I. Blood

A) Blood is composed of formed elements and plasma.

B) Blood is a viscous, slightly alkaline fluid

C) You have about 5 liters (about 8% of your weight)

II. Functions of blood:

A) delivery of oxygen & nutrients to the body tissues

B) removal of body wastes

C) transport of hormones

D) regulation of body temperature

E) regulation of constant blood pH

F) regulation of fluid volume

G) hemostasis (it contains elements that clot the blood when vessels are damaged)

H) prevention of infection

III. Composition of blood

A) Plasma
     1) a straw colored, viscous fluid that is 90% water
     2) the remaining 10% is composed of nutrients, respiratory gases, salts, hormones, & proteins
     3) it makes up about 55% of your blood
     4) plasma proteins include albumin, globulins, and clotting proteins
          a) albumin is an important blood buffer and helps regulate pressure

B) Formed elements - make up about 45% of the blood; they come from hemocytoblasts in red bone marrow
     1) erythrocytes
          a) also called red blood cells
          b) they have no nucleus and few organelles
          c) their main function is to transport oxygen (oxygen attaches to the hemoglobin in the cell)
          d) they live about 100-120 days
          e) there are several disorders related to erythrocytes
               i) anemia
                   1) insufficient red blood cells
                   2) decrease in hemoglobin (ie. iron deficiency)
                   3) abnormal hemoglobin
               ii) polycythemia - too many red blood cells
     2) leukocytes
          a) also called white blood cells; <1% of your blood
          b) they have nuclei
          c) there are 2 main types: granulocytes and agranulocytes
          d) granulocytes
               i) neutrophils - active phagocytes
               ii) basophils - contain histamine, which help send leukocytes to infected areas
               iii) eosinophils - attack parasitic worms; quantity increases during allergic reactions
          e) agranulocytes
               i) lymphocytes ("immune cells")
               ii) monocytes, which differentiate into macrophages
          f) there are several disorders related to leukocytes
               i) leukemia - too many leukocytes; "leukocyte cancer"
               ii) infectious mononucleosis
     3) platelets
          a) fragments of cells formed in the red marrow
          b) help to plug up damages in blood vessels (blood clots)

C) Hemostasis
     1) occurs in 3 phases
          a) vascular spasms - damaged blood vessel tightens
          b) platelet plug formation - platelets form a tempory blockage in the wound
          c) coagulation
               i) prothrombin activator is formed
               ii) the prothrombin activator converts prothrombin (a plasma protein) into thrombin
               iii) thrombin changes fibrinogen into a fibrin mesh, which traps blood cells and seals the wound (= a scab)
     2) Hemostasis disorders
          a) thromboembolytic disorders - unwanted blood clots
          b) thrombocytopenia - not enough platelets
          c) hemophilia - blood won't clot; a genetic disease

D) Blood Types
     1) There are 4 blood types
          a) A - has A antigens
          b) B - has B antigens
          c) AB - has A & B antigens
          d) O - has no antigens
     2) you cannot receive blood that has an antigen you don't already have
     3) if a mismatch occurs, agglutination (clumping of the blood) can occur
     4) O - universal donor type
     5) AB - universal recipient type
     6) Rh factors
          a) a variety of antigens that may or may not be present in your blood
          b) if present, you have Rh+ blood
          c) if absent, you have Rh- blood
          d) it is most problematic when an Rh- mother is carrying an Rh+ baby
               i) antibodies in the mother's blood can get into the baby's system and damge the baby
               ii) transfusions of the baby's blood are required to prevent anemia and hypoxia
               iii) if untreated, brain damage and even death may occur