Steps of Muscle Twitch

Question 1

3 Periods of Muscle Contraction

Answer 1

Latent, contraction, relaxation

Question 2

1.

Answer 2

Somatic motor neuron action potential

Question 3

2.

Answer 3

Voltage-gated Ca2+ channels open

Question 4

3.

Answer 4

Ca2+ induces vesicle exocytosis

Question 5

4.

Answer 5

ACh released in synapse (NMJ)

Question 6

5.

Answer 6

ACh binds to motor end plate nicotinic receptors

Question 7

6.

Answer 7

Muscle cell depolarizes

Question 8

7.

Answer 8

Action potential travels along sarcolemma

Question 9

8.

Answer 9

Action potential travels spread down t-tubles

Question 10

9.

Answer 10

DHP channels change shape

Question 11

10.

Answer 11

RyR channels in SR open

Question 12

11.

Answer 12

Ca2+ enters sarcoplasm

Question 13

12.

Answer 13

Ca2+ bind to troponin

Question 14

13.

Answer 14

Tropomyosin is shifted off of binding sites

Question 15

Steps 1-13

Answer 15

Latent Period

Between motor neuron AP and force

Question 16

14.

Answer 16

Myosin heads attach to actin

Question 17

15.

Answer 17

Myosin uses ATP to bend at hinge

Question 18

16.

Answer 18

Actin pulled towards M-line

Question 19

17.

Answer 19

Sarcomere shortens

Question 20

Steps 14-17

Answer 20

Contraction period

Force being produced

Question 21

18.

Answer 21

RyR channels close + ACh broken down in NMJ

Question 22

19.

Answer 22

Ca2+ actively pumped into SR

Question 23

20.

Answer 23

Ca2+ pops off of troponin

Question 24

21.

Answer 24

Tropomyosin re-covers binding sites on actin

Question 25

22.

Answer 25

Sarcomere returns to resting length due to elasticity

Question 26

Step 18-22

Answer 26

Relaxation period

Force reducing