neurons + synaptic transmission (AO1 only)

Question 1

What are neurons?

Answer 1

nerve cells that transmit messages through electrical and chemical signals

Question 2

draw and label a neuron

Question 3

what is the soma (cell body)?

Answer 3

• includes a nucleus with all the genetic information.
• takes all the information from the dendrites, and puts it together in a place called the axon hillock.

Question 4

what are dendrites?

Answer 4

• branch like structures - from the cell body.
• pick up messages from other neurons and send them to the cell body.

Question 5

what is the axon?

Answer 5

carries messages away from the cell body. It can be very long.

Question 6

what is the myelin sheath?

Answer 6

• covers the axon to preserve the message and speeds up electrical transmission of the signals.

Question 7

What are the nodes of ranvier?

Answer 7

gaps in the myelin sheath which help in speeding up the transmission of the nerve.

Question 8

What are axon terminals?

Answer 8

end of the axon are terminal buttons that communicate with the next neuron

Question 9

what is an action potential?

Answer 9

• If a signal coming from the dendrites is great enough, an action potential occurs, and the signal travels past the axon hillock and down the axon to the next neuron.
  -an explosion of electrical activity.
• occurs when a neuron sends information down an axon, away from the cell body.

Question 10

what is the sensory neurons function and fibre length?

Answer 10

PNS –> CNS
long dendrites, short axon

Question 11

what is the motor neurons function and fibre length?

Answer 11

CNS –> PNS
short dendrites, long axon

Question 12

relay neuron

Answer 12

sends information between neurons
(transfers messages from sensory neurons to other interconnecting neurons or motor neurons)

Question 13

what are neurotransmitters?

Answer 13

chemicals that are released from a synaptic vesicle into the synapse by neurons.

Question 14

what is the process of synaptic transmission?

Answer 14

1. nerve impulse travels down an axon
2. nerve impulse reaches synaptic terminal
3. this triggers the release of neurotransmitters
4. the neurotransmitters are fired into the synaptic gap
5. neurotransmitter binds with receptors on the dendrite of the
   adjacent neuron
6. if successfully transmitted the neurotransmitter is taken up by the post-synaptic neuron
7. the message will continue to be passed in this way via electrical impulses

Question 15

What are excitatory neurotransmitters?

Answer 15

trigger nerve impulses in the receiving neuron (excite) and stimulate the brain into action. e.g. dopamine

Question 16

What are inhibitory neurotransmitters?

Answer 16

These inhibit nerve impulses in order to calm the brain so each neuron is calmed or inhibited when enough serotonin is flowing. e.g. serotonin