Muscle Physiology

Question 1

What is isotonic concentric contraction

Answer 1

Muscles shorten (lift object)

Question 2

What is isotonic eccentric contraction

Answer 2

Muscles lengthens (put object down)

Question 3

What is isometric contraction

Answer 3

Stays the same length (holding something, posture or wall sit)

Question 4

What events happen at the Neuromuscular junction

Answer 4

1) v. gated calcium ch. open
2) calcium triggers exocytosis of synaptic vesicles
3) acetylcholine diffuses across cleft
4) Acetylcholine brings to ligand gated ch.
5) sodium enters and depolarizes cell to threshold
6) AP is generated along sarcolemma
7) Acetylcholinesterase removes acetylcholine to stop signal

Question 5

What happens in excitation- contraction coupling

Answer 5

1) AP travels across sarcolemma
2) Opens v. gated ca2+ ch.
3) calcium binds troponin
4) troponin changes shape, moves tropomyosin, now the myosin binding cites on actin are exposed
5) calcium is slowly pumped back in

Question 6

What is the cross bridge cycle

Answer 6

1) Myosin head binds actin *crossbridge
2) myosin pulls on actin *powerstroke shortens sarcomere causing contraction
3) ATP binds release myosin from actin
4) Atp split provides E to recock head ready for another power stoke