L5 P2

Question 1

Excitation Contraction Coupeling
Arrange the Order of the Following :

A) Ca2+ Entry causes some synaptic vesicles to release their contents (acetylcholine by exocytosis)
B)Action Potential arrives at the axon terminal of motor neurons.
C) Voltage-Gated Ca2+ channels open and Ca2+ enters the axon terminal

D)Acetylcholine a neurotransmitter diffuses across the synaptic cleft and binds to receptors in the sarcolemma

E) Ach effects are terminated by its enzymatic breakdown in the synaptic cleft by acetylcholinesterase.

F) Ach binding opens ion channels that allow simultaneous passage of NA+ into the muscle fiber and K+ out of the muscle fiber.

This is the same as aneural synapse but the exception is: The Specific neurotransmitter ______

Answer 1

1. B) Action potential arrives at the axon terminal of motor neurons
2. C) Voltage-gated Ca2+ channels open and Ca2+ enters the axon terminal
3. A) Ca2+ entry causes some synaptic vesicles to release their contents (acetylcholine by exocytosis)
4. D) Acetylcholine a neurotransmitter diffuses across the synaptic cleft and binds to receptors in the sarcolemma.
5. F) Ach binding opens ion channels that allow simultaneous passage of Na+ into the muscle fiber and K+ out of the muscle fiber.
6. E) ACh effects are terminated by its enzymatic breakdown in the synaptic cleft by acetylcholinesterase.

acetylcholine

Question 2

Explain the process of Local Depolarization in the Neuromuscular junction of the muscle cell.
First ACh binds to _______ this opens ____ ____ ion chenels. Na+ diffuses in then K+ diffuses out, twitch results in the localized changes called _____ _____ ____.

Answer 2

First ACh binds to receptors, this opens chemically gated ion channels. Na+ diffuses in then K+ diffuses out, which results in the localized changes called END PLATE POTENTIAL

Question 3

The series of steps from a neural impulse through the axon terminal of a motor neuron to the propagation of an action potential along a tube before a muscle contraction is called?

Answer 3

Excitation Contraction Coupling

Question 4

What does the SR contain?

Answer 4

Calcium

Question 5

A contraction is the______ of a ____bridge.

Answer 5

formation of a cross

Question 6

in a skeletal muscle, the functional unit of contraction is called

Answer 6

a sarcomere

Question 7

For a Contraction to happen it must be _____ ____ __ ___ ____.
It must generate ande propagate an action potential
There must be a brief rise in intracellular calcium.

Answer 7

stimulated by a nerve ending

Question 8

The local depolarization of the Sarcolema is a result of the Action potential at the synapse. However this does not make the muscles move,
this synapse causes a secondary set of events beginning with

1. the _____ ______ of the Sarcolemma this generates localized change called End Plate Potential. What is an End Plate Potential? it is a _____ _____ that is occurring on a muscle cell.
2. The Generation and Propagation of Action potential:
   Once the membrane reaches the threshold by the end gate potential ____ _____ _____ _____ memebrane. Depolarization occurs and the membrane reaches threshold creating an ____ _____.
3. Repolarization: As the Sarcolemmas action potential propagates it constantly _______ right behind the AP as it goes in and out of the _____ ______.
4. Calcium is _______. This is the End of Excitation Contraction Coupling

Answer 8

local depolarization
action potential
spreading all acorss the

action potential

Repolarizes, T Tubules

Question 9

Sliding FIlament Model

Calacium binds to ________ and removes the blocking action of ______.

The active sites are exposed and are ___ for _____ binding.

The myosin head ______ ATP and becomes ____ and orientated.

myosin head binds to _____ forming a ___ ____

This is the begining of the _______.

Myosin head pivots ______ the thin filament past the thick filament towards the center of the sarcomere known as the _____ _____.

As the myosin head binds ATP the cross-bridge ______from the actin.

Answer 9

Calcium binds to troponin and removes the blocking action of tropomyosin.

Are ready for myosin binding

The myosin head hydrolyzes ATP and becomes energized and orientated.

myosin head binds to actin forming a cross-bridge

This is the beginning of the contraction

Myosin head pivots, pulling the thin fillament past the thick filament towards the center of the sarcomere known as the POWER STROKE.

As the myosin head binds ATP the cross-bridge detaches from the actin