CH. 8 Synaptic Transmission and Neural Integration

Question 1

What is an electrical synapse and what are its 5 functions in the nervous system?

Answer 1

two neurons linked together by gap junctions

• rapid communication
• ions or second messengers
• usually bidirectional communication
• excitation and inhibition at the same synapse
• identified in the retina, cortex, brainstem (breathing), and hypothalamus (neuroendocrine neurons)

Question 2

What two things aid signal transduction at chemical synapses?

Answer 2

1. channel-linked receptors: fast change in membrane voltage
2. G-protein-coupled receptors: slow acting

Question 3

What is a postsynaptic potential?

Answer 3

change in membrane potential in response to receptor-neurotransmitter binding

Question 4

What are the two types of postsynaptic potentials?

Answer 4

1. excitatory postsynaptic potential (EPSP) - most common neurotransmitter: glutamate
2. inhibitory postsynaptic potential (IPSP) - most common neurotransmitter: GABA

Question 5

Where do all neurotransmitters originate?

Answer 5

brainstem

Question 6

What are the differences between excitatory vs. inhibitory synapses?

Answer 6

excitatory:

1. more likely to produce an action potential
2. depolarization

inhibitory:

1. less likely to produce an action potential
2. hyperpolarization
3. membrane stabilization

Question 7

What is summation?

Answer 7

the added effects of graded potentials

Question 8

What are the two types of summation?

Answer 8

1. temporal: one synapse through time (increase in tempo)

2. spatial: several synapses at the same time

Question 9

What is frequency coding?

Answer 9

the degree of depolarization at the axon hillock is signaled by the frequency of action potentials

Question 10

What is presynaptic modulation?

Answer 10

the regulation of communication across a synapse

Question 11

How is acetylcholine synthesized and where is it synthesized?

Answer 11

Acetyl CoA + choline - Acetylcholine + CoA

synthesized in axon terminal

Question 12

How is acetylcholine broken down and where does this occur?

Answer 12

Acetylcholine - acetate + choline

occurs in synaptic cleft

Question 13

What are catecholamines (dopamine, norepinephrine, and epinephrine derived from?

Answer 13

tyrosine

Question 14

Where are serotonin and histamine derived from?

Answer 14

serotonin: tryptophan
histamine: histidine

Question 15

What enzymes degrade biogenic amines?

Answer 15

monoamine oxidase and catechol-O-methyltransferase

Question 16

How are biogenic amines synthesized?

Answer 16

in the cytosol of the axon terminal and packaged into synaptic vesicles

Question 17

Where are dopamine and norepinephrine most common?

Answer 17

central nervous system but norepinephrine is also found in peripheral nervous system

Question 18

Where is epinephrine released?

Answer 18

comes from CNS, but more commonly released as a hormone by adrenal medulla

Question 19

What is serotonin and what are its main functions?

Answer 19

it is a CNS neurotransmitter

- regulates sleep and emotions

Question 20

What is histamine?

Answer 20

a CNS neurotransmitter mainly found in the hypothalamus

Question 21

What amino acid neurotransmitters are found at excitatory synapses?

Answer 21

aspartate and glutamate

Question 22

What amino acid neurotransmitters are found at inhibitory synapses?

Answer 22

glycine and GABA

Question 23

What are neuropeptides and what is their purpose?

Answer 23

short chains of amino acids

-modulate responses caused by other neurotransmitters