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Anatomy

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Anatomy & Physiology Fifth Edition Seeley/Stephens/Tate (c) The McGraw-Hill Companies, Inc. Blood Introduction Blood has been the source of mysteries for thousands of ... – PowerPoint PPT presentation

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Title: Anatomy


1
Chapter 19
  • Anatomy Physiology
  • Fifth Edition
  • Seeley/Stephens/Tate
  • (c) The McGraw-Hill Companies, Inc.

2
Blood
  • Introduction
  • Blood has been the source of mysteries for
    thousands of years.
  • Blood is a type of C.T. consisting of cells and
    liquid.
  • Blood is circulated by pumping action of the
    heart, the valves in blood vessels and by the
    contracting action of calf muscles.
  • The total volume of an adult female is 4 5 L,
    while that an adult is 5 6 L.
  • Blood constitutes about 8 of the total body
    weight of the human and the components may be
    divided with centrifugation.
  • Study Fig. 19.1 carefully.

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  • The Functions of Blood
  • At least 5 major functions of blood have been
    identified( I have broken down the functions to
    5, rather than 3 as shown in the text.)
  • Transportation for gases, nutrients, hormone,
    vitamins, and metabolic wastes.
  • Regulation of the pH, electrolytes and
    composition of interstitial fluids throughout the
    body.
  • Homeothermic keeping the organism at constant
    temperature.
  • Protection of damage sites with blood clots.
  • Immunogenic defense against toxins and
    pathogens.

5
  • Blood Collection and Analysis
  • Collection of human blood is usually performed
    from a superficial vein via venipuncture or from
    the finger tip or sole.
  • Only when needed an arterial puncture may be
    performed.
  • The temperature of blood is about 38C and is
    slightly higher than that of the body
    temperature.
  • Having a large quantity of proteins in plasma
    (7g/100ml) and corpuscles, bloods viscosity is
    more than five times higher than that of water.
  • The pH of blood is about 7.4.

6
  • Plasma (see Table 19.1)
  • The plasma volume remains relatively consistent.
  • Differences between plasma and interstitial
    fluids
  • The composition of plasma and that of
    interstitial fluid is about the same, but the
    former has more proteins and dissolved gases.
  • Plasma Proteins
  • 7g/100ml of plasma
  • Albumin 58 of plasma proteins. Osmotic balance.
  • Globulin 38. Immunoglobulins, lipoproteins and
    transport proteins antibodies and thyroid
    hormone-binding proteins.
  • Fibrinogen 4. Can form large fibrins to form
    blood clot.
  • 50 of plasma proteins are produced by plasma
    cells.
  • The other substances in plasma
  • In addition of dissolved proteins, plasma
    contains ions, nutrients, waste products, gases
    and regulatory substances.

7
  • Formed Elements
  • The hematocrit refers to the percentage of blood
    cells ( in practice the formed elements). This
    number is obtained by centrifuging the blood held
    in a thin glass tube at a high speed. The formed
    elements will settle down to the bottom and its
    ratio to the total volume is the hematocrit.
  • The hematocrit is about 46 for male and about
    42 for females.
  • Red blood cells 99.9 of the formed elements
    in volume or 4.2 6.2 million/mm³. Erythrocytes
    are enucleated and have little organelles.
  • White blood cells (leukocytes) have nuclei
  • Granulocytes are neutrophils, eosinophils and
    basophils.
  • Agranulocytes are lymphocytes, monocytes.
  • Platelets enucleated and have little
    organelles.

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  • Production of Formed Elements Hemopoiesis or
    hematopoiesis
  • The major production sites of the formed elements
    shift
  • The first 8 weeks they start at the embryonic
    yolk sac and they begin to settle in the liver,
    spleen, thymus, and bone marrow. They become stem
    cells.
  • Form the 8th week to 5th month in the liver and
    spleen are the primary sites of hemopoiesis.
  • No nucleus or organelles, thus only glycolytic
    enzymes to form energy by glycolysis.
  • Carbonic anhydrase responsible for conversion
    and transportation carbon dioxide.
  • Phospholipids and membrane proteins and others
    etc.

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  • Erythrocytes are
  • 99.9 in volume of the formed elements.
  • 5.4 million cells/ one microliter (ul or mm³) of
    blood for a man.
  • 4.8 million cells/ one microliter (ul or mm³) for
    a woman.
  • 260 million RBC/drop of blood.
  • 25 trillion RBCs in the blood of an adult 1/3
    of all the cells in the human body. (75 trillion
    cells)
  • The difference in the hematocrit mention earlier,
    I.e. 46 to men and 42 to women, arises from the
    fact that androgens in men stimulate
    erythropoiesis, while estrogens in women are
    inhibitory.
  • The ratio of white cells to red cells is 1 to
    1000.
  • The hematocrit vs disease anemia and
    polycythemia.

15
  • Structure of RBCs
  • Uniquely biconcaved and flexible (Fig 19.3), have
    excellent exchange of gases between the cells and
    the environment. Contrary to a sphere, the RBC
    has the maximum surface to volume ratio.
  • The diameter is 7.5 microns and the thickness
    varies at the edge (thick, 1.5 microns) and the
    center (thinner, 1 micron) making it possible to
    tumble and bend in tissue capillaries.

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  • The primary function of RBCs is performed by
    hemoglobin.
  • 33 of RBC is hemoglobin, Hb, an oxygen and CO2
    carrying protein.
  • Each Hb consist of two pairs of subunits (alpha
    and beta) and each subunit has an oxygen binding
    heme. (Fig. 19.4)
  • Since the oxygen binding to heme is reversible,
    the number of oxygen bound to heme depends upon
    the amount of oxygen is in the environment of Hb.
  • Thus, in the lungs, where oxygen pressure is
    high, Hb binds oxygen and carries the gas to the
    tissues where the oxygen pressure is low.

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  • Binding of CO2 to Hb is not at the heme, but is
    at the alpha amino group of the N-terminal ends
    of four subunits.
  • CO2 binding is essentially opposite to that of
    oxygen, but again follows the amount of CO2 in
    plasma.
  • (O2 - 95 w/Hb, 5 dissolved)
  • (CO - 7 dissolved, 23 w/ Hb, 70 as
    bicarbonate)
  • The circulation of CO2 also relies on the
    chemically dissolved form of CO2, i.e.,
    bicarbonate. This process is facilitated by
    carbonic anhydrase.
  • Thus carbon dioxide may be transported as
    carboamino hemoglobin, dissolved bicarbonate and
    free carbon dioxide.

19
  • Life Span and Circulation
  • Complete circulation of an erythrocyte in a body
    usually takes less than a minute.
  • During this period, especially while negotiating
    through tissue capillaries of less than several
    microns of diameter, pulsating motion of blood
    flow severely stresses the erythrocytes.
  • In addition, despite the presence of complex
    protective mechanisms, carrying of oxygen would
    provide ample opportunities to cause oxidative
    damages to the contents of the cells.
  • As a consequence, the life span of a RBC is about
    120 days.
  • Since the hematocrit of a normal person is
    relatively consistent, the loss of erythrocytes
    is compensated with continuous erythropoiesis.
  • Old or damaged erythrocytes are usually
    phagocytically broken down in the liver, spleen
    and bone marrow.
  • Recycled Hb, when in small quantities, its path
    is through the kidneys and into the urine. If
    this level goes up, there will be discoloration
    of the urine.(yellowish ---- iron)

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  • Recycling of RBC/hemoglobin Components
  • Macrophages in the spleen, liver, and other
    lymphatic tissues phagocytically engulf
    erythrocytes.
  • Globular proteins are broken down to amino acids
    for resumption.
  • Heme is separated from its iron and becomes
    biliverdin (green) then to bilirubin to be
    absorbed in the liver, there conjugated and then
    excreted in bile from the intestines. A build up
    of bilirubin in the circulation and intestinal
    spaces is known as jaundice.
  • Iron may be stored with the plasma protein,
    transferrin and recycled.
  • Erythropoiesis is regulated with erythropoetin
    from the kidneys, which appears in the plasma
    when peripheral tissues are exposed to low oxygen
    concentration, hypoxia.

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  • White Blood Cells leukocytes
  • They are different from RBC because of the
    presence of nuclei and the lack of hemoglobin
    thus the transparent or white appearance.
  • They are loosely divided into (Table 19.2)
  • Granulocytes Neutrophils, eosinophils, basophils
  • Agranulocytes monocytes, lymphocytes
  • There are as many as 6-8,000 leukocytes in 1
    microliter of blood, but most of the leukocytes
    are found on peripheral tissues.

24
  • WBC Movement
  • WBC are capable of amoeboid movement.
  • Thus, they can migrate out of the epithelia of
    capillary walls, diapedesis.
  • Positive chemotaxis leads them to the troubled
    spots. There they are phagocytotic.
  • General Functions
  • General defense neutrophils, eosinophils,
    basophils and monocytes
  • Specific immunity lymphocytes
  • Neutrophils polymorphonuclear
  • Live in the circulatory system for only 10-12
    hours, then move into tissues, where they live up
    to 1-2 days.
  • Phagocytic and secrete lysozymes to digest
    bacteria and others.

25
  • Eosinophils reduce inflammation and parasitic
    reaction.
  • Basophils releases histamines, which promotes
    inflammation also release heparin, which inhibits
    blood clotting.
  • In new born and young children, both have mostly
    red bone marrow.
  • In adults, red bone marrow found in the skull,
    fibs, sternum, vertebrae, pelvis, proximal femur
    and proximal humorous.
  • Observe the hematopoiesis of stem cell in Fig.
    19.2.
  • Stem cell are the origin of all formed elements.
  • Note the types of blast cells and the final cell
    types.
  • Monocytes live 2-3 days in circulation and
    migrate in the tissues as macrophages, which
    phagocytose foreign bodies. An increased number
    of monocytes is an indication of an infection.

26
  • Lymphocytes
  • They are about the size of an RBC and they
    contain a nucleus. Most of the lymphocytes dwell
    in the lymphatic system. There are three types
  • T-cells attack foreign bodies.
  • B-cells differentiate into plasma cells, which
    secrete antibodies.
  • Natural Killer cells (NK cells) destroys the
    bodies own abnormal cells.

27
  • Platelets
  • Megakaryocytes in bone marrow, which release
    their fragments into circulation, then called
    platelets.
  • Platelets have no nuclei.
  • Participate in blood clotting.
  • Platelets survive about 10-12 days in circulation
    and are about 150,000 300,000/ul
  • Thrombocytopenia is a loss of platelets and is a
    sign of bleeding etc..
  • Thrombocytosis is excess platelets and is a sign
    of infection.

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  • Hemostasis arrest of bleeding.
  • Prevents loss of blood in three phases.
  • The vascular phase immediate temporary closure
    of a blood vessel by constriction of vascular
    smooth muscles.
  • The platelet phase formation of a platelet plug
    by platelet adhesion and aggregation (Fig 19.9).
    Platelets bind to collagen in damaged tissues.
    Platelets are adhered and form a plug.
  • The coagulation phase for a large blood clot
    formation by the network of fibrin from
    fibrinogen. A large number of steps involving
    many factors are required, some of which require
    thrombin and Ca.

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  • The clotting process
  • Clotting is the phenomenon where blood cells are
    trapped in the framework of fibers.
  • The clotting process requires Ca and 11
    different plasma proteins, mostly enzymes.
  • The process goes through 3-stages
  • Activation of prothrombinase by either the
    extrinsic or intrinsic pathway.
  • Prothormbinase converts prothrombin to thrombin.
  • Thrombin converts fibrinogen to fibrin.
  • Extrinsic pathway the process is triggered by a
    tissue factor of damaged endothelial cells, the
    other enzymes are successively activated to
    complete the clotting process- a cascade. The
    process is fast and takes only 15 seconds.
  • Intrinsic pathway starts with the activation of
    factor XII by contacting the damaged blood
    vessels and is a slower process.

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  • Clot retraction am Removal
  • The platelets begin to contract clot
    retraction.
  • During the repair process of tissue, the clot
    gradually dissolves fibrinolysis.
  • This process draws a lot of attention because
    dissolving clots in heart attack or stroke
    patients is clinically important.
  • To dissolve a clot
  • Activated plasminogen by tissue plasminogen
    activator (t-PA) ? plasmin is produced ? plasmin
    digest the fibrin strands to dissolve the clot.

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  • Blood tests and RBCs (review)
  • Blood types
  • Genetically determined RBC antigens
    (glycoproteins) rest on the surface of the
    membrane.
  • There are at least 50 different kinds of antigens
    on the surface of an RBC.
  • Their antibodies are found in plasma.
  • One set of important antigens are A and B, typed
    ABO. Although A/B antibodies are not found in the
    blood until about 2 months after birth. (Fig
    19.12)

35
  • Blood Type Surface-antigen US pop
    In plasma antibodies
  • A B
    A B
  • TYPE A -
    40 -
  • TYPE B -
    10
    -
  • TYPE AB
    4 -
    -
  • TYPE O - -
    46
  • Rh D
  • Blood donor and Recipient
  • Blood may be received from the subject of the
    same blood type, but not from the other type,
    except one with subject with type O.
  • Type O subject, who has no surface A/B antigen,
    has been considered as a universal donor, since
    the donated RBC will not be coagulated.
  • However, the antibodies in the plasma can
    interact with the surface antigens of the
    recipient and may induce minor reactions. Thus,
    the word universal donor is misleading.

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  • Another important antigen is the Rh factor.
    Rh-positive or Rh-negative. The Rh positive
    subjects have the D antigen on the surface of the
    erythrocytes. About 86 of the people in the US
    are RH positive.
  • Hemolytic Disease of the Newborn (HDN)

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The End.
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