Topic 3 Flashcards

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1
Q

What is the structure of an axon?

A

surrounded by a myelin sheath

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2
Q

What is the function of the myelin sheath?

A

insulates the axon and increases the speed of impulse conduction from node to node.

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3
Q

What is the difference in myelin sheath in the first 2 years of life?

A

As a result responses to stimuli in the first two years of life are not as rapid or coordinated as those of an older child or adult.

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4
Q

What is an axon?

A

neural fibre that conducts impulses away from the cell body.

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5
Q

What is a dendrite?

A

neural fibre that conducts impulses from from the cell body.

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6
Q

What is the direction of flow of a neuron?

A

dendrite, cell body and axon

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7
Q

What is a sensory neuron?

A

a neuron that carries impulses into the CNS from a sense organ.

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8
Q

What is an inter neuron?

A

conducts impulses within the CNS, linking sensory and motor neurons

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9
Q

What is a motor neuron?

A

carries impulses from the CNS to muscles or glands.

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10
Q

What are glial cells?

A

Physically support neurons and produce the myelin sheath. They also maintain a homeostatic environment around the neurons
and remove debris by phagocytosis.

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11
Q

What is a neurotransmitter?

A

a chemical released into a synaptic cleft to transmit impulses to the next cell.

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12
Q

What do neurons connect with?

A

Neurons connect with other neurons,
muscle fibres and endocrine at a synaptic
clef

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13
Q

What is the synaptic cleft?

A

gap between neurons at a synapse.

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14
Q

What is the receptors?

A

protein found in the post synaptic membrane that binds neurotransmitter

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15
Q

What is the postsynaptic membrane?

A

the membrane of the neuron that contains receptors for neurotransmitters

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16
Q

What is the presynaptic membrane?

A

the membrane of the neuron that releases neurotransmitters

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17
Q

Why do neurotransmitters have to be removed?

A

The need for removal of neurotransmitters by enzymes or reuptake to prevent continuous stimulation of post-synaptic neurons.

18
Q

How do neurotransmitters diffuse across the synapse?

A

Neurotransmitters are stored in vesicles and released into the cleft on arrival of an impulse. They diffuse across the cleft and bind to receptors on nerve endings.

19
Q

What is a excitatory signal?

A

signal that affects a receptor and which can be passed on

20
Q

What is an inhibitory signal?

A

signal that affects a synaptic receptor but is not passed on.

21
Q

How are weak stimuli filtered out?

A

Synapses can filter out weak stimuli arising from insufficient secretion of neurotransmitters

22
Q

What is summation?

A

Summation of a series of weak stimuli can trigger enough neurotransmitter to fire an impulse.

23
Q

What is a converging pathway?

A

Converging neural pathways increase the

sensitivity to excitatory or inhibitory signals.

24
Q

What is a diverging pathway?

A

Diverging neural pathways influence several

neurons at the same time.

25
Q

What is a reverberating pathway?

A

Reverberating pathway neurons later in the pathway synapse with earlier ones sending the impulse back through the circuit.

26
Q

What is plasticity of response?

A

is created when new neural pathways are developed to create new responses, bypass areas of brain damage, to suppress reflexes or responses to sensory impulses

27
Q

What are endorphin’s?

A

Endorphins are neurotransmitters that stimulate neurons involved in reducing the intensity of pain.

28
Q

What is dopamine?

A

Dopamine induces the feeling of pleasure and reinforces particular behaviour in the reward pathway.

29
Q

What are increased levels of endorphin’s linked to?

A

Increased levels are also connected with euphoric feelings, appetite modulation and release of sex hormones.

30
Q

When is endorphin release increased?

A

Endorphin production increases in response
to severe injury, prolonged and continuous
exercise, stress and certain foods.

31
Q

When will the reward pathway be activated?

A

The reward pathway is activated on engagement of
beneficial behaviours, eg eating when
hungry.

32
Q

What is the reward pathway?

A

The reward pathway involves neurons which secrete or respond to the neurotransmitter dopamine.

33
Q

How do agonist drugs work?

A

Agonists bind to and stimulate receptors mimicking the neurotransmitter

34
Q

How do antagonistic drugs work?

A

Antagonists bind to specific receptors blocking the action

of the neurotransmitter

35
Q

Are drugs used to treat neurotransmitter related disorders similar or different to neurotransmitters?

A

similar

36
Q

How do inhibitor drugs work?

A

Other drugs inhibit the enzymes which degrade

neurotransmitters or inhibit re-uptake.

37
Q

What 4 actions can recreational drugs have?

A

Recreational drugs may stimulate the release of neurotransmitters, imitate their action (agonists), block their binding (antagonists), and/or inhibit their reuptake/enzymatic
degradation.

38
Q

What part of the neural pathways does recreational drugs affect?

A

Many recreational drugs affect neurotransmission in the reward circuit of the brain.

39
Q

What can changes in neurochemistry alter?

A

mood, cognition, perception and behaviour

40
Q

What is sensitization?

A

Sensitisation is an increase in the number and sensitivity of neurotransmitter receptors as a result of exposure to drugs that are antagonists and leads to addiction

41
Q

What is desensitization?

A

Desensitisation is a decrease in the number and sensitivity of receptors as a result of exposure to drugs that are agonists and leads to drug tolerance

42
Q

Does sensitization or desensitization lead to drug addiction?

A

sensitization