Lecture 7

Question 1

Critical threshold

Answer 1

-55mv,
once it reaches threshold, the action potential will fire ( all or nothing)

Question 2

3 phases of action potential

Answer 2

1. Rising
2. Falling
3. After-hyperpolarization

Question 3

Rising Phase

Answer 3

Voltage gated Na+ channel opens up and Na ion flows into the cell
Depolarization
very fast to open and close
peak at 30mv

Question 4

Falling Phase

Answer 4

voltage gated K channel opens up and K ion flows OUT of the cell
It repolarizes the cell making it more negative.
Slow to open and Slow to close resulting in after hyperpolarization

Question 5

After Hyperpolarization

Answer 5

The voltage gated K + channels are slow to close, goes below the resting membrane potential.

Question 6

Na + Channel

Answer 6

Has an activation and inactivation gate.
At rest: Activation gate is closed.
activation gate opens, and Na enters the cell
inactivation gate closes while K channel opens
Na+ channel gates reset to original position

Question 7

Refractory period

Answer 7

absolute refractory period: second aciton potential cannot be triggered
relative refractory period : larger than normal stimular is required to trigger another action potential. (after hyperpolarization phase)

Question 8

Factors influencing the conduction speed of action potential

Answer 8

Axon diameter : bigger -> less resistance
saltatory conduction : myelinated section vs node of Ranvier

Question 9

Saltatory conduction

Answer 9

myelinated section : faster than unmyelinated with fewer voltage gated channel
Node of Ranvier: bare section :

Question 10

Inotropic receptor

Answer 10

related to ion gates

Question 11

Metabotropic

Answer 11

Change in structure, linked with second messenger system and indirectly alter ion channels

Question 12

EPSP

Answer 12

Graded potential resulting in depolarization brings closer to -55mv

Question 13

IPSP

Answer 13

Graded potential resulting in hyper polarization
More negative
gaba neurotransmitter

Question 14

Spatial vs temporal summation

Answer 14

Spatial : space ( how many neuron fire at once)
temporatl: time ( how often does one neuron fire )

Question 15

Neurotransmitters and their receptors

Answer 15

Cholinergic receptor with ACh (nicotinic/muscarinic)
Glutamatergic receptor with Glutamate (AMPA/ NMDA)
GABA-ergic receptor with GABA

Question 16

Graded potential vs action potential

Answer 16

Flow of the charge is decreased as distance increased ( Graded)
size of potential is related to the stimulus
flow of the charge is not decreased as distance is increased ( action potential )

Question 17

Where do graded potential occur

Answer 17

Motor end plates
dendrites of interneuron/motoneurons
sensory receptor