Non Specific Body Defences 3.5 Flashcards
What is a pathogen
A pathogen is a disease causing microbe eg. Bacterium, viruses, parasites
2 types of immune system response
Non specific: targets all microbes
Specific: targets certain microbes
What is a physical defence
Mucous membranes of digestive/resprotry tracks made a closely packed epithelial cells which form a barrier
Example of physical defences
Epithelial cells act as a barrier
Chemical defences (3)
Tears: lysozyme enzyme digests cell walls
- mucous in the lungs trap pathogens and cilia cells move them away
- skin and stomach: acid secretions to kill pathogens
4 inflammatory cells responses
Mast
Phagocytes
Histamine
Clotting factors
What are mast cells
When activated releases histamine
What is histamine
Causes blood vessels to dilate and become more permeable
What are phagocytes
Engulf pathogens by phagocytosis
What are clotting factors
Arrive at site of infection to seal wound
First Process of inflammation
- After injury, mast cells become active and release histamine
Second process of inflammation
This causes vasodilation of blood vessels to the injured area becomes red and inflamed
The stretched capillary walls become more permeable and leak fluid into neighbouring tissues
Third process of inflammation
Increase in blood flow leads to more phagocytes which engulf pathogens by phagocytosis
Blood clotting elements also arrive at the site of the infection
Seals wound=clotting factors
What are cytokines
Protein molecules which act as a signal attracting more phagocytes to area of infection
4 steps of phagocytosis
- Phagocytes recognise pathogen
- Vacuole forming
- Trapped bacterium. Lysosome move towards and fuse with vacuole
- Bacterium being digested by enzymes from lysosome
