1. IMMUNITY
ABBOTTS
2010

2. INFECTIONS
DEFINITION
Are caused by pathogenic Monera [viruses and bacteria] and Protista [Protozoans] and Fungi
An infection is the detrimental colonization of a host organism by a foreign species.

3. PATHOGENS = disease causing micro-organisms bacteria virus fungi,
protozoa,

4. IMMUNE RESPONSE BY PLANTS
Plant pathogens harm plant growth and reproduction
Plants have an immune system to defend themselves against infections
A plant recognizes the shape of the infecting pathogen and the infected cells are stimulated

5. IMMUNE RESPONSE IN PLANTS
Produce salicylic acid
a plant hormone or signal
It is an asprin-like compound
Activate resistance genes which resist the pathogen – e.g. stop viral replication
Self destruct – form an area of dead cells to prevent the infection from spreading

6. SYSTEMATIC ACQUIRED RESISTANCE
Salicylic acid moves from the infected site through the phloem to uninfected parts of the plant to activate the immune system to produce defensive compounds to make the entire plant resistant to the pathogen

7. FIRST LINES OF DEFENCE tears antibacterial enzymes
Try to prevent the entry of germs
tears antibacterial enzymes
saliva antibacterial enzymes
mucus linings traps dirt and microbes
skin prevents entry
stomach acid low pH kills harmful microbes
“good” gut bacteria out compete bad

8. PATHOGENS = disease causing micro-organisms bacteria virus fungi,
protozoa,

9. SECOND LINES OF DEFENCE
IF GERMS DO GET INTO THE BODY:
Primary response – tries to destroy the germs and prevent them from spreading
Secondary response – if germs do spread, the immune system is activated

10. PRIMARY RESPONSE
Tries to destroy the germs and prevent them from spreading by:
Inflammation (if it is a local infection)
Fever (raised body temperature)

11. INFLAMMATION Local infection
Inflammation is a process by which the bodies white blood cells protect us from infection and foreign substances such as bacteria and viruses

13. SECONDARY RESPONSE/SPECIFIC RESPONSE
If germs do start to spread
Immune system becomes involved

14. IMMUNITY
The body’s active response to an infection

15. THE IMMUNE RESPONSE INVOLVES TWO MAIN MEASURES:
Destruction of the invading germs
Holding a memory of this response

16. TWO GROUPS OF WHITE BLOOD CELLS INVOLVED IN THE IMMUNE RESPONSE
LYMPHOCYTES
B LYMPHOCYTES
T LYMPHOCYTES
PHAGOCYTES
They are part of a huge army in our
bodies
There are about one trillion B lymphocytes
And one trillion T lymphocytes
They are found in the tonsils, lymph glands, spleen and blood

17. ANTIGENS all cells have surface markers called antigens.
body can recognise these as self or non-self (foreign)

18. B LYMPHOCYTES Also called antibody cells
If a germ gets into the body, it is detected by these cells

19. HOW B LYMPHOCYTES DESTROY GERMS
Germs have molecules called antigens on their surface
The antigen tells the B lymphocyte that the germ is ‘non-human’ and dangerous
There are countless types of B lymphocytes
Each is able to recognize its own specific antigen
The B lymphocyte replicates rapidly producing lots of identical cells (clones)
These newly formed B lymphocytes produce proteins called antibodies into the blood plasma

20. The antibodies combine with the antigens on the surface of the germ
BINDING OF ANTIBODIES AND ANTIGENS
This will destroy or neutralise the germ
Some of the B lymphocytes stay in the lymph glands as memory cells
If they encounter the antigen again, they mount a response very quickly and kill the germ before it can breed
This is the basis of immunity

21. HOW ANTIBODIES DESTROY GERMS
DIAGRAM: METHODS OF GERM DESTRUCTION BY ANTIBODIES
Antibodies could:
Cause bacterial cells to burst
Label germs for phagocytosis
Cause germs to clump together [clumps are easier to ingest by phagocytosis]
Neutralize bacterial toxins

22. T LYMPHOCYTES There are different types of T lymphocytes
Each cell has a unique role to play in the immune response
CD4 Cells [helper T cells]
Killer T cells
 Killer T cells
CD4 cells are a type of white blood cell (lymphocyte

23. CD4 CELLS/ HELPER T CELLS
Begin the immune response to infections
Without these cells the other cells will not do anything
Body’s ability to fight infections would be very poor

24. KILLER T CELLS/ CYTOTOXIC T CELLS
They attack and destroy:
Cancer cells
Cells infected with viruses and some parasites
Transplanted organs [unless immunosuppressive drugs are given to the patient]

25. PHAGOCYTES (CELLS THAT EAT!)
DIAGRAM:
Are large lymphocytes (white blood corpuscles)
Can change shape
They engulf germs by phagocytosis [and also dead cells and foreign particles]

26. HOW DO PHAGOCYTES DESTROY GERMS
Move around the body looking for germs
Squeeze through gaps in capillary walls and reach any part of the body
When it comes into contact with a germ, it engulfs it and takes the germ into the cell
Germ is digested and killed
Process called phagocytosis

27. Phagocytosis of E coli

28. DEALING WITH INFECTIONS

31. THE END