Summation and Unidirectionality

Question 1

Why is summation needed?

Answer 1

as some action potentials do not result in sufficient neurotransmitters to result in a new action potential

Question 2

What are the 2 types of summation?

Answer 2

spatial and temporal

Question 3

What is summation?

Answer 3

the rapid build up of neurotransmitters in the synapse (to help generate an action potential by either spatial or temporal summation)

Question 4

What is spatial summation?

Answer 4

where multiple pre-synaptic neurones attach to one synapse and post-synaptic neurone, allowing larger [neurotransmitters] to build up

Question 5

What is temporal summation?

Answer 5

only one neurone attached to the next, and neurotransmitter is released repeatedly

Question 6

How does spatial summation work?

Answer 6

the collective amount of neurotransmitter release by the multiple pre-synaptic neurones trigger an action potential

Question 7

How does temporal summation work?

Answer 7

over time, the amount of neurotransmitters add up, therefore more Na+ ions diffuse in, eventually triggering an action potential

Question 8

Why are synapses unidirectional?

Answer 8

• neurotransmitters only released at pre-synaptic membrane
• complementary receptor sites only found on post-synaptic membrane