U3: 20- 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 3 basic parts to the neurons?

Answer 3

• dendrite
• cell body
• axon

Question 4

What is the function of the dendrite?

Answer 4

Recieve 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

• physically support the neurons

* 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 nerve?

Answer 15

Synapse or synaptic cleft

Question 16

What name is given to the neuron before a synapse?

Answer 16

Presynaptic neuron

Question 17

What name is given to the neuron after a synapse?

Answer 17

Postsynaptic neuron

Question 18

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

Answer 18

Neurotransmitter

Question 19

Name 3 neurotransmitters.

Answer 19

Acetylcholine, noradrenaline/norepinephrine, dopamine

Question 20

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

Answer 20

Vesicles

Question 21

As soon as a neurotransmitter 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 a neurotransmitter as soon as it is received by the postsynaptic neuron’s dendrite?

Answer 22

It can either be broken down by an enzyme or 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

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

Answer 24

Threshold

Question 25

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

Answer 25

Subthreshold and the nerve impulse is lost

Question 26

Give an example of when subthreshold might happen.

Answer 26

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 27

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 27

Summation

Question 28

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

Answer 28

Converging neural pathway

Question 29

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

Answer 29

Diverging neural pathway

Question 30

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

Answer 30

Rods and cones feeding into one optic nerve in the eyes

Question 31

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

Answer 31

Fine motor control in 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 32

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 stimulate the presynaptic neurons?

Answer 32

Reverberating pathway

Question 33

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

Answer 33

Endorphins

Question 34

Under what circumstances would endorphins be released?

Answer 34

In response to physical and emotional stress, severe injury, lengthy periods of exercise, certain foodstuffs such as chocolate

Question 35

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

Answer 35

Dopamine

Question 36

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

Answer 36

Agonist

Question 37

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 impulse?

Answer 37

Antagonist

Question 38

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

Answer 38

Inhibitor

Question 39

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 it's effect, what type of drug is it?

Answer 39

An inhibitor

Question 40

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

Answer 40

Ecstasy (MDMA)

Question 41

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

Answer 41

Dopamine

Question 42

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

Answer 42

Repeated use of an antagonistic drug

Question 43

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

Answer 43

They increase in number and become more sensitive

Question 44

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 44

Sensitisation

Question 45

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

Answer 45

Drug tolerance

Question 46

What drug when overused leads to drug tolerance?

Answer 46

Repeated use of agonist drug

Question 47

Repeated use of an agonistic drug has an effect on the receptors of a postsynaptic neuron. What effect does it cause?

Answer 47

The number of receptors decrease and they become less sensitive

Question 48

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

Answer 48

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

Question 49

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

Answer 49

Desensitisation