synapses

Question 1

what are the main structures of an excitatory synapse

Answer 1

mitochondria, synaptic vesicle of neurotransmitter, calcium channel, neurotransmitter re-uptake pump, auto receptor, synaptic cleft, neurotransmitter receptor

Question 2

type of neurotransmitters

Answer 2

Acetylcholine (ACh) which is used in the voluntary and parasympathetic nervous systems. it is broken down by acetylcholinesterase

Question 3

why does a synapse have mitochondria

Answer 3

• energy is required for the active transport of sodium and chloride ions back out of the membrane
• energy is also required to resynthasise Acetylcholine.

Question 4

explain the process of a synapse transmitting an impulse across a cleft.

Answer 4

1. action potential arrives at axon terminal
2. voltage-gated Ca2+ channels open
3. Ca2+ enters the cell
4. Ca2+ signals to vesicle
5. vesicles move to the membrane and binds to docking protein
6. docked vesicle release neurotransmitter by exocytosis which requires energy
7. neurotransmitter diffuses across the synaptic cleft and binds to receptors

Question 5

what does unidirectional mean

Answer 5

signal crosses the synapse only in one direction

Question 6

what is summation

Answer 6

a number of weak stimuli added together to lead to the generation of a new impulse

Question 7

temporal summation

Answer 7

repeated stimulation of the same synapse

Question 8

spatial summation

Answer 8

where a number of synapses are stimulated at the same time

Question 9

agonistic chemicals

Answer 9

these are drugs which mimic the neurotransmitter as they are the same shape and then enhance the effect of the neurotransmitter

Question 10

antagonistic chemicals

Answer 10

fit into protein receptors on the post-synaptic membrane and stop the neurotransmitter fro binding, this blocks the synapse and prevents an action potential being generated.