Blood Chapter 12 - Blood

Introduction Blood, a type of connective tissue, is a complex mixture of cells, chemicals, and fluid. Blood transports substances throughout the body, and helps to maintain a stable internal environment. The blood includes red blood cells, white blood cells, platelets, and plasma.

Introduction D. Blood Volume and Composition Plasma is a mixture of water, amino acids, proteins, carbohydrates, lipids, vitamins, hormones, electrolytes, and cellular wastes. A blood hematocrit (HCT), is normally 45% cells and 55% plasma. An average-sized adult has a blood volume of about 5.3 quarts (5 liters). Men have more blood than women. On average, men have 5-6 liters (1.500 gallons), compared to 4-5 liters (0.875 gallons) for women.

Blood contains liquid portion (plasma) and solid portion (RBCs, WBCs, Platelets)

Blood Cells A. Red Blood Cells 1. Red blood cells (erythrocytes)- are biconcave discs that contain one-third oxygen-carrying hemoglobin by volume. 2. When oxygen combines with hemoglobin, bright red oxyhemoglobin results. 3. Deoxygenated blood (deoxyhemoglobin) is darker. 4. Red blood cells discard their nuclei during development and so cannot reproduce or produce proteins.

Red Blood Cells Biconcave shape makes it efficient at transporting gases.

Red Blood Cell Counts 1. Typical red blood cell count is 4.6-6.2 million RBC’s per mm^3 for males and 4.2-5.4 million cells per mm^3 for females. 2. Number of RBCs is a measure of the blood’s oxygen- carrying capacity. Males have more blood = More RBC’s

Red Blood Cell Production 1. In the embryo and fetus, RBC production occurs in the yolk sac, liver, and spleen; after birth, it occurs in the red bone marrow. 2. Average RBC life span = 120 days 3. Stages of RBC formation from hematopoietic stem cells is displayed in the figure on the next slide.

Hematopoietic stem cells in bone marrow produce RBC’s, WBC’s, and platelets.

RBC Production and Control 4. Total number of RBC’s remains relatively constant due to a negative feedback mechanism utilizing the hormone erythropoietin, which is released from the kidneys and liver in response to the detection of low oxygen levels.

Low blood oxygen causes the kidneys, and to a lesser degree, the liver to release erythropoietin. Erythropoietin stimulates target cells in red bone marrow to increase the production of RBCs that carry oxygen to the tissues.

Dietary Factors Affecting RBC Production Vitamins B12 and Folic Acid are needed for DNA synthesis, so they are necessary for the reproduction of all body cells, especially in hematopoietic tissue. Iron is needed for hemoglobin synthesis. A deficiency in RBCs or quantity of hemoglobin results in anemia. The body reuses much of the iron released by decomposition of damaged BCs, so the diet only needs small amounts of iron. Anemia – Reduces oxygen carrying capacity - Lack of energy, Appears pale Pregnant women are at a higher risk for iron deficiency anemia because of the increased iron requirements of pregnancy

Destruction of RBCs With age, RBC become increasingly fragile and are damaged by passing through narrow capillaries. Macrophages in the liver and spleen phagocytize damaged RBCs. Hemoglobin from the decomposed RBCs is converted into heme and globin. Heme is decomposed into iron which is stored or recycled and biliverdin and bilirubin which are excreted in bile. Biliverdin – green pigment ….. Then converted into orange pigment - Bilirubin

Life cycle of a red blood cell

White Blood Cells

White Blood Cells 1. White blood cells (leukocytes) help defend the body against disease. 2. They are formed from hemocytoblasts (hematopoietic stem cells). 3. Hormones that stimulate WBC production fall into two categories, interleukins and colony-stimulating factors (CSF’s). Similar to erythropoietin with RBC

White Blood Cells 4. Five types of WBCs are in circulating blood and are distinguished by size, granular appearance of the cytoplasm, shape of nucleus, and staining characteristics. 5. The types of WBCs are… Granulocytes = neutrophils, eosinophils, and basophils Agranulocytes = monocytes and lymphocytes Granular Cytoplasm – Granulocytes Not granular cytoplasm - Agranulocytes

Granulocytes Neutrophils – Red staining Fine cytoplasmic granules Multi-lobed nucleus Compromise 54-62% of leukocytes

Granulocytes Eosinophils – Deep red staining Course granules Bi-lobed nucleus Make up only 1-3% of circulating leukocytes

Granulocytes Basophils – Blue staining Few granules Account for fewer than 1% of leukocytes

Agranulocytes Monocytes – Largest blood cells Variably shaped nuclei Make up 3-9% of circulating leukocytes

Agranulocytes Lymphocytes – Long-lived (years) Large, round nucleus 25-33% of leukocytes

Functions of WBCs Leukocytes can squeeze between cells lining walls of blood vessels by diapedesis and attack bacteria and debris. Neutrophils/Monocytes – Both are phagocytic; the monocytes engulf larger particles. Eosinophils – moderate allergic reactions as well as defend against parasitic infections.

Functions of WBCs Basophils – Migrate to damaged tissues and release histamine to promote inflammation and heparin to inhibit blood clotting. Lymphocytes – Major players in specific immune reactions and some produce antibodies.

Breakdown of WBCs – Neutrophils the most, Basophils the least

WBC Counts Cubic milliliter of blood = 4,000 to 11,000 WBCs Leukocytosis – (higher than 11,000) occurs after an infection when excess numbers of leukocytes are present. (Bacterial Infection) Leukopenia – (lower than 4,000) occurs from a variety conditions, including AIDS, Measles, Influenza. (Viral Infection) A differential WBC count (DIFF) helps pinpoint the nature of an illness Lists the percentages of types of leukocytes in a blood sample #’s matter because they indicate a response to abnormal conditions Larger number indicates acute infection (runs short course) = such as appendicitis, HIGHLY ELEVATED = leukemia DIFF: leukocytes =bacterial infection, eosinophils = parasitic infections, AIDS = lymphocytes drop sharply

Blood Platelets Blood platelets (thrombocytes) - fragments of megakaryocytes, developed from hematopoietic stem cells in response to thrombopoietin. Platelets help repair damaged blood vessels by adhering their broken edges Normal platelet counts vary from 130,000 to 360,000 platelets per mm^3 Each platelet lacks a nucleus and is less than half the size of a RBC Lives 10 days

Blood Plasma

Blood Plasma Plasma – clear, straw colored fluid portion of the blood. Contains mostly water (92%) but contains a variety of substances Functions: transports nutrients and gases, regulate fluid and electrolyte balance, and maintain a favorable pH.

Plasma Proteins Plasma proteins are the most abundant dissolved substances in the plasma. Plasma proteins are not used for energy. Fall into three groups – albumins, globulins, and fibrinogen.

Plasma Proteins Albumins – help maintain osmotic pressure of the blood, account for 60% of the plasma proteins Globulins – compromise 36% of plasma proteins. Designated as alpha, beta, and gamma globulins. Alpha and Beta globulins – transport lipids and fat-soluble vitamins. Gamma globulins – type of antibody Fibrinogen – 4% of proteins, Primary role in blood coagulation

Gases and Nutrients Most important gases – Oxygen and Carbon Dioxide Plasma nutrients include: Amino Acids, Monosaccharides, Nucleotides, and Lipids Lipids are not soluble in the water of the plasma. They are surrounded by protein molecules for transport through the bloodstream as lipoproteins.

Non-protein Nitrogenous Substances Nonprotein nitrogenous substances generally include amino acids, urea, and uric acid, creatine, and creatinine. Urea and uric acid are the by-products of protein and nucleic acid catabolism.

Plasma Electrolytes Plasma Electrolytes are absorbed by the intestine or are by-products of cellular metabolism. Include: Sodium, Potassium, Calcium, Magnesium, Chloride, Bicarbonate, Phosphate, and Sulfate Ions, Some of these are important in maintaining osmotic pressure and pH of plasma. The goal in replenishing electrolytes is not so much to prevent cramping, but to maintain specific bodily functions at optimal levels. = gatorade

Hemostasis Hemostasis – stoppage of bleeding Following injury to a vessel, three types of hemostasis can occur 1. Blood vessel spasm 2. Platelet plug formation 3. Blood coagulation

Blood Vessel Spasm Cutting a blood vessel causes the muscle in its walls to contract in a reflex, or engage in vasospasm. This reflex only lasts a few minutes, but it lasts long enough (30 minutes) to initiate the second and third steps of hemostasis. Platelets release serotonin at this time = constricting smooth muscles in the blood vessels (vasoconstriction).

Platelet Plug Formation Platelets stick to the exposed edges of damaged blood vessels, forming a net with spiny processes protruding from their membranes. A platelet plug is most effective on a small vessel.

Platelet plug formation

Blood Coagulation Blood coagulation is the most effective means of hemostasis. Very complex – Uses clotting factors Damaged tissues release a chemical called tissue thromboplastin, which activates the first in a series of factors leading to the production of prothrombin activator. Forms a blood clot

Blood Coagulation Process Damaged tissues release a chemical called tissue thromboplastin, which activates the first in a series of factors leading to the production of prothrombin activator. Prothrombin activator converts prothrombin in the plasma into thrombin. This in turn catalyzes a reaction that converts fibrinogen into fibrin. The major event in blood clot formation is the conversion of soluble fibrinogen into net like insoluble fibrin causing the blood cells to catch. Serum is the plasma minus the clotting factors. The amount of prothrombin activator formed is proportional to the amount of tissue damage.

Blood Coagulation Process 6. Once a blood clot forms, it promotes more clotting through a positive feedback system. 7. After a clot forms, fibroblasts invade the area and produce fibers throughout the clots. A clot that forms abnormally in a vessel is a thrombus; if it dislodges, it is an embolus.

Clotting cascade

Blood Groups

Blood Groups and Transfusions After mixed success with transfusions, scientists determined that blood was of different types and only certain combinations were compatible.

Antigens and Antibodies Clumping of RBCs following transfusion is called agglutination. Agglutination is from interaction of proteins on the surfaces of RBCs (antigens) with certain antibodies, proteins carried in the plasma. Only a few of the antigens on RBCs produce transfusion reactions. These include ABO group and Rh group.

ABO Blood Group Type A blood has A antigens on RBCs and anti-B antibodies in the plasma Type B blood has B antigens on RBCs and anti-A antibodies in the plasma Type AB blood has both A and B antigens, but no antibodies in the plasma (Universal recipient) Type O blood has neither antigen, but BOTH (anti-A & anti-B) antibodies in the plasma (universal donor)

ABO Blood Group Adverse transfusion reactions are avoided by preventing the mixing of blood that contains matching antigens and antibodies Adverse reactions are due to the agglutination of red blood cells.

Rh Blood Group Rh blood group – named after rhesus monkey If the Rh factor surface protein is present on red blood cells, the blood is Rh positive; otherwise it is Rh negative (not present). There are no corresponding antibodies in the plasma unless a person with RH-negative blood is transfused with Rh-positive blood; the person will then develop antibodies for the Rh factor.

Rh Blood Group Erythroblastic Fetalis - Rh-negative woman who becomes pregnant with an Rh- positive fetus sometimes develops anti-bodies against the Rh factor in the fetus. This development usually causes no problem during the woman's first pregnancy, since the number of anti-bodies produced tends to be small. By the time a second pregnancy occurs, the situation has changed! The number of Rh antibodies produced by the mother's body has become large enough to cause destruction of red blood cells in the fetus. Can result in complications for fetus such as anemia, jaundice, or premature birth. Today, this reaction can be controlled by immunizing Rh negative women after their first pregnancy with a drug known as RhoGam. Jaundice – bile pigments build up in blood and cause skin, eyeballs, and urine to take on sickly yellow tone.