Occurs when an infection is relatively localised.
- Mast cells and white blood cells release histamines.
- The histamines cause the blood vessels to dilate = LOCAL HEAT and REDNESS
- The locally raised temperature reduces the effectiveness of pathogen reproduction in the area
- The capillary walls become more permeable
- Plasma, white blood cells and antibodies are forced out of the capillaries, causing SWELLING and PAIN.
- White blood cells and antibodies destroy the pathogens
The hypothalamus maintains a normal body temperature. When a pathogen infects the body. The hypothalamus rests to a higher body temperature.
This helps combat infection in two ways:
- Reduces pathogen reproduction
- The specific response works better at higher temperatures
If the body temperature rises oo much, enzymes will denature = permanent tissue damage
Two types of white blood cells: GRANULOCYTES and AGRANULOCYTES.
Main types of phagocytes:
- NEUTROPHILS: granulocytes, make up 70% of white blood cells
- MACROPHAGES: agranulocytes, make of 4%
They accumulate at the sie of infection to attack invading pathogens.
These are proteins that inhibit viral replication within the cells.
Effective against viruses ONLY.
- An interferon diffuses from the cell where it was made into the surrounding cells.
- It binds to receptors in the surface membranes of uninfected cells
- Stimulates a pathway which makes the cells more resistant to infection by viruses by preventing viral reproduction
- Prevents the infection of more cells when viruses break out of the first cell.