White Blood Cells (Leukocytes)
- Count 4000 – 8000 per mm3
- Have nucleus, amoeboid in shape.
- Increase in the number of WBCs at the cost of RBCs is called Leukemia.
- Abnormal decrease in the number of WBCs is called Leukopenia.
Production & death
- Produced in red bone marrow, lymph nodes & some time in liver & spleen.
- Average life about 2 weeks.
- Destroyed in the same manner as RBCs.
- Some (Neutrophils) live for only a few hours & 125 billion neutrophils produced each day.
- Phagocytosis – Engulfing bacteria a defensive mechanism against bacteria.
- Inflammation – Reaction of tissue to injury to localize invasion of germs such as local
heat, redness, swelling, pain etc.
- Formation of antibody – Kill germs or poisons from them (vaccination) by the
production of antitoxins.
- Diapedesis – WBCs can squeeze out through walls of the capillaries to injured tissue to
fight against disease causing germs & also destroy damaged cells.
- Pus cells are manly WBCs with tissue cells destroyed by the bacteria.
- Better known as white cells not white blood cells because spend most of their time in tissue
fluid & lymph (90%)& a very little time in blood (10 %)
- Abnormal increase in number of WBCs (50,000 per mm3) indicates an infection in the body.