Blood Physical properties • 8% of body weight • Heavier than water • 5x more viscous • About 38 o C • pH 7.35 - 7.45 • Salty and sticky
Jan 02, 2016
Blood Physical properties
• 8% of body weight
• Heavier than water
• 5x more viscous
• About 38o C
• pH 7.35 - 7.45
• Salty and sticky
Blood Functions
• Transportation– O2 and CO2
– Nutrients
– Waste
• Regulation– pH
– Body temperature
– Fluid volume and osmolarity
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
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
Physical Characteristics of RBCs
• Anucleated and lack most organelles
• Small in size and biconcave
• Flexible
• Mostly a “bag” to carry hemoglobin
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
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 PF3 , 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