Immunology

Question 1

What is the First line of defence?

Answer 1

Innate/non-specific.
• Consists of skins & mucous membranes - physical barriers.
• Aims to prevents organisms entering the body.

Question 2

What is the Second line of defence?

Answer 2

Innate/non-specific.
• Initiated if pathogens penetrate the first line.
• Includes inflammation, fever, antimicrobials & phagocytes + NK cells.

Question 3

What is Inflammation?

Answer 3

Damage to the bodies tissue triggers a defensive mechanism known as inflammation.
Functions to prevent the spread of microbes, clear cellular debris & repair damaged tissue.

Question 4

What are the THREE steps to Inflammation?

Answer 4

1- Vasodilation & increased blood vessel permeability.
2- Phagocyte migration to the damaged area.
3- Tissue repair.

Question 5

What are some common signs of Inflammation?

Answer 5

Heat, redness, swelling, pain, pus.

Question 6

What are the Phagocytes present in Inflammation?

Answer 6

Neutrophils,
Monocytes,
Natural killer cells.

Question 7

What is Fever?

Answer 7

A internal body temperature above 37.8°C.
Pyrogens trigger the hypothalamus to increase temperature. Pyrogens are released by phagocytosis.

Question 8

What is the function of Fever?

Answer 8

High temperatures slow bacterial growth, increases the rate of chemical reactions and induce the feeling of tiredness in the individual to ensure rest.

Question 9

What are Antimicrobial substances?

Answer 9

Substances which are released when the first line is penetrated. Four substances work to enhance the response of the second line.

Question 10

What are the FOUR antimicrobial substances?

Answer 10

Interferons,
complement proteins,
Transferrins,
antimicrobial protein.

Question 11

What is the function of Interferons?

Answer 11

enhance phagocytes & NK cells, suppress tumor formation and secrete proteins to inhibit virus replication.

Question 12

What is the function of Complement proteins?

Answer 12

Enhance inflammation, phagocytosis & help with antibody immunity.

Question 13

What is the function of Iron-binding proteins?

Answer 13

Transferrin: removes iron from circulation to inhibit bacterial growth.

Question 14

What is the function of Antimicrobial proteins?

Answer 14

Kill a wide range of microbes.

Question 15

What is the Third line of defence?

Answer 15

Adaptive, (specific) immunity.
Once the first and second line are penetrated, the third line produces an adaptive response to the invader.

Question 16

What is Immunity?

Answer 16

The capacity of the immune systems to successfully defend the body against potentially infectious agents.

Question 17

Which cells are vital in adaptive immunity?

Answer 17

Lymphocytes, particularly T & B lymphocytes.

Question 18

Where do the Lymphocytes originate?

Answer 18

Stem-cells in bone marrow.

Question 19

Where do T & B lymphocytes complete development?

Answer 19

B cells complete development in the Bone marrow.
T cells complete development in the Thymus.

Question 20

What occurs to T & B cells after developing?

Answer 20

They are equipped with hundreds of thousands of receptor molecules on their surface which recognise a specific foreign molecule (antigens).

Question 21

What is an Antigen?

Answer 21

any substance that the body recognises as foreign or non-self.
• Often components of the surface of microbes.

Question 22

What is Antibody mediated immunity?

Answer 22

A response which activates B cells to proliferate and produce:
•Plasma cells, which make antibodies.
•Memory cells, which persist in the body and can recognise the same antigen if it re enters.

Question 23

What is Antibody tire?

Answer 23

The concentration of an antibody in a persons serum (blood)

Question 24

What is the Primary response?

Answer 24

The response of the immune system the FIRST time it encounters a particular antigen.
• Has a ‘lag’ period of 5-7 days as B cells proliferate and plasma cells form.

Question 25

What is the Secondary response?

Answer 25

Occurs when increased numbers of specific memory cells are stimulated to produce more plasma cells. • Reaction occurs rapidly.

Question 26

What are Antibodies?

Answer 26

Y shaped, globular protein molecules. • also known as immunoglobulins. • found in blood, lymph, CSF, urine.

Question 27

What are the different types of antibody?

Answer 27

IgG, IgA, IgM, IgE.

Question 28

What is IgG?

Answer 28

Comprises about 80% of all antibodies in serum. • Protect from bacteria, neutralise toxin & viruses, trigger complement proteins. • Can cross the placenta. • Longest lasting.

Question 29

What is IgA?

Answer 29

Comprises about 10-15% of antibodies. • Most common antibody in secretions & on mucous membranes: mucus, saliva, tears, breast milk. • Binds to antigens before they invade tissue & prevent adhesion to mucous membranes.

Question 30

What is IgM?

Answer 30

Comprise about 5-10%. •First to be produced when antigen is detected. •Short lasting •Clump antigen & trigger complement proteins.

Question 31

What is IgE?

Answer 31

Only present in tiny amounts, •Binds to mast cells & basophils which release histamine when antigen binds to IgE. •Major defence in parasite infection. •Involved in allergic reactions.

Question 32

What are the main functions of Antibodies?

Answer 32

•Enhance phagocytes: coat the microbes making them easier to detect and ingest. •Activates complement: antibody binds to antigen and exposes an area for complement proteins to bind. •Neutralisation: antibodies bind to & block attachment site of microbes. •Agglutination: clumps microbes into larger complexes so phagocytes can consume them together.

Question 33

What is Cell mediated immunity?

Answer 33

T cells destroy cells which harbour bacteria, virus, cancer & parasites. •An infected cell displays microbial antigen fragments on its surface. • T cells bind to & insert perforin proteins into the cells. •Perforin allows enzymes to enter the cell and kill it. Stops virus multiplication & exposes it to antibodies. •Memory T cells are produced.

Question 34

How does the body know which cells are its own?

Answer 34

Major-histocompatibility complex (MHC proteins) •Proteins on the surface of our cells identify them as self. they are unique to each individual and all cells expect RBC have them. •An alternative form of MHC protein is produced by phagocytes after contact with a foreign cell- results in B&T cells specific to that pathogen.