Disease

Question 1

Infectious vs Non infectious disease

Answer 1

Infectious - caused by pathogen and can be transmitted from one host to another

Non infectious - Genetic, nutritional and environmental diseases (not caused by a pathogen)

Question 2

Prions

Answer 2

Non cellular pathogenic agent (protein) which is abnormally refolded, located on surface of brain and spin al chord. Prion Proteins aggregate together to form plaques which lead to neuronal deaths

Question 3

Viruses

Answer 3

Non living and very small- nucleic acid in protein coat. Only infect cells which possess receptors to which the virus can bind. Viruses can often change.

Question 4

Protozoans

Answer 4

Single celled eukaryotic cells - not always pathogenic - can release toxins

Question 5

Parasites

Answer 5

An organism that lives and feeds off of a host organism and benefits at the host’s expense.
Can be ectoparasites or endoparasites.

Question 6

Fungi

Answer 6

Decomposers which can be mulit or unicellular. Usually attack body’s surfaces.

Question 7

Bacteria

Answer 7

Unicellular prokaryotes - most are harmless.
Can release toxins and cause disease even after bacteria dies

Question 8

Adherence factors

Answer 8

Allow pathogen to bind to receptors on host cell’s surface.

Question 9

Invasion Factors

Answer 9

Receptors which interact with host cell receptors and can instigate endocytosis.

Question 10

Capsules

Answer 10

Prevent pathogen from immune system and may prevent phagocytosis.

Question 11

Toxins

Answer 11

Substance secreted by pathogen which damages host cell or disables immune system .
Can be exotoxins - substance secreted onto host tissue
or endotoxins - components of pathogen which is released when pathogen breaks down.

Question 12

Lifecyle Changes

Answer 12

Dormancy stages where they exist in slow growth state. This enables them to evade immune defences.

Question 13

Define vector

Answer 13

living thing that carries disease from reservoir to host

Question 14

4 steps of Inflammation (second line of defence)

Answer 14

Mast cells release histamines which increase the permeability of blood vessels so that phagocytic cells can leave the capilleries into the infected site.

Damages cells release prostaglandin which makes blood vessels bigger

Chemokines - chemical communicators recruits more phagocytic cells to the area

Phagocytosis becomes more effective

Question 15

Describe phagocytosis

Answer 15

A type of endocytosis where phagocytic cells (macrophages) identify non self markers and engulf and destroy pathogens.
The pathogen is engulfed into an internal vesicle, which fuses to a lysosome to destroy the pathogen.

Question 16

Describe the first line of defense

Answer 16

surface barriers that prevent pathogens entering
such as:
- skin
- mucus
-cilia
- stomach acid

Question 17

Parts of second line of defense

Answer 17

Phagocytosis
Natural KillerCells/Eosinophils
Inflammation
Fever
Interferons (release protein to stop virus replication)
Complement Proteins

Question 18

Antigen

Answer 18

Surface makers on pathogen which immune system identifies as foreign

Question 19

MHC ll vs MHC l markers

Answer 19

MHC ll - only found on antigen presenting cells
MHC l - found on all cells with a nucleus

Question 20

Describe fever

Answer 20

• Macrophage releases cytokine which resets the body’s thermostat to 37 celsius
  This reduces the growth rate of pathogens as well as activating heat shock proteins with strengthens the immune response,

Question 21

Describe interferons

Answer 21

a cytokine secreted by virally infected cell, and recruits leukocytes to site

Question 22

Cell mediated immune response

Answer 22

Involves T lymphocytes (T helper cells, cytotoxic T cells, T suppressor cells), which are stored in lymph nodes

Question 23

Role of T Helper cells

Answer 23

Binds with antigen fragment on MHC ll marker (if it had complementary T cell receptor) and is then activated
Replicates though clonal expansion and selection

Question 24

Role of cytotoxic T cells

Answer 24

Activated by cytokines released by T helper cells
They bind to infected cells and release cytokines which kill infected cells as well as storing memory cells.
Also causes clonal expansion of cytotoxic T cells

Question 25

Role of T suppressor cells

Answer 25

inhibit cytotoxic T cells once infection is destroyed to ensure normal cells aren’t attacked.

Question 26

Role of B cells (humoral immune response)

Answer 26

• Have antibodies (y shaped receptors) which bind with antigen and presents antigen fragment
  -finds specific T helper cell to fit antigen fragment which activates b cell
• clone to form memory plasma b cells which can release antibodies

Question 27

Two main types of immunity

Answer 27

Active - production of antibodies by organisms B cells after body’s defence is stimulated by antigens
Passive - acquisition of antibodies from another organism which has achieved active immunity

Question 28

Natural vs artificial active immunity

Answer 28

natural - producing antibodies in response to infection
artificial - controlled exposure to pathogens (eg vaccination) and producing antigens

Question 29

Natural vs artificial passive immunity

Answer 29

natural - receiving antigens from an external source naturally (eg feotus)
artificial - receiving antigens from external source via injection (eg blood transfusion)