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Human Body in Health and Illness The Barbara Herlihy Chapter 15: Blood What Blood Does • Three general functions: – Transportation: oxygen, carbon dioxide, nutrients, hormones – Regulation: body temperature, fluid and electrolyte balance – Protection: WBCs and platelets 2 Composition of Blood • Characteristics: – – – – Type of connective tissue Color varies with oxygenation pH between 7.35 to 7.45 Viscosity: thickness or stickiness compared to water (more viscious) 3 Composition of Blood (cont’d.) • Two Parts: – Plasma: pale, yellow fluid composed mostly of water – Blood cells (formed elements): • Red blood cells (RBCs) • White blood cells (WBCs) • Platelets 4 Hemopoiesis • Process of blood cell formation • Hemopoietic tissue: – Red bone marrow: found in the end of long bones, flat and irregular bones – Lymphatic tissue: spleen, lymph nodes and thymus 5 Myelosuppression • Condition in which bone marrow cannot produce enough blood cells • Myelosuppression can result in: – Aplastic anemia: RBC deficiency – Leukopenia: WBC deficiency – Thrombocytopenia: Platelet deficiency 6 Polycythemia Vera • Bone marrow overactivity leads to excess RBC production • Caused by a gene mutation • Excess thickened blood: – Burdens the heart – Overwhelms clotting system – Causes beet-red face • Treatment: drugs to suppress bone marrow and/or phlebotomy 7 Red Blood Cells • Red blood cells (RBCs): – Also called erythrocytes – Most numerous of the blood cells – Primarily responsible for the transport of oxygen and carbon dioxide – Large, disc-shaped, thick outer rim, thin center, bendable – Filled with hemoglobin (iron containing protein) – Color changes from bright red to blue-red 8 Sickle cell disease • Genetic disorder characterized by RBCs that form an abnormal, rigid, Cshape. • Blocks blood flow and restricts tissue of oxygen. 9 Hemoglobin • Iron containing protein in RBCs that transports oxygen and carbon dioxide • Heme: iron containing substance (O² attaches) • Globin: protein (CO² attaches) 10 Regulation of RBC Production 1. Low O² 2. Kidneys release erythropoietin (EPO) (hormone) 3. Stimulates bone marrow to produce RBCs 4. O² levels increase 5. EPO no longer released 11 Recycle! • Worn out RBCs are broken down into: – Heme: iron (used later) and bile (excreted) – Globin: amino acids (used later for proteins) 12 White Blood Cells • White blood cells (WBCs): – Large, round cells that contain nucleus – Also called leukocytes – Function to protect the body – Can leave the blood vessels 13 White Blood Cells (cont’d.) Type of WBC Granulocytes Neutrophils Eosinophils Function of Cell Basophils Inflammatory responses; release of heparin Phagocytosis Inflammatory responses; allergies Agranulocytes Lymphocytes Immunity Monocytes Phagocytosis 14 White Blood Cells (cont’d.) 15 Platelets • Platelets: – – – – – Tiniest blood cells Produced in red bone marrow Also called thrombocytes Life span is 5 to 9 days Function to prevent blood loss 16 Blood Diagnostic Tests • Differential white blood cell count: indicates the percentage of each type of white blood cell • Complete blood count (CBC): lists the normal ranges of the numbers of RBCs, WBCs, and platelets in blood 17 Hemostasis: process that stops bleeding • Vascular spasm: decreases the diameter of the blood vessel • Platelet plug: platelets stick together and adhering to the lining of the injured vessel • Coagulation: clotting of blood to seal off the opening in an injured blood vessel (caused by a series of chemical changes in blood) 18 Blood Types: ABO Grouping • ABO grouping: – Four blood types: A, B, AB, O • Agglutination: clumping together of RBCs; causes hemolysis (bursting of RBCs) • Compatible blood groups: blood types that mix without undergoing agglutination reactions • Universal donor: type O blood • Universal recipient: type AB blood 19 Blood Types: Rh Factor • Rh factor: an antigen located on the surface of the RBC • About 85% of people are Rhpositive (+) 20