Blood

1
Blood

• Chapter 19

2
Functions of blood

• Transportation
• Oxygen
• Carbon dioxide
• Nutrients Hormones
• Wastes
• Regulation
• Fluid balance Thermoregulation
• pH Electrolytes
• Protection
• Immune System bodies defenses
• Clotting and wound repair

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Physical characteristics of Blood

• Yes, it is thicker than water
• pH between 7.35 (venous) and 7.45 (arterial)
• Volume
• 5 to 6 liters in an average male (1.5 gal or 12
  pints)
• 4 to 6 liters in an average female (1.2 gal or 10
  pints)
• About 20 of the extracellular fluid
• About 8 of the body mass

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Composition of Blood

• Whole blood is divided into plasma and formed
  elements
• Plasma
• 55 of whole blood volume
• 91.5 water
• 7 soluble proteins
• Albumin 54 (osmotic balance, buffering,
  transport of steroid hormones and fatty acids)
• Globulins 38 (antibodies, etc)
• Fibrinogen 7 (produced by liver, for clotting)
• 1 other
• Other solutes
• Electrolytes, gases, nutrients, wastes, hormones

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Fig.19.01
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Formed Elements

• Erythrocytes (a.k.a. red blood cells)
• 4 to 6 million per mm3 (mL)
• About 7 - 8 mm in diameter
• Anucleate
• Amitotic at maturity
• No mitochondria, centrioles, or much else in the
  way of cytoplasm. Mostly hemoglobin.
• Live about 90 120 days
• Hematocrit The total volume of blood occupied
  by erythrocytes.
• 38 46 for females, average 42
• 40 54 for males, average 47

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Formed elements
Fig.19.02
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Hemopoiesis formation of blood cells

• Also known as hematopoiesis
• Occurs in the red marrow
• In adults, mostly in the proximal epiphysis of
  femur and bodies of the lumbar vertebrae
• Originally from pluripotent stem cells from
  mesenchyme
• In the fetus, hematopoiesis occurs in the liver,
  spleen, thymus, lymph nodes and yolk sac
• Red marrow is found in the spaces of spongy bone
• Erythropoietin from the kidneys stimulates
  hematopoiesis

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Development of blood cells
Fig. 19.03
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The anatomy of an erythrocyte the hemoglobin
molecule
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Hemoglobin (Hb)

• Each RBC contains an average of 250 million Hb
  molecules
• Each Hb molecule has 4 oxygen binding sites
• Thats about 1 billion oxygen molecules per RBC!
• CO (carbon monoxide) has approximately 200 times
  the affinity for Hb than oxygen and it fool O2
  saturation detectors

12
Erythrocyte catabolism

• After roughly 120 days red blood cells are worn
  out and must be recycled
• This occurs in the spleen and liver
• Iron (Fe)
• The Fe is removed from the heme group and
  bound to transferrin
• It is stored in the liver, muscle and spleen by
  transferring it to ferritin
• It can be transported on demand to the bone
  marrow where it can be reincorporated into new Hb

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RBC catabolism continued

• The rest of the heme molecule
• First converted to biliverdin (it is green)
• Then to bilirubin (it is yellow-orange)
• Its carried in the blood to the liver where it
  is secreted into bile
• Bile is stored in the gall bladder (if you have
  one) and then into the small intestine
• When it reaches the large intestine it is
  converted by bacteria into urobilinogen
• Some is reabsorbed and excreted in the urine
  (urobilin or urochrome). The rest is in the feces
  (stercobilin)

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RBC life cycle
Fig. 19.05
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Erythrocyte disorders

• Anemia polycythemia

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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

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Anemia Decreased Hemoglobin Content

• 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 B12
• Lack of intrinsic factor needed for absorption of
  B12
• Treatment is intramuscular injection of B12

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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 coding for an abnormal hemoglobin called
  hemoglobin S (HbS)
• HbS has a single amino acid substitution in the
  beta chain
• This defect causes RBCs to become sickle-shaped
  in low oxygen situations

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Polycythemia

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

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Sickle Cell Disease
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RBC homeostasis
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Leukocytes

• White blood cells are important for bodily
  defenses and immunity
• 2 General categories
• Granulocytes
• Neutrophils
• Eosinophils
• Basophils
• Agranulocytes
• Lymphocytes
• Monocytes

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Granulocytes

• Granulocytes neutrophils, eosinophils, and
  basophils
• Contain cytoplasmic granules that stain
  specifically (acidic, basic, or both) with
  Wrights stain
• Are larger and usually shorter-lived than RBCs
• Have lobed nuclei
• Are all phagocytic cells

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Neutrophils

• Neutrophils have two types of granules that
• Take up both acidic and basic dyes
• Give the cytoplasm a lilac color
• Contain peroxidases, hydrolytic enzymes, and
  defensins (antibiotic-like proteins)
• Neutrophils are our bodys bacteria slayers

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Eosinophils

• Eosinophils account for 14 of WBCs
• Have red-staining, bilobed nuclei connected via a
  broad band of nuclear material
• Have red to crimson (acidophilic) large, coarse,
  lysosome-like granules
• Lead the bodys counterattack against parasitic
  worms
• Lessen the severity of allergies by phagocytizing
  immune complexes

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Basophils

• Account for 0.5 of WBCs and
• Have U- or S-shaped nuclei with two or three
  conspicuous constrictions
• Are functionally similar to mast cells
• Have large, purplish-black (basophilic) granules
  that contain histamine
• Histamine inflammatory chemical that acts as a
  vasodilator and attracts other WBCs
  (antihistamines counter this effect)

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Agranulocytes

• Agranulocytes lymphocytes and monocytes
• Lack visible cytoplasmic granules
• Are similar structurally, but are functionally
  distinct and unrelated cell types
• Have spherical (lymphocytes) or kidney-shaped
  (monocytes) nuclei

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Lymphocytes

• Account for 25 or more of WBCs and
• Have large, dark-purple, circular nuclei with a
  thin rim of blue cytoplasm
• Are found mostly enmeshed in lymphoid tissue
  (some circulate in the blood)
• There are two types of lymphocytes T cells and B
  cells
• T cells function in the immune response
• B cells give rise to plasma cells, which produce
  antibodies

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Monocytes

• Monocytes account for 48 of leukocytes
• They are the largest leukocytes
• They have abundant pale-blue cytoplasms
• They have purple-staining, U- or kidney-shaped
  nuclei
• They leave the circulation, enter tissue, and
  differentiate into macrophages

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Monocytes

• Macrophages
• Are highly mobile and actively phagocytic
• Activate lymphocytes to mount an immune response

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Leukocytes
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Chemotaxis of neutrophils
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Leukocyte Disorders

• Leukemia
• Acute uncontrolled production of immature WBCs.
• Chronic accumulation of mature WBCs in the blood

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Leukocytes Disorders Leukemias

• 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

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Leukemia

• Immature white blood cells are found in the
  bloodstream in all leukemias
• Bone marrow becomes totally occupied with
  cancerous leukocytes
• 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

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Hemostasis clotting

• Involves
• platelets (fragments of megakaryocytes)
• Proteins Fibers (Thrombin Fibrin)
• Clotting factors

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Platelet plug formation
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Plug formation
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Clotting
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Hemostasis DisordersThromboembolytic Conditions

• Thrombus a clot that develops and persists in
  an unbroken blood vessel
• Thrombi can block circulation, resulting in
  tissue death
• Coronary thrombosis thrombus in blood vessel of
  the heart

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Hemostasis DisordersThromboembolytic Conditions

• Embolus a thrombus freely floating in the blood
  stream
• Pulmonary emboli can impair the ability of the
  body to obtain oxygen
• Cerebral emboli can cause strokes

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Prevention of Undesirable Clots

• Substances used to prevent undesirable clots
  include
• Aspirin an antiprostaglandin that inhibits
  thromboxane A2
• Heparin an anticoagulant used clinically for
  pre- and postoperative cardiac care
• Warfarin used for those prone to atrial
  fibrillation

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Hemostasis Disorders Bleeding Disorders

• Thrombocytopenia condition where the number of
  circulating platelets is deficient
• Patients show petechiae (small purple blotches on
  the skin) due to spontaneous, widespread
  hemorrhage
• Caused by suppression or destruction of bone
  marrow (e.g., malignancy, radiation)
• Platelet counts less than 50,000/mm3 is
  diagnostic for this condition
• Treated with whole blood transfusions

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Hemostasis Disorders Bleeding Disorders

• Inability to synthesize procoagulants by the
  liver results in severe bleeding disorders
• Causes can range from vitamin K deficiency to
  hepatitis and cirrhosis
• Inability to absorb fat can lead to vitamin K
  deficiencies as it is a fat-soluble substance and
  is absorbed along with fat
• Liver disease can also prevent the liver from
  producing bile, which is required for fat and
  vitamin K absorption

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Hemostasis Disorders Bleeding Disorders

• Hemophilias hereditary bleeding disorders
  caused by lack of clotting factors
• Hemophilia A most common type (83 of all
  cases) due to a deficiency of factor VIII
• Hemophilia B results from a deficiency of
  factor IX
• Hemophilia C mild type, caused by a deficiency
  of factor XI

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Hemostasis Disorders Bleeding Disorders

• Symptoms include prolonged bleeding and painful
  and disabled joints
• Treatment is with blood transfusions and the
  injection of missing factors

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Blood typing ABO groups
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ABO groups by frequency in US population
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Rh factor
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Blood Transfusions

• Whole blood transfusions are used
• When blood loss is substantial
• In treating thrombocytopenia
• Packed red cells (cells with plasma removed) are
  used to treat anemia