Essentials of Human Anatomy BLOOD Chapter 9 Dr Fadel Naim Ass. Prof. Faculty of Medicine IUG 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.

Blood Volume varies with about 8% of body weight about 5 liters body size changes in fluid concentration changes in electrolyte concentration amount of adipose tissue about 8% of body weight about 5 liters

Blood Whole blood can be separated: Liquid component cellular components

Components of Blood Erythrocytes (or red blood cells) Buffy coat 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

Components of Blood Erythrocytes and the components of the buffy coat are called the formed elements. Formed elements and the liquid plasma compose whole blood.

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

Functions of Blood – Regulation of Body Temperature 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

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.

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. 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.

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.

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 Water 92% Plasma proteins 7% Other solutes 1% Transports organic and inorganic molecules, formed elements, and heat

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

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.

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. Gamma-globulins: Also called immunoglobulins or antibodies. Produced by some of our defense cells to protect the body against pathogens that may cause disease.

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.

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.

Plasma Proteins

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.

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.

Difference between Plasma and Interstitial Fluid Plasma has more: Dissolved O2 O2 diffuses out into tissue Dissolved proteins (too big to cross caps.) Albumins Globulins  globulins  and  globulins Fibrinogen Similar concentration: Salts & small molecules

Plasma Electrolytes absorbed from the intestine or released as by-products of cellular metabolism sodium potassium calcium magnesium chloride bicarbonate phosphate sulfate sodium and chloride are most abundant

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

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

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.

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.

Hemoglobin in Erythrocytes Each hemoglobin molecule consists of four protein building blocks, called globins. Alpha (a) chains Beta (b) chains. All globin chains contain a nonprotein (or heme) group: ring shaped an iron (Fe) ion in its center.

Hemoglobin in Erythrocytes 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 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.

Red Blood Cell Counts number of RBCs in a cubic millimeter of blood 4,600,000 – 6,200,000 in males 4,200,000 – 5,400,000 in adult females 4,500,000 – 5,100,000 in children reflects blood’s oxygen carrying capacity

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

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

Types of Anemia

Sickle Cell

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.

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

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.

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

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

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.

White Blood Cells leukocytes protect against disease interleukins and colony-stimulating factors stimulate development granulocytes neutrophils eosinophils basophils agranulocytes lymphocytes monocytes

Neutrophils light purple granules in acid-base stain lobed nucleus other names segs polymorphonuclear leukocyte bands (young neutrophils) first to arrive at infections phagocytic 54% - 62% of leukocytes elevated in bacterial infections

Eosinophils deep red granules in acid stain bilobed nucleus moderate allergic reactions defend against parasitic worm infestations 1% - 3% of leukocytes elevated in parasitic worm infestations and allergic reactions

Basophils deep blue granules in basic stain release histamine release heparin less than 1% of leukocytes similar to eosinophils in size and shape of nuclei

Monocytes largest blood cell spherical, kidney-shaped, oval or lobed nuclei leave bloodstream to become macrophages 3% - 9% of leukocytes phagocytize bacteria, dead cells, and other debris

Lymphocytes slightly larger than RBC large spherical nucleus surrounded by thin rim of cytoplasm T cells and B cells important in immunity B cells produce antibodies 25% - 33% of leukocytes

Diapadesis leukocytes squeeze between the cells of a capillary wall and enter the tissue space outside the blood vessel

Positive Chemotaxis movement of leukocytes toward the damaged tissue region because of the chemicals that were released by damaged cells

White Blood Cell Counts procedure used to count number of WBCs per cubic millimeter of blood 5,000 – 10,000 per cubic millimeter of blood leukopenia low WBC count (below 5,000) typhoid fever, flu, measles, mumps, chicken pox, AIDS leukocytosis high WBC count (above 10,000) acute infections, vigorous exercise, great loss of body fluids differential WBC count lists percentages of types of leukocytes may change in particular diseases

White Blood Cell Counts

Platelets Irregular, membrane-enclosed cellular fragments about 2 micrometers in diameter (less than one-fourth the size of an erythrocyte). Sometimes called thrombocytes. Continually produced in the red bone marrow by cells called megakaryocytes.

Platelets 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.

Hemopoiesis Also called hematopoiesis Production of the formed elements of blood Occurs in red bone marrow Begins with hemopoietc stem cells Called Hemocytoblast Pluripotent cells Produce two cell lines Myloid line Everything but lymphocytes Lymphoid line lymphocytes

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