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Flashcards in Muscle 1 Deck (29):
1

What are the 3 types of muscle?

skeletal, smooth and cardiac

2

Give 2 examples of skeletal muscle.

voluntary muscles, diaphragm

3

Give 2 examples of where you would find smooth muscle.

blood vessels, airways

4

What is a skeletal muscle cell?

a muscle fibre

5

What are skeletal muscle cells formed from in utero? Comment on the nuclei.

multinucleate cells
formed from mononucleate myoblasts

6

What is the repair system of muscle like?

poor. Myoblasts do not replace cells if damaged

7

How can muscle try to repair itself? 2 ways

- cells replaced after injury by satellite cells which differentiate to form new muscle fibres
- other fibres undergo hypertrophy to compensate

8

What are striations in skeletal muscle?

repeating units of structures on muscle fibre myofibrils called sarcomeres

9

What are myofibrils?

clusters of units of many repeating units of sarcomeres inside a muscle cell (fibre)

10

What are myofibrils made up of? (i.e. sarcomeres)

myofilaments such as actin and myosin and titin

11

What is the 'thick filament'?

myosin

12

What is the 'thin' filament?

actin

13

How does the interaction of actin and myosin lead to contraction?

- myosin has lots of 'heads' that are capable of binding to sites on actin to form cross bridges
- myosin binds to actin, pulling on the actin filament, shortening the sarcomere
-ATP binds which causes the myosin head to release the actin
-when the ATP is broken down to ADP and Pi again, the myosin head cocks back into the optimum position to bind to actin again

14

What do troponin and tropomyosin do?

-tropomyosin partially covers the myosin binding site on the actin
-troponin holds the tropomyosin in the blocking position

15

How does the interaction of calcium help contraction?

it binds to the troponin causing it to change shape and move the tropomyosin out of the way so that myosin can bind to actin

16

Where is the calcium stored in the muscle fibre?

in the sarcoplasmic reticulum

17

What is the name given to the plasma membrane of a muscle fibre?

sarcolemma

18

What is a T -tubule?

a deep invagination of the sarcolemma

19

What do T-tubules do?

allow depolarisation of the sarcolemma to quickly reach the inside of the muscle cell to allow for voltage gated control of the calcium channels to mediate contraction

20

What is a motor unit?

a motor neurone and the muscle fibres it innervates

21

What is tension?

force exerted BY muscle

22

What is load?

force exerted ON muscle

23

What is isometric contraction?

contraction with constant length e.g weightlifting

24

What is isotonic contraction?

contraction with shortening length e.g running

25

What is lengthening contraction?

contaraction with increasing length e.g sitting down

26

What is a twitch?

When a muscle fibre is stimulated by a single Action potential to cause a brief contraction

27

What does contraction time depend on?

calcium

28

What is latent period when referring to contraction?

time before excitation contraction starts

29

What is tetanus?

sustained muscle contraction due to repeated stimulation of motor units - twitches summate