BMS 100 Outline - Chapter 12: BLOOD

• blood volume – approx. 4 to 6 liters (varies with body size).
• blood is a type of connective tissue with cells ("formed elements") suspended in a liquid matrix called plasma (mainly water and protein)

Red Blood Cells (Erythrocytes)
1. production: red bone marrow produces RBC
2. shape: biconcave disc (increases surface area)
3. red blood cells contain hemoglobin molecules
4. each hemoglobin (hgb or hb) molecule contains four polypeptide chains and four heme groups; each heme group contains one iron ion
5. oxygenation / deoxygenation cycle
   1. oxygenation
      1. in the lungs, the oxygen pressure (concentration) is higher in the air than it is in blood
      2. while blood is passing through the lungs, oxygen unites with hemoglobin
      3. What is the maximum number of oxygen molecules per hgb?
      4. oxygenated blood is bright red
   2. deoxygenation
      1. in organs such as the brain, muscles, kidneys, etc., the oxygen pressure in tissues is lower than it is in blood
      2. while blood is passing through such organs, oxygen separates from hemoglobin
      3. after they separate, oxygen diffuses into cells; hgb stays in RBC
      4. deoxygenated blood is crimson red/purple/blue
6. destruction of red blood cells
   1. cells in the liver and spleen destroy old/damaged red blood cells
   2. decomposition of hgb: iron and amino acids may be recycled; remainder of heme is nonrecyclable and excreted into digestive tract (bile pigments)
7. normally, rate of RBC destruction = rate of RBC production

White Blood Cells (Leukocytes)
1. formation: white blood cells develop from stem cells in bone marrow; lymphatic organs can produce lymphocytes
2. functions of white blood cells
   1. neutrophils and monocytes phagocytize ("eat") foreign particles
   2. lymphocytes 1) attack foreign/abnormal cells and 2) produce antibodies
   3. eosinophils kill parasites
   4. basophils release histamine to increase blood flow to injured tissues (inflammation)

Platelets (Thrombocytes) (pp. 310, 314-315)
1. platelets develop in red bone marrow (are fragments of giant cells)
2. platelet plug formation
   1. Platelets adhere to rough surfaces and exposed collagen
   2. Do healthy, undamaged vessels have rough surfaces or exposed collagen?
   3. Platelets adhere to each other at injury sites and form platelet plugs.
3. coagulation (blood clotting) - the most effective means of hemostasis
   1. fibrinogen - produced by liver, soluble, always present in plasma
   2. fibrin - insoluble, forms "threads" of blood clots
   3. thrombin - an enzyme that converts fibrinogen to fibrin
      • thrombin is usually "hidden" within platelets and other cells but is released when vessels are damaged

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Chapter 12 Questions at OLC - 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 13, 14, 15, 17, 20, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 38

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Fall 2010