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Higher Biology > Immunity > Flashcards

Immunity Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a pathogen

A

A bacterium, virus, or other disease-causing organism

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2
Q

What is the role of the non-specific defences of the immune system?

A

To defend the body against any type of invading pathogen

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3
Q

Non-specific immune response? (second line)

A

1) Inflammatory response
2) Action of phagocytes

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4
Q

What is involved in the first line of immune defence? (also are non-specific body defences)

A

1) Closely packed Epithelial Cells form a Physical barriers
(Skin, Inner linings of Respiratory and Digestive systems)

2) Chemical (defences) secretions produced against invaders

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5
Q

Name four examples of chemical secretions

A

1) Tears
2) Saliva
3) Mucus
4) Stomach acid

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6
Q

Describe the process of phagocytosis.

A

1) Phagocytes recognise foreign antigens on pathogens and destroy them by phagocytosis
2) Phagocytosis involves the engulfing of pathogens and their destruction by digestive enzymes contained in lysosomes

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7
Q

What is the role of the specific defences of the immune system? (third line)

A

To defend the body against a particular type of invading pathogen

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8
Q

What is the role of phagocytes in the specific immune response??

A

-Phagocytes release cytokines which attract more phagocytes to the site of infection.
- Cytokines are protein molecules that act as a signal to specific white blood cells causing them to accumulate at the site of infection.

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9
Q

Describe the stages involved in an inflammatory response.

A

1) Mast cells release histamine to trigger the inflammatory response.

2) Histamine causes vasodilation of blood vessels and increased capillary permeability.

3) Increased blood flow leads to the accumulation of phagocytes and clotting elements at the site of infection.

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10
Q

How does the action of phagocytes initiate the specific immune response?

A

Phagocytes releases cytokines which act as signals for specific WBC to accumulate at the site of injury or infection

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11
Q

What is involved in the third line of immune defence? (specific cellular defences)

A

1) Action of T and B lymphocytes
2) Immunological memory

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12
Q

What is the role of lymphocytes?

A

-Lymphocytes are the white blood cells involved in the specific immune response.
-They are the WBCs that respond to specific antigens on invading pathogens.

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13
Q

What is an antibody?

A
  • Y-shaped proteins that have 2 receptor binding sites specific to a particular antigen on a pathogen
  • Antibodies bind to antigens and inactivating the pathogen
  • The resulting antigen-antibody complex can then be destroyed by phagocytosis
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14
Q

What is the role of B-Lymphocytes?

A

Produce specific antibodies against foreign antigens to destroy a pathogen

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15
Q

What happens during the clonal selection of lymphocytes?

A

1) Antigen on a pathogen binds to the lymphocytes specific membrane receptor.

2) Selected lymphocyte undergoes repeated rounds of division to form a clonal population of identical lymphocytes specific to that antigen

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16
Q

What are the two types of lymphocyte ?

A

B lymphocytes and T lymphocytes.

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17
Q

What is the role of T-lymphocytes?

A

Destroy infected cells by recognising foreign antigens and inducing apoptosis
(Programmed cell death)

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18
Q

Describe the action of T-Lymphocytes during the process of apoptosis

A
  • Attach onto the pathogen’s antigen on the infected cell membrane and release proteins which diffuse into
    the infected cell
  • The Proteins cause the production of self-destructive enzymes inside the infected cell.
  • Self-destructive enzymes cause cell death
  • The remains of the cell are then removed by phagocytosis.
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19
Q

What are antigens ?

A

Antigens are molecules, often proteins located on the surface of cells that trigger a specific immune response.

20
Q

How do T-lymphocytes cause an autoimmune disease?

A
  • T lymphocytes can normally distinguish between self-antigens on the body’s own cells and foreign antigens on infected cells.
  • Failure of the regulation of the immune system leads to T lymphocytes responding to self-antigens.
  • This causes autoimmune diseases, where the T lymphocytes attack the body’s own cells.
  • This causes autoimmune diseases such as type 1 diabetes and rheumatoid arthritis.
21
Q

How do B-lymphocytes cause an allergic reaction?

A

B-Lymphocytes respond to antigens on substances that are harmless to the body. This hypersensitive response is called an allergic reaction.

Example: Pollen

B.All.

22
Q

How does immunological memory develop?

A

-Some of the cloned T and B Lymphocytes survive long-term as memory cells.

-When a secondary exposure to the same antigen occurs, these memory cells rapidly give rise to a new clone of specific lymphocytes,

-These destroy the invading pathogen before the individual shows symptoms.

23
Q

Describe the role of memory cells during a secondary exposure to the same antigen.

A

1) Rapidly give rise to a new clone of specific lymphocytes.

2) Destroy the invading pathogen before the individual shows symptoms.

24
Q

How do levels of antibody production during a secondary exposure compare to the primary exposure of a pathogen ?

A

1) Antibody production is greater
2) Antibody production is more rapid

25
Q

How does HIV compromise the immune system?

A

Virus attacks and destroys T-lymphocytes, causing a depletion of T Lymphocytes and the development of AIDS

26
Q

How does AIDS effect the health of an individual?

A

Individuals have a weakened immune system and are more vulnerable to opportunistic infections

27
Q

What is immunisation ?

A

The process by which a person develops immunity to a disease causing organism.

28
Q

What is vaccination ?

A

Immunity can be developed by vaccination using antigens from infectious pathogens, so creating memory cells.

29
Q

What can the antigens used in a vaccine be?

A

1) Inactivated pathogen toxins
2) Dead pathogens
3) Parts of pathogens
4) Weakened (attenuated) pathogens

30
Q

What does a vaccine normally consist of ?

A

Antigens from infectious pathogens are usually mixed with an adjuvant when producing the vaccine.

31
Q

What is an adjuvant ?

A

An adjuvant is a substance which makes the vaccine more effective, so enhancing the immune response.

32
Q

What is herd immunity ?

A

-Herd immunity occurs when a large percentage of a population is immunised.

-Establishing herd immunity is important in reducing the spread of diseases

-Non-immune individuals are protected as there is a much lower probability they will come into contact with infected individuals.

33
Q

What is the herd immunity threshold and what does it depend on ?

A

The herd immunity threshold is the percentage of immune people needed for effective herd immunity to occur.

The herd immunity threshold depends on the:
- type of disease
-effectiveness of the vaccine
- density of the population

34
Q

How is herd immunity established ?

A

Mass vaccination programmes are designed to establish herd immunity to a disease.

35
Q

Difficulties can arise when wide spread vaccination is not possible due to:

A

1) Poverty in the developing world (can’t access vaccine)

2) When vaccinations are rejected by a percentage of the population in the developed world.

36
Q

What is antigenic variation ?

A

-Some pathogens can change their antigens, meaning that memory cells are not effective against them.

-This makes it possible for new versions of a pathogen to appear, for which we have no immunity.

37
Q

Explain the role and impact of antigenic variation in influenza.

A

Antigenic variation occurs in the influenza virus explaining why it remains a major public health problem and why individuals who are at risk require to be vaccinated every year.

38
Q

Why are vaccines and drugs are subjected to clinical trials before being licensed for use?

A

to establish their:
-Safety ( no/minimum side effects/toxic effects)

-effectiveness (do what their intended for - produce an acceptable level of immunity)

39
Q

How are clinical trials designed to test vaccines and drugs ?

A

Involves double-blind, randomised and placebo-controlled protocols.

40
Q

What is a placebo controlled protocol ?

A

-One group of subjects receives the vaccine or drug while the second group receives a placebo-control
(like a control in an experiment)

-Ensures a valid comparisons of results

41
Q

What is a double blind trial ?

A

-Neither the subjects nor the researchers know which group subjects are in.

-Prevents biased interpretation of the results.

42
Q

What is a randomised trial ?

A

-Subjects in clinical trials are divided into groups in a randomised way, all individuals have equal chances of being placed in either group, e.g. by using a computer programme to allocates or names out a hat.

-Reduces bias in the distribution of characteristics such as age and gender.

43
Q

Explain the importance of group size in reducing experimental error and establishing statistical significance

A

-Groups must be of a suitable size to reduce the magnitude of experimental error.
-At the end of the trial, results from these two groups are compared to determine whether there are any statistically significant differences between them.

44
Q

What is an error bar

A

-Used to indicate the variability of data around the mean

-Used to determine statistically significant differences between mean results

-If the error bars in the treatment experiment overlap with the error bars in the control experiment, it is not usually possible to state with confidence that the treatment has had an effect.

Usually, a valid conclusion can be drawn where the average value in the control experiment is significantly different from the average when a treatment has been applied.

45
Q

Describe the action of B Lymphocytes

A

-B lymphocyte produces a specific antibody against antigens and this leads to the destruction of the pathogen.

-Antibodies are Y-shaped proteins that have receptor binding sites specific to a particular antigen on a pathogen.

-Antibodies become bound to antigens, inactivating the pathogen.

-The resulting antigen-antibody complex can then be destroyed by phagocytosis.

46
Q

What receptors do lymphocytes have ?

A

-Lymphocytes have a single type of membrane receptor which is specific for one antigen.

-The membrane receptors allow the lymphocytes to distinguish between the surface molecules of the body’s own cells (self-antigens) and the cells with foreign molecules on their surface (foreign antigens)

47
Q

How is herd immunity established ?

A

Mass vaccination programmes

Higher Biology (15 decks)

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