Human Anatomy,

First Edition McKinley & O'Loughlin Chapter 21: Blood 1

Blood

   Considered a connective tissue: contains   Cells a liquid ground substance (called plasma)  dissolved protein fibers. About four times more viscous (or thicker) than water.

Temperature of blood is about 1°C higher than measured body temperature.

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Blood

  Whole blood can be separated:  Liquid component  cellular components 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 blood is withdrawn from a vein and collected in a centrifuge tube   tube is placed into the centrifuge, which then spins it in a circular motion for several minutes rotational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 liquid and cellular components the blood into 21-3

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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 21-5

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 hormones that have been absorbed from the GI tract 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 21-8

Functions of Blood – Regulation of Body Temp.

 Regulates body temperature.

 plasma absorbs and distributes heat the body   throughout 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 21-9

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 pressure results. is absorbed in the blood, high blood If too much fluid escapes the bloodstream and enters the tissues, blood pressure drops levels , and the tissues swell to unhealthy 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 infection (white blood cells) help guard against by mounting an immune response pathogen or an antigen is found. if a Plasma transports antibodies , which are molecules that can immobilize antigens until a leukocyte can completely kill or remove the antigen. Platelets and blood proteins blood loss by forming blood clots on damaged vessels.

protect the body against 21-13

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 plasma’s total volume. water facilitates the transport of materials in the plasma 21-14

Plasma Proteins

   The next most abundant materials in plasma are the plasma proteins.

Make up about 7% of the plasma.

 The plasma proteins include:  albumins    6 and 8 grams milliliters of protein in a volume of 100 of blood (referred to as g/dl ) globulins fibrinogen regulatory proteins 21-15

Plasma Proteins – Albumins

   Smallest  and most abundant make up approximately 58% of the plasma proteins. of total plasma proteins Regulate water movement interstitial fluid.

between the blood and Albumins act as transport proteins that carry ions, hormones, and some lipids in the blood.

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Plasma Proteins – Globulins

    Second largest about 37% group of plasma proteins, forming 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.

Gamma-globulins: Also called immunoglobulins antibodies.

or 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.  <1% 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 energy production.

is higher in plasma than in interstitial fluid, because the cells take up and use the oxygen from the interstitial fluid during 21-20

Solutes

  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 21-22

Hematocrit

      Percentage of erythrocytes in the blood. Values vary slightly and are dependent on age Adult males Females range between range from 42% and 56% 38% to 46%.

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Childrens’ values. and sex.

hematocrit ranges also vary and differ from adult Altitude  can affect the hematocrit. body compensates by making more erythrocytes  more erythrocytes in the blood can carry more oxygen tissues to the 21-23

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Erythrocytes

   Mature erythrocytes lack nuclei.

Transport oxygen and carbon dioxide tissues and the lungs. to and from the 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 color no oxygen that is perceived as blue has a deep red 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 blocks, called globins.

  Alpha (a) chains Beta (b) chains.

All globin chains contain a nonprotein (or protein building heme ) group:   ring shaped an iron (Fe) ion in its center. Oxygen binds to these iron ions for transport in the blood. Each hemoglobin molecule:   four iron ions is capable of binding four molecules of oxygen.

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Hemoglobin in Erythrocytes

   Oxygen binding  is fairly weak ensures 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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Erythrocyte Life Cycle

     No organelles, therefore can not sustain itself. Finite life span of about 120 days. Daily:  About 1% of oldest RBCs are removed Are phagocytized by liver and spleen.

 By macrophages Some components saved, some discarded 21-31

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Erythrocyte Life Cycle

 Some components saved, some discarded   Heme group:   Converted to biliverdin (green pigment) Then converted to bilirubin   In bile, produced by liver Bile enters the digestive tract   Helps emulsify fat Bilirubin modified and removed via urine and feces Iron:   Transported by transferrin to liver  Transferred to ferritin for storage Ferritin can be transported to red bone marrow 21-33

Blood Types

    Determined by membrane proteins in the RBC cell membrane. Called surface antigens (agglutinogens). Most common group: ABO blood group  Two antigens: A and B ABO blood types:    Type A: have the A surface antigen Type B: have the B surface antigen Type AB: have both the A and the B surface antigens  Type O: have neither the A or the B surface antigen.

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Blood Types

  Antibodies (agglutinins) to the surface antigens are in the plasma ABO group has anti-A antibodies and anti-B antibodies     Type A: have anti-B Type B: have anti-A Type AB: has neither anti-A or anti-B Type O: has both anti-A and anti- B 21-36

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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Blood Types

   Rh blood type   Based on another surface antigen Called either Rh or D Rh positive (Rh + ): has the antigen Rh negative (Rh ): does not have the antigen 21-40

Blood Types

    Rh blood type Antibody only present with exposure to Rh + blood (the antigen) Only people with Rh antibody blood can have the Erthryroblastosis fetalis: Rh + plasma of an Rh placenta antibodies in mother can cross the  RhoGAM: prevent antibody development 21-41

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. 21-42

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Leukocytes

 The five types of leukocytes are divided into two distinguishable classes — granulocytes and agranulocytes —based upon the presence or absence of visible organelles termed specific granules.

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Leukocytes – Granulocytes

  

Neutrophil

 60–70% of the total number of leukocytes

Eosinophils

cytoplasm.

 have reddish, or pink-orange granules in their constitute about 2–4% 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 0.5–1% of the total number of leukocytes always exhibit a bilobed nucleus and abundant blue-violet granules in the cytoplasm 21-45

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Leukocytes – Agranulocytes

  Agranulocytes are leukocytes that have such small granules in their cytoplasm that they are frequently overlooked upon casual observation—hence the name agranulocyte. Agranulocytes include both monocytes .

lymphocytes and 21-47

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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 21-49

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Leukocytes – Agranulocytes Monocytes

    Up to three times the diameter of an erythrocyte. Constitute about 3–8% of all leukocytes.

Nucleus is kidney-shaped or U-shaped. Macrophages phagocytize bacteria, cell fragments, dead cells, and debris. 21-51

Platelets

    Irregular, membrane-enclosed cellular fragments  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.

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Platelets

  Severe trauma to a blood vessel causes the blood to coagulate, or clot.

Components in the plasma produce a web of flow. fibrin that traps erythrocytes and platelets in the web to halt blood 21-54

Hemopoiesis

   Also called hematopoiesis Production of the formed elements of blood Occurs in red bone marrow 21-55

Hemopoiesis

  Begins with hemopoietc stem cells Called Hemocytoblast  Pluripotent cells  Produce two cell lines  Myloid line  Everything but lymphocytes  Lymphoid line  lymphocytes 21-56

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Hemopoiesis

  Influenced by a number of hormones and growth factors Colony-stimulating factors:    Multi-CSF: RBCs,granulocytes,monocytes, platelets  From myloid stem cell GM-CSF: granulocytes, monocytes  From progenitor cell G-CSF: granulocytes  From myeloblast cells 21-58

Hemopoiesis

 Colony-stimulating factors: contined  M-CSF: monocytes  From monoblasts   Thrombopoietin: megakaryocytes and platelets Erythropoietin: hormone from the kidney, RBC’s 21-59

Hemopoiesis

   Erythropoiesis: from progenitor cell  Reticulocyte: loses all organelles Thrombopoiesis Leukopoiesis  Granulocyte maturation: from myeloblast   Monocyte maturation: from monoblast Lymphocyte maturation: from lymphoid stem cell   B-lymphoblast T-lymphoblast 21-60

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