Biopsych: neurons and synaptic transmission

Question 1

What is a neuron?

Answer 1

The basic building blocks of the nervous system, neurons are nerve cells that process and transmit messages through electrical and chemical signals

Question 2

What are sensory neurons?

Answer 2

Neurons which carry messages from the PNS to the CNS. They have long dendrites and short axons

Question 3

What are relay neurons?

Answer 3

Neurons which connect the sensory neurons to the motor or other relay neurons. They have short dendrites and short axons

Question 4

What are motor neurons?

Answer 4

Neurons which connect the CNS to effectors such as muscles and glands. They have short dendrites and long axons

Question 5

What are the three types of neurons?

Answer 5

Sensory, motor and relay

Question 6

Describe the cell body (soma)

Answer 6

The soma includes a nucleus, which contains the genetic material of the cell.

Question 7

Describe dendrites

Answer 7

Dendrites protrude from the cell body. They carry nerve impulses from neighbouring neurons towards the cell body

Question 8

Describe the axon

Answer 8

The axon carries impulses away from the cell body down the length of the neuron. It is covered in a fatty layer of myelin sheath

Question 9

Describe myelin sheath

Answer 9

Myelin sheath is a fatty layer that protects the axon and speeds up electrical transmission of the impulse

Question 10

Describe the nodes of ranvier

Answer 10

Gaps which segment the myelin sheath and speed up the transmission of the impulse by forcing it to ‘jump’ across the gaps along the axon

Question 11

Describe terminal buttons

Answer 11

At the end of the axon, they communicate with the next neuron in the chain across a gap known as the synapse

Question 12

What is the charge when a neuron is in resting state?

Answer 12

When a neuron is in a resting state the inside of the cell is negatively charged compared to the outside

Question 13

What happens when a neuron is activated by a stimulus?

Answer 13

The inside of the cell becomes positively charged for a split second causing an action potential to occur

Question 14

What does an action potential create?

Answer 14

An electrical impulse that travels down the axon towards the end of the neuron

Question 15

What groups do neurons communicate with each other within?

Answer 15

Neural networks

Question 16

What is the gap between neurons called?

Answer 16

The synapse

Question 17

What does an electrical impulse reaching the end of the presynaptic terminal trigger?

Answer 17

The release of neurotransmitters from tiny sacs called synaptic vesicles

Question 18

What are neurotransmitters?

Answer 18

Chemicals that diffuse across the synapse to the next neuron in the chain

Question 19

What is a neurotransmitter taken up by once it crosses the gap?

Answer 19

Postsynaptic receptor site on the dendrites of the next neuron

Question 20

What does each neurotransmitter have?

Answer 20

It’s own specific molecular structure that fits perfectly into a postsynaptic receptor site, similar to a lock and key

Question 21

What is synaptic transmission?

Answer 21

The process by which neighbouring neurons communicate with each other by sending chemical messages across the gap (the synapse) that separates them

Question 22

What is excitation?

Answer 22

When a neurotransmitter, such as adrenaline, increases the positive charge of the postsynaptic neuron. This increases the likelihood that the postsynaptic neuron will pass on the electrical impulse

Question 23

What is inhibition?

Answer 23

When a neurotransmitter, such as serotonin, increases the negative charge of the postsynaptic neuron. This decreases the likelihood that the postsynaptic neuron will pass on the electrical impulse.

Question 24

What is summation?

Answer 24

The process by which it is decided whether a postsynaptic neuron fires

Question 25

How do you calculate summation?

Answer 25

The excitatory and inhibitory influences are summed

Question 26

What happens if the net effect on the postsynaptic neuron is inhibitory?

Answer 26

The postsynaptic neuron is less likely to fire

Question 27

What happens if the net effect on the postsynaptic neuron is excitatory?

Answer 27

The postsynaptic neuron is more likely to fire

Question 28

The action potential of the postsynaptic neuron is only triggered if…

Answer 28

The sum of the excitatory and inhibitory signals at any one time reaches the threshold.