1. Blood (made of 45% formed elements)

2. Red Blood Cells (RBC's) Called Erythrocytes Small boconcave discs Loses nucleus when mature Each cell contains hemoglobin Heme (with iron, Fe) + globin Made in red bone marrow (skull, ribs, vertebrae, end of long bones)

3. RBC formation

4. Hemoglobin in red blood cells responsible for carrying O 2 Hemoglobin increase O 2 carrying capacity 60 times Red Blood Cells live approx 120 days Eventually destroyed by liver and spleen Hemoglobin also helps carry CO 2

5. High altitudes or blood loss.. Renal erythropoeitinis released This raises the O 2 capacity of the blood This also causes the blood to thicken Athletes will use this substance to enhance performance It is illegal (due to the dangers of blood thickening)

6. White Blood Cells Called Leukocytes 8 – 10 times larger than the RBC's Contain a nucleus (irregularily shaped) Exist in far fewer numbers than RBC's Most are neutrophils (immune cells that engulf invaders) Leukemia: a form of cancer characterized by uncontrolled production of leukocytes

8. Granulocytes WBC's with granules in cytoplasm Have irregular shaped (many lobed) nucleus called polymorphonuclear Formed in red bone marrow 3 kinds:  Neutrophils  Eosinophils  Basophils Destro bacteria, viruses, dead tissue by engulfing (phagocytes)

9. Agranulocytes WBC's with no granules in cytoplasm Have a circular nucleus 2 kinds:  Monocytes (huge, phagocytotic)  Lymphocytes (20 – 30% WBC's, produced in lymphoid tissue, responsible for immunity, produce antibodies)

10. Platelets Called thrombocytes Are actually fragments of huge cells Huge cells come from red bone marrow They are anucleate Blood stream has more than a trillion Responsible for blood clotting (combined with certain plasma proteins) Haemophiliac: a person whose blood doesn't clot