Neurons

Question 1

What are the three types of neurones ?

Answer 1

• Sensory
• Relay
• Motor

Question 2

What is the sensory neuron ?

Answer 2

• Forms part of the PNS (peripheral nervous system)
• They carry nerve impulses from the sensory receptors to the CNS
• Some sensory neurons terminate at the spinal cord
• As the sensory neuron reaches the brain, the impulses become sensations: Vision, heat, pain

Question 3

What is a relay neuron ?

Answer 3

• Located in the brain, spinal cord and visual systems
• Lies between sensory input and motor output
• Allows sensory neurons and motor neurons to communicate with eachother

Question 4

What is a motor neuron ?

Answer 4

• Connects the central nervous system to effectors (muscles and glands)
• From synapses with muscles to control the contractions
• Releases neurotransmitters that bind to receptors and leads to a muscle movement

Question 5

What are the dendrites and axons structure in each of the types of neurons

Answer 5

Sensory = long dendrites and short axons

Relay = short dendrites and axons

Motor neurons = long axons and short dendrites

Question 6

What is a dendrite ?

Answer 6

A short-branched extension of a nerve cell where impulses are received from others cells at synapses and transmit impulses to the cell body

Question 7

What is an axon ?

Answer 7

Portion of a nerve cell that carries nerve impulses away from the cell body

Question 8

What is action potential ?

Answer 8

The travelling information through neurons using electrical signals

Question 9

What are the 4 steps of action potential ?

Answer 9

Step 1 = Action potential has arrived at the terminal button (end of the axon)

Step 2 = Synaptic vesicles in the pre-synaptic neuron contain neurotransmitters (chemical messages)

Step 3 = The action potential causes vesicles to release their neurotransmitters from presynaptic membrane and travel across the synapse

Step 4 = The neurotransmitters then bind to receptors on the post-synaptic membrane

Question 10

What are neurotransmitters ?

Answer 10

• Can be classified as excitatory or inhibitory in the action
• Excitatory neuron firing (provides a positive charge)
• Inhibitory neurotransmitters decrease the likelihood of the neuron firing (provide a negative charge)

Question 11

What is summation ?

Answer 11

• Summation determines whether the neuron will continue to fire
• It is the net effect of influence on the neuron