Muscle Contraction

Question 1

Dendrites

Answer 1

Receives signals from other cells

Question 2

Cell body

Answer 2

Organizes and keeps the cell functional

Question 3

Cell membrane

Answer 3

Protects the cell

Question 4

Axon hillock

Answer 4

Generates impulse in the neuron

Question 5

Node of Ranvier

Answer 5

Allows diffusion of ions

Question 6

Schwann Cell

Answer 6

Produces the myelin sheath

Question 7

Nucleus

Answer 7

Controls the entire neuron

Question 8

Axon

Answer 8

Transfers signals to other cells and organs

Question 9

Myelin sheath

Answer 9

Increases the speed of the signal

Question 10

Axon terminal

Answer 10

Forms junctions with other cells

Question 11

Muscle contraction

Answer 11

Signal that originate in the CNS are conveyed along nerves (axons) to individual muscle fiber and then along the muscle fiber by electrical activity on the surface of the cells (nerve and muscle) known as Action Potential

Question 12

Steps to Muscle contraction

Answer 12

1) A nerve impulse travels to the neuromuscular junction on a muscle cell. The neuromuscular junction is the point where the axons of the nerve meet with the muscle cell.

2) Ach is released from the axon to receptors located on the sarcolemma

3) The binding Ach causes depolarization of the sarcolemma by opening ion channels and allowing Na+ ions into the muscle cell.

4) Na+ ions diffuse into the muscle fiber and depolarization occurs.

5) Depolarization creates a wave of action potential (electrical current) across the sarcolemma

6) Action potential travels across the sarcolemma and down the T-tubules which triggers the sarcoplasmic reticulum SR to release Ca+

7) As Ca+ levels rise, Ca+ ions bind with Troponin C which removes the blocking action of Tropomyosin from the Actin binding sites (Troponin I).

8) Myosin is now ready to bind with the actin and form cross bridges which begins the contraction process

9) In order to contract, ATP binds to the Myosin

10) ATP is then hydrolyzed (broken down) to ADP and Pi, which gives the myosin energy to “cock” its head to the high-energy position.

11) The myosin heads then pull the actin filaments inward and release the ADP and Pi .

12) The myosin is now ready for more ATP to bind and repeat the cycle. This process will continue for as long as there are Ca+ ions and ATP available.