The structure of neurons and synaptic transmission

Question 1

What is the structure of a neuron?

Answer 1

1. Cell body includes a nucleus which contains all genetic material of the cell
2. Branch like structures called dendrites which project from cell body- carry impulses from other neurons towards the cell body
3. Axon carries impulses away from the cell body down the length of the neuron
4. Axon is covered in a layer of myelin sheath that protects the axon and speeds up electrical impulses
5. Myelin sheath is segmented by gaps called nodes of ranvier- speed up transmission of impulses by forcing it to ‘jump’ across gaps along the axon
6. At end of axon are axon terminal buttons that communicate with the next neuron in the chain across synaptic gap by using neurotransmitters

Question 2

What are the 3 types of neurons?

Answer 2

1. Sensory neuron
2. Relay neuron
3. Motor neuron

Question 3

What does the sensory neuron do?

Answer 3

1. Nerve cells that are activated by sensory input from the environment
2. Carry messages from the PNS to the brain + spinal cord

Question 4

What does the relay neuron do?

Answer 4

Allows sensory and motor neurons to communicate with each other

Question 5

What does the motor neuron do?

Answer 5

1. Cells in the brain that allow us to move, speak, swallow and breathe by sending commands from the brain to the muscles that carry out these functions
2. Carries messages from CNS to effectors (glands/ muscles)

Question 6

What is the process of synaptic transmission?

Answer 6

1. A message is picked up by a dendrite and sends the action potential to terminal buttons
2. The action potential needs to be transferred by crossing a synaptic gap between a pre and post synaptic neuron
3. Neurotransmitters convert electrical impulses to chemical messages
4. Neurotransmitter gets released and crosses a synaptic gap
5. Neurotransmitter binds to specialised receptors
6. Receptor molecules produce an excitatory effect which strengthens the impulses or an inhibitory effect which weakens the impulses at a post synaptic level
7. Synaptic transmission is completed by reuptake

Question 7

What are neurotransmitters?

Answer 7

1. Chemicals that are released from a synaptic vesicle into the synapse by neurons
2. They affect the transfer of an impulse to another nerve or muscle
3. They’re taken back up into the terminal buttons of neurons through re-uptake or are broken down by enzymes

Question 8

What happens if neurotransmitters create excitation of the post synaptic neuron?

Answer 8

1. They create a positive charge and make the neuron more likely to fire
2. This rise in action potential will increase activity

Question 9

What happens if neurotransmitters create inhibition of the post synaptic neuron?

Answer 9

1. They create a negative charge and make the neuron less likely to fire
2. This fall in action potential will decrease activity

Question 10

What are examples of excitatory neurotransmitters?

Answer 10

1. Glutamate
2. Epinephrine
3. Noradrenaline

Question 11

What are examples of inhibitory neurotransmitters?

Answer 11

1. GABA
2. Serotonin