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Higher Human Biology > Neurobiology & Immunology > Flashcards

Neurobiology & Immunology Flashcards

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1
Q

What can the nervous system be divided into?

A

The central nervous system CNS

the peripheral nervous system PNS

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2
Q

What is the CNS made up of?

A

The brain

The spinal cord

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3
Q

Function of the brain in the CNS?

A

Processing of information

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4
Q

Function of the spinal cord in the CNS?

A

Connects brain with PNS

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5
Q

What structure is in the peripheral nervous system?

A

Nerves

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6
Q

Function of nerves in the PNS?

A

Carries information to and from all parts of the body

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7
Q

The overall functions of the PNS can be split into the _____ nervous system (SNS) and the _____ nervous system (ANS)

A

Somatic

Autonomic

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8
Q

Is the Somatic Nervous System voluntary or involuntary?

A

Voluntary

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9
Q

Is the Autonomic Nervous System voluntary or involuntary?

A

Involuntary

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10
Q

What does the autonomic nervous system consist of?

A

Sympathetic System

Parasympathetic system

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11
Q

Describe the sympathetic system of the ANS?

A

Prepares the body for action

‘Flight or fight’ response

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12
Q

Describe the parasympathetic system of the ANS?

A

Calms body down

Prepares body for rest and allows recovery - ‘rest and digest’

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13
Q

What does the somatic nervous system include?

A

The spinal nerves and contains sensory and motor neurones

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14
Q

What does the SNS control?

A

Voluntary movements of skeletal muscle and is also responsible for involuntary reflex actions

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15
Q

How does the ANS regulate the internal environment?

A

By controlling the heart, blood vessels, bronchioles, and alimentary canal to maintain heartbeat, breathing rate and digestive processes

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16
Q

What does the ANS control?

A

Involuntary functions through smooth muscle, cardiac muscle and glands

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17
Q

What does the ANS consist of?

A

Sympathetic and parasympathetic systems that work to regulate processes

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18
Q

Why is the relationship between the sympathetic and parasympathetic systems described as antagonistic?

A

They affect the same body structures but exert opposite effects

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19
Q

Describe the sympathetic effect of the ANS on heart rate

A

Increases rate

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20
Q

Describe the parasympathetic effect of the ANS on heart rate

A

Decreases rate

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21
Q

Describe the sympathetic effect of the ANS on breathing rate

A

Increases rate and depth

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22
Q

Describe the parasympathetic effect of the ANS on breathing rate

A

Decreases rate and depth

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23
Q

Describe the sympathetic effect of the ANS on peristalsis

A

Decreases rate

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24
Q

Describe the parasympathetic effect of the ANS on peristalsis

A

Increases rate

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25
Q

Describe the sympathetic effect of the ANS on secretion of digestive juices and bile

A

Decreases rate

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26
Q

Describe the parasympathetic effect of the ANS on secretion of digestive juices and bile

A

Increases rate

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27
Q

Examples of effectors

A

Muscles/glands

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28
Q

Examples of stimuli

A

Temperature of blood/skin

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29
Q

Example of a response

A

Muscle contraction

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30
Q

Describe a sensory and motor pathway

A
  • Stimulus is detected by receptors in external sensory organs (eyes, ears) or internally (thermoreceptors)
  • sensory neurone carry impulses from sense organs to CNS
  • motor neurone carry impulses from CNS to muscles and glands
  • response eg muscle contraction
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31
Q

What is a neural pathway?

A

The route that a nerve impulse follows through the nervous system

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32
Q

What’s a converging neural pathway?

A

Several impulses from several neurones all travel to one neurone

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33
Q

What’s the purpose of a converging neural pathway?

A

It increases the sensitivity to excitatory or inhibitory signals allowing weak stimulus to be amplified, as in the visual pathway

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34
Q

What are rods and cones?

A

Photoreceptors whose pigments break down in the presence of light

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35
Q

___ are not very sensitive to light so ___ is needed to break the pigments down

A

Cones

Daylight

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36
Q

___ are so sensitive to light they react in very __ light

A

Rods

Dim

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37
Q

What happens as light intensity entering the eye decreases?

A

Cones cease to function and rods take over

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38
Q

What kind of pathway do rods form and why?

A

Converging pathways, allowing several impulses to be transmitted simultaneously

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39
Q

The ____ effect for several rods with the same neuron results the in transmission _____ being met, enabling transmission of the nerve impulse. This allows vision in total darkness

A

Cumulative

Threshold

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40
Q

What happens in diverging neural pathways

A

Impulses from one single neuron travel to several neurons, allowing the pathway to reach several destinations at the same time

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41
Q

Diverging neural pathways allow ___ ___ control

A

Fine motor

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42
Q

The SNA controls skeletal muscles via what?

A

Motor neurons

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43
Q

The diverging pathway of motor neurons for skeletal muscles allows what?

A

Simultaneous stimulation of the muscles in the hand to allow the fingers and thumb to operate in unison

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44
Q

The neural pathway of the hypothalamus diverges into branches exerting what?

A

Coordinated control in temperature regulation

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45
Q

What is a reverberating pathway?

A

In a reverberating pathway, neurons later in the pathway link back to earlier neurons so that the nerve impulse passes repeatedly through the circuit

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46
Q

What do reverberating pathways allow?

A

Allow impulses to be recycled enabling repeating stimulation of the pathway

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47
Q

How long can a pathway reverberate and transmit impulses?

A

For seconds, hours or a lifetime

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48
Q

Example of a reverberating neural pathway?

A

Pathway that controls breathing

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49
Q

Function of the cerebrum

A

Responsible for memory, conscious thought and intelligence

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50
Q

Cerebral cortex =

A

Outer layer of cerebrum

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51
Q

Function of the cerebellum

A

Controls balance and muscle coordination

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52
Q

Function of the medulla

A

Controls heart rate and breathing rate

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53
Q

What is the cerebral cortex?

A

The outer part of the cerebrum and is the centre of conscious thought

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54
Q

What is the cerebral cortex able to do?

A

Recall memories and alter behaviour in light of past experience

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55
Q

3 key function of the cerebral cortex?

A
  • received sensory information
  • coordinates voluntary movement
  • makes decisions based on experience
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56
Q

What is the cerebrum divided into?

A

Two halves

Left and right cerebral hemispheres

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57
Q

Each cerebral hemisphere processes information from and controls?

A

The opposite side of the body

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58
Q

The left hemisphere receives info from the ___ visual field and controls the ___ side of the body

A

Right

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59
Q

What is the corpus callosum?

A

A bundle of nerve fibres which connects the cerebral hemispheres

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60
Q

What does the corpus callosum allow?

A

The transfer of information from one hemisphere to the other enabling the brain to act as an integrated whole

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61
Q

What would happen if the corpus callosum was absent?

A

The exchange of information between the cerebral hemispheres cannot take place and each hemisphere receives only half the field of view

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62
Q

Function of the motor area of the cerebral cortex?

A

Coordination of voluntary movement

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63
Q

Function of the sensory area of the cerebral cortex?

A

Receives information from body receptors

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64
Q

Functional areas of the cerebral cortex?

A
  • Motor area
  • Sensory area
  • Visual area
  • Auditory area
  • Speech motor area
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65
Q

What do the sensory areas of the cerebral cortex do?

A

Receive information as sensory impulses from receptors

eg touch receptors in skin

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66
Q

What do the association areas of the cerebral cortex do?

A

Analyse and interpret the impulses receives from the sensory areas and deal with thought processes, language, personality, imagination and intelligence (make decisions)

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67
Q

What do the motor areas of the cerebral cortex do?

A

Receive info from association areas and ‘carry out orders’ by sending motor impulses to the appropriate effectors

(Eg skeletal muscles)

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68
Q

What is memory?

A

The capacity of the brain to store information, retain it and retrieve it when required

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69
Q

How does the brain form new memories?

A

Info coming in is changed into a usable form - encoded - and then stored.

It must also be retrieved at a later date

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70
Q

What is encoding?

A

Information that we can see, hear, think, and feel is changed into a form the brain can process and store

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71
Q

What is storage?

A

The retention of information over a period of time - 30s or a lifetime

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72
Q

What is retrieval?

A

Recovery of stored material

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73
Q

What is the quality of the memory affected by during encoding?

A

The attention given to the task of encoding

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74
Q

What’s shallow encoding?

A

Information is encoded by rehearsal (less effective)

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75
Q

What is elaborative encoding?

A

Associating information or linking them to their meaning leads to improved information retention

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76
Q

What is the sensory memory?

A

Retains all visual and auditory input very briefly (0.5-3secs)

Only selected images and sounds are encoded and passed to the STM

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77
Q

What is the short term memory (STM)?

A

Limited capacity (~7 items)

Holds info for up to 30s

To avoid loss of info from STM we use rehearsal

This helps transfer info to LTM

Info not transferred is displaced

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78
Q

What happens to information that is not transferred to the LTM?

A

It is lost by displacement (pushed out by incoming info) or decay (breakdown of a fragile memory trace)

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79
Q

What’s the long term memory (LTM)?

A

Unlimited capacity and stored info for a long period of time

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80
Q

How can the STM be increased?

A

Chunking

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81
Q

What is STM chunking?

A

A meaningful unit of information made up of smaller units eg phone number

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82
Q

What is rehearsal?

A

Repeating a piece of information that you are trying to memorise over and over

helps extend the time the info is maintained in STM

Promotes transfer of info into LTM

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83
Q

What is the serial position effect?

A

Items at the start and end of a list are more easily recalled than the items in the middle

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84
Q

What is The transfer of information from STM to LTM aided by?

A
  • Rehearsal
  • Organisation
  • Elaboration
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85
Q

What is organisation?

A

Info organised into categories are more easily transferred to LTM

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86
Q

What is elaboration of meaning?

A

By analysing the meaning of the item to be memorised and taking note of its various features and properties it becomes more interesting and meaningful - makes an impression

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87
Q

What is a contextual clue?

A

Relates to the time and place when the information was encoded and committed to the LTM

Triggers memories

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88
Q

What are glial cells?

A

Support and maintain neurons

Produce the myelin sheath (lay down layers of plasma membrane)

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89
Q

What do neurones consist of?

A
  • Cell body
  • Axon
  • Several dendrites
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90
Q

What’s the cell body of a neurone?

A

Control centre of the cells metabolism

Contains ribosomes, nucleus and cytoplasm

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91
Q

What are dendrites?

A

Nerve fibres which receive impulses and pass them towards cell body

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92
Q

What’s an axon?

A

Single nerve fibre carries impulses away from cell body to effector

Pass of impulses to next neuron in sequence

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93
Q

What are the 3 types of neuron?

A

Sensory

Inter

Motor

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94
Q

What is the myelin sheath?

A

A layer of fatty material surrounding axons which insulated the acid and greatly increases the speed of impulse conduction from node to node along an axon

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95
Q

What’s myelination?

A

The development of myelin around the axon

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96
Q

Myelination is not complete when?

A

Not complete at birth and continued during development until adolescence

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97
Q

What are the small gaps in the myelin sheath called?

A

Nodes

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98
Q

What happens in unmyelinated fibres?

A

The axon is exposed and the speed of the impulse is greatly reduced

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99
Q

Why are responses to stimulus in the first 2 yrs of life not as rapid or coordinated?

A

Myelination is not complete

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100
Q

What is a synapse?

A

The tiny region of functional contact between the axon ending of one neuron and the dendrite of the next neuron in a pathway

101
Q

What is the nerve cell before the synaptic cleft called?

A

Presynaptic neuron

102
Q

What is the nerve cell after the synaptic cleft called?

A

Postsynaptic neuron

103
Q

What’s the synaptic cleft?

A

The space between the presynaptic and postsynaptic neurons

104
Q

How are messages relayed across synaptic clefts?

A

By neurotransmitters

105
Q

How do neurons connect muscle fibres and endocrine glands?

A

Via spaces similar to synaptic clefts

106
Q

What do neurotransmitters do?

A

Relay impulses across the synaptic cleft

107
Q

Where are neurotransmitters stored?

A

In vesicles in axons endings of presynaptic neurones

108
Q

When are neurotransmitters released into the synaptic cleft?

A

On arrival of an impulse

109
Q

What happens to neurotransmitters after they are release?

A

Diffuse across cleft and bind to receptor sites on postsynaptic membrane which opens ion channels, causing an impulse to be initiated in the postsynaptic membrane

110
Q

Examples of neurotransmitter?

A

Acetylcholine

Noradrenaline

111
Q

What does the removal of neurotransmitters prevent?

A

The continuous stimulation of postsynaptic neurons

112
Q

How is acetylcholine removed?

A

Broken down by an enzyme on the postsynaptic membrane

113
Q

How is noradrenaline removed?

A

Reabsorbed by the presynaptic membrane and stored in vesicles for reuse

114
Q

Describe what kind of signal acetylcholine released between a motor neurone and a heart muscle fibres produces?

A

An inhibitory effect

The rate and strength of contraction of cardiac muscle is reduced

115
Q

Describe the signal acetylcholine released between a motor neurone and a skeletal muscle fibre produces?

A

Excitatory effect on the muscle making it contract

116
Q

What kinds of signal can neurotransmitters produce?

A

Excitatory or inhibitory

117
Q

A nerve impulse is only transmitted across a synapse if?

A

It causes the release of a minimum number of neurotransmitter molecules to bind to a sufficient number of receptor sites and reach the threshold

118
Q

How is weak stimuli filtered out?

A

By the synapse acting as an unbridgeable gap

119
Q

Example of weak stimuli

A

The continuous low level drone of machinery does not trigger the release of enough neurotransmitter, but a sudden increase in volume can make a person aware of the machinery

120
Q

What is summation?

A

The cumulative effect of a series of weak stimuli that together bring about an impulse

121
Q

What are endorphins?

A

Neurotransmitters which act as natural pain killers in the body

They combine with receptors of synapses and block transmission of pain signals

122
Q

Where are endorphins produced?

A

The hypothalamus

123
Q

What does the level of production of endorphins increase in response to?

A
  • physical/emotional stress
  • severe injury
  • long periods of vigorous exercise
  • certain foods (chocolate)
124
Q

Increased levels of endorphins cause?

A
  • changes in appetite
  • release of sex hormones
  • feelings of euphoria
125
Q

What is dopamine?

A

A neurotransmitter which induces the feelings of pleasure and featured in a behavioural reward pathway

126
Q

What is the reward pathway?

A

Involves neurons which secrete or respond to dopamine

This is activated when an individual engaged in a survival behaviour that is beneficial to them (eating when hungry)

127
Q

What does centre ‘No in the reward pathway do?

A

Releases dopamine and induces a pleasurable feeling (nucleus accumbens)

128
Q

What does centre View in the reward pathway do?

A

Releases dopamine when a need is satisfied

129
Q

What is the frontal area of the cerebral cortex responsible for in the reward pathway?

A

Cognitive appreciation of pleasure

130
Q

What are the brains pleasure centres?

A

Centres N and V in the reward pathway

131
Q

What is Alzheimer’s disease?

A

An incurable and terminal form of dementia where the brain gradually degenerates

Impulses cannot be transmitted as normal

132
Q

What is the cause of Alzheimer’s?

A

It is thought the loss of neurons which make acetylcholine is the cause

133
Q

Treatment of Alzheimer’s?

A

Some drugs such as cholinesterase inhibitors, which increases the acetylcholine concentration in the synaptic clefts, improving communication between neurons

134
Q

Effectiveness of drugs for Alzheimer’s?

A

In some people they do improve the symptoms and temporarily slow down the disease but are mostly found to be ineffective

135
Q

What is Parkinson’s Disease?

A

A severe loss of dopamine leads to muscle tremors, difficulty in initiation of movement and speech, reduced fine motor control

136
Q

How is Parkinson’s caused?

A

By loss of neurons that synthesise dopamine

137
Q

Treatment for Parkinson’s?

A

L-dopa

Inhibition of MAO

Stem cells

138
Q

L-dopa treatment for Parkinson’s?

A

Dopamine cannot cross the BBB but L-soap can and is converted to dopamine

As it penetrates the whole brain (dopamine normally only releases in specific areas) can cause unpleasant side effects

139
Q

Inhibition of MAO treatment for Parkinson’s?

A

Drugs which inhibit the action of MAO so any dopamine present can have a longer lasting effect

140
Q

Stem cell treatment for Parkinson’s?

A

Skin cells are being used to produce IPSC’s which are then induced in vitro to develop into cultures of brain neurones.

These can be used to gain a better understanding of why these neurons die and could be used to treat PD

141
Q

Drugs treating neurotransmitter-related diseases are ____ in structure to _______ and act as ____ or ____

A

Similar

Neurotransmitters

Agonists

Antagonists

142
Q

Treatment of neurotransmitter-related disorders?

A

Agonist drugs

Antagonist drugs

Inhibitor drugs

144
Q

What is an agonist?

A

A chemical that binds to specific receptors and stimulates post synaptic neurones in a pathway

145
Q

Why do agonists do?

A

Mimic the action of neurotransmitters triggering the normal cellular response and promoting enhanced levels of nerve impulses

146
Q

What’s an antagonist drug?

A

A chemical which binds to specific receptors and blocks receptor sites

147
Q

What do antagonist drugs do?

A

Prevents the normal neurotransmitter from binding to receptor sites, resulting in a reduction of nerve impulses being transmitted

148
Q

What do recreational drugs lead to changes in?

A
  • Mood - more confident, happier, aggressive
  • Cognitive thinking - poorer at problem solving + decision making
  • Perception - misinterpretation of environment - sights colours etc
  • Behaviour - stay awake longer, increased self confidence
149
Q

How can recreational drugs interact with neurotransmitters?

A
  • stimulate the release of natural neurotransmitters
  • act as an agonist by initiating the action of a neurotransmitter
  • act as an antagonist by binding with receptors and block the action of a neurotransmitter
  • inhibit the reuptake of a neurotransmitter
  • inhibit the breakdown of a neurotransmitter by an enzyme
150
Q

Describe cocaine and what it does?

A

Produces feelings of well being and limitless energy

Induces hallucinations and leads to social withdrawal, depression an dependence

Inhibits dopamine reuptake and the pathway is overstimulated

151
Q

Describe MDMA and what it does?

A

Users feel more alert and energetic

Can cause anxiety, panic attacks, paranoia and depression

Dancing for long periods under the influence can cause overheating and dehydration

Inhibits serotonin reuptake, promoting temporary heightened well being

152
Q

Describe cannabis and what it does?

A

Acts as a pleasurable stimulant and then as a sedative

User may feel excited, restless and inhibited initially then drowsy and falls into a deep sleep

Heavy use can trigger schizophrenia

Cannabinoids bind to cannabinoid receptors which are normally occupied by a neurotransmitter which transmit impulses controlling muscles and regulation of pain sensitivity

153
Q

Describe nicotine and what it does?

A

Highly addictive and chemicals are responsible for diseases such as cancer

Normally nicotinic acetylcholine receptors in brain are occupied with acetylcholine causing transmission of nerve impulses

Such transmission leads to an increase in dopamine, serotonin and noradrenaline

Nicotine mimics effect and increases activity of these nicotinic acetylcholine receptors resulting in euphoria, relaxation and eventual addiction

154
Q

Describe alcohol and what it does?

A

A depressant, causes feelings of relaxation and good humour initially then loss of consciousness following excessive consumption

GABA receptors have an inhibitory effect and alcohol mimics this reducing feelings of anxiety

Can lead to elevated dopamine levels and person feels good temporarily as the reward system in the brain continued to be over stimulated

155
Q

What is drug addiction also know as?

A

Sensitisation

156
Q

What is drug addiction?

A

A chronic disease where the sufferer compulsively seeks the drug regardless of the consequences

The initial drug taking was voluntary but neural changes as a result of the addiction over ride self control

157
Q

What does repeated use of a drug that acts as an antagonist do? (Drug addiction)

A

Continually blocks specific receptors preventing the normal neurotransmitter from acting on them

The nervous system compensated for the reduced stimulation by increasing the number of receptors and their sensitivity

This leads to addiction as the user craves more of the drug

158
Q

What is drug tolerance also known as?

A

Desensitisation

159
Q

What does repeated use of a drug that acts as an agonist do? (Drug tolerance)

A

Results in receptors being repeatedly stimulated

The nervous system compensates for overstimulation by reducing the number of receptors and their sensitivity

A larger dose of the drug is now required to produce the original effect

160
Q

What is immunity?

A

The body’s ability to resist infection by a pathogen

161
Q

What is a pathogen?

A

Any bacterium, virus or other organism that can cause disease

162
Q

What’s a non specific immune response?

A

Works against any type of disease causing agent

163
Q

What’s a specific immune response?

A

Works against a particular pathogen

164
Q

Non specific chemical immune responses?

A
  • tears and saliva
  • mucus
  • secretions from sweat and sebaceous glands
  • stomach acid
165
Q

Describe the immune response of tears and saliva?

A

Tears and saliva contain lysozyme which digests bacterial cells walls + destroys them

166
Q

Describe the immune response of mucus?

A

Mucus traps micro-organisms which are swept up upward by cilia

167
Q

Describe the immune response of secretions from sweat and sebaceous glands?

A

Secretions from sweat and sebaceous glands keep skin at a low pH so microbes cannot thrive

168
Q

Describe the immune response of stomach acid?

A

Cells lining the stomach produce acid which destroys microbes

169
Q

Non specific physical responses?

A
  • skin

* mucous membranes

170
Q

Describe the immune response of skin

A

Skin is composed of densely packed epithelial cells and is found in the skin and inner lining of digestive + respiratory systems, offering physical protection against bacteria and viruses when it is intact

171
Q

Describe the immune response of mucous membranes?

A

Mucous membranes linings the digestive and respiratory tract form a physical barrier

172
Q

What is the 2nd line of defence for non specific immune responses?

A

Inflammatory response

Phagocytosis

173
Q

What is the inflammatory response?

A

When the body is physically injured, cut or invaded by micro organisms, it triggers the inflammatory response, a localised defence mechanism

174
Q

What are mast cells?

A

They are found throughout the body and contain histamine.

175
Q

What does histamine cause?

A

Vasodilation of the arteries

Increased capillary permeability

176
Q

Describe what happens with mast cells following injury?

A

1) Damaged mast cells become activated and release large quantities of histamine
2) Blood vessels in the area dilate
3) Capillaries in the area become more permeable
4) The area becomes red and inflamed

177
Q

Increased blood flow and permeability of capillaries due to histamine leads to?

A

• the accumulation of phagocytes to the damaged tissue

• accumulation of clotting elements to the injured area
Blood clots and tissue repair begins

178
Q

What is a phagocyte?

A

A phagocyte is a motile white blood cell, can recognise pathogens by their antigens and will destroy pathogen ya by phagocytosis

179
Q

Describe phagocytosis

A

Phagocyte engulfs the pathogen enfolding it within the membrane to form a vesicle

The cytoplasm of a phagocyte contains digestive enzymes - lysozyme sun vesicles called lysosomes

These fuse to the pathogen filled vesicle and destroy the pathogen

Dead bacteria and phagocytes accumulate at an infected area as pus

180
Q

What are cytokines and what do they do?

A

Protein molecules released by phagocytes

They act as a signal causing more phagocytes to accumulate at the site of infection

181
Q

What are antigens?

A

Proteins on the surface of cells that trigger on a specific immune response

182
Q

2 types of lymphocytes?

A

B-lymphocytes

T-lymphocytes

183
Q

Where are lymphocytes derived from and what to they develop into?

A

Lymphocytes are derived from stem cells in bone marrow

Some pass to the thymus gland and develop into T-lymphocytes

Others mature in the bone marrow and become B-lymphocytes

184
Q

What do B-lymphocytes do?

A
  • Produce antibodies against antigens leading to the destruction of a pathogen
  • Produce memory cells capable of making antibodies in future
185
Q

What are antibodies?

A

Y shaped protein molecule

Each arm has a receptor site specific to particular antigen on a pathogen

186
Q

How do antibodies work?

A

Antibodies bind to antigens, forming an antigen-antibody complex, inactivating the pathogen which is then destroyed by phagocytosis

187
Q

What is an allergic reaction?

A

Sometimes the immune system over reacts when B-lymphocytes respond to harmless substances (pollen, dust, feathers, penicillin)

This hypersensitivity in the form of an exaggerated (sometimes damaging) immune response is called an allergic reaction

188
Q

What’s anaphylactic shock?

A

A life threatening reaction caused by an allergen that has been injected (bee venom) or consumed (peanuts)

The person is so allergic that mast cells secrete large quantities of histamine which triggers vasodilation and great loss of circulatory fluid to the tissues and a drop in blood pressure

Death can occur within minutes if not treated

189
Q

How do inhibitor drugs work?

A

By preventing the removal of neurotransmitter from synaptic clefts by inhibiting enzyme action or reabsorption

190
Q

What do T-lymphocytes do?

A

Destroy infected cells by recognising the antigens of pathogens on the cell membrane and inducing apoptosis

191
Q

When does the T-lymphocyte become activated?

A

When the antigen receptor of a T-lymphocyte binds with the antigen on a pathogen

192
Q

What does the activated T-lymphocyte produce?

A
  • clones of activated T cells

* memory cells capable of recognising the same foreign antigen in the future

193
Q

What is apoptosis?

A

Programmed cell death

194
Q

Describe apoptosis

A

Activated T-lymphocytes attach to infected cells and release proteins

The proteins diffuse into the cell causing the production of self-destructive enzymes which cause cell death

The dead cell remains are engulfed and digested by phagocytosis

195
Q

Why are each person’s body cells different?

A

Because they posses a combination of cell surface proteins that is unique to that person

196
Q

Any T lymphocyte with an antigen receptor that ___ __ _ ___ ___ _____ _____ is identified and destroyed by apoptosis

A

would fit a body cell surface protein

197
Q

What is agglutination and what does it cause?

A

Clumping of red blood cells (caused by incompatibility between donor cells and recipients plasma)

Causes major blockage of small blood vessels

198
Q

What causes autoimmune diseases?

A

Failure of the regulation of the immune system leads to T-lymphocytes responding to self antigens

199
Q

Describe rheumatoid arthritis?

A

Causes chronic inflammation of the synovial membrane in joints

The membrane swells up, cartilage and bone are gradually destroyed and replaced by fibrous tissue

This can join the two bones together, making the joint immovable

200
Q

Describe Type 1 Diabetes (auto immunity)

A

Insulin producing beta cells in the pancreas are attacked and destroyed by T-lymphocytes from the body’s immune system

Blood glucose levels cannot then be controlled

201
Q

Describe multiple sclerosis

A

T-lymphocytes regard molecules on the myelin sheath as antigens

They attack + destroy the myelin sheath resulting in the ability of the nerve cells to transmit impulses being seriously impaired

202
Q

What are memory cells?

A

Some cloned B+T lymphocytes survive long term as memory cells -

these destroy invading pathogens before the individual shows symptoms

203
Q

What does the HIV virus do?

A

Attacks and destroys T-lymphocytes

204
Q

How can you get HIV?

A 
Via: 
• unprotected sex 
• passed from mother to baby 
• sharing injecting equipment 
• contaminated blood transfusions and organ transplants
205
Q

What is AIDS?

A

A deficiency disease caused by HIV

206
Q

How does HIV attack T lymphocytes?

A

By attaching to specific receptors on the T-lymphocyte and entering the host cell

207
Q

HIV contains ___

A

RNA

208
Q

Why does HIV need DNA and what does it do to produce it?

A

It needs DNA to transcribe the mRNA so it introduces an enzyme to bring about the reverse of normal transcription to produce viral DNA from viral RNA

209
Q

How long can viral DNA lie dormant for?

A

Viral DNA is incorporated into host cells DNA and can lie dormant for years before directing synthesis of new viral particles

210
Q

How do viral particles escape from the host cell?

A

By budding and infecting other cells

This causes the destruction and depletion of T lymphocytes

211
Q

What happens as the number of T lymphocytes decreases due to HIV?

A

The person is susceptible to opportunistic infections such as pneumonia

At this point the person is suffering from AIDS

212
Q

What is immunity?

A

Protection gained as a result of the person’s body producing its own antibodies

213
Q

What’s naturally acquired immunity?

A

Person survives an infection by a pathogen

Their second exposure to the same antigen results in a secondary response

214
Q

What is artificially acquired immunity?

A

Vaccination

215
Q

What is a vaccination?

A

A form of immunisation where a weakened or inactive form of the pathogen is deliberately introduced into the body

216
Q

What does a vaccine act as?

A

An antigen to initiate the immune response and create memory cells

217
Q

What do memory cells do?

A

Initiate the secondary response of the person is exposed to the disease at a later date

218
Q

Antigens used in vaccines can be?

A
  • Inactivated pathogen toxins (tetanus)
  • Dead pathogens (polio)
  • Weakened pathogen (MMR)
  • Parts of a pathogen (HPV)
219
Q

Why is an adjuvant used in vaccines?

A

In a vaccine, the antigen is mixed with an adjuvant which makes the vaccine more effective + increases the immune response (but does not cause the disease)

220
Q

When does herd immunity occur?

A

When a large percentage of the population is immunised

221
Q

Herd immunity reduces?

A

Reduced the spread of diseases (the probability of non-immune individuals coming into contact with an infected individual is low)

The normal chain of infection is therefore disrupted

222
Q

For herd immunity to be effective?

A

Only a minority of the population can be left unvaccinated

223
Q

Which non vaccinated/ vulnerable sub groups does herd immunity provide protection for?

A
  • Those who have a medical condition/ immune disorder

* the elderly and new born babies who are too young to be vaccinated

224
Q

What’s the herd immunity threshold?

A

The percentage of immune individuals in a population above which a disease no longer manages to persist

225
Q

What does the value of herd immunity threshold depend on?

A
  • the type of disease
  • effectiveness of the vaccine
  • population density
226
Q

What are mass vaccination programmes designed to do?

A

Establish herd immunity for common diseases

227
Q

Successful mass vaccination programmes?

A

TB

Polio

228
Q

When do difficulties in mass vaccination programmes arise?

A

When widespread vaccination is not possible due to malnutrition and poverty (in the developing world)

When vaccines are reflected by a percentage of the population (in the developed world)

229
Q

What is antigenic variation?

A

Some pathogens change their antigens (the antigens on their surface differ from the original strain)

Means memory cells are not effective against them

230
Q

What does antigenic variation enable the influenza virus to do?

A

Avoid immunological memory and re infect a person

231
Q

Why must at risk individuals be vaccinated every year with a new version of the influenza vaccine?

A

Antigenic variation - old vaccines ineffective against new strains

232
Q

What are new vaccines and drugs required to undergo and why?

A

Medical trails to establish their safety and efficacy (produce the intended result) before they can be licensed for use

233
Q

Describe phase 1 of a clinical trail

A

Small doses of treatment tested on a very small number (25-50) of volunteers to check that it is safe

234
Q

Describe phase 2 of a clinical trail

A

Treatment tested on a large number (150-300) of people who have the illness to test if the treatment is safe and effective to find out what the optimum dose may be

235
Q

Describe phase 3 of clinical trials

A

Treatment tested on a very large number (1000-2000) of people who have the illness using a randomised, placebo-controlled, double-blind protocol

236
Q

Describe what happens if phase 3 of a clinical trial is successful

A

Results submitted and license sought to manufacture the new treatment

237
Q

What is a placebo drug?

A

A drug with the same appearance as a new drug but lacking the active ingredient being tested

238
Q

What is the point of placebo drugs?

A

This assesses the placebo effect where people feel better because they think they’ve been given a treatment

Allows a valid comparison to be made between test group and control group to assess effect of new treatment

239
Q

What’s a double blind trail?

A

Neither the subjects nor the doctor know who is in which group (test or control) or who is receiving which treatment

This eliminates any bias affecting the results

240
Q

What is randomisation?

A

Participants are randomly placed in groups by a computer whilst ensuring that group composition is as similar as possible in distribution of age, gender, etc

This reduces bias and experimental error from the trial

241
Q

Why does using a very large sample size reduces experimental error?

A

The larger the group, the more confidence the researchers an have in the differences between the test and control groups

Also allows results to be compared to determine whether differences between the groups are statistically significant

242
Q

Why would 16 year olds have a faster average time to complete a puzzle than 8 year olds?

A

As children get older they learn faster how to complete puzzles

243
Q

What is herd immunity?

A

A large percentage of the population have been immunised

This means that there is a very low chance that non-immune individuals will come into contact with infected individuals

244
Q

How can diseases of infancy be reduced in countries through community responsibility, other than by vaccination programmes?

A

Better medical care
Or
Clean water

245
Q

Suggest how pulmonary TB (in the lungs) is transmitted between individuals?

A

Inhaled air/ droplet infection

246
Q

Non pulmonary TB is often associated with HIV infection

Suggest a reason for this association?

A

HIV attacks lymphocytes reducing the ability of the immune system to respond to the bacterial infection

247
Q

Name the part of the heart that regulates heart rate

A

Medulla

248
Q

Describe how an impulse is transmitted from neuron A to neuron B

A

1) Vesicle releases neurotransmitter
2) Neurotransmitter diffused across synaptic cleft
3) Neurotransmitter binds with receptor
4) A minimum amount of neurotransmitter is required to transmit impulse

249
Q

Describe the effect thy sensitisation has on the synapse and the consequences for the individual?

A

Effect - Increased number of/sensitivity of receptors

Consequences - leads to addiction

250
Q

Explain why the heart continues to contract when both the sympathetic and parasympathetic nerves are blocked?

A

The SAN controls the heart beat and still sends impulses to the AVN

Higher Human Biology (3 decks)

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