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Composition of Blood Consists of formed elements (cells) suspended & carried in plasma (fluid part) Total blood volume is about 5L Plasma is straw-colored.

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Presentation on theme: "Composition of Blood Consists of formed elements (cells) suspended & carried in plasma (fluid part) Total blood volume is about 5L Plasma is straw-colored."— Presentation transcript:

1 Composition of Blood Consists of formed elements (cells) suspended & carried in plasma (fluid part) Total blood volume is about 5L Plasma is straw-colored liquid consisting of H 2 0 & dissolved solutes –Includes ions, metabolites, hormones, antibodies 13-7

2 Physical Characteristics of Blood Average volume of blood: –5–6 L for males; 4–5 L for females (Normovolemia) –Hypovolemia - low blood volume –Hypervolemia - high blood volume Viscosity (thickness) (where water = 1) The pH of blood is 7.35–7.45; x = 7.4 Salinity = 0.85% –Reflects the concentration of NaCl in the blood Temperature is 38  C, slightly higher than “normal” body temperature Blood accounts for approximately 8% of body weight

3 Plasma Proteins Constitute 7-9% of plasma Three types of plasma proteins: albumins, globulins, & fibrinogen –Albumin accounts for 60-80% Creates colloid osmotic pressure that draws H 2 0 from interstitial fluid into capillaries to maintain blood volume & pressure Globulins carry lipids –Gamma globulins are antibodies (immunoglobulins) Fibrinogen serves as clotting factor –Converted to fibrin –Serum is fluid left when blood clots 13-8

4 Formed Elements Are erythrocytes (RBCs) & leukocytes (WBCs) RBCs are flattened biconcave discs –Shape provides increased surface area for diffusion –Lack nuclei & mitochondria –Each RBC contains 280 million hemoglobins 13-9

5 Leukocytes Have nucleus, mitochondria, & amoeboid ability Can squeeze through capillary walls (diapedesis) –Granular leukocytes help detoxify foreign substances & release heparin Include eosinophils, basophils, & neutrophils 13-10

6 Leukocytes continued Agranular leukocytes are phagocytic & produce antibodies Include lymphocytes & monocytes 13-11

7 Platelets (thrombocytes) Are smallest of formed elements, lack nucleus Are fragments of megakaryocytes Constitute most of mass of blood clots Release serotonin to vasoconstrict & reduce blood flow to clot area Secrete growth factors to maintain integrity of blood vessel wall Survive 5-9 days 13-12

8 Components of Whole Blood Withdraw blood and place in tube 1 2 Centrifuge Plasma (55% of whole blood) Formed elements Buffy coat: leukocyctes and platelets (<1% of whole blood) Erythrocytes (45% of whole blood) Hematocrit Males: 47% ± 5% Females: 42% ± 5%

9 Hematopoiesis Is formation of blood cells from stem cells in marrow (myeloid tissue) & lymphoid tissue Erythropoiesis is formation of RBCs –Stimulated by erythropoietin (EPO) from kidney Leukopoiesis is formation of WBCs –Stimulated by variety of cytokines = autocrine regulators secreted by immune system 13-13

10 Life Cycle of Red Blood Cells

11 Erythropoiesis 2.5 million RBCs are produced/sec Lifespan of 120 days Old RBCs removed from blood by phagocytic cells in liver, spleen, & bone marrow –Iron recycled back into hemoglobin production 13-14

12 Erythropoietin Mechanism Figure 17.6 Imbalance Reduces O 2 levels in blood Erythropoietin stimulates red bone marrow Enhanced erythropoiesis increases RBC count Normal blood oxygen levels Stimulus: Hypoxia due to decreased RBC count, decreased availability of O 2 to blood, or increased tissue demands for O 2 Imbalance Start Kidney (and liver to a smaller extent) releases erythropoietin Increases O 2 -carrying ability of blood

13 Erythropoiesis requires: –Proteins, lipids, and carbohydrates –Iron, vitamin B 12, and folic acid The body stores iron in Hb (65%), the liver, spleen, and bone marrow Intracellular iron is stored in protein-iron complexes such as ferritin and hemosiderin Circulating iron is loosely bound to the transport protein transferrin Dietary Requirements of Erythropoiesis

14 RBC Antigens & Blood Typing Antigens present on RBC surface specify blood type Major antigen group is ABO system –Type A blood has only A antigens –Type B has only B antigens –Type AB has both A & B antigens –Type O has neither A or B antigens 13-15

15 Transfusion Reactions People with Type A blood make antibodies to Type B RBCs, but not to Type A Type B blood has antibodies to Type A RBCs but not to Type B Type AB blood doesn’t have antibodies to A or B Type O has antibodies to both Type A & B If different blood types are mixed, antibodies will cause mixture to agglutinate 13-16

16 Transfusion Reactions continued If blood types don't match, recipient’s antibodies agglutinate donor’s RBCs Type O is “universal donor” because lacks A & B antigens –Recipient’s antibodies won’t agglutinate donor’s Type O RBCs Type AB is “universal recipient” because doesn’t make anti-A or anti-B antibodies –Won’t agglutinate donor’s RBCs Insert fig

17 May occur in an Rh- mom pregnanet with an Rh+ fetus Hemolytic disease of the newborn – Rh + antibodies of a sensitized Rh – mother cross the placenta and attack and destroy the RBCs of an Rh + baby Rh – mother becomes sensitized when Rh + blood (from a previous pregnancy of an Rh + baby or a Rh + transfusion) causes her body to synthesis Rh + antibodies The drug RhoGAM can prevent the Rh – mother from becoming sensitized Treatment of hemolytic disease of the newborn involves pre-birth transfusions and exchange transfusions after birth Hemolytic Disease of the Newborn

18 Hemostasis Is cessation of bleeding Promoted by reactions initiated by vessel injury: –Vasoconstriction restricts blood flow to area –Platelet plug forms Plug & surroundings are infiltrated by web of fibrin, forming clot 13-19

19 Role of Platelets Platelets don't stick to intact endothelium because of presence of prostacyclin (PGI 2 --a prostaglandin) & NO –Keep clots from forming & are vasodilators 13-20

20 Role of Platelets Damage to endothelium allows platelets to bind to exposed collagen –von Willebrand factor increases bond by binding to both collagen & platelets –Platelets stick to collagen & release ADP, serotonin, & thromboxane A 2 = platelet release reaction 13-21

21 Role of Platelets continued Serotonin & thromboxane A 2 stimulate vasoconstriction, reducing blood flow to wound ADP & thromboxane A 2 cause other platelets to become sticky & attach & undergo platelet release reaction –This continues until platelet plug is formed 13-22

22 Platelet plug becomes infiltrated by meshwork of fibrin Clot now contains platelets, fibrin & trapped RBCs –Platelet plug undergoes plug contraction to form more compact plug Role of Fibrin 13-23

23 Can occur via 2 pathways: –Intrinsic pathway clots damaged vessels & blood left in test tube Initiated by exposure of blood to negatively charged surface of glass or blood vessel collagen –This activates factor XII (a protease) which initiates a series of clotting factors –Ca 2+ & phospholipids convert prothrombin to thrombin »Thrombin converts fibrinogen to fibrin which polymerizes to form a mesh –Damage outside blood vessels releases tissue thromboplastin that triggers a clotting shortcut (= extrinsic pathway) Conversion of Fibrinogen to Fibrin 13-24

24 Fig

25 Dissolution of Clots When damage is repaired, activated factor XII causes activation of kallikrein –Kallikrein converts plasminogen to plasmin Plasmin digests fibrin, dissolving clot 13-26

26 Anticoagulants Clotting can be prevented by Ca +2 chelators (e.g. sodium citrate or EDTA) –or heparin which activates antithrombin III (blocks thrombin) Coumarin blocks clotting by inhibiting activation of Vit K –Vit K works indirectly by reducing Ca +2 availability 13-27

27 Prostaglandins (PGs) Are produced in almost every organ Belong to eicosanoid family -- all derived from arachidonic acid of plasma membrane 11-72

28 Have wide variety of functions –Different PGs may exert antagonistic effects in tissues Some promote smooth muscle contraction & some relaxation Some promote clotting; some inhibit –Promotes inflammatory process of immune system –Plays role in ovulation –Inhibits gastric secretion in digestive system Prostaglandins (PGs) continued 11-73

29 Cyclooxygenase (COX) 1 & 2 are involved in PG synthesis –Are targets of a number of inhibitory non-steroidal anti- inflammatory drugs (NSAIDs) Aspirin, indomethacin, ibuprofen inhibit both COX 1 & 2 thereby producing side effects Celebrex & Vioxx only inhibit COX 2 & thus have few side effects Prostaglandins (PGs) continued 11-74

30 Polycythemia –Abnormal excess of erythrocytes Increases viscosity, decreases flow rate of blood Anemia – blood has abnormally low oxygen-carrying capacity –It is a symptom rather than a disease itself –Blood oxygen levels cannot support normal metabolism –Signs/symptoms include fatigue, paleness, shortness of breath, and chills Erythrocyte Disorders

31 Anemia: Insufficient Erythrocytes Hemorrhagic anemia – result of acute or chronic loss of blood Hemolytic anemia – prematurely ruptured erythrocytes Aplastic anemia – destruction or inhibition of red bone marrow

32 Iron-deficiency anemia results from: –A secondary result of hemorrhagic anemia –Inadequate intake of iron-containing foods –Impaired iron absorption Pernicious anemia results from: –Deficiency of vitamin B 12 –Lack of intrinsic factor needed for absorption of B 12 –Treatment is intramuscular injection of B 12 Anemia: Decreased Hemoglobin Content

33 Anemia: Abnormal Hemoglobin Thalassemias – absent or faulty globin chain in hemoglobin –Erythrocytes are thin, delicate, and deficient in hemoglobin Sickle-cell anemia – results from a defective gene –Codes for an abnormal hemoglobin called hemoglobin S (HbS) –This defect causes RBCs to become sickle-shaped in low oxygen situations

34 Polycythemia Polycythemia – excess RBCs that increase blood viscosity Three main polycythemias are: –Polycythemia vera –Secondary polycythemia –Blood doping

35 Leukemia refers to cancerous conditions involving white blood cells Leukemias are named according to the abnormal white blood cells involved –Myelocytic leukemia – involves myeloblasts –Lymphocytic leukemia – involves lymphocytes Acute leukemia involves blast-type cells and primarily affects children Chronic leukemia is more prevalent in older people Leukocytes Disorders: Leukemias

36 Immature white blood cells are found in the bloodstream in all leukemias Bone marrow becomes totally occupied with cancerous leukocytes Severe anemia ensues due to excess production of WBC’s The white blood cells produced, though numerous, are not functional Death is caused by internal hemorrhage and overwhelming infections Treatments include irradiation, antileukemic drugs, and bone marrow transplants Leukemia


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