The structure and function of sensory, relay, and motor neurons

Question 1

Neurons

Answer 1

Neurons are the cells that make up the nervous system, they are specialized to conduct electrical impulses

Question 2

Sensory neurons

Answer 2

Found in receptors such as the eyes, ears, tongue and skin, and carry nerve impulses to the spinal cord and brain.
Not all sensory neurons reach the brain, some stop at the spinal cord, allowing for quick reflex actions.

Question 3

Relay neuron

Answer 3

Located within the CNS and serves to interconnect different parts of the CNS.

Question 4

Motor neurons

Answer 4

Carry commands from the motor cortex of the brain to the skeletal muscles of the body, allowing for movement.

When motor neurons are stimulated they release neurotransmitters that bind to the receptors on muscles to trigger a response, which lead to movement.

Question 5

Myelin sheath

Answer 5

Sheath/cover that forms around nerves.

Question 6

Central nervous system (CNS)

Answer 6

A major part of the nervous system made up of the brain and spinal cord.

Question 7

Nodes of Ranvier

Answer 7

The gaps in the myelin sheath

Question 8

Action potential/ nerve impulses

Answer 8

Pulses of electrical activity that travels down the axon.

Question 9

Synaptic transmission

Answer 9

The process by which one neuron communicates with another.

Presynaptic neuron - where the signal is initiated

Postsynaptic neuron- neuron that receive the signal

Excitation - when receptor stimulations increases the positive charge of the postsynaptic neuron making it more likely that the neuron fires an action potential

Inhibition - when receptor stimulations results in an increase in the negative charge of the postsynaptic neuron decreasing the likelihood of the neuron firing

Information is passed down the axon as an electrical pulse known as action potential. Once is reaches the axon terminal it excites the presynaptic neuron which then releases neurotransmitters which are chemical messengers stored in synaptic vesicles. Neurotransmitters then carry the signal across the synaptic gaps and once they reach the postsynaptic neuron they bind with receptor sites on the cell. This action can cause excitatory (increasing positive charge and likelihood that it will fire action potential) or inhibitory (increasing negative charge and decreasing the likelihood that it will fire action potential) effects on the postsynaptic cell.

Question 10

Synapse

Answer 10

A tiny gap between two neurons across which nerve impulses are passed.

Question 11

Neurotransmitters

Answer 11

Chemical signals in the presynaptic neuron packaged into small sacs named vesicles.

Question 12

Dendrites

Answer 12

Receives signal from neurons, connected to cell body, contains nucleus

Question 13

Axon

Answer 13

A long slender fibre that carries nerve impulses from the cell body to the axon terminals.

Question 14

Axon terminal

Answer 14

Where the neurons ends. Connects the neurons to other neurons using synaptic transmission