3.4

Question 1

What is the role of the axon on neurons?

Answer 1

axons carry nerve impulses away from the cell body

Question 2

What is the role of the dedrites on neurons?

Answer 2

dendrites receive nerve impulses from other neurons and transmit them to the cell body

Question 3

What is the role of myelin?

Answer 3

myelin insulates the axon, increasing the speed of nerve impulses along it.

Question 4

Which cells produce myelin?

Answer 4

glial cells

Question 5

Name two diseases that are caused by loss of myelin?

Answer 5

Poliomyelitis and multiple sclerosis

Question 6

What is myelination?

Answer 6

the process of myelin formation around the axon by glial cells

Question 7

What is a synapse?

Answer 7

the space between two neurons where electrical impulses are transmitted from one cell to another.

Question 8

What are neurotransmitters?

Answer 8

chemical messenger that help transmit signals from one neuron to another, across a synapse

Question 9

Summarise the process of signals transmitting across synapse

Answer 9

• an electrical impulse will travel down the axon of the neuron to the axon ending.
• neurotransmitters in the presynaptic neuron then travel to the synapse within synaptic vesicles.
• neurotransmitters are released into the synaptic cleft and diffuse towards receptors on the postsynaptic neuron.
• the signal is accepted by the complementary receptor, which stimulates the electrical impulse in the postsynaptic neuron.

Question 10

How do synapses prevent the continuous stimulation of postsynaptic neurons?

Answer 10

By re-uptake, neurotransmitters can be reabsorbed into the presynaptic neuron and stored for future use.

By enzyme degradation, neurotransmitters can be broken down by enzymes, and the inactive products are reabsorbed by the presynaptic neuron.

Question 11

What two types of signals that synapses can transmit?

Answer 11

excitatory and inhibitory, as determined by the postsynaptic receptors

Question 12

What is summation?

Answer 12

When a series of weak neurotransmitter stimuli in the synapse is added together to bring about a response.

Question 13

What stimuli are filtered out of the synapse?

Answer 13

synapses filter out weak stimuli when there is insufficient release of neurotransmitters.

Question 14

What are endorphins?

Answer 14

neurotransmitters that are released in response to pain, stress and pleasurable activities

Question 15

Give 4 actions that increase endorphins

Answer 15

exercise, injury/pain, eating, stress

Question 16

Give 2 functions of endorphins

Answer 16

• they reduce the intensity of pain
• they induce feelings of pleasure/euphoria

Question 17

What is dopamine?

Answer 17

an endorphin that elicits the feeling of pleasure as part of the brain’s reward pathway

Question 18

Give 3 responses that dopamine brings about

Answer 18

sex hormone release, euphoria/pleasure, regulation of appetite

Question 19

What is Alzheimer’s disease?

Answer 19

a condition associated with low levels of acetylcholine, resulting in cognitive decline due to the loss of these signals between neurons in the brain

Question 20

What is Parkinson’s disease?

Answer 20

a condition caused by low levels of dopamine in the brain, causing significant impact on movement, mood and cognition

Question 21

What is the mechanism of action of agonist drugs?

Answer 21

agonist drugs mimic the action of a specific neurotransmitter or hormone

Question 22

What is the mechanism of action of antagonist drugs?

Answer 22

antagonist drugs block the action of a specific neurotransmitter or hormone

Question 23

Give an example of an agonist medication used for pain management

Answer 23

morphine - stimulates opioid receptors and is used for pain management

Question 24

Give an example of an antagonist medication used to reverse pain medication toxicity

Answer 24

naloxone - blocks opioid receptors and is used to reverse opioid toxicity in morphine overdose

Question 25

What are recreational drugs?

Answer 25

drugs taken for pleasure rather than for medical reasons

Question 26

How can recreational drugs affect the brain?

Answer 26

Recreational drugs can affect mood, behaviour, perception and cognition by affecting neurotransmitters at synapses. They can be agonists or antagonists and many affect the brain by stimulating the reward pathway.

Question 27

How does drug tolerance occur?

Answer 27

Drug tolerance occurs with repeated use of agonist drugs. The body then requires increasing doses of the drug to gain the same response. The body decreases its quantity of receptors on the postsynaptic neurons' leading to desnesitisation.

Question 28

How does drug addiction occur?

Answer 28

Drug addiction occurs with repeated use of antagonist drugs. The body increases its quantity of receptors on the postsynaptic neurons, leading to sensitisation and making it very difficult to stop taking the drug.

Question 29

What is a cell body?

Answer 29

contains the nucleus and most of the cytoplasm

Question 30

What surrounds the myelin sheath?

Answer 30

axons

Question 31

What is the functions of the myelin sheath?

Answer 31

insulates the axon and increases the speed of impulse conduction

Question 32

When does myelination occur?

Answer 32

myelination continues from birth to adolescence. For this reason, responses to stimuli in the first two years of life are not as rapid or co-ordinated as those of an older child or adult.

Question 33

What happens to the myelin sheath if an individual has multiple sclerosis (MS)?

Answer 33

the myelin sheath becomes damaged or destroyed which causes a loss of muscular co-ordination

Question 34

what is the role of neurotransmitters?

Answer 34

when a nerve impulse passes through the presynaptic neuron and reaches the synaptic terminal, it stimulates the vesicle. The vesicles discharge. Once in the cleft, they diffuse across the synaptic cleft and bind to receptors on the membrane of the post-synaptic neurones.

Question 35

What is an angonist?

Answer 35

chemicals that bind to and stimulate specific receptors mimicking the action of a neurotransmitters at a synapse. Therefore , it triggers the normal cellular response.

Question 36

What is an antagonist?

Answer 36

chemicals that bind to specific receptors, blocking the action of neurotransmitter at a synapse