2.4

Question 1

3 basic parts of neurons

Answer 1

Dendrites
Cell body
Axons

Question 2

Dendrites

Answer 2

Nerve fibres that can receive nervous signals from another neuron or sense organ. They then pass these signals to the cell body

Question 3

Cell body

Answer 3

Cell body contains cytoplasm, nucleus, mitochondria and ribosomes for the neuron. The DNA is important as it contains genes for production neurotransmitters

Question 4

Axon

Answer 4

Long cell structure that can carry nervous signals at speed. The ends of the axon terminate at the synapse between 2 neurons. Axon surrounded by myelin sheath

Question 5

What is axon surrounded by

Answer 5

Myelin sheath

Question 6

Myelin sheath purpose

Answer 6

Insulates axon and allows speed of impulses to be increased , allowing cells to transmit signals more quickly. This is why children have slower reaction speeds

Question 7

When is myelin sheath formed

Answer 7

Myelin sheath formed during early development (conception) (myelination)

Question 8

Problems with myelin sheath if damaged

Answer 8

People lose coordination and speed in their movement. Neurones experience problems with correct transmission of signals

Question 9

Disease of myelin example

Answer 9

Multiple Sclerosis (MS)

Question 10

Synapse

Answer 10

The gap between two neurones.

Question 11

How do electrical signals cross synapses

Answer 11

First neuron releases chemicals called neurotransmitters to cross the gap and activate a signal in the second neurone.

Question 12

Synaptic cleft

Answer 12

Tiny region between the axon ending of one neurone and the dendrite of another neurone.

Question 13

Presynaptic neuron

Answer 13

Neuron carrying signal before the synapse

Question 14

Postsynaptic neuron

Answer 14

Neuron that generates signal after synapse

Question 15

Neurotransmitter

Answer 15

Protein that crosses the synapse and binds to receptor on postsynaptic membrane

Question 16

Vesicles

Answer 16

Small membrane bound organelles which act as containers for neurotransmitters.

Question 17

What do vesicles do when electrical signal arrives

Answer 17

Rise to the surface of presynaptic membrane and fuse with the membrane to allow the release of neurotransmitters into synaptic cleft

Question 18

Two ways you can dispose of neurotransmitters are

Answer 18

Reuptake by presynaptic membrane
Enzyme degradation (breakdown)

Question 19

How does reuptake work

Answer 19

Presynaptic membrane contains receptors that can collect and re absorb the neurotransmitter back into the Presynaptic knob.

The neurotransmitter can then be repackaged into vesicles or broken down

Question 20

Example of neurotransmitter reuptake

Answer 20

Adrenaline

Question 21

How does breakdown / enzyme degradation work

Answer 21

Certain enzymes act to break down specific neurotransmitters in the synaptic cleft, preventing them from further transmission

Question 22

Neurotransmitter enzyme degradation example

Answer 22

Acetylcholine

Question 23

Excitatory receptors

Answer 23

When a neurotransmitter binds to an excitatory receptor, the change of an impulse being created is increased

Question 24

Inhibitory receptors

Answer 24

If a neurotransmitter binds to an inhibitory receptor on the postsynaptic membrane, it decreases the chances of an impulse being created

Question 25

Threshold

Answer 25

In order for impulse transmission to be successful, there must be enough neurotransmitters bound to receptors on the postsynaptic membrane. This helps prevent constant stimulation of nervous pathways.

Question 26

Summation

Answer 26

If enough weak stimuli release enough neurotransmitters across a synapse, this can be enough to generate a signal in the postsynaptic neuron. (Several weak signals combining to reach threshold)

Question 27

Endorphins

Answer 27

Neurotransmitter released by brain. Stimulate neurones to reduce pain. Painkilling properties have been linked to improve mood and reduce depression.

Question 28

How to increase endorphins

Answer 28

Pain, intense exercise, stress, eating chocolate

Question 29

Dopamine

Answer 29

Neurotransmitter induces feelings of pressure and happiness . Involved in reward pathway

Question 30

Reward pathway

Answer 30

When body engages in beneficial behaviour, brain releases dopamine. Dopamine activates neurons which emit positive feelings, making them more likely to do it again.

Question 31

Behaviours that activate reward pathway

Answer 31

Eating when hungry Drinking when thirsty Having sex Positive social interactions

Question 32

Types of neurotransmitter treatments

Answer 32

Agonists Antagonists Drugs that inhibit reuptake Drugs that inhibit breakdown enzymes

Question 33

Agonists

Answer 33

Mimic the shape of a neurotransmitter. They can bind to receptors on the postsynaptic membrane and cause a similar action to the main neurotransmitter. They cause activation of those receptors in a similar way to the original neurotransmitter.

Question 34

Example of agonists used

Answer 34

Parkinsons treated by giving dopamine agonists.

Question 35

Antagonists

Answer 35

Antagonists bind to a receptor, but cause no action, blocking any neurotransmitters from stimulating the receptor. The normal action of the neurotransmitter, wether excitatory or inhibitory, is blocked.

Question 36

Antagonists example

Answer 36

Beta blockers, block noradrenaline

Question 37

Reuptake inhibitors

Answer 37

Allow the effects of some neurotransmitters to last longer as they prevent their reabsorptiom into the Presynaptic knob.

Question 38

Reuptake inhibitors example

Answer 38

Depression by seratonin Reuptake inhibitors (SSRIS)

Question 39

Neurotransmitter breakdown enzymes inhibitor

Answer 39

Prevent breakdown of neurotransmitters in the synaptic cleft, allowing for longer duration and more signalling of neurotransmitters.

Question 40

Recreational drugs can affect

Answer 40

Mood , cognition, perception, behaviour, movement, digestion, reproduction

Question 41

Addiction

Answer 41

Needing drug to feel normal

Question 42

Tolerance

Answer 42

Requiring more of the drug to feel an effect

Question 43

How is addiction caused

Answer 43

Addiction caused by repeated use of antagonists. Blockage of receptors causes the postsynaptic neuron to make more receptors and they become more sensitive. sensitisation !!

Question 44

How is tolerance caused

Answer 44

Tolerance caused by repeated use of agonists. Repeated activation of receptors causes Presynaptic neuron to lower their number. This means larger amount of drug needed for same effect. Desensitisation

Question 45

Tolerance example

Answer 45

Alcohol

Question 46

Addiction example

Answer 46

Ketamine

Question 47

Sensitisation

Answer 47

Number of receptors increase

Question 48

Desentisisation

Answer 48

Number of receptors decrease