Biopsychology: Sensory, Relay and Motor Neurons

Question 1

What are sensory neurons?

Answer 1

• Sensory neurons are 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, as some neurons stop at the spinal cord, allowing for quick reflex actions.

Question 2

What are relay neurons?

Answer 2

• Relay neurons are found between sensory input and motor output/response.
• Relay neurons are found in the brain and spinal cord and allow sensory and motor neurons to communicate.

Question 3

What are motor neurons?

Answer 3

Motor neurons are found in the central nervous system (CNS) and control muscle movements.
-When motor neurons are stimulated they release neurotransmitters that bind to the receptors on muscles to trigger a response, which lead to movement.

Question 4

What are dendrites?

Answer 4

• The dendrites receive signals from other neurons or from sensory receptor cells.
• The dendrites are typically connected to the cell body, which is often referred to as the ‘control centre’ of the neuron, as it’s contains the nucleus.

Question 5

What is a axon?

Answer 5

The axon is a long slender fibre that carries nerve impulses, in the form of an electrical signal known as action potential, away from the cell body towards the axon terminals, where the neuron ends.
-Most axons are surrounded by a myelin sheath (except for relay neurons) which insulates the axon so that the electrical impulses travel faster along the axon.

Question 6

What is a axon terminal?

Answer 6

The axon terminal connects the neuron to other neurons (or directly to organs), using a process called synaptic transmission.

Question 7

How is information passed down an axon?

Answer 7

Information is passed down the axon of the neuron as an electrical impulse known as action potential.

Question 8

What happens when information reaches the end of the axon?

Answer 8

Once the action potential reaches the end of the axon it needs to be transferred to another neuron or tissue. It must cross over a gap between the pre-synaptic neuron and post-synaptic neuron – which is known as the synaptic gap.

Question 9

What is synaptic vesicles?

Answer 9

• At the end of the neuron (in the axon terminal) are the synaptic vesicles which contains chemical messengers, known as neurotransmitters.
• When the electrical impulse (action potential) reaches these synaptic vesicles, they release their contents of neurotransmitters.

Question 10

What do neurotransmitters do?

Answer 10

Neurotransmitters then carry the signal across the synaptic gap. They bind to receptor sites on the post-synaptic cell that then become activated.
Once the receptors have been activated, they either produce excitatory or inhibitory effects on the post-synaptic cell.

Question 11

What do excitatory neurotransmitters do?

Answer 11

Excitatory neurotransmitters (e.g. noradrenaline) make the post-synaptic cell more likely to fire

For example, if an excitatory neurotransmitter like noradrenaline binds to the post-synaptic receptors it will cause an electrical charge in the cell membrane which results in an excitatory post-synaptic potential (EPSP), which makes the post-synaptic cell more likely to fire.

Question 12

What do inhibitory neurotransmitters do?

Answer 12

inhibitory neurotransmitters (e.g. GABA) make synaptic cells less likely to fire.

if an inhibitory neurotransmitter like GABA binds to the post-synaptic receptors it will result in an inhibitory post-synaptic potential (IPSP), which makes the post-synaptic cell less likely to fire.

Question 13

What happens if post synaptic cells fire?

Answer 13

causes the transmission of a signal to another neuron

Question 14

What is a myelin sheath and it’s purpose?

Answer 14

a myelin sheath (except for relay neurons) which insulates the axon so that the electrical impulses travel faster along the axon.

Question 15

What is Summation?

Answer 15

Summation is the addition of positive and negative post-synaptic potentials. A nerve cell can receive both positive and negative potentials simultaneously. These potentials are summed and if the net effect on the postsynaptic neuron is inhibitory, the neuron will be less likely to fire, and if the net effect is excitatory, the neuron will be more likely to fire.

Question 16

What is the action potential

Answer 16

An electric signal

Question 17

What is synaptic transmission?

Answer 17

1.Synaptic transmission is the process by which one neuron communicates with another. Information is passed down the axon of the neuron as an electrical impulse known as action potential.
2.Once the action potential reaches the end of the axon it needs to be transferred to another neuron or tissue. It must cross over the synaptic gap between the presynaptic neuron and post-synaptic neuron.
3.At the end of the neuron (in the axon terminal) are the synaptic vesicles, which contain chemical messengers, known as neurotransmitters. When the electrical impulse (action potential) reaches these synaptic vesicles, they release their contents of neurotransmitters.
4.Neurotransmitters then carry the signal across the synaptic gap. They bind to receptor sites on the post-synaptic cell, thereby completing the process of synaptic transmission.

Question 18

What is excitatory post-synaptic potential?

Answer 18

For example, if an excitatory neurotransmitter like noradrenaline binds to the post-synaptic receptors it will cause an electrical charge in the cell membrane which results in an excitatory post-synaptic potential (EPSP), which makes the post-synaptic cell more likely to fire.

Question 19

What is inhibitory post-synaptic potential?

Answer 19

if an inhibitory neurotransmitter like GABA binds to the post-synaptic receptors it will result in an inhibitory post-synaptic potential (IPSP), which makes the post-synaptic cell less likely to fire.