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Higher Human Biology > U3: 20- Cells Of The Nervous System And Neurotransmitters At Synapses > Flashcards

U3: 20- Cells Of The Nervous System And Neurotransmitters At Synapses Flashcards

1
Q

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

A
  • nerve cells (neurons)

* glial cells

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2
Q

Name the three types of neuron in the body.

A
  • sensory
  • inter
  • motor
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3
Q

What are the 3 basic parts to the neurons?

A
  • dendrite
  • cell body
  • axon
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4
Q

What is the function of the dendrite?

A

Recieve nerve impulse and pass them towards the cell body

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5
Q

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

A
  • cytoplasm

* nucleus

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6
Q

What is the function of the axon?

A

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

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7
Q

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

A

Myelin sheath

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8
Q

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

A

Myelination

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9
Q

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

A

Unmyelinated fibre

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10
Q

What is the purpose of the myelin sheath?

A

To greatly increase the speed at which nerve impulses pass

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11
Q

Name an autoimmune disease that breaks down the myelin sheath.

A

Multiple sclerosis

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12
Q

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

A

The hypothalamus that controls temperature is not fully myelinated yet

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13
Q

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

A

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

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14
Q

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

A
  • physically support the neurons

* carry out myelination

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15
Q

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

A

Synapse or synaptic cleft

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16
Q

What name is given to the neuron before a synapse?

A

Presynaptic neuron

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17
Q

What name is given to the neuron after a synapse?

A

Postsynaptic neuron

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18
Q

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

A

Neurotransmitter

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19
Q

Name 3 neurotransmitters.

A

Acetylcholine, noradrenaline/norepinephrine, dopamine

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20
Q

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

A

Vesicles

21
Q

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

A

The dendrite of the post synaptic neuron

22
Q

What must happen to a neurotransmitter as soon as it is received by the postsynaptic neuron’s dendrite?

A

It can either be broken down by an enzyme or reabsorbed by the presynaptic neuron and stored in the vesicle for reuse

23
Q

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

A

Mitochondria

24
Q

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

A

Threshold

25
Q

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

A

Subthreshold and the nerve impulse is lost

26
Q

Give an example of when subthreshold might happen.

A

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.

27
Q

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?

A

Summation

28
Q

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

A

Converging neural pathway

29
Q

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

A

Diverging neural pathway

30
Q

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

A

Rods and cones feeding into one optic nerve in the eyes

31
Q

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

A

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.

32
Q

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?

A

Reverberating pathway

33
Q

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

A

Endorphins

34
Q

Under what circumstances would endorphins be released?

A

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

35
Q

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

A

Dopamine

36
Q

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

A

Agonist

37
Q

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?

A

Antagonist

38
Q

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?

A

Inhibitor

39
Q

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?

A

An inhibitor

40
Q

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

A

Ecstasy (MDMA)

41
Q

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

A

Dopamine

42
Q

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

A

Repeated use of an antagonistic drug

43
Q

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

A

They increase in number and become more sensitive

44
Q

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?

A

Sensitisation

45
Q

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?

A

Drug tolerance

46
Q

What drug when overused leads to drug tolerance?

A

Repeated use of agonist drug

47
Q

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

A

The number of receptors decrease and they become less sensitive

48
Q

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

A

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

49
Q

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?

A

Desensitisation

Higher Human Biology (24 decks)

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