lecture 6

Question 1

electrical synapses

Answer 1

• CNS and less common
• pass through gap junctions
• bi directional
• synchronizes the activity of network of cells

Question 2

chemical synapses

Answer 2

• more common and both CNS and PNS
• use transmitters that cross synaptic cleft

Question 3

connexon channels

Answer 3

gap junctions have these to allow current to flow passively from presynaptic cell to psynaptic cell

Question 4

why is there a delay in transmission across the chemical synapse?

Answer 4

because of the time necessary for the neurotransmitter to be released, diffuse across the synaptic cleft, and bind with receptors on the postsynaptic membrane

Question 5

desentization

Answer 5

receptor loses sensitivity if overused that is why neurotransmitters need to be terminated

Question 6

neurotransmitter termination: reuptake

Answer 6

neurotransmitter is taken up by presynaptic cell for recycling or transported into glial cells

Question 7

neurotransmitter termination: diffusion

Answer 7

diffuse out of the synaptic cleft

Question 8

neurotransmitter termination: degradation

Answer 8

enzymes are present in and around the synapse which degrade the neurotransmitter

Question 9

divergence

Answer 9

one presynaptic neuron branches to affect a larger number of postsynaptic neurons

Question 10

convergent

Answer 10

many presynaptic neurons provide input to influence a smaller number of post synaptic neurons

Question 11

synaptic plasticity

Answer 11

• a change of activity at the synapses
• occurs primarily in the CNS
• may be short-term or long-term
• may be enhance or reduce synaptic activity

Question 12

spatial summation

Answer 12

when two or more neurons simultaneously fire and have an additive effect

Question 13

temporal summation

Answer 13

summation occurs when graded potentials overlap in time and has a additive effect

Question 14

synaptic inhibition

Answer 14

one inhibitory post synaptic potential sums with two excitatory post synaptic potentials to prevent an action potential in the post synaptic cell

Question 15

presynaptic facilitation

Answer 15

favors the release of neurotransmitters. input from an IESP neuron increases neurontransmitter release by the presynaptic cell

Question 16

presynaptic inhibition

Answer 16

prevents the release of neurotransmitters. The modulation of a neuron decreases its neurotransmitter release

Question 17

chemical synapses are capable of undergoing..

Answer 17

• plastic changes
• occurs in the CNS

Question 18

short term plasticity

Answer 18

enhance activity at the synpase (facilitation) or decrease it (depression)

Question 19

long term depression or potentation

Answer 19

changes at the synapse persist for a significant period. important for learning and memory

Question 20

long term potentation

Answer 20

• similar to facilitation
• glutamate is key element. AMPA receptors and NMDA receptors
• disorders of synaptic transmission are responsible for many diseases ( parkinson’s disease, schizophrenia, and depression)