Immunology

Question 1

What is a pathogen?

Answer 1

A pathogen is a bacterium, virus or other organism that can cause disease.

Question 2

What are epithelial cells?

Answer 2

Epithelial cells form a physical barrier. Closely packed epithelial cells are found in the skin and inner linings of the digestive and respiratory system.

Question 3

What is the inflammatory response?

Answer 3

The inflammatory response is a defence mechanism triggered by damage to living tissue.

Question 4

What is histamine?

Answer 4

Histamine is released by mast cells, causing vasodilation and increased capillary permeability. The increased blood flow leads to an accumulation of phagocytes and clotting elements at the site of infection.

Question 5

What are phagocytes?

Answer 5

Phagocytes recognise pathogens and destroy them by phagocytosis. They also release cytokines.

Question 6

What is phagocytosis?

Answer 6

Phagocytosis involves the engulfing of pathogens and their destruction by digestive enzymes contained in lysosomes.

Question 7

What are cytokines?

Answer 7

Cytokines are protein molecules that act as a signal to specific white blood cells, causing them to accumulate at the site of infection.

Question 8

What are lymphocytes?

Answer 8

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

Question 9

What are antigens?

Answer 9

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

Question 10

What are the two types of lymphocytes?

Answer 10

B- lymphocytes and T- lymphocytes.

Question 11

What are B-cells?

Answer 11

B-cells produce antibodies against antigens and this leads to the destruction of the pathogen.

Question 12

What are T-cells?

Answer 12

T-cells destroy infected body cells by recognising antigens of the pathogen on the cell membrane and inducing apoptosis.

Question 13

What are antibodies?

Answer 13

Antibodies are Y-shaped proteins that have receptor binding sites which are specific to a particular antigen on a pathogen. They become bound to antigens, inactivating the pathogen.

Question 14

What happens to the antigen-antibody complex?

Answer 14

It is destroyed by phagocytosis.

Question 15

What is an allergic reaction?

Answer 15

An allergic reaction is a hypersensitive response that comes around when B-cells respond to substance that are harmless to the body. (Pollen)

Question 16

What is apoptosis?

Answer 16

Apoptosis is programmed cell death.

Question 17

What happens to a cell once apoptosis has happened?

Answer 17

It is removed by phagocytosis.

Question 18

What happens when T-cells fail to distinguish between self-antigens and non-self antigens?

Answer 18

Autoimmune disease.

Question 19

What are memory cells?

Answer 19

Cloned B and T cells that survive long term.

Question 20

What happens in a secondary response?

Answer 20

Antibody production is greater and more rapid then during the primary response.

Question 21

What is HIV?

Answer 21

HIV attacks and destroys T-cells. HIV causes the depletion of T-cells, which leads to AIDS.

Question 22

What happens to individuals with AIDS?

Answer 22

Individuals with AIDS have a weakened immune system and so are more vulnerable to opportunistic infections (pneumonia).

Question 23

How can immunity be developed?

Answer 23

By vaccination using antigens form infectious pathogens, so creating memory cells.

Question 24

What is an adjuvant?

Answer 24

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

Question 25

What is herd immunity?

Answer 25

Herd immunity occurs when a large percentage of a population is immunised. Non-immune individuals are protected as there is lower probability they will come into contact with infected individuals.

Question 26

What does the herd immunity threshold depend on?

Answer 26

- the type of disease - the effectiveness of the vaccine - the density of the population

Question 27

What are mass vaccine programmes designed for?

Answer 27

To establish herd immunity.

Question 28

What difficulties arise from widespread vaccination?

Answer 28

- poverty in the developing world | - when vaccines are rejected by a % of the population in the developed world.

Question 29

What is antigenic variation?

Answer 29

Antigenic variation occurs in the influenza virus explains why it remains a major health problem and why individuals are required ti be vaccinated every year.

Question 30

What does the design of clinical trails to test vaccines and drugs involve?

Answer 30

- randomised trails - double- blind trials - placebo- controlled trials

Question 31

What is immunity?

Answer 31

Immunity is the ability of the human body to resist pathogens, some toxins and cancer cells through the immune system.

Question 32

What are mast cells?

Answer 32

Mast cells are types of white blood cells which release histamine and various cytokines when skin is injured.

Question 33

What is a self antigen?

Answer 33

A self antigen is found on the bodies own cells and is recognised as belonging to ‘self’

Question 34

What is a non-self antigen?

Answer 34

A non-self antigen belongs to invading bacteria , transfused cells and trigger an immune response.

Question 35

What is so special about the membrane receptor on a lymphocyte?

Answer 35

It is specific for one antigen.

Question 36

What happens once an antigen binds to a lymphocyte?

Answer 36

Antigen binding leads to repeated lymphocyte division, resulting in the formation of a clonal population of identical lymphocytes.

Question 37

How can immunity be developed?

Answer 37

By vaccination using antigens from infectious pathogens, so creating memory cells.

Question 38

What is different about the antigens used in a vaccine to one found on a pathogen?

Answer 38

It has either inactivated,dead part of it or weakend.

Question 39

What is an adjuvant?

Answer 39

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

Question 40

What substance is commonly used as an adjuvant?

Answer 40

Aluminium salts.

Question 41

What is herd immunity?

Answer 41

Herd immunity occurs when a large percentage of the population is immunised. Non-immune individuals are then protected as there is a lower probability they will come into contact with infected individuals.

Question 42

What does the herd immunity threshold depend on?

Answer 42

- type of disease - the effectiveness of the vaccine - the density of the population

Question 43

What are mass vaccination programmes designed to establish?

Answer 43

Herd immunity

Question 44

What difficulties can arise with widespread vaccination?

Answer 44

Due to poverty in the developing world or when the vaccines are rejected by a percentage of the population in the developed world.

Question 45

When are memory cells ineffective?

Answer 45

When the antigens change shape.

Question 46

What is antigenic variation?

Answer 46

Antigenic variation is when the antigens on a pathogen change shape causing memory cells not to work.

Question 47

What is a clinical trial?

Answer 47

A clinical trial is a research study to evaluate the effectiveness of drugs or vaccines by monitoring their affects on a large group of people.

Question 48

What three parts are part of a clinical trial?

Answer 48

Randomised trials, double-blind trials and placebo controlled trials.

Question 49

What is meant by randomised trial?

Answer 49

Subjects in clinical trials are divided into groups in a randomised way to reduce bias in the distribution of characteristics within a group.

Question 50

What is meant by a double-blind trial?

Answer 50

In a double-blind trial neither the subjects nor the doctor know which group subjects are in to prevent bias.

Question 51

What is meant by placebo controlled trial?

Answer 51

One group of subjects receives the vaccine or drug well the second group received a placebo control to ensure valid comparisons.

Question 52

In a clinical trial should the group sizes be small or large and why?

Answer 52

Group sizes should be large to reduce experimental experimental error and established statistical significance.