Blood & Circulatory System

Blood – The River of Life About 8% of body weight Only fluid tissue in the body Functions: Transports oxygen, carbon dioxide, nutrients, wastes, hormones, & enzymes Helps regulate pH, body temperature, & water content of cells Prevents excess fluid loss through clotting Protects against toxins and microbes Contains erythrocytes (RBCs), leucocytes (WBCs) & thrombocytes (platelets)

Blood Major component of the circulatory system Composed of cells, fluid, & cell fragments Component Characteristic Red Blood Cells (44%) Transports oxygen and CO2, lacks a nucleus; contain hemoglobin (binds oxygen) produced by red bone marrow White Blood Cells (1%) Large; contain a nucleus; defend the body against disease. Live only a few hours/days Platelets Cell fragments needed for blood clotting – removed from the blood by the spleen Plasma (55%) Fluid; contains proteins, transports RBC & WBC, platelets, nutrients, enzymes, hormones, gases, & salts (91.5% water & 8.5% solutes)

Hematopoisesis Blood Cell Formation Hemocytoblast Controlled by hormones Occurs in red bone marrow Hemocytoblast Type of blood stem cell Produces: Lymphoid Stem Cells – lymphocytes Myeloid Stem Cells – all other formed elements in the blood

Hematopoisesis

Hemostasis Prevention of blood loss Three phases Vascular spasms Smooth muscle of blood vessel contracts to stop bleeding Platelet plug formation Platelets begin to clump Coagulation or blood clotting Involves coagulation factors Normally…blood clots in 3-6 minutes

Disorders of Hemostasis Undesirable Clotting (Thrombus) Can lead to heart attack or strokes Bleeding Disorders Thrombocytopenia Spontaneous bleeding Insufficient number of circulating platelets Hemophilia Lack of clotting factors (proteins needed for normal blood clotting)

Blood Types Three Blood Type Antigens: A, B, & O An antigen is a blood protein found on a blood cell surface. Four Blood Types: A, B, AB, O Type A Antigen A present Type B Antigen B present Type AB Antigens A & B Universal recipient Type O Neither A nor B antigens Universal donor

Blood Type - Antibodies Antibodies are produced by the body in reaction to foreign proteins being present Individuals will not produce antibodies for proteins on their own red blood cells, but do produce antibodies for foreign proteins.

Rh Factor 1937 – Rh factor in blood was demonstrated leading to the discovery of many other blood groups Presence of Rh Factor – Rh positive Absences of Rh Factor – Rh negative Mixing of different blood types can have serious consequences Rh incompatibility rarely causes complications in a first pregnancy But Rh antibodies that develop during later pregnancies can be dangerous to mother and child. can result in severe anemia, jaundice, brain damage, heart failure or death

Blood Disorders Anemia Polycythemia Infectious Mononucleosis – viral Decreased erythrocyte count (RBCs) Decrease in oxygen in the blood Polycythemia Abnormal increase in the number of erythrocytes (RBCs) – thickens blood Infectious Mononucleosis – viral Elevated white cell count Leukemia (type of Cancer) Uncontrolled production of white blood cells that interferes with normal clotting & vital body activities