Topic 3

Question 1

What is the structure of an axon?

Answer 1

surrounded by a myelin sheath

Question 2

What is the function of the myelin sheath?

Answer 2

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

Question 3

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

Answer 3

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.

Question 4

What is an axon?

Answer 4

neural fibre that conducts impulses away from the cell body.

Question 5

What is a dendrite?

Answer 5

neural fibre that conducts impulses from from the cell body.

Question 6

What is the direction of flow of a neuron?

Answer 6

dendrite, cell body and axon

Question 7

What is a sensory neuron?

Answer 7

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

Question 8

What is an inter neuron?

Answer 8

conducts impulses within the CNS, linking sensory and motor neurons

Question 9

What is a motor neuron?

Answer 9

carries impulses from the CNS to muscles or glands.

Question 10

What are glial cells?

Answer 10

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

Question 11

What is a neurotransmitter?

Answer 11

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

Question 12

What do neurons connect with?

Answer 12

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

Question 13

What is the synaptic cleft?

Answer 13

gap between neurons at a synapse.

Question 14

What is the receptors?

Answer 14

protein found in the post synaptic membrane that binds neurotransmitter

Question 15

What is the postsynaptic membrane?

Answer 15

the membrane of the neuron that contains receptors for neurotransmitters

Question 16

What is the presynaptic membrane?

Answer 16

the membrane of the neuron that releases neurotransmitters

Question 17

Why do neurotransmitters have to be removed?

Answer 17

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

Question 18

How do neurotransmitters diffuse across the synapse?

Answer 18

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.

Question 19

What is a excitatory signal?

Answer 19

signal that affects a receptor and which can be passed on

Question 20

What is an inhibitory signal?

Answer 20

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

Question 21

How are weak stimuli filtered out?

Answer 21

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

Question 22

What is summation?

Answer 22

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

Question 23

What is a converging pathway?

Answer 23

Converging neural pathways increase the

sensitivity to excitatory or inhibitory signals.

Question 24

What is a diverging pathway?

Answer 24

Diverging neural pathways influence several

neurons at the same time.

Question 25

What is a reverberating pathway?

Answer 25

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

Question 26

What is plasticity of response?

Answer 26

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

Question 27

What are endorphin's?

Answer 27

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

Question 28

What is dopamine?

Answer 28

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

Question 29

What are increased levels of endorphin's linked to?

Answer 29

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

Question 30

When is endorphin release increased?

Answer 30

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

Question 31

When will the reward pathway be activated?

Answer 31

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

Question 32

What is the reward pathway?

Answer 32

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

Question 33

How do agonist drugs work?

Answer 33

Agonists bind to and stimulate receptors mimicking the neurotransmitter

Question 34

How do antagonistic drugs work?

Answer 34

Antagonists bind to specific receptors blocking the action | of the neurotransmitter

Question 35

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

Answer 35

similar

Question 36

How do inhibitor drugs work?

Answer 36

Other drugs inhibit the enzymes which degrade | neurotransmitters or inhibit re-uptake.

Question 37

What 4 actions can recreational drugs have?

Answer 37

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

Question 38

What part of the neural pathways does recreational drugs affect?

Answer 38

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

Question 39

What can changes in neurochemistry alter?

Answer 39

mood, cognition, perception and behaviour

Question 40

What is sensitization?

Answer 40

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

Question 41

What is desensitization?

Answer 41

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

Question 42

Does sensitization or desensitization lead to drug addiction?

Answer 42

sensitization