Psychology and Sociology

Question 1

What factors are involved in maintaining resting membrane potential?

Answer 1

Na/K+ ATPase and the potassium leak channels

Question 2

Na/K pump

Answer 2

Pumps three sodium out of the cell and two potassium in with the hydrolysis of one ATP molecule

Question 3

Leak channel

Answer 3

channels that are open all the time and allow ions to leak across the membrane according to their gradient there are quite a few potassium leak channels but very few sodium leak channels

Question 4

Cells in resting membrane potential are..

Answer 4

Polarized, negative on the inside and positive on the outside

Question 5

Key proteins in the propagation of action potentials

Answer 5

Voltage gated sodium channels open and let sodium ions flow down their gradient into the cell and depolarize that section of the membrane

Question 6

How are the channels opened?

Answer 6

Threshold potential of approximately -50 mV. Below this, they are closed and do not allow the passage of any ions through the channel. Sodium ions depolarize to 35 mV before inactivating

Question 7

Repolarization Events

Answer 7

1. Voltage gated sodium channels inactivate very quickly until membrane potential nears resting potential values
2. Voltage gated potassium channels open more slowly than the sodium ones and stay open longer
3. potassium leak channels and the pump work to restore resting potential

Question 8

nodes of ranvier

Answer 8

periodic gaps in the myelin sheath that house voltage gated sodium and potassium channels

Question 9

Saltatory conduction

Answer 9

myelin sheath dramatically speeds the movement of action potentials by forcing the action potential to jump from node to node

Question 10

Oligodendrocytes

Answer 10

In CNS- form myelin

Question 11

Astrocytes

Answer 11

In CNS- guide neuronal development, regulate synaptic communication via regulation of neurotransmitter levels

Question 12

Microglia

Answer 12

In CNS- remove dead cells and debris

Question 13

Ependymal Cells

Answer 13

In CNS- produce and circulate cerebrospinal fluid

Question 14

Na equilibrium potential

Answer 14

+50 mV. But if the inside of the cell is too positive the cells are repelled and the electrical gradient would drive them out

Question 15

K equilibrium potential

Answer 15

-90 mV. If the inside of the cell is too negative, they will not be able to leave. the electrical gradient drives potassium in

Question 16

Temporal summation

Answer 16

Presynaptic neuron fires action potentials so rapidly that they just pile on top of one another

Question 17

Spatial summation

Answer 17

all the excitatory and inhibitory potentials are summed at a given moment. If it reaches the threshold potential then an action potential will be fired