Synaptic Transmission

Question 1

What is synaptic transmission?

Answer 1

When messages between neurones are transmitted chemically across a synapse.

Question 2

What are neurotransmitters?

Answer 2

• A chemical messenger which can trigger an electrical impulse
• They are very fast and have immediate effects
• Neurones are specific to one neurone

Question 3

Process of synaptic transmission

Answer 3

1. An action potential travels down the axon and triggers the synaptic vesicle to release neurotransmitters
2. Neurotransmitters then chemically diffuse across the synapse and bind to receptor sites of the post-synaptic neurone
3. Neurotransmitters that do not bind to the receptor sites are reabsorbed by the presynaptic neurone. Any leftover neurotransmitters are broken down by enzymes

Question 4

6 features of a neurone

Answer 4

• Dendrites: protrudes from the cell body and takes messages to the neurone
• Cell Body: contains the nucleus of the cell which contains genetic material
• Axon: carries impulses away from the cell across the entire neurone (action potential)
• Node of Ranvier: impulse to jump across which speed up transmission
• Synapse: communicates with the next neurone in the chain
• Myelin Sheath: a fatty layer which helps speed up the transmission of electrical impulses

Question 5

6 features of a neurone

Answer 5

• Dendrites: protrudes from the cell body and takes messages to the neurone
• Cell Body: contains the nucleus of the cell which contains genetic material
• Axon: carries impulses away from the cell across the entire neurone (action potential)
• Node of Ranvier: impulse to jump across which speed up transmission
• Synapse: communicates with the next neurone in the chain
• Myelin Sheath: a fatty layer which helps speed up the transmission of electrical impulses

Question 6

3 examples of neurotransmitters

Answer 6

• Adrenaline (fight or flight): increases heart rate and blood flow
• Gaba (calming): calms firing nerves in the CNS
• Dopamine (pleasure): feelings of pleasure, addiction, movement, motivation

Question 7

Excitatory Neurotransmitters

Answer 7

• Create a positive charge in the post-synaptic neurone
• creates excitatory post-synaptic potential (EPSP)

Question 8

Inhibitory Neurotransmitters

Answer 8

• Quiets down signals by having a negative charge
• creates inhibitory post-synaptic potential (IPSP)
• filters out unnecessary excitatory signals

Question 9

Summation

Answer 9

• A nerve cell can receive both EPSPs and IPSPs
• the likelihood of a cell firing is therefore determined by calculating the difference between the excitatory and inhibitory input
• net effect has to be excitatory