Unit Three Immunology

Question 1

Define immunity

Answer 1

Immunity is the state of being resistant to a pathogen or infectious disease

Question 2

What are antigens

Answer 2

Any substrate that causes the body to make an immune response against it

Question 3

Describe the three lines of defence

Answer 3

1. Non-specific physical barriers
2. Non-specific immune cells
3. Specific immune cells

Question 4

Inborn,nonspecific and does not change over time. Give examples

Answer 4

Sneezing
Coughing

Question 5

Describe acquired immunity

Answer 5

Antibodies

Question 6

Briefly describe how the skin provides immunity

Answer 6

Closely packed epithelial cells from a physical barrier against he entry of pathogens

Question 7

List your other nonspecific defences

Answer 7

Saliva- antibacterial enzymes
Tears- antibacterial enzymes
Mucus-lungs trap city and microbes
Skin- prevents entry

Question 8

Explain the role of mast cells

Answer 8

Histamine is released

Question 9

Describe the role of cytokines in phagocytosis

Answer 9

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

Question 10

Explain how lymphocytes are selective

Answer 10

Each lymphocyte has a single type of membrane receptor which is specific for one antigen

Question 11

Explain how lymphocytes are selective

Answer 11

They have a membrane receptor which is specific for one antigen

Question 12

What is the process that occurs to produce a lymphocyte clone

Answer 12

Antigen binding leads to repeated lymphocyte decision resulting in the formation of a clinal population of identical lymphocytes

Question 13

What are 5 foreign particles

Answer 13

Cells infected by pathogens
Toxins released by pathogens
Antigens
Transplanted tissue
Cancer cells

Question 14

What are the two main types of lymphocytes

Answer 14

B-lymphocytes
T-lymphocytes

Question 15

Explain the role of T-lymphocytes in normal conditions

Answer 15

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

Question 16

Explain the role of T-lymphocytes in autoimmune disease

Answer 16

Failure of the regulation of the immune system leads to T-lymphocytes responding to self antigens. This causes autoimmune diseases

Question 17

What is the cellular validity of an allergic reaction

Answer 17

B-lymphocytes can respond to antigens on substances that are harmless to the body
The hypersensitive responds is called an allergic reaction

Question 18

What substance do B lymphocytes produce

Answer 18

Antibodies against antigens on an invading pathogen which leads to destruction of the pathogen

Question 19

Describe phagocytosis

Answer 19

The engulfing of pathogens and their destruction by digestive enzymes contained in lysosomes

Question 20

What are memory cells

Answer 20

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

Question 21

How do memory cells enhance immunity

Answer 21

When a secondary exposure to the same antigen occurs, these memory cells rapidly give rise to a new clone of specific lymphocytes.
During the secondary response antibody production is greater and more rapid than during primary tepobcr
These destroy the pathogens before symptoms occur

Question 22

What is the purpose of vaccination

Answer 22

To prepare your immune system so it can give a better response

Question 23

What is active immunity

Answer 23

Immunity to a pathogen that occurs following exposure to said pathogens

Question 24

What can be in vaccines

Answer 24

Dead pathogens
Weakend pathogens
Parts of pathogen
Inactivated toxin

Question 25

What is the role of the adjuvant in a vaccine

Answer 25

Antigens usually mixed with adjuvant when producing the vaccine An adjuvant is a substance which makes the vaccine more effective so enhancing the immune response

Question 26

As the antigens in a vaccine are identified to the known pathogen, they stimulate a primary response. How does this primary response help with long term immunity

Answer 26

After the initial response a memory cell is created. This decreases the time when infected for the second time

Question 27

What is herd immunity

Answer 27

When a large percentage of a population is immunised

Question 28

Who does herd immunity benefit

Answer 28

Everyone as it reduces the spread of diseases

Question 29

What does the threshold for herd immunity depend on

Answer 29

Type of disease The effectiveness of vaccine The density of the population

Question 30

Describe the difficulties that can arise obtaining widespread vaccination in the developing world

Answer 30

Costs a lot of money poverty

Question 31

Describe the difficulties that can arise obtaining widespread vaccination in the developed world

Answer 31

When people don’t want to get vaccinated

Question 32

What is antigenic variation

Answer 32

Some pathogens can change their antigens this means that memory cells are not effective against them

Question 33

Some pathogens directly attack the immune system. What is the consequence of the attack

Answer 33

Weakened immune system More vulnerable to opportunistic infections

Question 34

Explain the difference between aids and hiv

Answer 34

HIV is higher number of white blood cells

Question 35

Why must a vaccine be subjected to a clinical trial

Answer 35

To establish theirs safety and effectiveness before being licensed for use.

Question 36

Statistical significance

Answer 36

At the end of the trial the results form two groups are compared to determine whether there are any statistically significant differences between the groups

Question 37

Describe randomised clinical trial

Answer 37

Divided into groups randomly Reduces bias in the distribution of characteristics such as agr and gender

Question 38

describe a double-blind clinical trial

Answer 38

neither of the subjects nor the researchers know which group the subjects are in. this prevents biased interpretation of the results

Question 39

describe a placebo-controlled clinical trial

Answer 39

one group of subjects receives the vaccine or drug whilst the second group receives a placebo- control to ensure valid comparisons.

Question 40

what do all clinical trials have in common

Answer 40

always in large groups this is to reduce magnitude of experimental error and to establish statistical significance .