THE BLOOD

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• THE BLOOD
•  
• General Function of the Blood
•     Transportation
• molecules O2, CO2, hormones
• heat
•     Protection
• phagocytes
• antibodies
• coagulants
•     Regulation
• regulating ECF pH
• osmolarity

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• Properties of Whole Blood
• A.  Components
•         plasma
•         formed elements
• erythrocytes (RBC)
• leukocytes (WBC)
• plateletes (thrombocytes)
•         hematocrit
• B.  Physical characteristics
•         color
•         density (specific gravity)
•         viscosity
•         pH
•         7 of body mass

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• 2. Plasma
• A.  Chemical composition
• 93 H2O
• 7 solutes
• 86 proteins
• 11 inorganic solutes
• 3 nonprotein organic substances
• B.  Plasma proteins
• functions
• cell nutrition
• carries
• pH buffers
• clotting factors
• water distribution

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• albumin
• globulins
• alpha-1 globulin
• alpha-2 globulin
• beta globulins
• gamma globulins
• fibrinogen
• 2. Erythrocytes
• A.  Characteristics
• 8 µm diameter and 2 µm maximum thick
• deformable, biconcave disks
• anuucleated/no organelles
• male, 5.4 million/µl female, 4.8 million/µl
• pale red color (hemoglobin)

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• B. Oxygen-carrying capacity
•   hemoglobin (Hb)
• normal values male, 16gm/dl female, 14gm/dl
• 4 hemes 1 globin
• two types of Hb
• type A1 (2 ? chains, 2 ? chains)
• type A2 (2 ? chains, 2 ? chains)
• type F (2 ? chains, 2 ? chains)
• sickle cell disease - altered DNA templates of ?
  chains
• hemoglobin H disease - altered DNA templates of ?
  chains
• oxyhemoglobin (98 O2) oxygen-carrying capacity
  20ml O2/dl blood (1 gm of Hb can combine with
  1.34 ml O2)
• deoxyhemoglobin

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• C. Hematopoiesis Erythropoiesis
•    organs that produce RBCs
• liver, spleen, etc. (only in the fetus)
• red bone marrow (both in the fetus and adult)
• humerus, femur, ribs, sternum, skull,
  vertebrae, pelvis, etc.
•     regulation of RBC production
• erythropoietin
• hypoxia
• low blood volume
• anemia
• poor blood flow
• pulmonary disease

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•    vitamins and iron essential requirements
• vitamin B12 and folic acid
• 65 of iron supply is in Hb
• iron is stored bound to ferritin and transported
  by transferrin
• D. Fate and destruction of RBCs
•     life span 100-120 days
•     iron recycled, formation of bilirubin
• E. Erythrocyte disorders
•     anemias
• insufficient numbers (lt 37 hematocrit, aplastic
  anemia)
• decreased Hb content (lt12gm/dl)
• abnormal Hb (thalassemias)
•     polycythemia - too many RBCs (6.2 million/µl)

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• F. Blood Types
•   membrane glycoproteins (antigens) on surface
  of RBC provide unique antigenic identity
•    RBC antigens (agglutinogens) and plasma
  antibodies (agglutinins) promote agglutination
•    three strong antigens in RBC A, B, and D
• The ABO blood group contains four major blood
  types
• Type A A antigen anti-B
• Type B B antigen anti-A
• Type AB A B antigens no antibodies
• Type O no antigens anti-A and anti-B
• Rh blood group
• D antigen (Rh factor) on surface of RBCs

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• 3. Leukocytes White blood Cells (WBCs)
• lack of pigmented molecules (no color)
• total cell count 7,000-11,000/mm3
• diapedesis
• chemotaxis
• two main categories
• granulocytes
• agranulocytes
• A. Granular leukocytes
• neutrophils
• most numerous WBCs (50-70)
• very motile and phagocytic
• most granules are lysosomes containing hydrolytic
  enzymes
• numbers increase during bacterial infections

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•   eosinophils
• 1-5 of WBCs
• more numbers in connective tissues lung, mammary
  glands
• not actively phagocytic
• lysosomes contain oxidase, peroxidase, and
  phosphatase
• main functions detoxification of foreign
  proteins and other substances
•    basophils
• 0-1 WBCs
• more numbers in loose connective tissues
• granules contain heparin and histamine

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• B. Agranular leukocytes - lack visible granules
• lymphocytes
• 20-40 of WBCs
• T-lymphocytes
• the most numerous lymphocytes in the blood
• participating in cell-mediated immunity
• B-lymphocytes
• participate in humoral or antibody-mediated
  immunity

•      monocytes
• 1-6 of WBCs, largest in size
• differentiate into macrophages
• actively phagocytic
• contain a variety of digestive enzymes
• very effective in destroying bacteria,
  detoxifying harmful chemicals, cleaning up
  cellular debris

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• C. Leukopoiesis
•     pluripotential hemopoietic stem cell (PHSC)
  makes commitment to a pathway in the bone marrow
• granulopoiesis
• stimulated by leukocyte-inducing factor
• regulated by colony stimulating factors (CSFs)
•     lymphopoiesis
• regulated by lymphokines (interleukins)
•     life span of WBCs
• neutrophils a few minutes to a few days
• lymphocytes years

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• Thrombocytes (Platelets)
•    cytoplasmic fragments of megkaryocytes (2-4
  µm in diameter)
•    150, 000-350,000/µl
•     contain chemicals needed in clotting process
•     life span 10 days

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• 5. Hemostasis Mechanisms to Prevent Blood Loss
• A. Vasoconstriction
• reduces blood flow
• respond to sympathetic reflexes
• release of vasoconstrictors by platelets
• B. Platelet aggregation
• initiated by ADP released from the injured blood
  vessel
• platelets release ADP, serotonin, thromboxane A
• pseudopodia (footlike extentions)
• plug formed by platelets provide the framework
  for coagulation

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• C. Coagulation
• a process by which liquid blood becomes gel
• thrombin needed to convert fibrinogen to fibrin
  (3 stages)
• Stage I formation of a prothrombin converting
  factor
• extrinsic pathway
• intrinsic pathway
• Stage II conversion of prothrombin to thrombin
• Stage III conversion of fibrinogen to fibrin
• D. Clot retraction
• retraction is induced after stabilization of clot
  
• via thrombosthernin, a contractile platelet
  factor
• ATP required for the process
• serve to bring ruptured edge together, open the
  occluded vessel, increase blood flow and promote
  tissue repair

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E. Fibrinolysis degradation of
clots     fibrin is broken down into soluble
fragments by plasmin     plamin is derived from
plasminogen     a balance between deposition of
fibrin and fibrinolysis limits coagulation to the
area of vascular injury