Ch.3 physiology of blood.pptx

Dr. Abdullah Alrethaia Chapter 3 Physiology of Blood Functions of Blood  Transportation:     Transport waste products from cells for elimination Transport hormones Regulation:     Deliver O2 and nutrients to all body cells Maintain body temp (distribute heat) Maintain pH (carry b...

Dr. Abdullah Alrethaia Chapter 3 Physiology of Blood Functions of Blood  Transportation:     Transport waste products from cells for elimination Transport hormones Regulation:     Deliver O2 and nutrients to all body cells Maintain body temp (distribute heat) Maintain pH (carry buffers) Maintain fluid volume Protection:   Prevent blood loss (clotting) Prevent infection (WBCs, antibodies) 2 Components of Blood  Blood plasma – water liquid extracellular matrix   91.5% water, 8.5% solutes (primarily proteins) Hepatocytes synthesize most plasma proteins    Albumins, fibrinogen, antibodies Other solutes include electrolytes, nutrients, enzymes, hormones, gases and waste products Formed elements – cells and cell fragments 3 Formed Elements of Blood 4 Formation of Blood Cells 5 Red Blood Cells/  Contain Erythrocytes oxygen-carrying protein      hemoglobin Production = destruction with at least 2 million new RBCs per second Biconcave disc – increases surface area Strong, flexible plasma membrane Glycolipids in plasma membrane responsible for ABO and Rh blood groups Lack nucleus and other organelles  No mitochondria – doesn’t use 6 Erythrocytes   Shaped like round plates indented in the center. Have no nucleus Hemoglobin     Globin – 4 polypeptide chains Heme group in each of 4 chains Iron ion can combine reversibly with one oxygen molecule Also transports 23% of total carbon dioxide   Combines with amino acids of globin Normal hemoglobin range   Adult males have 13.5 to 18 g/100mL of blood Adult females have 12 to 16 g/100mL 8 Structure of Hemoglobin 9 Red Blood Cells/  RBC lifeErythrocytes cycle     Live only about 120 days Cannot synthesize new components – no nucleus Old red blood cells removed from circulation and destroyed by fixed phagocytic macrophages in spleen and liver Breakdown products recycled    Globin’s amino acids reused Iron reused Non-iron heme ends as yellow pigment urobilin in urine or brown 10 Regulation of Erythropoiesis 11 Erythrocyte Disorders  Anemia:   This is an abnormally low oxygencarrying capacity of the blood. Common causes of anemia include: 1) an insufficient number of red blood cells 2) decreased hemoglobin content 3) abnormal hemoglobin  Examples are thalassemias and sickle-cell anemia, which are caused by genetic defects. 12 Erythrocyte Disorders  Contd. Normal Erythrocyte Count:   Polycythemia   Male: 5 - 6 million/ l Female: 4.5 – 5 million/ l Is an abnormal excess of erythrocytes that increases the viscosity of the blood and slows rate of blood flow Common causes of polycythemia include: 1) Bone marrow cancer 13 Hematocrit (Hct)/Packed Cell Volume  Definition: percentage of red blood cells volume in whole blood    Male : 40-54% (47%), female: 38-46% (42%) Indicates RBC production and state of hydration Abnormal Hct         High altitude – hypoxia  Polycythemia  Anemias  Hemorrhage  Malaria  Cancer  Chemotherapy  Radiation  14 White Blood Cells/ Leukocytes  Have nuclei    Do not contain hemoglobin Granular or agranular based on staining of cytoplasmic granules Granular leukocytes   Neutrophils, eosinophils, basophils Agranular leukocytes  Lymphocytes and monocytes 15 White Blood Cells     Fight infections Large in size Have a nucleus Phagocyte White Blood Cells       Contd. Usually live a few days Except for lymphocytes – live for months or years Far less numerous than RBCs Leukocytosis is a normal protective response to invaders, strenuous exercise, anesthesia and surgery Leukopenia is never beneficial General function: defend the body against diseases by phagocytosis or immune responses 17 Leukocyte Disorders   Normal Leukocyte Count: 4,000 – 11,000/ l Leukopenia: < 4,000/ l normal leukocytes  Leukopenia is one major side effect of chemotherapy.  Leukocytosis: > 11,000/ l normal leukocytes  Leukemia:  Leukemia refers to a group of cancerous 18 conditions of white blood cells.  Special Functions of White Blood Cells Neutrophils and macrophages are active phagocytes   Neutrophils respond most quickly to tissue damage by bacteria   Attracted by chemotaxis Uses lysozymes, strong oxidants, and defensins Monocytes take longer to arrive but arrive in larger numbers and destroy more microbes  Enlarge and differentiate into 19  Special Functions of White Blood Cells Basophils leave capillaries and release granules containing heparin, histamine and serotonin, at sites of inflammation    Intensify inflammatory reaction Involved in hypersensitivity reactions (allergies) Eosinophils leave capillaries and enter tissue fluid  Release histaminase, phagocytize antigen-antibody complexes and effective against certain parasitic 20 Lymphocytes  Lymphocytes are the major soldiers of the immune system    B cells – destroying bacteria and inactivating their toxins T cells – attack viruses, fungi, transplanted cells, cancer cells and some bacteria Natural Killer (NK) cells – attack a wide variety of infectious microbes and certain tumor cells 21 Platelets/ Thrombocytes       Myeloid stem cells develop eventually into a megakaryocyte Megakaryocyte split into 2000-3000 fragments Each fragment enclosed in a piece of plasma membrane becoming a platelet Disc-shaped with many vesicles but no nucleus Function: help stop blood loss by forming platelet plug Granules contain blood clot promoting 22 Platelets     Smallest part of blood No nucleus Live 2-4 days Involved in clotting of blood Hemostasis The stoppage of bleeding when blood vessel is injured is called hemostasis 3 mechanisms reduce blood loss Vascular spasm   1.  Platelet plug formation 2.  3. Smooth muscle in artery or arteriole walls contracts Platelets stick to parts of damaged blood vessel, become activated and accumulate large numbers Blood clotting (or coagulation) 24 Bleeding Disorders 1) Thrombocytopenia   The number of circulating platelets is deficient (<50,000/ l) Causes spontaneous bleeding from small blood vessels all over the body 2) Deficiency of clotting factors due to impaired liver function 3) Hemophilias  Hereditary bleeding disorders due to deficiency of clotting factors 25 Blood Groups and Blood Types  Surface of RBCs contain genetically    determined varities of antigens (or agglutinogens) Blood group – based on presence or absence of various antigens Antibodies (or agglutinins) for these antigens are present in plasma At least 24 blood groups and more than 100 antigens  Most important blood groups used are:  ABO and Rh 26 ABO Blood Group  Based on the presence or absence of A and B antigens on surface of RBCs  Type A blood has only antigen A (42%)   Type B blood has only antigen B (12%)   Anti- A antibodies are present in plasma Type AB blood has antigens A and B (3%)   Anti- B antibodies are present in plasma Neither anti-A nor anti- B antibodies are present in plasma Type O blood has neither antigen (43%)  Both anti-A and anti- B antibodies are present in plasma 27 28 Rh Blood Group  Rh blood group     People whose RBCs have Rh antigen are Rh+ (~ 85%) People who lack the Rh antigen are Rh(~ 15%) Normally, blood plasma does not contain anti-Rh antibodies Hemolytic disease of the newborn (HDN)   If blood from Rh+ fetus contacts Rhmother during birth, anti-Rh antibodies are produced Hemolysis of Rh+ RBCs in the fetus, causing death (erythroblastosis fetalis) 29 Blood Typing     Single drops of blood samples are mixed with anti-A, and anti-B serum Agglutination with an antisera indicates the presence of that antigen on the RBC 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 30 31 Transfusion Reactions   If blood types do not match, the recipient’s antibodies attach to donor’s RBCs and agglutinate. Type O:  Universal donor:    Lack A and B antigens. Recipient’s antibodies cannot agglutinate the donor’s RBCs. Type AB:  Universal recipient:   Lack the anti-A and anti-B antibodies. Cannot agglutinate donor’s RBCs. 32