Dr. KO lecture 2

Question 1

Electrical signals (receptor potential, synaptic potential and action potential) are all caused by transient changes in the (blank), that drives the electrical potential across the plasma membrane away of its resting condition.

Answer 1

current flow into and out of the membrane

Question 2

Stimuli that elicit an action potential are (blank)

Answer 2

suprathreshold

Question 3

Action potentials are (nearly) (blank) of the stimulus.

Answer 3

independent

Question 4

WHen you inject a negative charge into a cell you will get what?
how bout a positive?

Answer 4

hypepolarization

depolarization

Question 5

The resting potential is set by the K+ (blank) channels.

Answer 5

leak

Question 6

When s the refractory period?

Answer 6

From peak to resting potential

Question 7

(blank) affects the nervous system in such a way as to prevent the propagation of nerve impulses.

Answer 7

Tetrodotoxin

Question 8

Describe difference between absolute refractory period and relative refractory period

Answer 8

Absolute; all Na+ channels are close, nothing can activate them to create action potential
Relative, some Na+ channels are closed and others are open, a very strong stimulus can create action potential

Question 9

premature contraction in the heart is an example of a stimulus being so big it messes with allows the (blank) to create an action potential.

Answer 9

relative refractory

Question 10

What size cells conduct faster?

Answer 10

larger cells

Question 11

The rate of conduction depends on?

Answer 11

number of open Na channels, amount of influx of Na, cell size (larger is better),

Question 12

The speed of conduction depends on?

Answer 12

1. Electrical resistance of the plasma membrane to current flow.
2. The resistance of the longitudinal path down the inside of the fiber.

Question 13

What can reduce resistance in an axon?

Answer 13

increased diameter

Question 14

In Sequential activation of Neuromuscular Transmission (neuromuscular junction) what happens at the presynaptic cleft.

Answer 14

depolarization induces calcium channels to open which makes ACh get released into synaptic cleft

Question 15

In Sequential activation of Neuromuscular Transmission (neuromuscular junction) what happens at the postsynaptic cleft.

Answer 15

Ach binds to cation channels which create deplorazation and allows Na channels to open and create more depolarization.

Question 16

In Sequential activation of Neuromuscular Transmission (neuromuscular junction) how does calcium get released in the postsynpatic terminal?

Answer 16

Depolarization of muscle cell activates Ca2+ channels which induces CICR (calcium induced calcium release) from ER

Question 17

What do these mess with:
Curare
a-bungarotoxin
Myasthenia gravis-tx

Answer 17

acetylcholine release