1. Immunology
3.1.1.

2. Antibody
Antigen
An antigen stimulates an immune response from a specific antibody
Antibody can only take part in an immune response if the correct antigen presents itself

3. Pathogens
A micro organism that is capable of causing infectious disease
- bacteria
- fungi
- virus
Once inside the cells a pathogen releases toxins

4. FIRST LINE OF DEFENSE Physical barriers = first line of defence
- non specific
- response to pathogens always the same
- immediate response
- skin, mucosal surfaces, digestive system, blood
- phagocytosis

5. SECOND LINE OF DEFENSE Immune system = second line of defence
- highly specific
- slower response
- more powerful and effective
- provides memory
- white blood cells = lymphocytes, cell mediated = T cells and humoral – B cells

6. Inflammation First sign of an immune response
- ‘Alarm chemicals’ released
- blood vessels enlarge and capillaries become ‘leaky’ this allows white blood cells to pass move freely
- Redness, swelling, heat and pain all caused by extra blood carrying immune systems cells
Alarm chemicals signal further immune response from white blood cells

8. Phagocytosis Second stage of immune response
Neutrophils and macrophages
- squeeze through the capillary wall to access the infected tissue
- attracted to the pathogen via chemotaxis
(cells move down the concentration gradient)

10. Phagocytosis Chemotaxis = the bacteria is attracted to the phagocyte
2. Ingestion = Phagocyte begins to engulf the bacteria
3. Phagososome = Phagocyte surrounds the bacteria in a vesicle known as a phagosome
4. Phagolysosome = Lysosomes inside the phagocyte, containing digestive material is attracted towards the phagosome and fuse together
5. Digestion = Digestive enzymes break down the bacteria via hydrolysis reaction
6. Bacteria is destroyed, residual body is formed containing indigestible material
Discharge = waste materials are pushed out of the body
Phagocyte presents antigen markers on its surface to trigger an antibody response

11. When you get pus and goo from a wound, it’s the removal of dead neutrophils presenting there digested material as waste

12. Third line of defence Lymphocytes = T cells and B cells
Both created in the bone marrow
- T cells mature in the thymus gland
- B cells mature in the bone marrow
Both circulate in the blood looking for foreign antigens
Both stimulated by complementary shaped receptors, causing clonal selection (enlarge and divide)

13. Cell mediated response
T cells
- Killer T cells: combine with antigens and release powerful chemicals (lymphokines) that can directly kill pathogens
- Helper T cells: Co-operative with B cells in antibody production. They also promote further inflammation and phagocytosis
- Memory T cells: Remain in the blood system after pathogens have been killed to prevent re-infection

14. Humoral response
B cells: differentiate into mostly plasma cells and some memory cells (prevent re-infection)
Remember they don’t leave the bone marrow, but produce antibodies which can travel in the blood to the infected site
Complementary shape to fit the antigens as this shape initiated clonal selection in the first place

15. Antibodies Attach to antigens and ‘tag’ the
pathogen, making it more visible
to other cells (killer T and phagocytes)
= neutralisation
Many antibodies-antigen
complexes join together
creating a ‘clump’ of easily
recognisable pathogens
= agglutination

17. Immunological memory Plasma cells and T cells die after a few days
Memory B cells and Memory T cells survive
Each memory cell can only recognise the specific antigen already defeated
Upon secondary infection
an immune response is quicker
and more powerful

18. Monoclonal antibodies
Antibodies specifically targeted
To treat disease e.g. cancer
Animal is injected with disease and an immune response is triggered
Antibodies are collected and grown in vitro
Drugs can be attached to the antibodies making them more effective
They can then be injected into humans

20. Artificial immunity Vaccines
Injecting small artificially weakened pathogens into the body to allow an immune response
Do not say ‘safe dose’
Memory cells are created
If real disease is encountered, immunological memory exists and the body is ready to fight off the disease

21. Natural immunity Pathogen in encountered naturally
Natural activation of the immune system involving T cells and B cells
Natural immunological memory

22. Passive immunity Breast feeding Placental transfer
Injection of cells from another person/animal
Short term immunity
B cells and T cells are non activated
Memory cells are not created

23. Active immunity Trigger of immune response Cell mediated
Memory cells created

24. Natural immunity
Artificial immunity
Active immunity
Cell mediated immune response involving B cells, T cells and antibodies as a result of infection. Memory cells are created.
Cell mediated immune response triggered by a vaccination. Involves B cells and T cells , Memory cells created
Passive immunity
Antibodies passed on from mother to baby through breast feeding, and mother to foetus through placenta. Short lived immunity with no memory cells created.
Monoclonal antibodies passed on from an animal or human. Short lived immunity which no memory cells created.