Blood Physical properties 8% of body weight Heavier than water 5x more viscous About 38 o C pH Salty and sticky

Blood Functions Transportation –O 2 and CO 2 –Nutrients –Waste Regulation –pH –Body temperature –Fluid volume and osmolarity

Blood Functions Protection –Prevention of blood loss –Prevention of infection

Blood Components Plasma Formed elements

Plasma Water - 90% of plasma volume Solutes - 8% of plasma volume –Proteins »Albumin »Globulins - alpha, beta and gama »Clotting proteins »other –Non protein nitrogenous waste –Nutrients (organic) –Electrolytes –Respiratory gases

Formed Elements Erythrocytes Leukocytes Platelets

Unusual Features of Formed Elements Erythrocytes and platelets are not “true cells” Most of formed elements survive in blood stream only a few days Most blood cells do not divide

Formation of blood cells

Physical Characteristics of RBCs Anucleated and lack most organelles Small in size and biconcave Flexible Mostly a “bag” to carry hemoglobin

Function of RBCs Transport of oxygen and carbon dioxide

Erythrocytes disorders Anemias – Insufficient number of RBC »Hemorrhagic »Hemolytic »Aplastic –Decreases in hemoglobin content »Iron deficiency »B12 deficiency (pernicicous ) –Abnormal hemoglobin »Thalassemias »Sickle cell Polycythemia

General Characteristics of Leukocytes Diapedesis - the ability of WBCs to exit the circulatory system Ameboid motion - The characteristic motion of leukocytes through tissue spaces Positive chemotaxis - The motion of WBCs towards certain chemicals released by damaged cells or other leukocytes

WBCs Classification Granulocytes –Neutrophyls –Eosinophils –basophils Agranulocytes –Lymphocytes »T lymphocytes »B lymphocytes –Monocytes

Neutrophils Account for about half of all leukocytes and are twice as big as erythrocytes Take up both basic (blue) and acidic (red) dyes resulting in lilac color. Their nucleus has 3-6 lobes resulting in polymorphonuclear (PMNs) or Polys Phagocytic especially bacteria and fungi Kill by respiratory burst and defenses

Eosinophyls Account for 1- 4% of all leukocytes Shaped as a old fashion telephone receiver Large coarse granules stained in red brick color Most important role fight against invasion of parasitic worms –Reduce allergenic reactions by phagocytizing allergens

Basophyls Rarest of all leukocytes about 0.5% of population Have large histamine granules which stain purplish black Main role in inflammatory reaction by dilating blood vessels and attacking other leukocytes to the site of inflammation –Mast cells may be tissue basophils

Lymphocytes Second most numerous leukocytes Large round deep purple nucleus- classified by size Found mainly in lymphoid tissue –T Lymphocytes- cell mediated immunity –B Lymphocytes - humoral immunity

Monocytes Largest of all leukocytes Abundant gray-blue cytoplasm and dark blue-purple kidney shaped nucleus Wonder into tissues and become macrophages with prodigal appetites Great increase in chronic infections

Leukocyte Disorders Excessive production of leukocytes occur in leukemias –Cancer of white blood cells »Usually single clone lines tend to remain unspecialized mitotic and functionally inoperative »their sheer number impairs bone marrow function resulting in severe anemia, bleeding problems and inability to mount a defense response against infections Leukopenia - low white cell count –usually drug induced, particularly glucocorticoids and anti-cancer drugs

Platelets (thrombocytes) Cytoplasmic fragments megakaryocytes Essential for clotting process –Contain, serotonin, Ca +2, a variety of enzymes, ADP, PDGF. Formation controlled by thrombopoietin

Hemostasis Vascular spasms Platelet plug formation Coagulation

Vascular Spasms Damage of smooth muscle in blood vessels causes a reflexive contraction Release of chemicals from injured endothelial cells and platelets release vasoactive chemical which cause vasoconstriction These mechanisms result in reduction in blood loss Thought question : Would you rather be injured by blunt or sharp object

Platelet Plug Formation Platelets adhesion- Sharp edges, release of sticky chemical such as ADP and exposure of collagen which is under injured epithelia Platelets release- Release of chemicals which will attract more platelets and will make them stick Platelet aggregation- by sending extensions Plug formation- fibrogen gets converted to fibrin forms a mesh which traps formed elements and make a plug

Coagulation Phase 1 - A complex substance called prothrombin activator is formed –Two pathways extrinsic and intrisic »Once factor X is activated it complexes with tissue thromboplastin PF 3, factor V and calcium ions to form prothrombin activator Phase 2 - conversion of prothrombin to thrombin - by the action of prothombin –common pathway Phase 3 - conversion of fibronogen to fibrin by the action of thrombin –common pathway

Human Blood Groups ABO blood groups Rh blood groups