Nerve Transmission

Question 1

Nerve Impulse

Answer 1

weak electric current, like a wave

Question 2

Steps of Action Potential

Answer 2

Resting Potential, Depolarization, Repolarization, Return to Rest Potential

Question 3

Resting Potential

Answer 3

No message is sent
-70 millivolts
Sodium and Potassium channels are closed
Ions are not moving

Question 4

Depolarization

Answer 4

Switch charges in/out of cell
Threshold stimulus is reached -55 milivolts
Na+ channels open and Na+ moves into the cell
-Na+ moves into cells (inside postivie as Na+ enters) (outside becomes negative)

Question 5

Repolarization

Answer 5

Reset nerve cell tube negative inside
Membrane potential = +40mv
Na+ channels close
K+ channels open and K+ moves out of the cell
Positive potassium leaves cell

Question 6

Return to Resting Potential

Answer 6

Membrane potential = -70mv
Sodium and potassium channels are closed
Ions are not moving through ion channels
Na+/K+ pump - moves 3 Na+ out and 2 K+ into go to resting potential

Question 7

Action Potential

Answer 7

Causes a local bioelectric current that stimulates the membrane

Question 8

Propagation

Answer 8

Wave of action potentials travel the length of the axon as a nerve impulse

Question 9

Factors that Affect Propagation

Answer 9

Speed is proportional to the size of the axon
Greater diameter = faster impulse
Myelinated axons conduct impulses faster than unmyelinated ones