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CVS : Blood
              1
The CVS : Blood




                  2
Fluids of the Body
 • Cells of the body are serviced by 2 fluids
   • blood
      • composed of plasma and a variety of cells
      • transports nutrients and wastes
   • interstitial fluid
      • bathes the cells of the body
 • Nutrients and oxygen diffuse from the blood into the interstitial
   fluid & then into the cells
 • Wastes move in the reverse direction

                                                                 3
Functions of Blood
• Transportation
  • O2, CO2, metabolic wastes, nutrients, heat & hormones
• Regulation
  • helps regulate pH through buffers
  • helps regulate body temperature
     • coolant properties of water
     • vasodilatation of surface vessels dump heat
  • helps regulate water content of cells by interactions with
    dissolved ions and proteins
• Protection from disease & loss of blood
                                                                 4
Physical Characteristics of
Blood
• Thicker (more viscous) than water and flows more slowly than
  water
• Temperature of 100.4 degrees F (38 degrees C)
• pH 7.4 (7.35-7.45)
• 8 % of total body weight
• Blood volume
  • 5 to 6 liters in average male
  • 4 to 5 liters in average female
  • hormonal negative feedback systems maintain constant blood
    volume and osmotic pressure                              5
COMPONENTS OF BLOOD

• Blood consists of 55% plasma and 45% formed elements
• Blood plasma consists of 91.5% water and 8.5% solutes.
• Principal solutes include proteins (albumins, globulins,
  fibrinogen), nutrients, enzymes, hormones, respiratory
  gases, electrolytes, and waste products.




                                                             6
Components of Blood
• Hematocrit
  ▫ 55% plasma
  ▫ 45% cells
      99% RBCs
      < 1% WBCs and
       platelets




                       7
Blood Plasma
• 0ver 90% water                        • 2% other substances
• 7% plasma proteins                      • electrolytes, nutrients,
    • created in liver                      hormones, gases, waste
    • confined to bloodstream               products
  • albumin
    • maintain blood osmotic pressure
  • globulins (immunoglobulins)
    • antibodies bind to foreign
      substances called antigens
    • form antigen-antibody
      complexes
  • fibrinogen
    • for clotting


                                                                       8
Formed Elements of Blood
• Red blood cells ( erythrocytes )
• White blood cells ( leukocytes )
  • granular leukocytes
     • neutrophils, eosinophils, basophils
  • agranular leukocytes
     • lymphocytes = T cells, B cells, and natural killer cells
     • monocytes
• Platelets (special cell fragments)




                                                                  9
• Blood cells are formed from pluripotent hematopoietic
  stem cells
• Bone marrow may be obtained through aspiration or
  biopsy. The sample is then sent to pathology for
  examination.
• Originating from the pluripotent stem cells are the
  myeloid stem cells and lymphoid stem cells.



FORMATION OF BLOOD
CELLS                                                     10
Hematocrit
 • Percentage of blood occupied by cells
   • female normal range
      • 38 - 46% (average of 42%)
   • male normal range
      • 40 - 54% (average of 46%)
      • testosterone
 • Anemia
   • not enough RBCs or not enough hemoglobin
 • Polycythemia
   • too many RBCs (over 65%)
   • dehydration, tissue hypoxia, blood doping in athletes



                                                             11
Formation of Blood Cells
• Most blood cells types need to be continually replaced
  • die within hours, days or weeks
  • process of blood cells formation is hematopoiesis or
     hemopoiesis
• In the embryo
  • occurs in yolk sac, liver, spleen, thymus, lymph nodes &
     red bone marrow
• In adult
  • occurs only in red marrow of flat bones like sternum,
     ribs, skull & pelvis and ends of long bones           12
13
Hematopoiesis
Blood Cells
• Myeloid stem cells give rise to RBCs, platelets, and all WBCs
  except for lymphocytes.
• Lymphoid stem cells give rise to lymphocytes.
• Myeloid stem cells differentiate into progenitor cells or
  precursor cells (blast cells) which will develop into the actual
  formed elements of blood.
• Lymphoid stem cells differentiate into pre-B and
  prothymocytes which develop into B-lymphocytes and T-
  lymphocytes, respectively.
• This process of hemopoiesis (or hematopoiesis) is stimulated
  by several hematopoietic growth factors. These hematopoietic
  growth factors stimulate differentiation and proliferation of the
  various blood cells.                                          14
Stages of Blood Cell Formation
 • Pluripotent stem cells
   • 0.1% of red marrow cells
   • replenish themselves as they differentiate into either myeloid or
      lymphoid stem cells
 • Myeloid stem cell line of development continues:
   • progenitor cells(colony-forming units) no longer can divide and are
      specialized to form specific cell types
       • example: CFU-E develops eventually into only red blood cells
   • next generation is blast cells
       • have recognizable histological characteristics
       • develop within several divisions into mature cell types
 • Lymphoid stem cell line of development
                                                                  15
   • pre-B cells & prothymocytes finish their development into B & T
      lymphocytes in the lymphatic tissue after leaving the red marrow
Hemopoietic Growth Factors
• Regulate differentiation & proliferation
• Erythropoietin (EPO)
  • produced by the kidneys increase RBC precursors
• Thrombopoietin (TPO)
  • hormone from liver stimulates platelet formation
• Cytokines are local hormones of bone marrow
  • produced by some marrow cells to stimulate proliferation in
    other marrow cells
  • colony-stimulating factor (CSF) & interleukin stimulate WBC
    production                                             16
• Erythropoietin increases the number of RBC precursors.
• Thrombopoietin increases the number of platelet
  precursors.
• Cytokins (colony-stimulating factors and interleukins)
  increase the number of WBC precursors.
• Growth factors, available through recombinant DNA
  technology, hold great potential for use in patients who
  cannot normally form the blood cells.




Hormones                                                17
Red Blood Cells or Erythrocytes
• Contain oxygen-carrying protein hemoglobin that gives blood its red
  color
  • 1/3 of cell’s weight is hemoglobin
• Biconcave disk 8 microns in diameter
  • increased surface area/volume ratio
  • flexible shape for narrow passages
  • no nucleus or other organelles
     • no cell division or mitochondrial ATP formation
• Normal RBC count
  • male 5.4 million/drop ---- female 4.8 million/drop
  • new RBCs enter circulation at 2 million/second            18
Hemoglobin




• Globin protein consisting of 4 polypeptide chains
• One heme pigment attached to each polypeptide chain
  • each heme contains an iron ion (Fe+2) that can combine
    reversibly with one oxygen molecule

                                                             19
Transport of O2, CO2 and Nitric Oxide
• Each hemoglobin molecule can carry 4 oxygen molecules from
  lungs to tissue cells
• Hemoglobin transports 23% of total CO2 waste from tissue cells
  to lungs for release
   • combines with amino acids in globin portion of Hb
• Hemoglobin transports nitric oxide & super nitric oxide helping to
  regulate BP
   • Fe ions pick up nitric oxide (NO) & super nitric oxide (SNO) &
     transport it to & from the lungs
   • NO causing vasoconstriction is released in the lungs
   • SNO causing vasodilation is picked up in the lungs        20
RBC Life Cycle

  • RBCs live only 120 days
     • wear out from bending to fit through capillaries
     • no repair possible due to lack of organelles
  • Worn out cells removed by fixed macrophages in spleen &
    liver
  • Breakdown products are recycled




                                                              21
Recycling of Hemoglobin Components




• In macrophages of liver or spleen
  • globin portion broken down into amino acids & recycled
  • heme portion split into iron (Fe+3) and biliverdin (green pigment)
                                                                      22
Fate of Components of Heme
• Iron(Fe+3)
  • transported in blood attached to transferrin protein
  • stored in liver, muscle or spleen
     • attached to ferritin or hemosiderin protein
  • in bone marrow being used for hemoglobin synthesis
• Biliverdin (green) converted to bilirubin (yellow)
  • bilirubin secreted by liver into bile
     • converted to urobilinogen then stercobilin (brown pigment in feces) by
       bacteria of large intestine
     • if reabsorbed from intestines into blood is converted to a yellow pigment,
       urobilin and excreted in urine
                                                                          23
Erythropoiesis: Production of RBCs
• Erythrocyte formation, called erythropoiesis, occurs in adult red
  bone marrow of certain bones
• The main stimulus for erythropoiesis is hypoxia

• Proerythroblast starts to produce hemoglobin
• Many steps later, nucleus is ejected & a reticulocyte is formed
  ▫ orange in color with traces of visible rough ER
• Reticulocytes escape from bone marrow into the blood
• In 1-2 days, they eject the remaining organelles to become a
  mature RBC                                                   24
Feedback Control of RBC Production
• Tissue hypoxia (cells not getting enough
  O2)
  ▫ high altitude since air has less O2
  ▫ anemia
     RBC production falls below RBC
      destruction
  ▫ circulatory problems
• Kidney response to hypoxia
  ▫ release erythropoietin
  ▫ speeds up development of
    proerythroblasts into reticulocytes
                                             25
Normal Reticulocyte Count
  • Should be .5 to 1.5% of the circulating RBC’s
  • Low count in an anemic person might indicate bone marrow
    problem
     • leukemia, nutritional deficiency or failure of red bone marrow
       to respond to erythropoietin stimulation
  • High count might indicate recent blood loss or successful iron
    therapy


                                                            26
• Leukocytes (white blood cells or WBCs) are nucleated cells
  and do not contain hemoglobin. Two principal types are
  granular (neutrophils, eosinophils, basophils) and agranular
  (lymphocytes and monocytes)
  ▫ Granular leukocytes include eosinophils, basophils, and
    neutrophils based on the straining of the granules.
  ▫ Agranular leukocytes do not have cytoplasmic granules and
    include the lymphocytes and monocytes, which differentiate into
    macrophages (fixed and wandering).
• Leukocytes have surface proteins, as do erythrocytes. They
  are called major histocompatibility antigens (MHC), are
  unique for each person (except for identical siblings), and can
  be used to identify a tissue.




WHITE BLOOD CELLS                                                 27
WBC Physiology
• Less numerous than RBCs
  • 5000 to 10,000 cells per drop of blood
  • 1 WBC for every 700 RBC
• Leukocytosis is a high white blood cell count
  • microbes, strenuous exercise, anesthesia or surgery
• Leukopenia is low white blood cell count
  • radiation, shock or chemotherapy
• Only 2% of total WBC population is in circulating blood at any
  given time
  • rest is in lymphatic fluid, skin, lungs, lymph nodes & spleen
                                                              28
Function of WBCs
• Different WBCs combat inflammation and infection in different
  ways.
  ▫ Neutrophils and wandering or fixed macrophages (which
    develop from monocytes) do so through phagocytosis.
  ▫ Eosinophils combat the effects of histamine in allergic
    reactions, phagocytize antigen-antibody complexes, and combat
    parasitic worms.
  ▫ Basophils develop into mast cells that liberate heparin,
    histamine, and serotonin in allergic reactions that intensify the
    inflammatory response.
  ▫ B lymphocytes, in response to the presence of foreign
    substances called antigens, differentiate into tissue plasma cells
    that produce antibodies.                                    29
  ▫ T lymphocytes destroy foreign invaders directly.
• WBCs leave the blood stream by emigration
• Some WBCs, particularly neutrophils and macrophages,
  are active in phagocytosis.
• The chemical attraction of WBCs to a disease or injury
  site is termed chemotaxis.




Function of WBCs                                       30
Principles of Human Anatomy and Physiology, 11e
• A differential white blood cell count is a diagnostic test in
  which specific white blood cells are enumerated. Because
  each type of WBC plays a different role, determining the
  percentage of each type in the blood assists in diagnosing
  the condition.
• Bone marrow transplants may be used to treat several
  types of anemia, leukemia, and numerous other blood
  disorders.




WBC examination                                              31
Neutrophils (Granulocyte)
• Polymorphonuclear Leukocytes or Polys
• Nuclei = 2 to 5 lobes connected by thin strands
  • older cells have more lobes
  • young cells called band cells because of horseshoe shaped
    nucleus (band)
• Fine, pale lilac practically invisible granules
• Diameter is 10-12 microns
• 60 to 70% of circulating WBCs



                                                                32
Eosinophils (Granulocyte)

 • Nucleus with 2 or 3 lobes connected by a thin strand
 • Large, uniform-sized granules stain orange-red with acidic
   dyes
   • do not obscure the nucleus
 • Diameter is 10 to 12 microns
 • 2 to 4% of circulating WBCs



                                                                33
Basophils (Granulocyte)

 • Large, dark purple, variable-sized granules stain with basic
   dyes
   • obscure the nucleus
 • Irregular, s-shaped, bilobed nuclei
 • Diameter is 8 to 10 microns
 • Less than 1% of circulating WBCs




                                                                  34
Lymphocyte (Agranulocyte)
 • Dark, oval to round nucleus
 • Cytoplasm sky blue in color
   • amount varies from rim of blue to normal amount
 • Small cells 6 - 9 microns in diameter
 • Large cells 10 - 14 microns in diameter
   • increase in number during viral infections
 • 20 to 25% of circulating WBCs



                                                       35
Monocyte (Agranulocyte)
• Nucleus is kidney or horse-shoe shaped
• Largest WBC in circulating blood
  • does not remain in blood long before migrating to the tissues
  • differentiate into macrophages
     • fixed group found in specific tissues
        • alveolar macrophages in lungs
        • Kupffer cells in liver
     • wandering group gathers at sites of infection
• Diameter is 12 - 20 microns
• Cytoplasm is a foamy blue-gray
• 3 to 8% o circulating WBCs


                                                                    36
Emigration & Phagocytosis in WBCs
             • WBCs roll along endothelium, stick to it
               & squeeze between cells.
               • adhesion molecules (selectins) help
                 WBCs stick to endothelium
                  • displayed near site of injury
               • molecules (integrins) found on
                 neutrophils assist in movement
                 through wall
             • Neutrophils & macrophages phagocytize
               bacteria & debris
               • chemotaxis of both
                  • kinins from injury site & toxins


                                                       37
Neutrophil Function
• Fastest response of all WBC to bacteria
• Direct actions against bacteria
  • release lysozymes which destroy/digest bacteria
  • release defensin proteins that act like antibiotics & poke holes in
    bacterial cell walls destroying them
  • release strong oxidants (bleach-like, strong chemicals ) that
    destroy bacteria




                                                                          38
Monocyte Function

• Take longer to get to site of infection, but arrive
  in larger numbers
• Become wandering macrophages, once they
  leave the capillaries
• Destroy microbes and clean up dead tissue
  following an infection




                                                        39
Basophil Function
 • Involved in inflammatory and allergy reactions
 • Leave capillaries & enter connective tissue as
   mast cells
 • Release heparin, histamine & serotonin
   • heighten the inflammatory response and
     account for hypersensitivity (allergic) reaction




                                                        40
Eosinophil Function

• Leave capillaries to enter tissue fluid
• Release histaminase
  • slows down inflammation caused by basophils
• Attack parasitic worms
• Phagocytize antibody-antigen complexes




                                                  41
Lymphocyte Functions
• B cells
  • destroy bacteria and their toxins
  • turn into plasma cells that produces antibodies
• T cells
  • attack viruses, fungi, transplanted organs, cancer cells & some
    bacteria
• Natural killer cells
  • attack many different microbes & some tumor cells
  • destroy foreign invaders by direct attack
                                                                42
Complete Blood Count
 • Screens for anemia and infection
 • Total RBC, WBC & platelet counts; differential WBC;
   hematocrit and hemoglobin measurements
 • Normal hemoglobin range
   • infants have 14 to 20 g/100mL of blood
   • adult females have 12 to 16 g/100mL of blood
   • adult males have 13.5 to 18g/100mL of blood

                                                         43
Differential WBC Count
• Detection of changes in numbers of circulating WBCs (percentages
  of each type)
  • indicates infection, poisoning, leukemia, chemotherapy, parasites
     or allergy reaction
• Normal WBC counts
  • neutrophils 60-70% (up if bacterial infection)
  • lymphocyte 20-25% (up if viral infection)
  • monocytes 3 -- 8 % (up if fungal/viral infection)
  • eosinophil 2 -- 4 % (up if parasite or allergy reaction)
  • basophil <1% (up if allergy reaction or hypothyroid)     44
PLATELETS
• Thrombopoietin stimulates myeloid stem cells to produce platelets.
• Myeloid stem cells develop into megakaryocyte-colony-forming cells
  that develop into megakaryoblasts (Figure 19.2).
• Megakaryoblasts transform into megakaryocytes which fragment.
• Each fragment, enclosed by a piece of cell membrane, is a platelet
  (thrombocyte).
• Normal blood contains 250,000 to 400,000 platelets/mm3. Platelets
  have a life span of only 5 to 9 days; aged and dead platelets are
  removed by fixed macrophages in the spleen and liver.

                                                               45
PLATELETS
 • Platelets help stop blood loss from damaged vessels by
   forming a platelet plug. Their granules also contain
   chemicals that promote blood clotting.
 • A complete blood count (CBC) is a test that screens for
   anemia and various infections. It usually includes counts
   of RBCs, WBCs, and platelets per μL of whole blood;
   hematocrit and differential white blood cell count. The
   amount of hemoglobin in grams per ml is also
   determined.

                                                           46
Platelet
(Thrombocyte)
Anatomy
• Disc-shaped, 2 - 4 micron cell fragment with no
  nucleus
• Normal platelet count is 150,000-400,000/drop of
  blood
• Other blood cell counts
  • 5 million red & 5-10,000 white blood cells



                                                     47
Platelets--Life History
• Platelets form in bone marrow by following steps:
  • myeloid stem cells to megakaryocyte-colony forming
    cells to megakaryoblast to megakaryocytes whose cell
    fragments form platelets
• Short life span (5 to 9 days in bloodstream)
  • formed in bone marrow
  • few days in circulating blood
  • aged ones removed by fixed macrophages in liver and
    spleen



                                                           48
HEMOSTASIS
• A clot is a gel consisting of a network of insoluble protein
  fibers (fibrin) in which formed elements of blood are trapped
• The chemicals involved in clotting are known as coagulation
  (clotting) factors; most are in blood plasma, some are released
  by platelets, and one is released from damaged tissue cells
• Blood clotting involves a cascade of reactions that may be
  divided into three stages: formation of prothrombinase
  (prothrombin activator), conversion of prothrombin into
  thrombin, and conversion of soluble fibrinogen into insoluble
  fibrin
                                                             49
• The clotting cascade can be initiated by either the extrinsic
  pathway or the intrinsic pathway.
• Normal coagulation requires vitamin K and also involves clot
  retraction (tightening of the clot) and fibrinolysis (dissolution
  of the clot).
• The fibrinolytic system dissolves small, inappropriate clots
  and clots at a site of damage once the damage is repaired.
• Plasmin (fibrinolysin) can dissolve a clot by digesting fibrin
  threads and inactivating substances such as fibrinogen,
  prothrombin, and factors V, VIII, and XII.




HEMOSTASIS                                                       50
Hemostasis
• Stoppage of bleeding in a quick & localized fashion when blood
  vessels are damaged
• Prevents hemorrhage (loss of a large amount of blood)
• Methods utilized
  • vascular spasm
  • platelet plug formation
  • blood clotting (coagulation = formation of fibrin threads)

                                                           51
Vascular Spasm

  • Damage to blood vessel produces stimulates pain
    receptors
  • Reflex contraction of smooth muscle of small blood
    vessels
  • Can reduce blood loss for several hours until other
    mechanisms can take over
  • Only for small blood vessel or arteriole




                                                          52
Platelet Plug Formation
• Platelets store a lot of chemicals in granules needed for platelet
  plug formation
  • alpha granules
     • clotting factors
     • platelet-derived growth factor
      • cause proliferation of vascular endothelial cells, smooth
        muscle & fibroblasts to repair damaged vessels
  • dense granules
     • ADP, ATP, Ca+2, serotonin, fibrin-stabilizing factor, & enzymes that
       produce thromboxane A2
• Steps in the process
  • (1) platelet adhesion (2) platelet release reaction (3) platelet
    aggregation                                                 53
Platelet Adhesion
• Platelets stick to exposed collagen underlying
  damaged endothelial cells in vessel wall




                                                   54
Platelet Release Reaction
• Platelets activated by adhesion
• Extend projections to make contact with each other
• Release thromboxane A2 & ADP activating other
  platelets
• Serotonin & thromboxane A2 are vasoconstrictors
  decreasing blood flow through the injured vessel




                                                       55
Platelet Aggregation
• Activated platelets stick together and activate new
  platelets to form a mass called a platelet plug
• Plug reinforced by fibrin threads formed during
  clotting process




                                                    56
Blood Clotting
• Blood drawn from the body thickens into a gel
   • gel separates into liquid (serum) and a clot of insoluble fibers
     (fibrin) in which the cells are trapped
• If clotting occurs in an unbroken vessel is called a thrombosis
• Substances required for clotting are Ca+2, enzymes synthesized
  by liver cells and substances released by platelets or damaged
  tissues
• Clotting is a cascade of reactions in which each clotting factor
  activates the next in a fixed sequence resulting in the formation of
  fibrin threads
   • prothrombinase & Ca+2 convert prothrombin into thrombin
   • thrombin converts fibrinogen into fibrin threads

                                                                         57
Overview of the
Clotting Cascade

 • Prothrombinase is formed by either
   the intrinsic or extrinsic pathway
 • Final common pathway produces
   fibrin threads




                                        58
Extrinsic Pathway

• Damaged tissues leak tissue factor
  (thromboplastin) into bloodstream
• Prothrombinase forms in seconds
• In the presence of Ca+2, clotting
  factor X combines with V to form
  prothrombinase


                                       59
Intrinsic Pathway
• Activation occurs
  • endothelium is damaged & platelets
    come in contact with collagen of
    blood vessel wall
  • platelets damaged & release
    phospholipids
• Requires several minutes for
  reaction to occur
• Substances involved: Ca+2 and
  clotting factors XII, X and V
                                         60
Final Common Pathway
• Prothrombinase and Ca+2
  • catalyze the conversion of prothrombin
    to thrombin
• Thrombin
  • in the presence of Ca+2 converts
    soluble fibrinogen to insoluble fibrin
    threads
  • activates fibrin stabilizing factor XIII
  • positive feedback effects of thrombin
     • accelerates formation of
       prothrombinase
     • activates platelets to release
       phospholipids


                                               61
Clot Retraction & Blood Vessel
Repair
• Clot plugs ruptured area of blood
  vessel
• Platelets pull on fibrin threads
  causing clot retraction
   • trapped platelets release factor XIII
     stabilizing the fibrin threads
• Edges of damaged vessel are pulled
  together
• Fibroblasts & endothelial cells repair
  the blood vessel

                                             62
Role of Vitamin K in Clotting
• Normal clotting requires adequate vitamin K
  • fat soluble vitamin absorbed if lipids are present
  • absorption slowed if bile release is insufficient
• Required for synthesis of 4 clotting factors by hepatocytes
  • factors II (prothrombin), VII, IX and X
• Produced by bacteria in large intestine

                                                                63
Hemostatic Control Mechanisms
• Fibrinolytic system dissolves small, inappropriate clots & clots at a
  site of a completed repair
  • fibrinolysis is dissolution of a clot
• Inactive plasminogen is incorporated into the clot
  • activation occurs because of factor XII and thrombin
  • plasminogen becomes plasmin (fibrinolysin) which digests fibrin
     threads
• Clot formation remains localized
  • fibrin absorbs thrombin
  • blood disperses clotting factors
  • endothelial cells & WBC produce prostacyclin that opposes
     thromboxane A2 (platelet adhesion & release)
• Anticoagulants present in blood & produced by mast cells       64
Intravascular Clotting
• Thrombosis
  • clot (thrombus) forming in an unbroken blood vessel
     • forms on rough inner lining of BV
     • if blood flows too slowly (stasis) allowing clotting factors to build up locally
       & cause coagulation
  • may dissolve spontaneously or dislodge & travel
• Embolus
  • clot, air bubble or fat from broken bone in the blood
     • pulmonary embolus is found in lungs
• Low dose aspirin blocks synthesis of thromboxane A2 & reduces
  inappropriate clot formation
   • strokes, TIAs and myocardial infarctions              65
Anticoagulants and Thrombolytic Agents
  • Anticoagulants suppress or prevent blood clotting
    ▫ heparin
       administered during hemodialysis and surgery
    ▫ warfarin (Coumadin)
       antagonist to vitamin K so blocks synthesis of clotting factors
       slower than heparin
    ▫ stored blood in blood banks treated with citrate phosphate
      dextrose (CPD) that removes Ca+2
  • Thrombolytic agents are injected to dissolve clots
    ▫ directly or indirectly activate plasminogen
    ▫ streptokinase or tissue plasminogen activator (t-PA)
                                                               66
• Clots are generally localized due to fibrin absorbing thrombin
  into the clot, clotting factors diffusing through blood, and the
  production of prostacyclin, a powerful inhibitor of platelet
  adhesion and release.
• Substances that inhibit coagulation, called anticoagulants, are
  also present in blood. An example is heparin.
• Patients who are at increased risk of forming blood clots may
  receive an anticoagulant drug such as heparin or warfarin. To
  prevent clots in donated blood, a substance that removes Ca+2
  such as EDTA or CPD may be added to the blood.
• Despite the anticoagulating and fibrinolytic mechanisms,
  blood clots sometimes form within the cardiovascular system.


Hemostatic Control
Mechanisms                                                      67
• Clotting in an unbroken blood vessel is called
  thrombosis.
• A thrombus (clot), bubble of air, fat from broken bones,
  or piece of debris transported by the bloodstream that
  moves from its site of origin is called an embolus.
• At low doses aspirin inhibits vasoconstriction and
  platelet aggregation thereby reducing the chance of
  thrombus formation. Thrombolytic agents are injected
  into the body to dissolve clots that have already formed.
  Streptokinase or tissue plasminogen activator (TPS) are
  thrombolytic agents.




HEMOSTASIS                                                68
• In the ABO system, agglutinogens (antigens) A and B
  determine blood types
• Plasma contains agglutinins (antibodies), designated as a
  and b, that react with agglutinogens that are foreign to the
  individual.




ABO Group                                                   69
Principles of Human Anatomy and Physiology, 11e
Blood Groups and Blood Types




• RBC surfaces are marked by genetically determined glycoproteins
  & glycolipids
  • agglutinogens or isoantigens                          70
  • distinguishes at least 24 different blood groups
    • ABO, Rh, Lewis, Kell, Kidd and Duffy systems
ABO Blood Groups
• Based on 2 glycolipid isoantigens called A and B found on the
  surface of RBCs
  ▫   display only antigen A -- blood type A
  ▫   display only antigen B -- blood type B
  ▫   display both antigens A & B -- blood type AB
  ▫   display neither antigen -- blood type O
• Plasma contains isoantibodies or agglutinins to the A or B antigens
  not found in your blood
  ▫ anti-A antibody reacts with antigen A
  ▫ anti-B antibody reacts with antigen B

                                                              71
RH blood groups
• Antigen was discovered in blood of Rhesus monkey
• People with Rh agglutinogens on RBC surface are Rh+. Normal
  plasma contains no anti-Rh antibodies
• Antibodies develop only in Rh- blood type & only with exposure to
  the antigen
   • transfusion of positive blood
   • during a pregnancy with a positive blood type fetus
• Transfusion reaction upon 2nd exposure to the antigen results in
  hemolysis of the RBCs in the donated blood
                                                                72
Hemolytic Disease of Newborn




• Rh negative mom and Rh+ fetus will have mixing of blood at birth
• Mom's body creates Rh antibodies unless she receives a RhoGam shot soon after first
  delivery, miscarriage or abortion
   • RhoGam binds to loose fetal blood and removes it from body before she reacts
• In 2nd child, hemolytic disease of the newborn may develop causing hemolysis of
  the fetal RBCs
                                                                                 73
Transfusion and Transfusion Reactions
  • Transfer of whole blood, cells or plasma into the bloodstream of
    recipient
    • used to treat anemia or severe blood loss
  • Incompatible blood transfusions
    • antigen-antibody complexes form between plasma antibodies
       & “foreign proteins” on donated RBC's (agglutination)
    • donated RBCs become leaky (complement proteins) & burst
    • loose hemoglobin causes kidney damage
  • Problems caused by incompatibility between donor’s cells and
    recipient’s plasma
  • Donor plasma is too diluted to cause problems             74
Universal Donors and Recipients

   • People with type AB blood called “universal
     recipients” since have no antibodies in plasma
     • only true if cross match the blood for other antigens
   • People with type O blood cell called “universal
     donors” since have no antigens on their cells
     • theoretically can be given to anyone

                                                           75
• The Rh and ABO blood groups may be detected by a
  simple medical test, blood typing, in which a sample of
  blood is mixed with serum containing agglutinins to each
  of the major agglutinogens (AB, B, and Rh)
• Typing is the determination of blood types, whereas
  cross-matching is the mixing of donor and recipient blood
  for compatibility.



Typing and Cross-Matching
Blood for Transfusion                                   76
DISORDERS: HOMEOSTATIC
IMBALANCES

  •   Anemia
  •   Sickle-cell
  •   Hemophilia
  •   Disseminated intravascular clotting
  •   Acute leukemia
  •   Chronic leukemia
                                            77
Anemia = Not Enough RBCs
• Symptoms
  • oxygen-carrying capacity of blood is reduced
  • fatigue, cold intolerance & paleness
     • lack of O2 for ATP & heat production
• Types of anemia
  • iron-deficiency =lack of absorption or loss of iron
  • pernicious = lack of intrinsic factor for B12 absorption
  • hemorrhagic = loss of RBCs due to bleeding (ulcer)
  • hemolytic = defects in cell membranes cause rupture
  • thalassemia = hereditary deficiency of hemoglobin
  • aplastic = destruction of bone marrow (radiation/toxins) 78
Sickle-cell Anemia (SCA)
• Genetic defect in hemoglobin molecule (Hb-S) that changes 2 amino
  acids
  • at low O2 levels, RBC is deformed by changes in hemoglobin
     molecule within the RBC
     • sickle-shaped cells rupture easily = causing anemia & clots
• Found among populations in malaria belt
  • Mediterranean Europe, sub-Saharan Africa & Asia
• Person with only one sickle cell gene
  • increased resistance to malaria because RBC membranes leak K+
    & lowered levels of K+ kill the parasite infecting the red blood
    cells                                                      79
Hemophilia
• Inherited deficiency of clotting factors
  • bleeding spontaneously or after minor trauma
  • subcutaneous & intramuscular hemorrhaging
  • nosebleeds, blood in urine, articular bleeding & pain
• Hemophilia A lacks factor VIII (males only)
  • most common
• Hemophilia B lacks factor IX (males only)
• Hemophilia C (males & females)
  • less severe because alternate clotting activator exists
• Treatment is transfusions of fresh plasma or concentrates of the
  missing clotting factor
                                                              80
Disseminated Intravascular
Clotting
 • Life threatening paradoxical presence of blood clotting and
   bleeding at the same time throughout the whole body
    • so many clotting factors are removed by widespread clotting
      that too few remain to permit normal clotting
 • Associated with infections, hypoxia, low blood flow rates,
   trauma, hypotension & hemolysis
 • Clots cause ischemia and necrosis leading to multisystem organ
   failure

                                                            81
Leukemia
• Acute leukemia
  • uncontrolled production of immature leukocytes
  • crowding out of normal red bone marrow cells by production of
    immature WBC
  • prevents production of RBC & platelets
• Chronic leukemia
  • accumulation of mature WBC in bloodstream because they do
    not die
  • classified by type of WBC that is predominant---monocytic,
    lymphocytic.                                            82

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2 blood rev12

  • 2. The CVS : Blood 2
  • 3. Fluids of the Body • Cells of the body are serviced by 2 fluids • blood • composed of plasma and a variety of cells • transports nutrients and wastes • interstitial fluid • bathes the cells of the body • Nutrients and oxygen diffuse from the blood into the interstitial fluid & then into the cells • Wastes move in the reverse direction 3
  • 4. Functions of Blood • Transportation • O2, CO2, metabolic wastes, nutrients, heat & hormones • Regulation • helps regulate pH through buffers • helps regulate body temperature • coolant properties of water • vasodilatation of surface vessels dump heat • helps regulate water content of cells by interactions with dissolved ions and proteins • Protection from disease & loss of blood 4
  • 5. Physical Characteristics of Blood • Thicker (more viscous) than water and flows more slowly than water • Temperature of 100.4 degrees F (38 degrees C) • pH 7.4 (7.35-7.45) • 8 % of total body weight • Blood volume • 5 to 6 liters in average male • 4 to 5 liters in average female • hormonal negative feedback systems maintain constant blood volume and osmotic pressure 5
  • 6. COMPONENTS OF BLOOD • Blood consists of 55% plasma and 45% formed elements • Blood plasma consists of 91.5% water and 8.5% solutes. • Principal solutes include proteins (albumins, globulins, fibrinogen), nutrients, enzymes, hormones, respiratory gases, electrolytes, and waste products. 6
  • 7. Components of Blood • Hematocrit ▫ 55% plasma ▫ 45% cells  99% RBCs  < 1% WBCs and platelets 7
  • 8. Blood Plasma • 0ver 90% water • 2% other substances • 7% plasma proteins • electrolytes, nutrients, • created in liver hormones, gases, waste • confined to bloodstream products • albumin • maintain blood osmotic pressure • globulins (immunoglobulins) • antibodies bind to foreign substances called antigens • form antigen-antibody complexes • fibrinogen • for clotting 8
  • 9. Formed Elements of Blood • Red blood cells ( erythrocytes ) • White blood cells ( leukocytes ) • granular leukocytes • neutrophils, eosinophils, basophils • agranular leukocytes • lymphocytes = T cells, B cells, and natural killer cells • monocytes • Platelets (special cell fragments) 9
  • 10. • Blood cells are formed from pluripotent hematopoietic stem cells • Bone marrow may be obtained through aspiration or biopsy. The sample is then sent to pathology for examination. • Originating from the pluripotent stem cells are the myeloid stem cells and lymphoid stem cells. FORMATION OF BLOOD CELLS 10
  • 11. Hematocrit • Percentage of blood occupied by cells • female normal range • 38 - 46% (average of 42%) • male normal range • 40 - 54% (average of 46%) • testosterone • Anemia • not enough RBCs or not enough hemoglobin • Polycythemia • too many RBCs (over 65%) • dehydration, tissue hypoxia, blood doping in athletes 11
  • 12. Formation of Blood Cells • Most blood cells types need to be continually replaced • die within hours, days or weeks • process of blood cells formation is hematopoiesis or hemopoiesis • In the embryo • occurs in yolk sac, liver, spleen, thymus, lymph nodes & red bone marrow • In adult • occurs only in red marrow of flat bones like sternum, ribs, skull & pelvis and ends of long bones 12
  • 14. Blood Cells • Myeloid stem cells give rise to RBCs, platelets, and all WBCs except for lymphocytes. • Lymphoid stem cells give rise to lymphocytes. • Myeloid stem cells differentiate into progenitor cells or precursor cells (blast cells) which will develop into the actual formed elements of blood. • Lymphoid stem cells differentiate into pre-B and prothymocytes which develop into B-lymphocytes and T- lymphocytes, respectively. • This process of hemopoiesis (or hematopoiesis) is stimulated by several hematopoietic growth factors. These hematopoietic growth factors stimulate differentiation and proliferation of the various blood cells. 14
  • 15. Stages of Blood Cell Formation • Pluripotent stem cells • 0.1% of red marrow cells • replenish themselves as they differentiate into either myeloid or lymphoid stem cells • Myeloid stem cell line of development continues: • progenitor cells(colony-forming units) no longer can divide and are specialized to form specific cell types • example: CFU-E develops eventually into only red blood cells • next generation is blast cells • have recognizable histological characteristics • develop within several divisions into mature cell types • Lymphoid stem cell line of development 15 • pre-B cells & prothymocytes finish their development into B & T lymphocytes in the lymphatic tissue after leaving the red marrow
  • 16. Hemopoietic Growth Factors • Regulate differentiation & proliferation • Erythropoietin (EPO) • produced by the kidneys increase RBC precursors • Thrombopoietin (TPO) • hormone from liver stimulates platelet formation • Cytokines are local hormones of bone marrow • produced by some marrow cells to stimulate proliferation in other marrow cells • colony-stimulating factor (CSF) & interleukin stimulate WBC production 16
  • 17. • Erythropoietin increases the number of RBC precursors. • Thrombopoietin increases the number of platelet precursors. • Cytokins (colony-stimulating factors and interleukins) increase the number of WBC precursors. • Growth factors, available through recombinant DNA technology, hold great potential for use in patients who cannot normally form the blood cells. Hormones 17
  • 18. Red Blood Cells or Erythrocytes • Contain oxygen-carrying protein hemoglobin that gives blood its red color • 1/3 of cell’s weight is hemoglobin • Biconcave disk 8 microns in diameter • increased surface area/volume ratio • flexible shape for narrow passages • no nucleus or other organelles • no cell division or mitochondrial ATP formation • Normal RBC count • male 5.4 million/drop ---- female 4.8 million/drop • new RBCs enter circulation at 2 million/second 18
  • 19. Hemoglobin • Globin protein consisting of 4 polypeptide chains • One heme pigment attached to each polypeptide chain • each heme contains an iron ion (Fe+2) that can combine reversibly with one oxygen molecule 19
  • 20. Transport of O2, CO2 and Nitric Oxide • Each hemoglobin molecule can carry 4 oxygen molecules from lungs to tissue cells • Hemoglobin transports 23% of total CO2 waste from tissue cells to lungs for release • combines with amino acids in globin portion of Hb • Hemoglobin transports nitric oxide & super nitric oxide helping to regulate BP • Fe ions pick up nitric oxide (NO) & super nitric oxide (SNO) & transport it to & from the lungs • NO causing vasoconstriction is released in the lungs • SNO causing vasodilation is picked up in the lungs 20
  • 21. RBC Life Cycle • RBCs live only 120 days • wear out from bending to fit through capillaries • no repair possible due to lack of organelles • Worn out cells removed by fixed macrophages in spleen & liver • Breakdown products are recycled 21
  • 22. Recycling of Hemoglobin Components • In macrophages of liver or spleen • globin portion broken down into amino acids & recycled • heme portion split into iron (Fe+3) and biliverdin (green pigment) 22
  • 23. Fate of Components of Heme • Iron(Fe+3) • transported in blood attached to transferrin protein • stored in liver, muscle or spleen • attached to ferritin or hemosiderin protein • in bone marrow being used for hemoglobin synthesis • Biliverdin (green) converted to bilirubin (yellow) • bilirubin secreted by liver into bile • converted to urobilinogen then stercobilin (brown pigment in feces) by bacteria of large intestine • if reabsorbed from intestines into blood is converted to a yellow pigment, urobilin and excreted in urine 23
  • 24. Erythropoiesis: Production of RBCs • Erythrocyte formation, called erythropoiesis, occurs in adult red bone marrow of certain bones • The main stimulus for erythropoiesis is hypoxia • Proerythroblast starts to produce hemoglobin • Many steps later, nucleus is ejected & a reticulocyte is formed ▫ orange in color with traces of visible rough ER • Reticulocytes escape from bone marrow into the blood • In 1-2 days, they eject the remaining organelles to become a mature RBC 24
  • 25. Feedback Control of RBC Production • Tissue hypoxia (cells not getting enough O2) ▫ high altitude since air has less O2 ▫ anemia  RBC production falls below RBC destruction ▫ circulatory problems • Kidney response to hypoxia ▫ release erythropoietin ▫ speeds up development of proerythroblasts into reticulocytes 25
  • 26. Normal Reticulocyte Count • Should be .5 to 1.5% of the circulating RBC’s • Low count in an anemic person might indicate bone marrow problem • leukemia, nutritional deficiency or failure of red bone marrow to respond to erythropoietin stimulation • High count might indicate recent blood loss or successful iron therapy 26
  • 27. • Leukocytes (white blood cells or WBCs) are nucleated cells and do not contain hemoglobin. Two principal types are granular (neutrophils, eosinophils, basophils) and agranular (lymphocytes and monocytes) ▫ Granular leukocytes include eosinophils, basophils, and neutrophils based on the straining of the granules. ▫ Agranular leukocytes do not have cytoplasmic granules and include the lymphocytes and monocytes, which differentiate into macrophages (fixed and wandering). • Leukocytes have surface proteins, as do erythrocytes. They are called major histocompatibility antigens (MHC), are unique for each person (except for identical siblings), and can be used to identify a tissue. WHITE BLOOD CELLS 27
  • 28. WBC Physiology • Less numerous than RBCs • 5000 to 10,000 cells per drop of blood • 1 WBC for every 700 RBC • Leukocytosis is a high white blood cell count • microbes, strenuous exercise, anesthesia or surgery • Leukopenia is low white blood cell count • radiation, shock or chemotherapy • Only 2% of total WBC population is in circulating blood at any given time • rest is in lymphatic fluid, skin, lungs, lymph nodes & spleen 28
  • 29. Function of WBCs • Different WBCs combat inflammation and infection in different ways. ▫ Neutrophils and wandering or fixed macrophages (which develop from monocytes) do so through phagocytosis. ▫ Eosinophils combat the effects of histamine in allergic reactions, phagocytize antigen-antibody complexes, and combat parasitic worms. ▫ Basophils develop into mast cells that liberate heparin, histamine, and serotonin in allergic reactions that intensify the inflammatory response. ▫ B lymphocytes, in response to the presence of foreign substances called antigens, differentiate into tissue plasma cells that produce antibodies. 29 ▫ T lymphocytes destroy foreign invaders directly.
  • 30. • WBCs leave the blood stream by emigration • Some WBCs, particularly neutrophils and macrophages, are active in phagocytosis. • The chemical attraction of WBCs to a disease or injury site is termed chemotaxis. Function of WBCs 30 Principles of Human Anatomy and Physiology, 11e
  • 31. • A differential white blood cell count is a diagnostic test in which specific white blood cells are enumerated. Because each type of WBC plays a different role, determining the percentage of each type in the blood assists in diagnosing the condition. • Bone marrow transplants may be used to treat several types of anemia, leukemia, and numerous other blood disorders. WBC examination 31
  • 32. Neutrophils (Granulocyte) • Polymorphonuclear Leukocytes or Polys • Nuclei = 2 to 5 lobes connected by thin strands • older cells have more lobes • young cells called band cells because of horseshoe shaped nucleus (band) • Fine, pale lilac practically invisible granules • Diameter is 10-12 microns • 60 to 70% of circulating WBCs 32
  • 33. Eosinophils (Granulocyte) • Nucleus with 2 or 3 lobes connected by a thin strand • Large, uniform-sized granules stain orange-red with acidic dyes • do not obscure the nucleus • Diameter is 10 to 12 microns • 2 to 4% of circulating WBCs 33
  • 34. Basophils (Granulocyte) • Large, dark purple, variable-sized granules stain with basic dyes • obscure the nucleus • Irregular, s-shaped, bilobed nuclei • Diameter is 8 to 10 microns • Less than 1% of circulating WBCs 34
  • 35. Lymphocyte (Agranulocyte) • Dark, oval to round nucleus • Cytoplasm sky blue in color • amount varies from rim of blue to normal amount • Small cells 6 - 9 microns in diameter • Large cells 10 - 14 microns in diameter • increase in number during viral infections • 20 to 25% of circulating WBCs 35
  • 36. Monocyte (Agranulocyte) • Nucleus is kidney or horse-shoe shaped • Largest WBC in circulating blood • does not remain in blood long before migrating to the tissues • differentiate into macrophages • fixed group found in specific tissues • alveolar macrophages in lungs • Kupffer cells in liver • wandering group gathers at sites of infection • Diameter is 12 - 20 microns • Cytoplasm is a foamy blue-gray • 3 to 8% o circulating WBCs 36
  • 37. Emigration & Phagocytosis in WBCs • WBCs roll along endothelium, stick to it & squeeze between cells. • adhesion molecules (selectins) help WBCs stick to endothelium • displayed near site of injury • molecules (integrins) found on neutrophils assist in movement through wall • Neutrophils & macrophages phagocytize bacteria & debris • chemotaxis of both • kinins from injury site & toxins 37
  • 38. Neutrophil Function • Fastest response of all WBC to bacteria • Direct actions against bacteria • release lysozymes which destroy/digest bacteria • release defensin proteins that act like antibiotics & poke holes in bacterial cell walls destroying them • release strong oxidants (bleach-like, strong chemicals ) that destroy bacteria 38
  • 39. Monocyte Function • Take longer to get to site of infection, but arrive in larger numbers • Become wandering macrophages, once they leave the capillaries • Destroy microbes and clean up dead tissue following an infection 39
  • 40. Basophil Function • Involved in inflammatory and allergy reactions • Leave capillaries & enter connective tissue as mast cells • Release heparin, histamine & serotonin • heighten the inflammatory response and account for hypersensitivity (allergic) reaction 40
  • 41. Eosinophil Function • Leave capillaries to enter tissue fluid • Release histaminase • slows down inflammation caused by basophils • Attack parasitic worms • Phagocytize antibody-antigen complexes 41
  • 42. Lymphocyte Functions • B cells • destroy bacteria and their toxins • turn into plasma cells that produces antibodies • T cells • attack viruses, fungi, transplanted organs, cancer cells & some bacteria • Natural killer cells • attack many different microbes & some tumor cells • destroy foreign invaders by direct attack 42
  • 43. Complete Blood Count • Screens for anemia and infection • Total RBC, WBC & platelet counts; differential WBC; hematocrit and hemoglobin measurements • Normal hemoglobin range • infants have 14 to 20 g/100mL of blood • adult females have 12 to 16 g/100mL of blood • adult males have 13.5 to 18g/100mL of blood 43
  • 44. Differential WBC Count • Detection of changes in numbers of circulating WBCs (percentages of each type) • indicates infection, poisoning, leukemia, chemotherapy, parasites or allergy reaction • Normal WBC counts • neutrophils 60-70% (up if bacterial infection) • lymphocyte 20-25% (up if viral infection) • monocytes 3 -- 8 % (up if fungal/viral infection) • eosinophil 2 -- 4 % (up if parasite or allergy reaction) • basophil <1% (up if allergy reaction or hypothyroid) 44
  • 45. PLATELETS • Thrombopoietin stimulates myeloid stem cells to produce platelets. • Myeloid stem cells develop into megakaryocyte-colony-forming cells that develop into megakaryoblasts (Figure 19.2). • Megakaryoblasts transform into megakaryocytes which fragment. • Each fragment, enclosed by a piece of cell membrane, is a platelet (thrombocyte). • Normal blood contains 250,000 to 400,000 platelets/mm3. Platelets have a life span of only 5 to 9 days; aged and dead platelets are removed by fixed macrophages in the spleen and liver. 45
  • 46. PLATELETS • Platelets help stop blood loss from damaged vessels by forming a platelet plug. Their granules also contain chemicals that promote blood clotting. • A complete blood count (CBC) is a test that screens for anemia and various infections. It usually includes counts of RBCs, WBCs, and platelets per μL of whole blood; hematocrit and differential white blood cell count. The amount of hemoglobin in grams per ml is also determined. 46
  • 47. Platelet (Thrombocyte) Anatomy • Disc-shaped, 2 - 4 micron cell fragment with no nucleus • Normal platelet count is 150,000-400,000/drop of blood • Other blood cell counts • 5 million red & 5-10,000 white blood cells 47
  • 48. Platelets--Life History • Platelets form in bone marrow by following steps: • myeloid stem cells to megakaryocyte-colony forming cells to megakaryoblast to megakaryocytes whose cell fragments form platelets • Short life span (5 to 9 days in bloodstream) • formed in bone marrow • few days in circulating blood • aged ones removed by fixed macrophages in liver and spleen 48
  • 49. HEMOSTASIS • A clot is a gel consisting of a network of insoluble protein fibers (fibrin) in which formed elements of blood are trapped • The chemicals involved in clotting are known as coagulation (clotting) factors; most are in blood plasma, some are released by platelets, and one is released from damaged tissue cells • Blood clotting involves a cascade of reactions that may be divided into three stages: formation of prothrombinase (prothrombin activator), conversion of prothrombin into thrombin, and conversion of soluble fibrinogen into insoluble fibrin 49
  • 50. • The clotting cascade can be initiated by either the extrinsic pathway or the intrinsic pathway. • Normal coagulation requires vitamin K and also involves clot retraction (tightening of the clot) and fibrinolysis (dissolution of the clot). • The fibrinolytic system dissolves small, inappropriate clots and clots at a site of damage once the damage is repaired. • Plasmin (fibrinolysin) can dissolve a clot by digesting fibrin threads and inactivating substances such as fibrinogen, prothrombin, and factors V, VIII, and XII. HEMOSTASIS 50
  • 51. Hemostasis • Stoppage of bleeding in a quick & localized fashion when blood vessels are damaged • Prevents hemorrhage (loss of a large amount of blood) • Methods utilized • vascular spasm • platelet plug formation • blood clotting (coagulation = formation of fibrin threads) 51
  • 52. Vascular Spasm • Damage to blood vessel produces stimulates pain receptors • Reflex contraction of smooth muscle of small blood vessels • Can reduce blood loss for several hours until other mechanisms can take over • Only for small blood vessel or arteriole 52
  • 53. Platelet Plug Formation • Platelets store a lot of chemicals in granules needed for platelet plug formation • alpha granules • clotting factors • platelet-derived growth factor • cause proliferation of vascular endothelial cells, smooth muscle & fibroblasts to repair damaged vessels • dense granules • ADP, ATP, Ca+2, serotonin, fibrin-stabilizing factor, & enzymes that produce thromboxane A2 • Steps in the process • (1) platelet adhesion (2) platelet release reaction (3) platelet aggregation 53
  • 54. Platelet Adhesion • Platelets stick to exposed collagen underlying damaged endothelial cells in vessel wall 54
  • 55. Platelet Release Reaction • Platelets activated by adhesion • Extend projections to make contact with each other • Release thromboxane A2 & ADP activating other platelets • Serotonin & thromboxane A2 are vasoconstrictors decreasing blood flow through the injured vessel 55
  • 56. Platelet Aggregation • Activated platelets stick together and activate new platelets to form a mass called a platelet plug • Plug reinforced by fibrin threads formed during clotting process 56
  • 57. Blood Clotting • Blood drawn from the body thickens into a gel • gel separates into liquid (serum) and a clot of insoluble fibers (fibrin) in which the cells are trapped • If clotting occurs in an unbroken vessel is called a thrombosis • Substances required for clotting are Ca+2, enzymes synthesized by liver cells and substances released by platelets or damaged tissues • Clotting is a cascade of reactions in which each clotting factor activates the next in a fixed sequence resulting in the formation of fibrin threads • prothrombinase & Ca+2 convert prothrombin into thrombin • thrombin converts fibrinogen into fibrin threads 57
  • 58. Overview of the Clotting Cascade • Prothrombinase is formed by either the intrinsic or extrinsic pathway • Final common pathway produces fibrin threads 58
  • 59. Extrinsic Pathway • Damaged tissues leak tissue factor (thromboplastin) into bloodstream • Prothrombinase forms in seconds • In the presence of Ca+2, clotting factor X combines with V to form prothrombinase 59
  • 60. Intrinsic Pathway • Activation occurs • endothelium is damaged & platelets come in contact with collagen of blood vessel wall • platelets damaged & release phospholipids • Requires several minutes for reaction to occur • Substances involved: Ca+2 and clotting factors XII, X and V 60
  • 61. Final Common Pathway • Prothrombinase and Ca+2 • catalyze the conversion of prothrombin to thrombin • Thrombin • in the presence of Ca+2 converts soluble fibrinogen to insoluble fibrin threads • activates fibrin stabilizing factor XIII • positive feedback effects of thrombin • accelerates formation of prothrombinase • activates platelets to release phospholipids 61
  • 62. Clot Retraction & Blood Vessel Repair • Clot plugs ruptured area of blood vessel • Platelets pull on fibrin threads causing clot retraction • trapped platelets release factor XIII stabilizing the fibrin threads • Edges of damaged vessel are pulled together • Fibroblasts & endothelial cells repair the blood vessel 62
  • 63. Role of Vitamin K in Clotting • Normal clotting requires adequate vitamin K • fat soluble vitamin absorbed if lipids are present • absorption slowed if bile release is insufficient • Required for synthesis of 4 clotting factors by hepatocytes • factors II (prothrombin), VII, IX and X • Produced by bacteria in large intestine 63
  • 64. Hemostatic Control Mechanisms • Fibrinolytic system dissolves small, inappropriate clots & clots at a site of a completed repair • fibrinolysis is dissolution of a clot • Inactive plasminogen is incorporated into the clot • activation occurs because of factor XII and thrombin • plasminogen becomes plasmin (fibrinolysin) which digests fibrin threads • Clot formation remains localized • fibrin absorbs thrombin • blood disperses clotting factors • endothelial cells & WBC produce prostacyclin that opposes thromboxane A2 (platelet adhesion & release) • Anticoagulants present in blood & produced by mast cells 64
  • 65. Intravascular Clotting • Thrombosis • clot (thrombus) forming in an unbroken blood vessel • forms on rough inner lining of BV • if blood flows too slowly (stasis) allowing clotting factors to build up locally & cause coagulation • may dissolve spontaneously or dislodge & travel • Embolus • clot, air bubble or fat from broken bone in the blood • pulmonary embolus is found in lungs • Low dose aspirin blocks synthesis of thromboxane A2 & reduces inappropriate clot formation • strokes, TIAs and myocardial infarctions 65
  • 66. Anticoagulants and Thrombolytic Agents • Anticoagulants suppress or prevent blood clotting ▫ heparin  administered during hemodialysis and surgery ▫ warfarin (Coumadin)  antagonist to vitamin K so blocks synthesis of clotting factors  slower than heparin ▫ stored blood in blood banks treated with citrate phosphate dextrose (CPD) that removes Ca+2 • Thrombolytic agents are injected to dissolve clots ▫ directly or indirectly activate plasminogen ▫ streptokinase or tissue plasminogen activator (t-PA) 66
  • 67. • Clots are generally localized due to fibrin absorbing thrombin into the clot, clotting factors diffusing through blood, and the production of prostacyclin, a powerful inhibitor of platelet adhesion and release. • Substances that inhibit coagulation, called anticoagulants, are also present in blood. An example is heparin. • Patients who are at increased risk of forming blood clots may receive an anticoagulant drug such as heparin or warfarin. To prevent clots in donated blood, a substance that removes Ca+2 such as EDTA or CPD may be added to the blood. • Despite the anticoagulating and fibrinolytic mechanisms, blood clots sometimes form within the cardiovascular system. Hemostatic Control Mechanisms 67
  • 68. • Clotting in an unbroken blood vessel is called thrombosis. • A thrombus (clot), bubble of air, fat from broken bones, or piece of debris transported by the bloodstream that moves from its site of origin is called an embolus. • At low doses aspirin inhibits vasoconstriction and platelet aggregation thereby reducing the chance of thrombus formation. Thrombolytic agents are injected into the body to dissolve clots that have already formed. Streptokinase or tissue plasminogen activator (TPS) are thrombolytic agents. HEMOSTASIS 68
  • 69. • In the ABO system, agglutinogens (antigens) A and B determine blood types • Plasma contains agglutinins (antibodies), designated as a and b, that react with agglutinogens that are foreign to the individual. ABO Group 69 Principles of Human Anatomy and Physiology, 11e
  • 70. Blood Groups and Blood Types • RBC surfaces are marked by genetically determined glycoproteins & glycolipids • agglutinogens or isoantigens 70 • distinguishes at least 24 different blood groups • ABO, Rh, Lewis, Kell, Kidd and Duffy systems
  • 71. ABO Blood Groups • Based on 2 glycolipid isoantigens called A and B found on the surface of RBCs ▫ display only antigen A -- blood type A ▫ display only antigen B -- blood type B ▫ display both antigens A & B -- blood type AB ▫ display neither antigen -- blood type O • Plasma contains isoantibodies or agglutinins to the A or B antigens not found in your blood ▫ anti-A antibody reacts with antigen A ▫ anti-B antibody reacts with antigen B 71
  • 72. RH blood groups • Antigen was discovered in blood of Rhesus monkey • People with Rh agglutinogens on RBC surface are Rh+. Normal plasma contains no anti-Rh antibodies • Antibodies develop only in Rh- blood type & only with exposure to the antigen • transfusion of positive blood • during a pregnancy with a positive blood type fetus • Transfusion reaction upon 2nd exposure to the antigen results in hemolysis of the RBCs in the donated blood 72
  • 73. Hemolytic Disease of Newborn • Rh negative mom and Rh+ fetus will have mixing of blood at birth • Mom's body creates Rh antibodies unless she receives a RhoGam shot soon after first delivery, miscarriage or abortion • RhoGam binds to loose fetal blood and removes it from body before she reacts • In 2nd child, hemolytic disease of the newborn may develop causing hemolysis of the fetal RBCs 73
  • 74. Transfusion and Transfusion Reactions • Transfer of whole blood, cells or plasma into the bloodstream of recipient • used to treat anemia or severe blood loss • Incompatible blood transfusions • antigen-antibody complexes form between plasma antibodies & “foreign proteins” on donated RBC's (agglutination) • donated RBCs become leaky (complement proteins) & burst • loose hemoglobin causes kidney damage • Problems caused by incompatibility between donor’s cells and recipient’s plasma • Donor plasma is too diluted to cause problems 74
  • 75. Universal Donors and Recipients • People with type AB blood called “universal recipients” since have no antibodies in plasma • only true if cross match the blood for other antigens • People with type O blood cell called “universal donors” since have no antigens on their cells • theoretically can be given to anyone 75
  • 76. • The Rh and ABO blood groups may be detected by a simple medical test, blood typing, in which a sample of blood is mixed with serum containing agglutinins to each of the major agglutinogens (AB, B, and Rh) • Typing is the determination of blood types, whereas cross-matching is the mixing of donor and recipient blood for compatibility. Typing and Cross-Matching Blood for Transfusion 76
  • 77. DISORDERS: HOMEOSTATIC IMBALANCES • Anemia • Sickle-cell • Hemophilia • Disseminated intravascular clotting • Acute leukemia • Chronic leukemia 77
  • 78. Anemia = Not Enough RBCs • Symptoms • oxygen-carrying capacity of blood is reduced • fatigue, cold intolerance & paleness • lack of O2 for ATP & heat production • Types of anemia • iron-deficiency =lack of absorption or loss of iron • pernicious = lack of intrinsic factor for B12 absorption • hemorrhagic = loss of RBCs due to bleeding (ulcer) • hemolytic = defects in cell membranes cause rupture • thalassemia = hereditary deficiency of hemoglobin • aplastic = destruction of bone marrow (radiation/toxins) 78
  • 79. Sickle-cell Anemia (SCA) • Genetic defect in hemoglobin molecule (Hb-S) that changes 2 amino acids • at low O2 levels, RBC is deformed by changes in hemoglobin molecule within the RBC • sickle-shaped cells rupture easily = causing anemia & clots • Found among populations in malaria belt • Mediterranean Europe, sub-Saharan Africa & Asia • Person with only one sickle cell gene • increased resistance to malaria because RBC membranes leak K+ & lowered levels of K+ kill the parasite infecting the red blood cells 79
  • 80. Hemophilia • Inherited deficiency of clotting factors • bleeding spontaneously or after minor trauma • subcutaneous & intramuscular hemorrhaging • nosebleeds, blood in urine, articular bleeding & pain • Hemophilia A lacks factor VIII (males only) • most common • Hemophilia B lacks factor IX (males only) • Hemophilia C (males & females) • less severe because alternate clotting activator exists • Treatment is transfusions of fresh plasma or concentrates of the missing clotting factor 80
  • 81. Disseminated Intravascular Clotting • Life threatening paradoxical presence of blood clotting and bleeding at the same time throughout the whole body • so many clotting factors are removed by widespread clotting that too few remain to permit normal clotting • Associated with infections, hypoxia, low blood flow rates, trauma, hypotension & hemolysis • Clots cause ischemia and necrosis leading to multisystem organ failure 81
  • 82. Leukemia • Acute leukemia • uncontrolled production of immature leukocytes • crowding out of normal red bone marrow cells by production of immature WBC • prevents production of RBC & platelets • Chronic leukemia • accumulation of mature WBC in bloodstream because they do not die • classified by type of WBC that is predominant---monocytic, lymphocytic. 82