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Lecture Outline Chapter 18 Blood
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I. Overview: Composition and Functions of Blood A. Components 1. Formed Elements- blood cells or blood corpuscles that are suspended in the fluid matrix known as plasma. •
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corpuscles / cells
plasma
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a. Erythrocytes- red blood cells (rbc) 1) Hematocrit- a measure of the packed cell volume of red blood cells, a) Expressed as a % of the total blood volume. b) Normal ranges 1. males 47 % 5 % 2. females 42 % 5 % •
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b. Leukocytes- white blood cells (wbc) 1) Less than 1 % •
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c. Thrombocytes- platelets 1) Less than 1 % •
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2. Plasma- non-living fluid matrix a. 55 % of total blood volume •
plasma
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B. Physical Characteristics and Volume 1. blood: a. has a salty and metallic taste b. oxygenated blood will be bright red in color c. unoxygenated blood will be dark red- never blue d. is more dense than water; about 5 X thicker e. has a pH 7.35- 7.45, slightly basic f. has a temperature around 380C / 100.4 0F g. makes up about 8 % of your body weight h. the average volume is 1) male:5-6 L (1.5 gal) 2) female: 4-5 L •
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C. Functions- all are designed to maintain homeostasis (balance of the internal environment) 1. Distribution functions: a. Delivering to all body cells 1) oxygen from the respiratory system and 2) Nutrients from the digestive system. b. Transporting metabolic waste products to excretory organs 1) Carbon dioxide- lungs 2) Nitrogenous wastes- kidneys c. Transporting hormones from endocrine glands to target organs. •
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2. Regulation a. Maintaining body temperature b. Maintaining normal pH in body tissues c. Maintaining adequate fluid volume •
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3. Protection a. Preventing blood loss- forming a clot b. Preventing infection- white blood cells, antibodies, etc. •
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D. Blood Plasma 1. straw-colored fluid 2. 90 % water 3. contains nutrients, gases, hormones, various wastes, cell products, ions, and proteins. a. Plasma proteins (8%)- most abundant solute 1) Most are produced by the liver (except hormones and gamma globulins) 2) Not used for cellular energy 3) Albumin (60 % of plasma proteins) a) Carrier molecule b) Blood buffer c) Maintains osmotic pressure •
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E. Formed Elements 1. Erythrocytes a. Structure: 1) Small biconcave cells 7.5 micrometers in diameter 2) ~5 million/mm3. 3) Lack a nucleus and most other organelles 4) Basically a “sack of hemoglobin”. 5) Flexible plasma membrane that allows the cell’s shape to change as needed. 6) Since RBC have no mitochondria they don’t undergo cellular respiration but anaerobic respiration. This way they don’t consume the oxygen they are carrying •
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b. Function: 1) Picks up oxygen in the lungs and releases it to tissue cells throughout the body. 2) Small size and biconcave shape produce a large surface area for the absorption of oxygen when passing through the capillaries in the lungs. •
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3) The major chemical compound in the RBC is hemoglobin. a) Hemoglobin readily bonds to oxygen and transports oxygen to the tissues. b) When hemoglobin combines with oxygen it becomes oxyhemoglobin (bright red compound). c) In the reverse reaction oxygen detaches producing deoxyhemoglobin (a dark red compound).
iron atom
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4) Transports ~20 % of the CO2 released by tissue cells back to the lungs. a) Carbon dioxide is carried by the hemoglobin molecules as carbaminohemoglobin •
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c. Production of Erythrocytes 1) Hematopoiesis/ hemopoisesis- blood cell formation a) Occurs in the red bone marrow b) Located in the flat bones of the axial skeleton and the epiphyses of the long bones. c) ~100 million new cells on a daily basis, 600 RBC:1WBC •
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stem cell •
d) Blood cells develop from stem cells, called Hematopoiesis stem cells / a hemocytoblast.
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e) The pathway from stem cell to erythrocyte: 1. Hemocytoblast 2. Myeloid stem cell 3. erythroblast 4. Normoblast 5. Reticulocytea. early erythrocyte b. make up 1-2 % of normal blood c. used as an indicator to determine abnormal rate of blood cell production. 6. Erythrocyte a. Requires 3- 5 days to develop •
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d. Regulation and Requirements for Erythropoiesis 1) the erythrocyte number is kept in balance; a) too few; produces tissue hypoxia (oxygen deprivation) b) too many; produces thick blood 2) Controlled by a) Adequate supplies of: 1. iron, 2. amino acids, 3. certain B vitamins and •
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4. erythropoietin; a hormone a. Small amount normally circulates in the bloodstream b. Kidneys are the major producers of erythropoietin. Responds to drop in oxygen levels in the blood. rbc loss due to hemorrhage or rbc destruction. reduced oxygen availability (high altitudes or lung impairment) increased demands for oxygen due to greater activity. c. Kidney failure causes low production of erythropoietin d. Recombinant erythropoietin is used to replace that normally produced by the kidneys. Can be abused by athletes. e. Testosterone also boosts erythropoietin •
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e. Destruction of erythrocytes 1) RBC can not grow or reproduce. 2) They become old, fragile and inflexible with age. 3) Most have a life span of 100 to 120 days (3 – 4 months). 4) They become trapped and fragment in smaller blood vessels. a) Commonly this happens in the spleen (spleen is known as the blood cell graveyard) •
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5) Dying rbc are phagocytosized by macrophages. a) The iron is salvaged and reused. b) The heme group is broken down to bilirubin which circulates in the blood stream. 1. bilirubin is absorbed by the liver cells 2. the liver secretes the bilirubin into the bile that flows into the small intestine 3. In the small intestine it undergoes metabolism into urobilinogen 4. Urobilinogen produces a brownish pigment which passes through the body in feces. •
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f. Erythrocyte Disorders 1) Anemias- blood that has an abnormally low oxygencarrying capacity, symptom of disease. a) Insufficient Numbers of RBCs1. hemorrhagic anemiasa. caused by blood loss from wounds 2. hemolytic anemias-destruction of RBCs a. incorrect transfusions b. bacterial and parasitic infection and •
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3. aplastic anemia-bone marrow failure. a. Caused by: Bacterial toxins Drugs Ionizing radiation b. Since all blood solids are involved Blood clotting is affected (platelets) Immunity is affected (antibodies/lymphocytes) c. treatments Transfusions Bone marrow transplants Umbilical blood infusions •
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b) Nutritional anemias- caused by nutritional insufficiencies. 1. Iron-Deficiency Anemia a. usually follows hemorrhagic anemias b. may result from inadequate intake of iron in foods c. may result from inadequate absorption of iron •
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2. Pernicious Anemia a. is due to a vitamin B12 deficiency. (found in meats, poultry and fish) b. poor diet; strict vegetarians c. also caused by a lack of “intrinsic factor” (a chemical secreted by the stomach mucosa; needed for absorption. d. rbcs become large and pale, known as macrocytes. e. elderly patients are most at risk because the stomach lining atrophies with age. f. treatment involves regular intramuscular injections of B12. •
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3. Abnormal Hemoglobin- genetically inherited a. Thalassemias mediterranean ancestry low blood cell count usually doesn’t require treatment if severe monthly blood transfusions are given b. Sickle-Cell Anemia abnormal shape stiff and inflexible tend to rupture and clog up small blood vessels black ancestry treated with hydroxyurea, turns on the a gene that produces more normal shaped cells. •
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2) Polycythemiaa) abnormal excess of rbcs b) thickens the blood 3) Polycythemia Vera a) Result of bone marrow cancer b) Dizziness and high rbc count. 4) Secondary Polycythemias a) Develops when less oxygen is available. b) High altitudes c) May be treated by diluting the blood with saline solution. 5) Blood Doping a) Used by some athletes, considered unethical and is banned in competition. b) Artificially induced by injecting blood cells before an athletic event. •
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2. Leukocytes: White blood cells a. Structure and Function: 1) Larger cell when compared to RBCs. 2) Compose ~ 1% of blood 3) 4000 – 11000 WBCs/mm3 4) Major defenders •
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5) Diapedesis- they have the ability to slip through the capillary walls to reach infected areas. 6) They move by amoeboid motion. 7) They show chemotaxis, they respond to chemical stimulation released by damaged cells or other leukocytes.
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b. Types: 1) Granulocytes: a) Basically spherical in shape b) Contain distinct granules in the cytoplasm that stain well with Wright’s stain. c) Large size d) Short lived e) Multi-lobed nuclei f) Phagocytic g) 3 types •
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1. Neutrophils a. Most numerous of the WBCs (40%-70%) b. ~ 2X larger that a RBCs c. Staining pattern cytoplasm stains a pale lilac: their granules take up both the acidic (red) dye and the basic (blue) dye producing the lilac color. the nucleus stains purple •
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d. polymorphonuclear: their nucleus has several lobes which vary from 3-6 lobes. Often referred to as “polys”. e. Attracted to areas of inflammation f. Active phagocytes particularly with bacteria and some fungi g. Granules some contain peroxidases and act like lysosomes. others contain defensins (antibiotic-like proteins).
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2. Eosinophils a. Compose 1-4 % of all leukocytes b. Same size as the Neutrophils c. Staining pattern nucleus stains reddish, absorbing the acidic stain. These are sometimes called acidophils. Typically the nucleus is shaped like a dumbbell. granules stain red. •
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d. granules are filled with digestive enzymes functions: 1. destroying parasitic worms that are too large to be phagocytized. 2. lessening the severity of allergies by phagocyting antigen-antibody complexes and inactivating inflammatory chemicals released during allergic reactions. •
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3. Basophils a. Rarest WBCs (~.5%) b. About the same size as the neutrophil or slightly smaller. c. Staining pattern nucleus stains a deep purple and is U or S shaped the granules absorb the basic dye which is blue. they are also known as basophiles d. Their granules contain heparin which is an anticoagulant and histamines which acts a vasodilators and attract other WBCs in inflamed areas. •
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2) Agranulocytes a) Lack visible granules b) Nuclei are large and spherical or kidney shaped. c) 2 types •
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1. Lymphocytes a. 2nd most numerous leukocyte b. Staining pattern large, dark-purple nucleus fairly spherical in shape cytoplasm stains a pale blue c. size varies: when inactive they are small but when stimulated by a pathogen, they become much larger. d. Some circulate in the blood but most lymphocytes are found in the lymph tissue. •
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e. 2 categories of lymphocytes exist: T-lymphocytes; these cells go the an inflamed, infected site and fight pathogens. Crucial role in immunity. They are active against bacteria, viruses and tumors. B-lymphocytes: these cells give rise to plasma cells which produce antibodies (immunoglobulins). These antibodies circulate in the blood while the B-lymphocytes stay in the lymphatic tissue.
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2. Monocytes a. Largest leukocyte b. Make up about 4-8 % c. Staining: dark purple staining nucleus that is U shaped or kidney bean shaped. pale blue cytoplasm large and spherical cell d. Very mobile macrophages e. Function in defense against viruses and bacterial parasites. f. Also play a role in activating lymphocytes to fight infections. •
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c. Production and Life Span of Leukocytes 1) Leukopoiesis- the production of WBCs 2) WBCs are produced according to the health of the individual. 3) Hormones will regulate the increase or decrease in production. depending on the amount of stimulation by pathogens. 4) WBCs are made at a rate of 3:1 to RBCs, however, they only survive for a short period of time (.5 -9 days) usually succumbing in battle with pathogenic invaders. Monocytes may live a couple of months. •
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5) All leukocytes have a common ancestry. a) Hemocytoblast b) From the hemocytoblast stem cell the granulocytes continue development in the bone marrow. c) The Agranulocytes migrate from the bone marrow and finish their development in the lymphatic tissues. 6) Most are stored in bone marrow or lymphatic tissue. •
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d. Leukocyte Disorders 1) Leukemias-an abnormal overproduction of leukocytes a) Acute leukemia- quickly advancing leukemia, often seen in children, involves the “blast” precursors. b) Chronic leukemia- slower form, involves a later stage of precursor cell, usually affects older people •
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2) Infectious Mononucleosisa) Highly contagious viral disease b) Often seen in children and young adults. c) Caused by the Epstein-Barr virus d) Recognized by large numbers of Agranulocytes, sore throat, low grade fever, fatigue, and achiness. •
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3) Leucopeniaa) Abnormally low number of WBCs. b) Often induced by drugs or radiation. •
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3. Platelets a. Platelets form from a large multinucleated cell known as a megakaryocyte that fragments apart. b. These cytoplasmic fragments contain chemicals that aid in clotting. c. Sometimes called Thrombocytes. d. Necessary for clotting, but not the sole factor responsible for clotting. e. Platelets stick to the leak in damaged blood vessels. They form a temporary plug. f. They only last about 10 days and are then replaced. •
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Platelets
Erythrocyte
Plasma
Basophil
Monocyte
Lymphocyte
Acidophil / Eosinophil
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g. Hemostasis: the stoppage of bleeding, this involves a series of reactions to produce a clot and stop the bleeding. 1) Vascular Spasms- this produces constriction of the damaged vessel reducing the amount of blood flow. 2) Platelet Plug Formation- temporary plug to seal the break. a) Platelets are stimulated by endothelium damage and exposed CT fibers b) The platelets swell and form spiked processes and become sticky. c) They adhere to the CT fibers that are exposed in the area. d) Once this happens the platelets begin to break down and release several chemicals that call more platelets to the area and make them sticky too. •
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3) Coagulation- complicated chemical process a) Involves over 30 substances, many of which are carried as plasma proteins. Vit K (indirectly) and Ca++ are also involved in the clotting process. •
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b) The final reactions leading to clotting. 1. Prothrombin activator 2. Prothrombin thrombin (an enzyme that joins fibrinogen molecules together to form fibrin fibers) fibrinogen is formed by the liver. 3. Fibrinogen fibrin mesh. The fibrin mesh traps the glues platelets together to form the clot. •
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4) Clot Retraction and Repair a) Platelets contain contractile proteins (actin and myosin) and they contract similar to they way they contract in muscle tissue. This causes the fibrin strands to pull together, squeezing out excess serum. The clot becomes more compact and torn blood vessels are sealed. Healing begins immediately stimulated by platelet-derived growth factor. 5) Fibrinolysis- the removal of unneeded clots when healing has occurred. This is done by a fibrin-digesting enzyme called plasmin •
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h. Disorders of Hemostasis 1) Thromboembolytic Conditions-undesirable clot formation a) Thrombus- a clot that develops and persists in an unbroken blood vessel. If the thrombus is large enough and blocks blood flow to tissues, they will die. This can cause a heart attack or a stroke. b) Embolus-If a clot breaks away and travels through the vessels, it is known as an embolus. If this clot is trapped in smaller blood vessels it can cause the death of cells / or the person as well. c) Drugs that dissolve blood clots are used to try and dissolve the clots. Aspirin is often recommended to thin the blood and prevent clots from developing. Warfarin/Coumadin are often used as well. •
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2) Bleeding Disorders- abnormalities that prevent normal clot formation. a) Thrombocytopenia- low numbers of platelets results in widespread bleeding. The purplish blotches are called petechiae. Transfusions may be given to provide temporary improvement. b) Impaired Liver Function- the liver produces are variety of products needed for proper blood coagulation. Any disfunctioning of the liver could produce severe bleeding. A lack of Vitamin K, lipid absorption problems, reduced procoagulants and even the absence of bile will interfere with the clotting process. c) Hemophilia- refers to different genetic disorder where the blood does not clot normally. •
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1. There are 3 types, hemophilia A and hemophilia B that are carried on the X chromosome giving males an increased chance of inheriting the disorder. 2. Hemophilia C is seen in both sexes. 3. Treated by transfusions and injections of the correct clotting factors.
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F. Transfusion and Human Blood Groups 1. ABO Blood Groups- There are many different proteins that are found the plasma membrane of the erythrocyte. Each person is genetically different and has produced unique tissue according to the genetic information they inherited. •
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BLOOD TYPES Blood type A;
genetically AA or AO,
whites 40% , blacks 27% , & asian 28% . Native Am 16%
plasma will produce antiB (antibodies against rbc protein B).
can receive blood types A or O
Blood type B;
genetically BB or BO
whites 11%, blacks 20%, asian 27%. Native Am 4%
plasma will produce antiA (antibodies against rbc protein A).
can receive blood types B or O
Blood type O:
genetically OO
whites 45%, blacks 49%, asian 40%. Native Am 79%
plasma will produce antiA and anti-B
can receive blood type Ouniversal donor
Blood type AB:
genetically AB
whites 4%, blacks 4%, asian 5% Native Am
