Synapse

Question 1

what happens when an AP reaches the pre-synaptic terminal?

Answer 1

• voltage-gated Ca++ channels open
• influx of Ca++ causes release of NT by regulated exocytosis

Question 2

NT release from the pre-synaptic terminal occurs by ____

Answer 2

regulated exocytosis

Question 3

ligand-gated ion channels can be ____ or ____

Answer 3

excitatory
inhibitory

Question 4

what would make a ligand-gated ion channel excitatory?

Answer 4

Ca++ or Na+ enter the post-synaptic cell = post-synaptic membrane more +/ve

Question 5

what would make a ligand-gated ion channel inhibitory?

Answer 5

K+ leaves or Cl- enters post-synaptic cell = post-synaptic membrane more -/ve

Question 6

what are the actions of metabotropic, second messenger receptors?

Answer 6

• open channel
• activate adenyl cyclase or guanyl cyclase
• activate enzymes
• activate gene transcription

Question 7

metabotropic, second messenger receptors are 75% ____

Answer 7

G-reactive proteins

Question 8

name the 4 characteristics of synapses

Answer 8

1. fatigue
2. post-tetanic facilitation (^Ca++ in pre-synaptic terminal)
3. synaptic delay
4. summation (temporal or spatial)

Question 9

post-tetanic facilitation is thought to be the result of…

Answer 9

build-up of Ca++ in presynaptic terminal

Question 10

summation results in…

Answer 10

increased frequency of firing

Question 11

release of NT at a chemical synapse in the CNS is dependent on…

Answer 11

influx of Ca++ into pre-synaptic terminal

Question 12

activation of a second messenger G-protein system in the post-synaptic neuron would ____ an ion channel

Answer 12

open

Question 13

the excitatory or inhibitory action of a NT is determined by…

Answer 13

function of its post-synaptic receptor

Question 14

at an excitatory synapse, ligand-gated channels are…

Answer 14

opened to allow Na+ into post-synaptic neuron (more +/ve membrane)

Question 15

a NT that selectively opens ligand-gated Cl- channels in the post-synaptic neuron would cause ____

Answer 15

inhibitory post-synaptic potential

Question 16

an input that changes the membrane potential of a target neuron from -65 to -55mV is an…

Answer 16

excitatory post-synaptic potential (+10, more positive)

Question 17

prolonged changes in neuronal activity are usually achieved through activation of ____

Answer 17

G-protein-coupled channels

Question 18

what is the all-or-none principle?

Answer 18

once an AP is initiated, it will always run its course to completion

Question 19

a neuron is “facilitated” when its membrane potential is…

Answer 19

moved in the less negative or depolarizing direction