Action Potentials and Synaptic Transmission

Question 1

Define action potential

Answer 1

When a nerve impulse travels down a neurone

Question 2

Define neurone

Answer 2

A cell within the nervous system

Question 3

Define dendrites

Answer 3

Branches on a neurone which collect signals from other neurones

Question 4

Define cell body

Answer 4

Integrates incoming signals and generates outgoing signals to the axon (turns into one big signal)

Question 5

Define axon

Answer 5

Long branch that passes down electrical impulses to the other end, allowing it to communicate with others

Question 6

Define myelin sheath

Answer 6

Provides electrical insulation for the axon and ensures electricity travels in the right direction

Question 7

Define axon hillock

Answer 7

Area that connects the cell body to the axon

Question 8

Define axon terminal

Answer 8

The end of the axon that leads to the terminal buttons

Question 9

Define nodes of ranvier

Answer 9

Gaps between adjacent myelin sheaths

Question 10

Define neurotransmitters and their function

Answer 10

Chemical messengers that act between the neurones in the brain - allows the brain to process thoughts and memories

Question 11

What is the synaptic transmission process?

Answer 11

• Nerve impulses arrive at the axon terminal-pre-synaptic bulb
• Vesicles in thee PSB move to the cell’s edge
• Neurotransmitters are released into the synaptic gap
• Neurotransmitters drift across the synaptic gap and bind with the receptors on the others neurone
• Once they’re bound to thee receptors, the nerve impulse begins again on the second cell

Question 12

What happens to used neurotransmitters?

Answer 12

They’re reuptaken (reabsorbed) into the first cell and are either stored for later use or destroyed by an enzyme

Question 13

What type of system do neurotransmitters fit in?

Answer 13

A lock and key system - receptors are the locks. If a certain chemical fits, the message is passed on. If not, it is blocked.

Question 14

What is the process of action potential?

Answer 14

• Nerve cell will be at its resting membrane potential of -70mV
• When the neurone is stimulated, 3 Na+ ions enter whilst 2 K+ ions leave, causing the voltage to rise to -55mV (depolarisation)
• Once the action potential has been reached at 40mV, the nerve impulse fires and it goes through a proccess of repolarisation
• 3 Na+ ions leave whilst 2 K+ ions enter, making the nerve more polarised
• Once it has been repolarised, there is a refractory period where the nerve is below its resting potential of -70mV

Question 15

Which two things can happen when a neuron gets activated?

Answer 15

Excitatory postsynaptic potential - More likely to fire the charge

Imhibitory postsynaptic potential - Less likely to fire the charge

Question 16

Define vesicle

Answer 16

A tiny sac that contains neurotransmitter chemicals

Question 17

What is the function of the terminal buttons?

Answer 17

They release release neurotransmitters to the next neurone