1. Unit 4 - Immunology and Public Health

2. Unit 4 – Immunology and Public Health
1. The Immune System
2. Infectious Diseases and immunity
Non-specific defences
Specific cellular defences
Transmission and control
Active Immunisation and Vaccination and the evasion of immune responses

3. By the end of this section you will be able to …..
1. The Immune System a) non-specific defences
By the end of this section you will be able to …..
describe the role and process of phagocytosis
describe the action of natural killer (NK) cells

4. The many types of White blood cells

5. AKA phagocyte
How do phagocytes work?

6. All your cells have protein surface markers on them.
These markers let your immune cells know that your cells are yours and belong in the body.
However, pathogens such as bacteria or viruses also have markers on their surface. But because they do not belong in the body and are ‘foreign’, they are known as surface antigen molecules
The phagocytes RECOGNISE these foreign markers and engulf them!

7. Engulfing

8. Phagocytosis Lysosome containing powerful digestive enzymes
Phagocyte (a.k.a. Mr / Mrs / Ms Pac Man or Mrs / Ms Pac Woman)
Bacterial particles
Lysosome containing powerful digestive enzymes

9. Process of phagocytosis

10. Phagocytes
There are many different white blood cells in the body and each have a different defensive role.
Phagocytes are a non-specific type of white blood cell since it provides a general protection against a WIDE RANGE of pathogens.
Phagocytes recognise surface antigens molecules on pathogens and destroy them by phagocytosis (foreign particle is engulfed and then digested by enzymes present in lysosomes).

12. Natural Killer (NK) cells
(apoptosis summary)
(NK cells in LOTS of detail)

13. Natural Killer (NK) cells
Natural killer (NK) cells are found in the blood and are constantly looking for signs of an infection.
They can also release cytokines but they have an important role in destroying a virus-infected cell or cancer cell.
They look for a cell which has not got the normal ‘self’ surface molecules and knows that it must be infected.
It then releases toxins and a ‘signal’ molecule which enters the infected cell and triggers the production of self-destructive enzymes. These enzymes destroy the cell by breaking down DNA and vital proteins. The cell then shrinks and dies.
The process is called apoptosis (programmed cell death / self-destruction).

15. Can you now …. Describe the role and process of phagocytosis
Describe the action of natural killer (NK) cells