A liquid connective tissue made of cells surrounded by plasma (liquid extracellular matrix) - Components: - Formed Elements (45%): - RBC (erythrocytes) 99% - Transport Oxygen from lungs → cells - Deliver CO2 from cells → lungs - % Total blood volume of RBC is hematocrit - WBC (leukocytes) - Protect body from pathogens and foreign substances - Normal ratio of neutrophils, lymphocytes, monocytes, eosinophils, and basophils - Lymphocytes: B Cells, T Cells and Natural Killers - Can live for years unlike other formed elements - Amount of WBC depend on invading pathogens and antigens - Platelets (thrombocytes) - Release chemicals for blood clottings - Plasma (55%) → on top - Water: - Absorb, transport and release heat - Protein: - Fibrinogen → clots blood - Globulins → Antibodies/ Immunoglobulins for immunity - Albumins → osmotic attraction - Solutes: - Electrolyte, nutrients, gas, regulatory substance, waste - Functions: - Transports - Oxygen from the Lungs → Interstital fluid → Cells - Nutrients and Hormones from the Gi and Endocrine→ IF → Cells - CO2 from the Cells → Interstitial Fluid → Blood → Lung