Action Potentials

Question 1

What does the presence of the absolute refractory period prevent? And what does this mean?

Answer 1

The signal going back on itself. It means that when you stimulate an action potential on the membrane, it will always move away from the point of stimulation

Question 2

Where do action potential usually start in an axon?

Answer 2

The axon hillock

Question 3

Where can current loops form in a myelinated neurone?

Answer 3

Node of ranvier

Question 4

What are two advantages of saltatory conduction?

Answer 4

1. Speed
2. Energy efficiency

Question 5

What is the best way to increase the speed of action potential transmission?

Answer 5

Myelination

Question 6

What is a con of myelination?

Answer 6

Myelinated neurones take up more space

Question 7

What is the difference between convergent and divergent systems?

Answer 7

• In convergent systems, the activity of many cells influence the activity of one/few (multiple neurones feed information to a single cell)
• In divergent systems, the activity of one cell influence the activity of many (one cell is going to branch its terminals and they’re going to influence multiple cells)

Question 8

Describe the process of a chemical synapse

Answer 8

Electrical signal in the presynaptic cell gets converted into a chemical signal, and it’s that chemical signal that will then transfer between the cells using the synapse, and that will then induce an electrical signal in the post synaptic cell

Question 9

What is a neurotransmitter?

Answer 9

a chemical messenger which is used for transmitting information from neurons

Question 10

What are some of the ways to get rid of excess neurotransmitters in synaptic clefts?

Answer 10

• they will diffuse and move away
• reuptake of neurotransmitter into the pre-synaptic cell
• enzymes that sit within the synaptic cleft, there to break down the neurotrannsmitter

Question 11

What are some presynaptic factors that effect synaptic effectiveness?

Answer 11

• availability of neurotransmitters
• availability of enzymes
• Calcium ion concentrations
• presynaptic receptors

Question 12

What are some postsynaptic factors that affect synaptic effectiveness?

Answer 12

• immediate history (IPSPs, EPSPs)
• drugs
• disease
• receptor concentrations
• NT concentrations in cleft
• NT agonists/antagonists