55% of total blood, pale yellow liquid that surrounds cells, 91%water, 7% proteins, and 2% other
Formed elements
45% of total blood, cells and cell fragments, erythrocytes, leukocytes, thrombocytes
Plasma proteins
Albumin
Globulins
Fibrinogen
Albumin
58% of plasma proteins, helps maintain water balance
Globulins
38% of plasma proteins, helps immune system
Fibrinogen
4% of plasma proteins, aids in clot formation
Hematopoiesis
1. Occurs in fetal liver, thymus, spleen, lymph nodes, and red bone marrow
2. After birth, primarily in red bone marrow, some white blood cells produced in lymphatic tissues
3. Stem cells differentiate to give rise to different cell lines, each ending with a particular type of formed element
Erythrocytes (Red Blood Cells)
Disk-shaped with thick edges
Nucleus is lost during development
Live for 120 days
Erythrocyte function
Transport O2 to tissues
Hemoglobin
Main component of erythrocytes, transports O2, each globin protein attached to a heme molecule containing one iron atom, O2 binds to iron, oxyhemoglobin is hemoglobin with O2 attached
Production of erythrocytes
1. Decreased blood O2 levels cause kidneys to increase production of erythropoietin
2. Erythropoietin stimulates red bone marrow to produce more erythrocytes
3. Increased erythrocytes cause an increase in blood O2 levels
Fate of old erythrocytes and hemoglobin
1. Old red blood cells removed from blood by macrophages in spleen and liver
2. Hemoglobin is broken down, globin broken down into aminoacids, iron recycled, heme converted to bilirubin, bilirubin taken up by liver and released into small intestine as part of bile
Most common, remain in blood for 10 to 12 hours then move to tissues, phagocytes
Eosinophils
Reduce inflammation, destroy parasites
Basophils
Least common, release histamine and heparin
Monocytes
Largest sized white blood cells, produce macrophages
Lymphocytes
Immune response, several different types (T cells and B cells), lead to production of antibodies
Platelets
Minute fragments of cells, each consisting of a small amount of cytoplasm surrounded by a cell membrane, produced in red bone marrow from megakaryocytes, play an important role in preventing blood loss
Preventing blood loss
1. Vascular spasm (temporary constriction of blood vessel)
2. Platelet plug formation (can seal up small breaks in blood vessels)
3. Blood clotting (blood can be transformed from a liquid to a gel)
Steps in clot formation
1. Injury to a blood vessel causes inactive clotting factors to become activated
2. Prothrombinase (clotting factor) is formed and acts upon prothrombin
3. Prothrombin is switched to its active form thrombin
4. Thrombin activates fibrinogen into its active form fibrin
5. Fibrin forms a network that traps blood (clots)
Clot formation control
Anticoagulants (prevent clots from forming, e.g. heparin and antithrombin)
Clot retraction and fibrinolysis
1. Clot retraction (condensing of clot, serum in plasma is squeezed out of clot, helps enhance healing)
2. Fibrinolysis (process of dissolving clot, plasminogen breaks down fibrin)
Blood grouping
Antigens
Antibodies
Blood groups
ABO blood groups
Type A has A antigens, type B has B antigens, type AB has both A and B antigens, type O has neither A nor B antigens
Plasma from type A blood contains anti-B antibodies, plasma from type B blood contains anti-A antibodies, type AB blood plasma has neither type of antibody, type O blood plasma has both anti-A and anti-B antibodies
In Caucasians in the United States, the distribution is type O, 47%; type A, 41%; type B, 9%; and type AB, 3%. Among African-Americans, the distribution is type O, 46%; type A, 27%; type B, 20%; and type AB, 7%.
Rh blood group
Rh positive means you have Rh antigens, 95 to 85% of the population is Rh+, antibodies only develop if an Rh- person is exposed to Rh+ blood
Rh incompatibility in pregnancy
1. If the mother isRh- and the fetus is Rh+, the mother can be exposed to Rh+ blood if fetal blood leaks through the placenta and mixes with the mother's blood
2. First time this occurs, mother's blood produces antibodies against antigens
3. Any repeated mixing of blood causes a reaction
Hemolytic disease of newborn
Occurs when mother produces anti-Rh antibodies that cross placenta and agglutination and hemolysis of fetal erythrocytes occurs, can be fatal to fetus, prevented if mother is treated with RhoGAM which contains antibodies against Rh antigens
Diagnostic blood tests
Complete blood count
Hematocrit
Hemoglobin
Prothrombin time
White blood cell count
White blood cell differential count
Complete blood count
Provides information such as RBC count, hemoglobin, hematocrit, and WBC count
Hematocrit
Percentage of total blood volume composed of RBC
Hemoglobin
Determines amount of hemoglobin, indicates anemia
Prothrombin time
Time it takes for blood to begin clotting (9 to 12 sec.)
White blood cell count
Total number of white blood cells
White blood cell differential count
Determines the percentage of each 5 kinds of leukocytes: neutrophils 60-70%, lymphocytes 20-25%, monocytes 3-8%, eosinophils 2-4%, basophils 0.5-1%