1. CHAPTER 10: BLOOD The “river of life” Transportation system Carries nutrients, wastes, body heat Only “fluid” body tissue: Connective tissue Both solid and liquid components Formed elements – living blood cells Plasma – nonliving fluid matrix

2. COMPOSITION Erythrocytes – RBC (red blood cells) – carry oxygen to all parts of body; 45 % total blood volume Leukocytes – WBC (white blood cells) – functions in protection of the body; less than 1% blood volume Platelets – cell fragments that help with blood-clotting; less than 1% blood volume Plasma – mostly water – makes up remaining 55% of whole blood Metallic tasting, somewhat salty Coloring – depends on amount of oxygen it is carrying Oxygen rich – scarlet red Oxygen poor – dull red Blood heavier than water, 5 times thicker Slightly alkaline – pH is between 7.35 to 7.45. Blood temperature in humans is 100.4 0 F, slightly higher than body temperature Blood makes up 8% of our body weight On average about 5-6 quarts

4. BLOOD PLASMA Liquid part of blood; about 90% water; straw colored Many dissolved substances (solutes) in plasma: Nutrients, Metal ions (salts), Respiratory gases, Hormones, Plasma proteins, Wastes, Cell metabolism products Plasma proteins – most formed by liver Albumin – regulates osmotic pressure of blood keeping water in bloodstream Clotting proteins – help to stem blood loss when a blood vessel is injured Antibodies – help protect the body from pathogens Plasma proteins are not part of the by cells for fuel, etc. like other components such as glucose, fatty acids, oxygen Composition of blood plasma varies continuously as cells remove or add substances to the blood. It is kept relatively constant by various homeostatic mechanisms of body. Example: if blood proteins drop, liver is stimulated to make more; if blood too acidic, (acidosis) or too basic (alkalosis) the respiratory system and kidneys help restore normal pH. Plasma distributes body heat throughout.

7. FORMED ELEMENTS: ERYTHROCYTES – RBC – carry oxygen, lack a nucleus (anucleated), contain few organelles, lack mitochondria. Mature RBC are like sacs of hemoglobin molecules. Hemoglobin – iron-containing protein, transports bulk of oxygen carried in blood (also binds with small amount of carbon dioxide) It is the amount of hemoglobin in bloodstream that determines how well the RBC are performing in their role of oxygen transport. - concave, flattened disks with depressed centers. - outnumber WBC 1000 to 1 and give blood it’s viscosity; About 5 million RBC per cubic mm of blood (size of tiny drop of blood) ANEMIA – decrease in oxygen carrying ability of blood. Results from low count of RBC or deficiency in hemoglobin content in RBC. SICKLE-CELL ANEMIA – abnormal hemoglobin formed becomes spiky, sharp, when RBC unload oxygen or when oxygen content is low, (vigorous exercise, anxiety, stressful situations) the deformed (crescent-shaped) RBC rupture and dam up small blood vessels. Oxygen is not able to be transported well and can cause extreme pain. POLYCYTHEMIA – too many RBC. Can be due to bone marrow cancer, living at high altitudes where air is thinner. With this you get an increase in blood viscosity, which causes it to flow sluggishly in body and impairs circulation.

8. LEUKOCYTES – WBC – fight disease, 4000 to 11,000 WBC per cubic mm. Only complete cell in blood; contain nuclei and normal organelles found in most cells. Fight bacteria, viruses, parasites, tumor cells. -Able to move into and out of blood vessels (diapedesis). Circulatory system provides transportation to infected part of body. - Positive chemotaxis – WBC “catch scent” of damaged tissue or infection in body by way of these chemicals released by damaged tissues. - Can move by amoeboid motion, moving to infection in large numbers to surround and destroy foreign substance or dead cells. -WBC mobilize for action and body speeds up their production making twice the normal number within a few hours. Leukocytosis – total # of WBC above 11,000 cells/mm 3 Indicates bacterial or viral infection Leukopenia – abnormally low WBC count. Usually caused by drugs, such as corticosteroids and anticancer agents. LEUKEMIA – means “white blood” – the bone marrow becomes cancerous and huge numbers of WBC are turned out rapidly. “Newborn” WBC are incapable of fighting disease and the body becomes easy prey for bacteria and viruses. Many classes of leukocytes as seen in table above.

9. PLATELETS - Derived from ruptured multinucleate cells (megakaryocytes, large bone marrow cell with a lobulated nucleus responsible for the production of blood), needed for the clotting process, normal platelet count = 300,000/mm3.

10. HEMATOPOIESIS – blood cell formation, occurs in red bone marrow, all blood cells are derived from a common stem cell (hemocytoblast). Once a cell is committed to a specific blood pathway, it cannot change. Red bone marrow has may of the blood formation: Hemocytoblast differentiation Lymphoid stem cell produces lymphocytes Myeloid stem cell produces other formed elements RBC live about 100 to 120 days. Their remains, once broken apart, are filtered out and “eaten” by phagocytes in the spleen, liver, and other body tissues. Control of Erythrocyte Production - Rate is controlled by a hormone (erythropoietin) - Kidneys produce most erythropoietin as a response to reduced oxygen levels in the blood -Homeostasis is maintained by negative feedback from blood oxygen levels

11. HEMOSTASIS - Stoppage of blood flow Result of a break in a blood vessel Hemostasis involves three phases  Vascular spasms  Platelet plug formation  Coagulation Vascular Spasms  Anchored platelets release serotonin  Serotonin causes blood vessel muscles to spasm  Spasms narrow the blood vessel, decreasing blood loss Platelet Plug Formation  Collagen fibers are exposed by a break in a blood vessel  Platelets become “sticky” and cling to fibers  Anchored platelets release chemicals to attract more platelets  Platelets pile up to form a platelet plug

12. Coagulation  Injured tissues release thromboplastin  PF3 (a phospholipid) interacts with thromboplastin, blood protein clotting factors, and calcium ions to trigger a clotting cascade  Prothrombin activator converts prothrombin to thrombin (an enzyme)  Thrombin joins fibrinogen proteins into hair-like fibrin  Fibrin forms a meshwork (the basis for a clot) Blood Clotting  Blood usually clots within 3 to 6 minutes  The clot remains as endothelium regenerates  The clot is broken down after tissue repair Undesirable Clotting  Thrombus  A clot in an unbroken blood vessel  Can be deadly in areas like the heart  Embolus  A thrombus that breaks away and floats freely in the bloodstream  Can later clog vessels in critical areas such as the brain

14. Bleeding Disorders  Thrombocytopenia Platelet deficiency Even normal movements can cause bleeding from small blood vessels that require platelets for clotting  Hemophilia Hereditary bleeding disorder Normal clotting factors are missing Blood Groups and Transfusions  Large losses of blood have serious consequences Loss of 15 to 30 percent causes weakness Loss of over 30 percent causes shock, which can be fatal  Transfusions are the only way to replace blood quickly  Transfused blood must be of the same blood group

15. ABO Blood Groups  Based on the presence or absence of two antigens Type A Type B  The lack of these antigens is called type O  The presence of both A and B is called type AB  The presence of either A or B is called types A and B, respectively

16.  Named because of the presence or absence of one of eight Rh antigens (agglutinogen D)  Most Americans are Rh+ Rh Dangers During Pregnancy  Problems can occur in mixing Rh+ blood into a body with Rh– blood  Danger is only when the mother is Rh– and the father is Rh+, and the child inherits the Rh+ factor  The mismatch of an Rh– mother carrying an Rh+ baby can cause problems for the unborn child  The first pregnancy usually proceeds without problems  The immune system is sensitized after the first pregnancy  In a second pregnancy, the mother’s immune system produces antibodies to attack the Rh+ blood (hemolytic disease of the newborn)

17. Blood Typing  Blood samples are mixed with anti-A and anti-B serum  Coagulation or no coagulation leads to determining blood type  Typing for ABO and Rh factors is done in the same manner  Cross matching – testing for agglutination of donor RBCs by the recipient’s serum, and vice versa Developmental Aspects of Blood  Sites of blood cell formation  The fetal liver and spleen are early sites of blood cell formation  Bone marrow takes over hematopoiesis by the seventh month  Fetal hemoglobin differs from hemoglobin produced after birth