oxygen – red
o Many mitochondria
o Many cytochromes
o Fatigue resistant
o Endurance type activities, standing and walking

Question 24

intermediate features

Answer 24

o	Rich capillary supply
o	Fatty acids and glycogen- lactase
o	Aerobic
o	High myoglobin- red to pink
o	Many intermediate mitochondrial numbers
o	Many cytochromes
o	Moderate fatigue resistant
o	Standing/walking- assist type 1 and 2B activities

Question 25

fast twitch features

Answer 25

``` o Poor capillary supply o Glycogen- lactate/little ATP o Anaerobic o Low myoglobin levels (white) o Few mitochondria and cytochromes o Rapidly fatigues o Strength and anaerobic type activities o Sprinting etc ```

Question 26

what is produced in fast witch fibres

Answer 26

lactate - no oxidative phosphorylation and only small production of ATP - insufficient oxygen supply

Question 27

colour of slow twitch

Answer 27

red (myoglobin)

Question 28

why does slow twitch need myoglobin

Answer 28

in constant need of oxygen- sustained exercise e.g. endurance

Question 29

colour of intermediate

Answer 29

pink (some myoglobin)

Question 30

colour of fast twitch

Answer 30

white

Question 31

extrinsic muscle

Answer 31

have insertions in bone or cartilage e.g. protruding the tongue, retracting is and moving it from side to side

Question 32

intrinsic muscle

Answer 32

Not attached to bone- attached to other muscle. e.g. allows the tongue to change shape but not position- aids swallowing

Question 33

skeletal muscle is

Answer 33

striated

Question 34

Innervation of skeletal muscle- Neuromuscular junctions (NMJs)

Answer 34

- Small terminal swellings of the axon which contain Ach o Nerve impulses release acetylcholine o Ach binds to receptors on the sarcolemma and initiated AP to be propagated along the muscle (T-tubule- deep into the muscle)

Question 35

myasthenia graves is what type of disease

Answer 35

autoimmune

Question 36

in myasthenia gravis antibodies are directed against

Answer 36

ACh receptor | - blocking it

Question 37

30% reduction in receptor number

Answer 37

sufficient for symptoms - endplate invaginations reduced - reduced synaptic transmission

Question 38

what does myasthenia gravis cause

Answer 38

intermittent muscle weakness