Human Anatomy, First Edition McKinley

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Human Anatomy, First EditionMcKinley
O'Loughlin

• Chapter 21 Lecture Outline
• Blood

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Blood

• Considered a connective tissue because it
  contains cells, a liquid ground substance (called
  plasma), and dissolved protein fibers.
• About four times more viscous (or thicker) than
  water.
• Temperature of blood is about 1C higher than
  measured body temperature.
• Can be broken down into its liquid and cellular
  components by a machine called a centrifuge.
• blood is withdrawn from a vein and collected in a
  centrifuge tube
• tube is placed into the centrifuge, which then
  spins it in a circular motion for several minutes
  
• rotational movement separates the blood into
  liquid and cellular components

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Components of Blood

• Erythrocytes (or red blood cells)
• form the lower layer of the centrifuged blood
• typically make up about 44 of a blood sample
• Buffy coat
• makes up the middle layer
• thin, slightly gray-white layer composed of cells
  called leukocytes (or white blood cells) and cell
  fragments called platelets
• forms less than 1 of a blood sample
• Plasma
• straw-colored liquid that rises to the top
• generally makes up about 55 of blood

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Components of Blood

• Erythrocytes and the components of the buffy coat
  are called the formed elements.
• not cells, merely fragments broken off from a
  larger cell
• Formed elements and the liquid plasma compose
  whole blood.

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Functions of Blood Transportation

• Transports numerous elements and compounds
  throughout the body.
• erythrocytes carry oxygen from the lungs to body
  cells and then transport carbon dioxide from the
  cells back to the lungs for expulsion from the
  body
• blood plasma
• transports nutrients that have been absorbed from
  the GI tract
• hormones secreted by the endocrine organs to
  their target cells
• plasma
• carries waste products from the cells to organs
  such as the kidneys, where these waste products
  are removed

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Functions of Blood Regulation of Body Temp.

• Regulates body temperature.
• plasma absorbs and distributes heat throughout
  the body
• for cooling the blood vessels in the dermis
  dilate and dissipate the excess heat through the
  integument
• when the body needs to conserve heat, the dermal
  blood vessels constrict, and the warm blood is
  shunted to deeper blood vessels in the body

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Functions of Blood Regulation of pH Levels

• pH is a measure of how alkaline or acidic a fluid
  is.
• Neutral pH is measured at exactly 7.
• Acidic fluids (e.g., orange juice) are between 0
  and 7.
• Alkaline fluids (e.g., milk) are between 7 and
  14.
• Blood plasma contains compounds and ions that may
  be distributed to the fluid among tissues
  (interstitial fluid) to help maintain normal
  tissue pH.
• Blood plasma pH is continuously regulated at a
  value of 7.4 the pH level required for normal
  cellular functioning.

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Functions of Blood Maintenance of Fluid Levels

• Maintains normal fluid levels in the
  cardiovascular system.
• Prevents fluid loss.
• Constant exchange of fluid between the blood
  plasma and the interstitial fluid.
• If too much fluid is absorbed in the blood, high
  blood pressure results.
• If too much fluid escapes the bloodstream and
  enters the tissues, blood pressure drops to
  unhealthy low levels, and the tissues swell with
  excess fluid.

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Functions of Blood Maintenance of Fluid Levels

• To maintain balance of fluid exchange between the
  blood and the interstitial fluid, blood contains
  compounds (such as salts and some proteins) to
  prevent excess fluid loss in the plasma.

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Functions of Blood Protection

• Leukocytes (white blood cells) help guard against
  infection by mounting an immune response if a
  pathogen or an antigen is found.
• Plasma transports antibodies, which are molecules
  that can immobilize antigens until a leukocyte
  can completely kill or remove the antigen.
• Platelets and blood proteins protect the body
  against blood loss by forming blood clots on
  damaged vessels.

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Components of Plasma

• Complex mixture of water, proteins, and other
  solutes.
• When the proteins are moved from plasma, the
  remaining fluid is termed serum.
• Water makes up about 92 of plasmas total
  volume.
• water facilitates the transport of materials in
  the plasma

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Plasma Proteins

• The next most abundant materials in plasma are
  the plasma proteins.
• Make up about 7 of the plasma.
• 6 and 8 grams of protein in a volume of 100
  milliliters of blood (referred to as g/dl)
• The plasma proteins include
• albumins
• globulins
• fibrinogen
• regulatory proteins

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Plasma Proteins Albumins

• Smallest and most abundant of the plasma
  proteins.
• make up approximately 58 of total plasma
  proteins
• Regulate water movement between the blood and
  interstitial fluid.
• Albumins act as transport proteins that carry
  ions, hormones, and some lipids in the blood.

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Plasma Proteins Globulins

• Second largest group of plasma proteins, forming
  about 37 of all plasma proteins.
• Smaller alpha-globulins and the larger
  beta-globulins primarily bind, support, and
  protect certain water-insoluble or hydrophobic
  molecules, hormones, and ions.
• Also called immunoglobulins or antibodies.
• Produced by some of our defense cells to protect
  the body against pathogens that may cause
  disease.

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Plasma Proteins Fibrinogen

• Makes up about 4 of all plasma proteins.
• Responsible for blood clot formation.
• Following trauma to the walls of blood vessels,
  fibrinogen is converted into long, insoluble
  strands of fibrin, which is the essence of a
  blood clot.

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Plasma Proteins Regulatory Proteins

• Form a very minor class of plasma proteins.
• lt1 of total plasma proteins
• Include enzymes to accelerate chemical reactions
  in the blood and hormones being transported
  throughout the body to target cells.

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Solutes

• Plasma is an extracellular fluid (ECF).
• it includes all body fluids that are not found
  inside cells
• Plasma is somewhat like interstitial fluid, in
  that
• both have similar concentrations of nutrients,
  waste products, and electrolytes
• Concentration of dissolved oxygen is higher in
  plasma than in interstitial fluid, because the
  cells take up and use the oxygen from the
  interstitial fluid during energy production.
• Difference in concentration ensures that oxygen
  will continue to diffuse from the blood into the
  tissues.
• Difference in concentration ensures that carbon
  dioxide will readily diffuse from the
  interstitial fluid into the blood, where it will
  be carried to the lungs and discharged from the
  body.

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Formed Elements in the Blood

• Erythrocytes
• make up more than 99 of formed elements
• primary function is to transport respiratory
  gases in the blood
• Leukocytes
• make up less than .01 of formed elements
• contribute to defending the body against
  pathogens
• Platelets
• make up less than 1 of formed elements and
• help with blood clotting

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Hematocrit

• Percentage of erythrocytes in the blood.
• Values vary slightly and are dependent on age and
  sex.
• Adult males range between 42 and 56 .
• Females range from 38 to 46.
• Childrens hematocrit ranges also vary and differ
  from adult values.
• Altitude can affect the hematocrit.
• body compensates by making more erythrocytes
• more erythrocytes in the blood can carry more
  oxygen to the tissues

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Erythrocytes

• Mature erythrocytes lack nuclei.
• Transport oxygen and carbon dioxide to and from
  the tissues and the lungs.
• Lack of nuclei enables them to carry respiratory
  gases more efficiently.

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Hemoglobin in Erythrocytes

• Every erythrocyte is filled with approximately
  280 million molecules of a red-pigmented protein
  called hemoglobin.
• Transports oxygen and carbon dioxide, and is
  responsible for the characteristic bright red
  color of arterial blood.
• Hemoglobin that contains no oxygen has a deep red
  color that is perceived as blue because the blood
  within these veins is observed through the layers
  of the skin and the subcutaneous tissue.

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Hemoglobin in Erythrocytes

• Each hemoglobin molecule consists of four protein
  building blocks, called globins.
• Alpha (a) chains and beta (b) chains.
• All globin chains contain a nonprotein (or heme)
  group that is in the shape of a ring, with an
  iron (Fe) ion in its center.
• Oxygen binds to these iron ions for transport in
  the blood.
• Each hemoglobin molecule has four iron ions and
  is capable of binding four molecules of oxygen.
• Oxygen binding is fairly weak to ensure rapid
  attachment and detachment of oxygen with
  hemoglobin.
• Oxygen binds to the hemoglobin when the
  erythrocytes pass through the blood vessels of
  the lungs.
• It leaves the hemoglobin when the erythrocytes
  pass through the blood vessels of body tissues.

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Antibodies

• An antibody interacts with a specific antigen.
• The ABO blood group has both anti-A and anti-B
  antibodies that react with the surface antigen A
  and the surface antigen B, respectively.
• The antibodies in your blood plasma do not
  recognize the surface antigens on your
  erythrocytes.

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Leukocytes

• Leukocytes help initiate an immune response and
  defend the body against invading pathogens.
• Leukocytes are true cells in that they contain
  a nucleus and cellular organelles.
• Leukocytes also differ from erythrocytes in that
  they are about 1.5 to 3 times larger, and they do
  not contain hemoglobin.

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Leukocytes

• The five types of leukocytes are divided into two
  distinguishable classesgranulocytes and
  agranulocytesbased upon the presence or absence
  of visible organelles termed specific granules.

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Leukocytes Granulocytes

• Neutrophil
• 6070 of the total number of leukocytes
• Eosinophils have reddish, or pink-orange granules
  in their cytoplasm.
• constitute about 24 of the total number of
  leukocytes
• nucleus usually has two lobes, which are
  connected by a thin strand
• Basophils are
• 1.5 times larger than erythrocytes
• least numerous of the granulocytes
• constitute about 0.51 of the total number of
  leukocytes
• always exhibit a bilobed nucleus and abundant
  blue-violet granules in the cytoplasm

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Leukocytes Agranulocytes

• Agranulocytes are leukocytes that have such small
  granules in their cytoplasm that they are
  frequently overlooked upon casual
  observationhence the name agranulocyte.
• Agranulocytes include both lymphocytes and
  monocytes.

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Leukocytes Agranulocytes -Lymphocytes

• T-lymphocytes (T-cells)
• manage and direct an immune response
• some directly attack foreign cells and
  virus-infected cells
• B-lymphocytes (B-cells)
• stimulated to become plasma cells and produce
  antibodies
• Natural killer cells (NK cells)
• attack abnormal and infected tissue cells

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Leukocytes Agranulocytes - Monocytes

• Up to three times the diameter of an erythrocyte.
  
• Constitute about 38 of all leukocytes.
• Nucleus is kidney-shaped or U-shaped.
• Macrophages phagocytize bacteria, cell fragments,
  dead cells, and debris.

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Platelets

• Irregular, membrane-enclosed cellular fragments
  that are about 2 micrometers in diameter (less
  than one-fourth the size of an erythrocyte).
• In stained preparations, they exhibit a dark
  central region.
• Sometimes called thrombocytes.
• Continually produced in the red bone marrow by
  cells called megakaryocytes.
• Severe trauma to a blood vessel causes the blood
  to coagulate, or clot.
• Components in the plasma produce a web of fibrin
  that traps erythrocytes and platelets in the web
  to halt blood flow.