Blood

Functions Carries O2, hormones, and nutrients to the body tissues Helps to remove CO2 and other wastes from the body helps to regulate and distribute body heat Helps protect against infection Clotting to prevent excessive bleeding from the wound

Composition Plasma (55%) Erythrocytes (RBC’s) Leukocytes (WBC’s) Thrombocytes (platelets)

Erythrocyte Red blood cell (35 trillion) Primary function to carry oxygen to all of the cells (oxygen binds with a protein called hemoglobin). RBC formation (erythropoiesis) in adults takes place in the red bone marrow Average life span 90 to 120 days As they become fragile they are removed by macrophages in the liver, spleen and bone marrow.

Leukocyte White blood cell (lifespan 9 days) Primary effector cells against fighting infection and tissue damage. Neutralize and destroy organisms Act as scavengers clean up damaged cells by phagocytosis to initiate the repair process Normal WBC count 5,000 to10,000/mm3 Differential count: measures % of each type of WBC

5 Types of Leukocytes Neurophils –Most prevalent –Fight by phagocytosis (process of engulfing and swallowing germs) Basophils –Promote the inflammatory response Eosinophils –Increase in response to allergic reactions Lymphocytes –Formed in red bone marrow, lymph nodes, and spleen –Important role in immunity Monocytes –Formed in red bone marrow, lymph nodes, and spleen –Important role in immunity –Elevation usually indicates a chronic infection

Thrombocytes Platelets; smallest blood cell 130,000 to 400,000 mm3 Play an important role in blood coagulation, hemostasis, and blood thrombus formation Platelets can form a “plug” (by adhering to each other) to seal a small vessel or start the clotting process Can be beneficial or harmful (eg. Includes coronary occlusion)

Plasma Liquid part of lymph and blood 91% water 9% - consists of serum, protein and chemical substances like electrolytes and glucose Important role in fighting infection and in the clotting (coagulation) of blood

Blood Typing A person’s blood type is an inherited characteristic of the blood A blood type is determined by the antigens located on the surface of the red blood cell Clumping of incompatible cells blocks blood vessels and may cause death

Types A- 41% B- 12% AB-3% Universal Recipient O- 44% Universal donor

Reasons for blood transfusions To replace blood lost through hemorrhage to treat anemia To treat shock To exchange blood in certain disorders To aid recovery as a preoperative or postoperative procedure

BLOOD TYPEDONATE TORECEIVE FROM AA or ABA or O BB or ABB or O AB A, B, AB, O O O

Rh Factor Red Blood Cell Protein 85% of population have protein and are + 15% are Negative When Rh + blood given to a Rh - person, Rh antibodies are formed and the Rh+ blood is destroyed. Rh - blood can be given to RH+ persons

Rh Factor and Pregnancy An Rh negative mother may become sensitized by proteins from an RH positive baby (inherited from the father) During pregnancies following the sensitization, the mother’s antibodies may pass into the blood of the unborn infant and cause erythroblastosis, a destruction of RBC’s Rhogam (Rh immune globulin) - prevents the development of these antibodies

Innovations in Blood Transfusions Autologous transfusions Interoperative salvage (e.g., open heart) Apheresis – donated blood is separated into parts using a centrifuge. (before apheresis, 1 platelet transfusion required 5 to 10 donors)

Common Assessment Techniques Direct Examination Chemical Tests Coagulation Studies

Direct Examination Hemoglobin (Hgb) test measures the amount of oxygen-carrying ability of the blood Hematocrit (Hct) measures the volume of erythrocytes in the blood Sedimentation rates measure how long it takes for erythrocytes in the blood to settle to the bottom of a container Reticulocyte studies measure the number of immature red blood cells

Assessment Techniques (continued) Red blood cell (RBC) counts determine the number of circulating red blood cells in 1 mm 3 of blood Platelet or thrombocyte counts measure the number of platelets in 1 mm 3 of blood to determine clotting ability Aspiration biopsy cytology (ABC) studies examine bone marrow from the iliac crest of the hip

Chemical Tests Spectophotometry – calculates the concentration of substances in solution by measuring the amount of light it absorbs Examples: Complete Blood Count (CBC), Sequential Multiple Analysis (SMA)

Coagulation Studies Bleeding Time – amt of time an incision takes to clot Prothrombin Time (PT) – uses an anticoagulant to measure the blood sample’s clotting time