Signal across a synapse

Question 1

define synapse

Answer 1

connections between neuron and effector

Question 2

define neuromuscular junction

Answer 2

synapse between motor neuron and muscle cell

Question 3

define synaptic cleft

Answer 3

gap between neurons (most of the are not connected directly)

Question 4

Define neurotransmitter

Answer 4

chemical messengers that work between neurons

Question 5

define synaptic vesicle

Answer 5

sac containing neurotransmitter

Question 6

what happens when a signal reaches the end of an axon ?

Answer 6

1. action potential causes synaptic vesicle containing neurotransmitter to fuse
2. neurotransmitter released into cleft by exocytosis
3. neurotransmitters diffuse across synapse and bind to special receptors on postsynaptic membrane
4. ion channels are signaled to open on postsynaptic membrane
5. enzymes break down neurotransmitter

Question 7

what happens in the excitatory neurotransmitters?

Answer 7

• sodium channels are triggered to open
• nerve because depolarized
• if signal is strong enough, action potential is initiated

Question 8

what happens in the inhibitory neurotransmitters?

Answer 8

• signals potassium channels to open, potassium reaches out
• neuron becomes hyperpolarized

Question 9

what is the role of the cell body?

Answer 9

• sometimes a neuron is receiving excitatory and inhibitory signals at the same time
• the cell body helps to sort through the information and send a signal (if strong enough) to the axon

Question 10

What is an acetylcholine

Answer 10

• example of an excitatory neurotransmitter
• excites muscle cell membrane
• causes muscle contraction
• broken down by the enzyme, cholinesterase