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Higher Biology > 3.4 > Flashcards

3.4 Flashcards

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1
Q

What is the role of the axon on neurons?

A

axons carry nerve impulses away from the cell body

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2
Q

What is the role of the dedrites on neurons?

A

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

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3
Q

What is the role of myelin?

A

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

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4
Q

Which cells produce myelin?

A

glial cells

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5
Q

Name two diseases that are caused by loss of myelin?

A

Poliomyelitis and multiple sclerosis

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6
Q

What is myelination?

A

the process of myelin formation around the axon by glial cells

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7
Q

What is a synapse?

A

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

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8
Q

What are neurotransmitters?

A

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

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9
Q

Summarise the process of signals transmitting across synapse

A
  • 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.
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10
Q

How do synapses prevent the continuous stimulation of postsynaptic neurons?

A

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.

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11
Q

What two types of signals that synapses can transmit?

A

excitatory and inhibitory, as determined by the postsynaptic receptors

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12
Q

What is summation?

A

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

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13
Q

What stimuli are filtered out of the synapse?

A

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

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14
Q

What are endorphins?

A

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

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15
Q

Give 4 actions that increase endorphins

A

exercise, injury/pain, eating, stress

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16
Q

Give 2 functions of endorphins

A
  • they reduce the intensity of pain
  • they induce feelings of pleasure/euphoria
17
Q

What is dopamine?

A

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

18
Q

Give 3 responses that dopamine brings about

A

sex hormone release, euphoria/pleasure, regulation of appetite

19
Q

What is Alzheimer’s disease?

A

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

20
Q

What is Parkinson’s disease?

A

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

21
Q

What is the mechanism of action of agonist drugs?

A

agonist drugs mimic the action of a specific neurotransmitter or hormone

22
Q

What is the mechanism of action of antagonist drugs?

A

antagonist drugs block the action of a specific neurotransmitter or hormone

23
Q

Give an example of an agonist medication used for pain management

A

morphine - stimulates opioid receptors and is used for pain management

24
Q

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

A

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

25
Q

What are recreational drugs?

A

drugs taken for pleasure rather than for medical reasons

26
Q

How can recreational drugs affect the brain?

A

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.

27
Q

How does drug tolerance occur?

A

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.

28
Q

How does drug addiction occur?

A

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.

29
Q

What is a cell body?

A

contains the nucleus and most of the cytoplasm

30
Q

What surrounds the myelin sheath?

A

axons

31
Q

What is the functions of the myelin sheath?

A

insulates the axon and increases the speed of impulse conduction

32
Q

When does myelination occur?

A

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.

33
Q

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

A

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

34
Q

what is the role of neurotransmitters?

A

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.

35
Q

What is an angonist?

A

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

36
Q

What is an antagonist?

A

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

Higher Biology (24 decks)

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