The immune system is a complex network of cells and proteins that defends the body against infection. The immune system keeps a record of every germ (microbe) it has ever defeated so it can recognise and destroy the microbe quickly if it enters the body again.
The immune system is spread throughout the body and involves many types of cells, organs, proteins, and tissues. Crucially, it can distinguish our tissue from foreign tissue — self from non-self.
- White blood cells circulate in the body in blood vessels and the lymphatic vessels that parallel the veins and arteries. When they find a target, they begin to multiply and send signals out to other cell types to do the same.
Our white blood cells are stored in different places in the body, which are referred to as lymphoid organs. so recognized and cleared away by the immune system.
These include the following:
- Thymus — a gland between the lungs and just below the neck.
- Spleen — an organ that filters the blood. It sits in the upper left of the abdomen.
- Bone marrow — found in the center of the bones, it also produces red blood cells.
- Lymph nodes —small glands positioned throughout the body, linked by lymphatic vessels.
John Deo Mockup | PSD Mockup 