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Higher Human Bio > 3.4 Cells Of The Nervous System And Neurotransmitters At Synapses > Flashcards

3.4 Cells Of The Nervous System And Neurotransmitters At Synapses Flashcards

1
Q

What are neurons composed of?

A
  • Dendrites
  • A Cell Body
  • Axons
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2
Q

What direction do nerve impulses travel?

A

Dendrite to Cell Body to Axon

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3
Q

What is the cell body?

A
  • Contains a nucleus and cytoplasm
  • Cytoplasm contains a mitochondria to provide energy for impulses and ribosomes which synthesise proteins for the synthesis of neurotransmitters
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4
Q

What is the dendrite?

A

Receives nerve impulses and carries them towards the cell body

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5
Q

What is the axon?

A

Carries nerve impulses away from the cell body

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6
Q

What is the myelin sheath?

A

A layer of fatty material that surrounds the axon that insulates the axon and increases the speed of nerve impulses

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7
Q

What is myelination?

A

Myelination is not complete at birth and it continues until adolescene

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8
Q

What diseases destroy the myelin sheath causing a loss of coordination?

A
  • Polio
  • Multiple Sclerosis (MS)
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9
Q

What do glial cells do?

A
  • Physically support neurons
  • Produce the myelin sheath
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10
Q

What is the area called between an axon of one neuron and the dendrite of another?

A

A synapse

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11
Q

What is the synaptic cleft?

A

The space that separates the plasma membranes of each neuron

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12
Q

What is the presynaptic cleft?

A

The neuron before the synaptic cleft

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13
Q

What is the postsynaptic cleft?

A

The neuron after the synaptic cleft

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14
Q

What are neurotransmitters?

A

Chemicals that pass messages across synaptic clefts

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15
Q

What are two examples of neurotransmitters?

A
  • Acetylcholine
  • Noradrenaline
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16
Q

What is stimulated when a nerve impulse passes through a neuron and reaches the axon?

A

Many vesicles containing neurotransmitters

17
Q

When do neurotransmitters within the vesicles get released into the synaptic cleft?

A

When the vesicles move to and fuse with the membrane at the surface of the axon terminal

18
Q

What happens after neurotransmitters diffuse across the synaptic cleft?

A

They bind to receptor molecules on the dendrites of the next neuron, transmitting the impulse to the next neuron

19
Q

Why should neurotransmitters be rapidly removed as soon as the impulse has been transmitted?

A

To prevent continuous stimulation of the postsynaptic neuron so that the membrane is sensitive to the next stimulus

20
Q

How can neurotransmitters be removed from the synaptic cleft?

A
  • Enzymes
  • Reuptake
21
Q

What is excitatory signal?

A

Causes an increase in action

22
Q

What is inhibitory signal?

A

Causes a decrease in action

23
Q

What is summation?

A

The cumulative effect of many weak stimuli

24
Q

What are endorphins?

A

Neurotransmitters that stimulate neurons involved in reducing the intensity of pain

25
Q

What does endorphin production increase in response to?

A
  • Severe Injury
  • Prolonged and continuous exercise
  • Physical and emotional stress
  • Chocolate and chilli peppers
26
Q

What does increased levels of endorphins bring about in the body?

A
  • Europhic feelings
  • Regulation of appetite
  • Release of sex hormones
27
Q

What is dopamine?

A

A neurotransmitter which induces the feeling of pleasure

28
Q

What is dopamine involved in?

A

Reinforcing particular behaviour by activating the reward pathway in the brain when an individual engages in a behaviour that is beneficial to them

29
Q

What are agonists?

A

Chemicals that bind to and stimulate specific receptors on postsynaptic neurons

30
Q

What does an agonist do?

A

Mimic the action of natural neurotransmitters at the synapse and so normal cell responses occur

31
Q

What are antagonists?

A

Chemicals that bind to and block specific receptors on postsynaptic neurons

32
Q

What do antagonists prevent?

A

The normal neurotransmitter from acting by blocking the receptor sites

33
Q

What do antagonists do?

A

Greatly reduce or stop the normal transmission of nerve impulses

34
Q

What do inhibitors do to neurotransmitters?

A

Degrade neurotransmitters by inhibiting the enzymes

35
Q

What do recreational drugs do?

A

Act as agonists and antagonists and therefore effect neurotransmission at a synapse

36
Q

What can the use of recreational drugs lead to?

A
  • Person feeling happier
  • Poorer at carrying out complex mental tasks
  • Misinterprets enviromental stimuli
  • Stay awake for longer
37
Q

What do antagonists cause an increase in?

A

The number and sensitivity of neurotransmitter receptors

38
Q

What do agonists cause a decrease in?

A

The number and sensitivity of neurotransmitter receptors

Higher Human Bio (22 decks)

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