Synapses

Question 1

synapse

Answer 1

a junction between 2 nerve cells

types: electrical and chemical

Question 2

electrical synapse

Answer 2

aka gap junction
tight contact between neurons
thin membrane
has low resistance

Question 3

chemical synapse

Answer 3

uses neurotransmitters that are stored in vesicles

Question 4

synaptic cleft

Answer 4

space between 2 neurons

Question 5

neurotransmitter receptors

Answer 5

proteins specialized to detect a specific neurotransmitter in the cleft
change when neurotransmitter binds
types: ionic and metabolic

Question 6

ionic receptors

Answer 6

receptor molecule directly opens ion gates

releases postsynaptic potentials (EPSPs or IPSPs)

Question 7

IPSP

Answer 7

Inhibitory PostSynaptic Potential

produced by opening Cl- gates or opening K+ gates

Question 8

EPSP

Answer 8

Excitatory PostSynaptic Potential

produced by opening Na+ gates

Question 9

ways neurotransmitters are cleared from the synaptic cleft:

Answer 9

degradation via enzymes

re-uptake by transporter molecules

Question 10

metabolic receptors

Answer 10

activate intracellular signals (G-protein)

Question 11

how G-protein activates a response in metabolic receptors

Answer 11

• releases alpha subunit to open ion gates or increase 2nd messenger production (cAMP)
• 2nd messenger changes ion gates or other processes; and control gene activation within neurons via a 3rd messenger (c-fos gene and Fos protein)

Question 12

which type of synapses do humans mostly have?

Answer 12

inhibitory (75%)

Question 13

temporal summation

Answer 13

successive inputs of action potentials

Question 14

spatial summation

Answer 14

neighboring inputs of action potentials

Question 15

presynaptic autoreceptors

Answer 15

detects its own neurotransmitter release
activation inhibits neurotransmitter release (negative feedback loop)
highly sensitive to neurotransmitter of interest
has paradoxical drug effects (low dose has opposite effect of a high dose)

Question 16

presynaptic inhibition

Answer 16

• a 3rd neuron or feedback from the 2nd makes a synapse on the 1st neuron
• 1st neuron is slightly depolarized by neuron 3
• neurotransmitter release is determined by the relative height of the action potential
• “raised floor” (initial potential) lowers the relative height and neurotransmitter release
• temporal signal is sharpened

Question 17

presynaptic facilitation

Answer 17

neuron 3 hyperpolarizes neuron 1 (IPSP)

-lowers “floor,” increases the relative height of the action potential and neurotransmitter release