Lecture 14: Muscular System Cont.

Question 0

Synaptic cleft

Answer 0

Space between axon terminal and target cell

Question 1

Synapse

Answer 1

Consists of axon terminal, target cell, and synaptic cleft

Question 2

Neurotransmitter

Answer 2

Chemical messenger (ligand that binds to receptor)

Question 3

Synaptic vesicles

Answer 3

Carry NTs

Question 4

Acetylcholine (ACh)

Answer 4

NT causes muscle fiber to contract

Question 5

ACh release

Answer 5

Neuron action potential causes exocytosis of ACh into the synaptic cleft

Question 6

ACh receptor activation

Answer 6

ACh bonds to receptors on muscle fibers

Question 7

Muscle action potential

Answer 7

Na+ moves into muscle fiber and thru cell

Question 8

ACh activity termination

Answer 8

Acetylcholinesterase (AChE) breaks down ACh and closes ion channel

Question 9

Excitation-Contraction Coupling

Answer 9

1) Muscle action potential causes Ca ion channels to open and 2) release calcium, which 3) binds to troponin, which shifts tropomyosin off the binding site. 4) ATP stops and the Ca active transport pump brings Ca back into SR.

Question 10

ATP hydrolysis

Answer 10

When ATP is used

Question 11

Cross bridge formation

Answer 11

Myosin head attaches to actin at myosin bonding site

Question 12

Power stroke

Answer 12

Myosin head rotates, releases ATP, pulls actin to M line

Question 13

Myosin detachment

Answer 13

Myosin head detaches once new ATP arrives

Question 14

Contraction cycle

Answer 14

1) cross bridge formation: myosin head attaches to actin at myosin binding site
2) power stroke: myosin head rotates, releases ATP, pulls actin towards M line
3) myosin detachment: myosin head detaches once a new ATP arrives

Question 15

Muscle contraction and relaxation

Answer 15

ACh release
ACh receptor activation
Muscle action potential
ACh activity termination