infectious disease - immunity

Question 1

inflammation response

Answer 1

Blood vessels around an infected area are supplied with extra blood, making the area red and swollen. This leads to an increase in temperature in the region, leading to possible pathogen death.

Question 2

mast cells

Answer 2

release of histamines in damaged tissue increasing the permeability of blood vessels, which allows phagocytes to leave the blood vessels and move into the damaged tissue.

Question 3

mast cells

Answer 3

release of histamines in damaged tissue increasing the permeability of blood vessels, which allows phagocytes to leave the blood vessels and move into the damaged tissue.

Question 4

phagocyte

Answer 4

A type of white blood cell (macrophage or neutrophil) capable of engulfing and
absorbing bacteria and other foreign particles.

Question 5

phagocytosis

Answer 5

Phagocytes change their shape to flow around bacteria and other foreign particles. The phagocytes completely enclose the invading bacteria within their cell, where they are broken up by cellular enzymes.

Question 6

lymph system

Answer 6

Bacteria and other microbes are picked up in the lymphatic fluid and trapped inside lymph nodes, where they can be attacked and destroyed by phagocytes.

Question 7

cell death to seal off pathogen

Answer 7

Involves infected cells, or macrophages that have engulfed pathogens undergoing apoptosis. In doing so, both the cell and pathogens inside die.

Question 8

Innate immune system – 2nd line of defence

Answer 8

The innate immune system provides non-specific resistance that attempts to destroy any invading pathogens.

Question 9

antibodies

Answer 9

Proteins produced by B cells in response to specific antigens.

Question 10

Lymphocytes

Answer 10

White blood cells that are responsible for adaptive immune responses.

Question 11

Memory B cells

Answer 11

accumulate in the spleen and lymph system for a long period of time. If another exposure to the same antigen occurs the required antibody will be produced quickly, and in large amounts.

Question 12

antibodies

Answer 12

proteins naturally produced by B cells in response to antigens. They therefore play a critical role in the immune systems defence against infection and disease.

Question 13

antibody structure

Answer 13

Each antibody consists of four polypeptides – two heavy chains and two light chains joined to form a “Y” shaped molecule.
The heavy chain and lower end of the light chain are conserved in all antibodies.
The 2 variable regions of the light chain are identical antigen-binding sites and attach to identical antigens.

Question 14

antibody function

Answer 14

Neutralisation – Antibodies bind to antigen molecules on the surface of pathogens.

Agglutination – Antibodies bind to antigens on the surface of host cells and form antibody-antigen complexes which activate phagocytes and the complement cascade leading to destruction of the cell and pathogens.

Question 15

types of T cells

Answer 15

killer
helper
memory
supressor

Question 16

Killer T cells (Tc cells)

Answer 16

Attack and destroy foreign cells, infected host cells and abnormal ‘self’ cell, including tumor cells.

Question 17

Helper T cells (Th cells)

Answer 17

Become activated by APC (including activated B cells). They stimulate the cloning of specific B and T cells by the secretion of interleukins.

Question 18

Memory T cells

Answer 18

Remain in the body and reactivate quickly with subsequent exposure to the same antigen.

Question 19

Suppressor T cells

Answer 19

Stop the immune response when the antigen is destroyed.

Question 20

interleukin

Answer 20

One of a group of related proteins made by white blood cells to regulate immune responses.

Question 21

Major histocompatibility complex (MHC)

Answer 21

Cell surface proteins essential for the acquired immune system to recognise antigens

Question 22

innate immunity

Answer 22

Innate (natural) immunity is present from birth, unlike acquired immunity which is ‘learnt’ from exposure to pathogens.

Innate immunity provides a non-specific, immediate response to pathogens.

The cells involved recognise a limited number of antigens

Innate immunity retains no ’memory’ of exposure to a pathogen

provides no ongoing protection from continued exposure to the same microbe.

Question 23

(NBMEN) White blood cells involved in innate immunity:

Answer 23

Monocytes (which develop into macrophages and
dendritic cells)

Neutrophils

Eosinophils

Basophils

Natural killer cells

Question 24

Monocytes, macrophages and dendritic cells

Answer 24

develop from monocytes after they move from the bloodstream into tissues. This occurs in response to infection.

As macrophages and dendritic cells mature, they increase in size and produce enzyme filled granules.

When they phagocytose bacteria or other foreign cells, they release the enzymes that kill the ‘invaders’.

Both macrophages and dendritic cells are antigen presenting cells (APCs) and they therefore participate in acquired immunity.

Question 25

Neutrophils

Answer 25

most common type of white blood cell in the bloodstream.

Like macrophages, they are phagocytes.

produce neutrophil extracellular traps (NETs), which are networks of fibres that bind and trap pathogen, preventing further spread.

neutrophils are not antigen presenting cells and therefore play no role in acquired immunity.

Question 26

Eosinophils

Answer 26

Eosinophils also possess enzyme filled granules which help destroy bacteria that they phagocytose.

Their primary role, however is to target foreign cells that are too large to engulf, for example internal parasites.

They attach on mass to the parasites and immobilise it.

Question 27

Basophils

Answer 27

Basophils do not carry out phagocytosis.

They contain histamine filled granules.

When released in response to antigen detection the histamine increases blood flow to damaged tissues resulting in inflammation and the attraction neutrophils and eosinophils.

Question 28

Natural Killer cells (NK cells)

Answer 28

primarily involved in the initial defence against viral pathogens and cancer cells

cytotoxic.

They contain cytoplasmic granules filled with perforin and proteases.

Once a NK cell detects a ‘non-self’ cell it attaches to it and releases these cytotoxic molecules causing the lysis, and death of the target cell.

Question 29

acquired immunity

Answer 29

During the first exposure to an antigen, the adaptive immune system must ‘learn’ how to attack and destroy a pathogen.

Once a ‘memory’ of a pathogen has been obtained, a secondary exposure will result in a much more rapid response. The individual has acquired immunity.

Question 30

clonal selection theory

Answer 30

first proposed by the Australian scientist Macfarlane Burnet in 1957.

It explains the process by which a specific antigen only activates its counter-specific B cell to multiply and produce specific antibodies to the antigen.