Neurobiology and Immunology: The Cells of the Nervous System and Neurotransmitters at Synapses

Question 1

Neurons are what?

Answer 1

Nerve cells

Question 2

Neurons have what?

Answer 2

A cell body and fibres called dendrites and axons

Question 3

Axons are surrounded by what? What does this do?

Answer 3

Myelin Sheath.

It insulates the axon and increases the speed of impulse conduction.

Question 4

Myelination continues from when to when?

Answer 4

Birth to adolescence

Question 5

Response to stimuli in the first two years of life are what?

Answer 5

Not as rapid or coordinated as those of an older child or adult

Question 6

Certain diseases can do what?

Answer 6

Destroy the myelin sheath causing a loss of coordination

Question 7

Glial cells produce and do what?

Answer 7

Myelin sheath.

Physically support Neurons.

Question 8

Synapses are what?

Answer 8

Gaps between neurons

Question 9

Neurons connect with other neurons or muscle fibres where?

Answer 9

At a synapse

Question 10

Neurotransmitters relay impulses across what?

Answer 10

The synaptic cleft

Question 11

Where are neurotransmitters stored?

Answer 11

In synaptic vesicles in the axon endings of the pre-synaptic neuron

Question 12

Neurotransmitters do what on arrival of an electrical impulse?

Answer 12

Are released into the synaptic cleft

Question 13

Neurotransmitters do what next?

Answer 13

Diffuse across the synaptic cleft and bind to receptors on the membrane of the post-synaptic neuron

Question 14

What happens to neurotransmitters after diffusion?

Answer 14

They are removed by enzymes or reuptake to prevent continuous stimulation of post-synaptic neurons

Question 15

Receptors do what?

Answer 15

Determine whether the signal is excitatory or inhibitory

Question 16

Synapses can do what?

Answer 16

Filter out weak stimuli arising from insufficient secretion of neurotransmitters

Question 17

A minimum number of neurotransmitter molecules must attach to receptors in order to reach the threshold on the post-synaptic membrane in order for what to happen?

Answer 17

An impulse to be transmitted

Question 18

What can release enough neurotransmitter to trigger an impulse?

Answer 18

Summation of a series of weak stimuli

Question 19

Converging neural pathways can do what?

Answer 19

Release enough neurotransmitter molecules to reach threshold and trigger an impulse

Question 20

What are endorphins?

Answer 20

Neurotransmitters that stimulate neurons involved in reducing the intensity of pain

Question 21

Endorphins production increases in response to what?

Answer 21

Severe injury, prolonged and continuous exercise, stress and certain foods

Question 22

Increased levels of endorphins are also linked to what?

Answer 22

The feelings of pleasure obtained from activities such as eating, sex and prolonged exercise

Question 23

What is dopamine?

Answer 23

It is a neurotransmitter that induces feelings of pleasure and reinforces particular behaviour by activating the reward pathway in the brain

Question 24

What does the reward pathway involve?

Answer 24

Neurons which secrete or respond to dopamine

Question 25

When is the reward pathway activated?

Answer 25

When an individual engages in a behaviour that is beneficial to them, such as eating when hungry

Question 26

What are many drugs used to treat neurotransmitter-related disorders?

Answer 26

Agonists or antagonists

Question 27

What are agonists?

Answer 27

They are chemicals that bind to and stimulate specific receptors, mimicking the action of a neurotransmitter at a synapse

Question 28

What are antagonists?

Answer 28

Antagonists are chemicals that bind to specific receptors blocking the action of a neurotransmitter at a synapse

Question 29

How do other drugs act?

Answer 29

They inhibit the enzymes that degrade neurotransmitters or inhibit reuptake of the neurotransmitter at the synapse causing an enhanced effect

Question 30

What can recreational drugs do?

Answer 30

Act as agonists or antagonists

Question 31

What do recreational drugs do?

Answer 31

Affect neurotransmission at synapses in the brain altering an individual’s mood, cognition, perception and behaviour.

Question 32

Many recreational drugs can also affect what?

Answer 32

Neurotransmission in the reward pathway of the brain

Question 33

Drug addiction is caused by what?

Answer 33

Repeated use of drugs that act as antagonists

Question 34

Antagonists block specific receptors, causing the nervous system to increase both the number and sensitivity of these receptors. What does this lead to?

Answer 34

This sensitisation leads to addiction where the individual craves more of the drug

Question 35

Drug tolerance is caused by what?

Answer 35

The repeated use of drugs that act as agonists

Question 36

Agonists stimulate specific receptors, causing the nervous system to decrease both the number and sensitivity of these receptors. What does this lead to?

Answer 36

This desensitisation leads to drug tolerance whereby the individual must take more of the drug to experience an effect