Blood Composition Blood is a fluid tissue made up of water, many types of chemicals and millions of cells. Blood volume – 4-6 liters depending on sex, size and age. Color – arterial blood is bright red and venous blood is dark red.
Blood Composition pH – normal is 7.35 – 7.45; venous blood will have a lower pH because it has a higher concentration of CO2. pH (parts hydrogen) is a measure of the amount of H+ in a solution. Values range from 0-14. Neutral pH is 7.0 and a pH below 7 is acid while a pH above 7 is alkaline. Blood is slightly ?
Blood Composition Plasma 91% water, with proteins (albumen and globulins), salts, a little oxygen, nutrients, wastes, hormones, antibodies and clotting factors. Also contains formed elements – cells and cell fragments. Serum – plasma minus the clotting factors; retains antibodies.
Blood Composition - Cells Red blood cells (RBCs) or erythrocytes Function: transport oxygen to other cells of the body. Key – hemoglobin contained in the RBC. Hemoglobin (Hgb) has 4 iron (Fe) atoms that bind O2. Hgb picks up O2 as it passes through the lungs. Life cycle – 120 days Normal Hgb – 12-18 grams per 100 ml of blood (dl). Normal RBC count – 4.5 – 5.5 million/cubic mm Hematocrit – %, volume of RBC in a volume of blood; normal is 35-50%.
Blood Composition - Cells Anemia – Term used to describe a number of different conditions caused by an inability of the blood to carry sufficient O2 to the cells of the body. May be a result of low RBC count or low Hgb. Causes – inadequate diet, hemorrhage, infections, cancers or treatments where the myeloid tissue is not able to produce enough RBCs.
Blood Composition - Cells Anemias Pernicious anemia – a deficiency of RBCs due to lack of vitamin B12. Iron deficiency anemia – caused by lack of dietary iron. Aplastic anemia – caused by suppression of myeloid tissue resulting in decreased RBCs. May be due to radiation or chemical exposure. Hemolytic anemia – disorder that causes RBCs to rupture before the end of their normal life span. Includes malaria and sickle cell anemia.
Blood Composition - Cells Other RBC abnormalities Polycythemia vera – condition in which the myeloid tissue produces an excess of RBCs; blood becomes too thick to flow properly.
Blood Composition - Cells White Blood Cells (WBCs) or leukocytes Normal WBC count = 5,000 to 10,000/microliter Buffy Coat – after blood is centrifuged (separating cells from plasma) the thin layer between the RBC and the plasma consists of WBCs and platelets. 5types of WBCs
Blood Composition - Cells WBC types Neutrophils – phagocytes (phagocytosis means that they “eat” and destroy invaders, etc.”) Eosinophils – defense against parasites; helps protect the body from irritants that cause allergies. Basophils – function in the inflammatory response/allergic reactions; produce histamines and Heparin.
Blood Composition - Cells WBC types Lymphocytes – “B” cells produce antibodies, T- cells recognize foreign antigens and destroy them = immune response. Monocytes – phagocytes; become macrophages.
Blood Composition - Cells WBC – abnormalities Leukopenia – abnormally low WBC count (viral infections). Leukocytosis – abnormally high WBC count (bacterial infections) Leukemia – malignant disease in which the number of WBCs increases tremendously but cells do not function normally.
Blood Composition - Cells Platelets or thrombocytes Not cells but fragments of megakryocytes that live in the bone marrow. Function in the clotting process. Normal value – 150,000 to 300,000/cubic millimeter. Thrombocytopenia – low platelet count.
Cells – Myeloid Tissue 2 types of connective tissue that produce blood cells for the body: Myeloid tissue – red bone marrow located in the sternum, ribs and pelvis. Stem cells produce all types of blood cells except some lymphocytes and monocytes. Lymphatic tissue – located primarily in the lymph nodes, thymus, and spleen. Produces lymphocytes and monocytes.
Clotting Process Hemostasis – prevention of blood loss. Injury to a blood vessel occurs. Myogenic response – smooth muscle lining of blood vessel contracts causing vasoconstriction. Rough spot forms on the lining of the vessel (lining is simple squamous epithelium). Platelets break up as they pass over the injured area – releasing platelet factors that make the platelets sticky and they stick to the wound. (In small vessels the platelet plug is all that is necessary to stop the bleeding).
Clotting Process Hemostasis Platelet factors combine with prothrombin (protein manufacture in the liver), calcium and other substances to form thrombin (an enzyme). Thrombin reacts with fibrinogen (a blood protein) to change it into fibrin that forms a fibrous gel in the area of the wound. Fibrin is like a web of fine threads that traps RBCs and form a barrier across the vessel.
Clotting Process Hemostasis Clot retraction – fibrin threads pull the edges of the break in the vessel together. Note: vitamin K (produced in the colon) stimulates the production of prothrombin by the liver. Embolus – blood clot that moves Thrombus – stationary blood clot
Blood Types ABO Blood Group 4 blood types – A, B, AB, O Types are identified by antigens located on the RBC surface. Antigens – protein substances that can stimulate the body to make antibodies. Antibody – proteins made by the body in response to stimulation by an antigen – causes clumping or agglutination in the case of RBCs.
Blood Types ABO group A person with Type A blood has A antigens on their RBC and a person with Type B blood has B antigens. What antigens does a person with type AB blood have? type O? Natural antibodies are also present in the plasma: A person with type A blood has anti-B antibodies and a person with type B blood has anti A antibodies. What antibodies do people with type AB or type O blood have?
Blood Types Typing and cross-matching – process by which blood type is identified and donor blood is tested for possible transfusion. Transfusion: Type O is a “universal donor”, i.e.can give blood to anyone. Type AB is the “universal recipient”, i.e. can receive blood from anyone.
Blood Types Transfusion Type A can receive type A or type O blood Type B can receive type B or type O blood Type AB can receive type B, A, AB, or O Type O can receive type ??? Blood.
Blood Types Rh factor – another antigen which may be present (Rh +) or absent (Rh -) on RBCs. Rh negative (-) do not have natural antibodies to the Rh antigen. If they receive blood that is Rh positive (+) antibodies form but not a problem. The second exposure can produce a transfusion reaction (hemolysis and possible kidney damage).
Blood Types Rh factor People with Rh negative blood should receive Rh negative blood. ??? What blood type is the “real Universal donor”?