Synaptic Transmission

Question 1

decreasing the extracellular potassium concentration will result in which o the following changes to resting membrane potential 
A. Become more negative 
B. Become more positive 
C. No change
D. Make it easier to depolarize

Answer 1

A become more negative

Question 2

Lowering restnig membrane potential below the equilibrium potential for potassium will result in which of the following 
A. More potassium will exit the cell
B. Less potassium will exit the cell 
C. There will be no change on potassium 
D. More sodium will enter the cell

Answer 2

??

Question 3

Which of the following would be an appropriate means to slow an AP
A. Reduce sodium permeability during phase 4
B. Increase sodium permeability during phase 3
C. Decrease sodium permeability during phase 0
D. Increase potassium permeability during phase 3

Answer 3

C. phase 0 is depolarization

Question 4

presynaptic cells _____ the signal while postsynaptic cells _____ the signal

Answer 4

presynaptic send the signal

postsynaptic recieve the signal

Question 5

two types of synapses

Answer 5

electrical - fast

Chemical - slower

Question 6

characteristics of electrical synapses

Answer 6

fast
cells have shared cytosol using gap junctions (made up of connexins)
Multidirectional signals

Question 7

characteristics of chemical synapses

Answer 7

slower 
larger synaptic gap >20nm 
unidirectonal signal (some feedback from postsynaptic cell to presynaptic) 
two steps: 
release of chemicals from pre-synaptic
reaction of chemicals by post-synaptic

Question 8

excitatory post-synaptic potential effects on membrane potential

Answer 8

K out and Na in, but not enough to induce AP

Result: membrane potential closer to threshold (hypopolarizing event)

Question 9

inhibitory post-synaptic potential effects on membrane potential

Answer 9

K out of cell or flow of negative charge into cell
Hyperpolarization
Result: membrane potential further away from threshold

Question 10

temporal summation is the same _____ neuron with a _____ signal

Answer 10

same pre-synaptic neuron with a repeated signal

Question 11

spatial summation is the result of ______ pre-synaptic neuron that elicit a response through

Answer 11

different pre-synaptic neurons that elicit a response through signaling together

Question 12

calcium acts as a _______ messenger: an _______ in calcium concentration will result in a _______ ________ ________

Answer 12

secondary messenger

an increase in Ca concentration will result in a greater NT release

Question 13

NT are developed under what two conditions

Answer 13

Derived from food substrates
or
Synthesized in soma of neurons and transmitted to axon terminal in synaptic vesicles

Question 14

criteria of a NT

Answer 14

1) synthesis in pre-synaptic neuron
2) Released in response to pre-synaptic AP
3) Post-synaptic receptors receive signal and respond
4) Inactivation

Question 15

release of NT is a _____ dependent process

Answer 15

calcium: 1/1 ratio

Question 16

NT release is equal to ___ + ____

Answer 16

increase in calcium + increase in AP

Question 17

NT cannot act on its target unless

Answer 17

specific receptors are present on post-synaptic membrane

Question 18

nicotinic

Answer 18

Acetylcholine binding transiently increases permeability to Na and K
Na flows in and depolarizes
something happens postsynaptic (muscle contractions)

Question 19

muscarinic

Answer 19

acetylcholine binding elicites IC response via G proteins
Initiate wider variety of responses
generally slower