Fighting Disease

There are 2 types of pathogen: Bacteria and Viruses.

Bacteria: Small living cells.

Very small and are 1/100th of the size of a human cell. They make you feel ill by producing toxins and damaging cells.

Viruses:

They are not cells, they are 1/100th the size of a bacterium. They replicate themselves by invading your cells a dusing the cells' machinery to produce many copies of themselves which then burst aned release many new viruses. The cell damage is what makes you feel ill.

Defence system:

Your skin, plus hairs and mucus in your respiratory tract stop pathogens from getting inside your body. Platelets try and prevent microorganisms getting inside your body through cuts by small fragments of cells clot the blood quickly to seal wounds. If something does make its way through your immune system kicks in. Your white blood cells travel around your blood and constantly look out for microbes. If it detects one there is 3 lines of defence.

1. Consuming them: white blood cells engulf foreign cells and digest them
2. Produce antibodies: Each invading cell has unique molecules (ANTIGENS) on its surface, when a white blood cell comes acorss a foreign cell they start to produce proteins called antibodies to kill invading cells. The antibodies produced are specific to the type of antigen. Antibodies are then produced rapidly and carried around the body to kill all similar bacteria/viruses. If the person is infected with the same pathogen again the white blood cells will rapidly produce the antibodies to kill it - the person is naturally immune to that pathogen and won't get i
3. Produce anti-toxins: These counteract toxins produced by the invading bacteria.