U.3 K.A-4 Cells of the Nervous System and Neurotransmitters at Synapses

Question 1

Name the two types of cell that make up the nervous system.

Answer 1

• Nerve cells (neurons)

- Glial cells

Question 2

Name the three types of neuron in the body.

Answer 2

• Sensory
• Inter
• Motor

Question 3

What are the three basic parts to the neurons?

Answer 3

• Dendrite
• Cell body
• Axon

Question 4

What is the function of the dendrite?

Answer 4

Receive nerve impulse and pass them towards the cell body

Question 5

What two parts are found in the cell body of the neuron?

Answer 5

• Cytoplasm

- Nucleus

Question 6

What is the function of the axon?

Answer 6

A single nerve fibre that carries nerve impulses away from the cell body

Question 7

What name is given to the layer of fatty material that surrounds an axon?

Answer 7

Myelin sheath

Question 8

What process lays down the myelin sheath from before birth to adolescence?

Answer 8

Myelination

Question 9

What name is given to a nerve fibre that is lacking a myelin sheath?

Answer 9

Unmyelinated fibre

Question 10

What is the purpose of the myelin sheath?

Answer 10

To greatly increase the speed at which nerve impulses pass

Question 11

Name an autoimmune disease that breaks down the myelin sheath.

Answer 11

Multiple sclerosis

Question 12

Why is a baby unable to regulate their own body temperature until they are about 6 months old?

Answer 12

The hypothalamus that controls temperature is not fully myelinated yet

Question 13

Why are infants not able to control their full lower body until about 2 years old?

Answer 13

The neurons that lead to the lower body are not fully myelinated yet

Question 14

What is the purpose of glial cells in the nervous system?

Answer 14

To physically support the neurons and carry out myelination

Question 15

What name is given to the tiny space between the axon ending of one nerve and the dendrite of the next neuron?

Answer 15

Synapse of synaptic cleft

Question 16

What name is given to the neuron before a synapse?

Answer 16

A presynaptic neuron

Question 17

What name is given to a neuron after a synapse?

Answer 17

A postsynaptic neuron

Question 18

Name the type of chemical messenger relayed across the synapse from neuron to neuron.

Answer 18

Neurotransmitter

Question 19

Name three neurotransmitters.

Answer 19

• Acetylcholine
• Noradrenaline
• Dopamine

Question 20

What structures are found in each synaptic terminal (axon ending) that contain neurotransmitter?

Answer 20

Vesicles

Question 21

As soon as the neurotransmitter acetylcholine is released from the vesicles of the axon ending in the presynaptic neuron, where is it passed to?

Answer 21

The dendrite of the post synaptic neuron

Question 22

What must happen to the neurotransmitter acetylcholine as soon as it is received by the postsynaptic neutrons dendrite?

Answer 22

It must be broken down by an enzyme before being reabsorbed by the presynaptic neuron and stored in the vesicle for reuse.

Question 23

Which organelles present in the axon endings provide the energy ATP for the process of nerve transmission?

Answer 23

Mitochondria

Question 24

Does the neurotransmitter noradrenaline need to be broken down first before being reabsorbed by the presynaptic neuron and stored in the vesicles for reuse?

Answer 24

No, it is reabsorbed straight away after reaching the dendrite of the postsynaptic neuron

Question 25

What name is given to the critical number of neurotransmitter molecules that must be released in order for a nerve impulse to fire?

Answer 25

Threshold

Question 26

If the critical minimum number if neurotransmitter molecules are not reached what do we call this and what happens?

Answer 26

- Subthreshold | - The nerve impulse is lost

Question 27

Give an example of when subthreshold might happen.

Answer 27

If there is continuous low-level hum of machinery in the background, it fails to evoke a response because it is a weak stimuli that does not release enough neurotransmitter. The person ignores the noise.

Question 28

If one presynaptic neuron fires only a little neurotransmitter then threshold might not be reached and the nerve impulse is not transmitted. If, however, several presynaptic neurons all fire a little neurotransmitter each, then the cumulative effect of all of them allow threshold to be reached and the impulse to fire along one postsynaptic neuron. What name is given to the cumulative effect of a series of neurons all bringing about an impulse?

Answer 28

Summation

Question 29

What name is given to a complex neural pathway where several presynaptic neurons feed into one postsynaptic neuron?

Answer 29

Converging neural pathway

Question 30

What name is given to a complex neural pathway where one presynaptic neuron feeds into several postsynaptic neurons?

Answer 30

Diverging neural pathway

Question 31

Given an example of where a converging neural pathway is found in the body.

Answer 31

Rods and cones feeding into one optic nerve in the eyes

Question 32

Give an example of where a diverging neural pathway is found in the body.

Answer 32

- Fine motor control in the hand when operating several fingers at once when using a pen. - Temperature control where several parts of the body are sent messages from one presynaptic nerve in the hypothalamus.

Question 33

What name is given to a complex neural pathway where the axon branch from a neuron later in the pathway joins with a neuron earlier in the pathway and allows a nerve impulse to be recycled and repeatedly stimulated the presynaptic neuron?

Answer 33

Reverberating pathway

Question 34

Name a chemical released by the brain that acts as natural painkiller and blocks the pain receptors stopping the transmission of pain signals.

Answer 34

Endorphins

Question 35

Under what circumstances would endorphins be released?

Answer 35

- In response to physical and emotional stress - Severe injury - Lengthy period of exercise or certain foodstuffs such as chocolate

Question 36

Which neurotransmitter is associated with the brain's reward pathway and induces a pleasurable feeling?

Answer 36

Dopamine

Question 37

What type of drug is used to treat neurotransmitter disorders where this drug mimics the action of a naturally occurring neurotransmitter?

Answer 37

Agonist

Question 38

What type of drug is used to treat neurotransmitter disorders where this drug blocks the receptor sites on the postsynaptic neuron and prevents normal transmission of the nerve impulses?

Answer 38

Antagonist

Question 39

What name is given to drugs that prevent the reuptake of neurotransmitter by the presynaptic neuron so that they spend longer in the synapse and the persistence of this neurotransmitter causes the effect to be continued or enhanced?

Answer 39

Inhibitor

Question 40

If Prozac (a drug for treating depression) is a drug that prevents the reuptake of the neurotransmitter serotonin and keeps it in the synapse for longer and prolongs its effect. What type of drug is it?

Answer 40

An inhibitor

Question 41

Name another drug apart from Prozac, that stops serotonin reuptake and acts as an inhibitor therefore.

Answer 41

Ecstasy (MDMA)

Question 42

What neurotransmitter is prevented from being reabsorbed by the presynaptic neuron when cocaine is used, therefore enhancing its effect on the postsynaptic neuron?

Answer 42

Dopamine

Question 43

What causes drug addiction where a person compulsively seeks out the drug and is incapable of resisting the urge to take it?

Answer 43

Repeated use of an antagonistic drug

Question 44

If an antagonistic drug is repeatedly used, what happens to the number of receptors on the postsynaptic neuron?

Answer 44

They increase in number and become more sensitive

Question 45

What name is given to the process involving an increase in number and sensitivity of receptors as a result of repeated exposure to an antagonistic drug?

Answer 45

Sensitisation

Question 46

What is a drug user said to have built up when their reaction to an addictive drug is found to have decreased in intensity compared with previous times, even though the concentration of the drug is still the same?

Answer 46

Drug tolerance

Question 47

What drug has been overused that leads to drug tolerance?

Answer 47

Repeated use of an agonistic drug

Question 48

Repeated use of an agonist drug has an affect on the receptors of a postsynaptic neuron, what effect doe it cause?

Answer 48

The number of receptors increase and they are now loess sensitive

Question 49

Why does the receptors on the postsynaptic neuron being less sensitive lead to drug tolerance?

Answer 49

A larger dose is now needed to stimulated the reduced number of less sensitive receptors

Question 50

What name is given to the process involving a decrease in number and sensitivity of receptors as a result of repeated exposure to an agonist drug?

Answer 50

Desensitisation