Blood - Study Notes PDF

17.1 Blood Functions – Internal ofTransport Blood System Learning Objectives: Blood List and describe functions of blood. Describe the cellular elements and extracellular matrix (plasma) of blood. Compare and contrast the morphological fea...

17.1 Blood Functions – Internal ofTransport Blood System Learning Objectives: Blood List and describe functions of blood. Describe the cellular elements and extracellular matrix (plasma) of blood. Compare and contrast the morphological features and major functions of the three main cellular elements of blood: erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets). Identify the site of erythropoietin (EPO) production, the stimulus for EPO release, the target tissue(s) for EPO, and the action of EPO at its target. Describe the structure of hemoglobin (Hb, Hgb) and relate its structure to its functions © 2016 Pearson Education, Ltd.  17.1 Blood Functions – Internal ofTransport Blood System Blood is the life-sustaining transport vehicle of the cardiovascular system Functions include – Transport – Regulation – Protection © 2016 Pearson Education, Ltd.  Functions of Blood Transport functions include: – Delivering O2 and nutrients to body cells – Transporting metabolic wastes to lungs and kidneys for elimination – Transporting hormones from endocrine organs to target organs Regulation functions include: – Maintaining body temperature by absorbing and distributing heat – Maintaining normal pH using buffers; alkaline reserve of bicarbonate ions – Maintaining adequate fluid volume in circulatory system Protection functions include: – Preventing blood loss Plasma proteins and platelets in blood initiate clot formation – Preventing infection Agents of immunity are carried in blood – Antibodies – Complement proteins – White blood cells © 2016 Pearson Education, Ltd.  17.2 Composition of Blood Blood is the only fluid tissue in body Type of connective tissue – Matrix is nonliving fluid called plasma – Cells are living blood cells called formed elements Cells are suspended in plasma Formed elements – Erythrocytes (red blood cells, or RBCs) – Leukocytes (white blood cells, or WBCs) – Platelets Spun tube of blood yields three layers: – Erythrocytes on bottom (~45% of whole blood) Hematocrit: percent of blood volume that is RBCs – WBCs and platelets in Buffy coat (< 1%) Thin, whitish layer between RBCs and plasma layers – Plasma on top (~55%) © 2016 Pearson Education, Ltd.  Blood Figure 10.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 10.1b  Physical Characteristics and Volume Blood is a sticky, opaque fluid with metallic taste Color varies with O2 content – High O2 levels show a scarlet red – Low O2 levels show a dark red pH 7.35–7.45 Makes up ~8% of body weight Average volume: Males: 5–6 L; Females: 4–5 L Blood plasma is straw-colored sticky fluid – About 90% water Over 100 dissolved solutes – Nutrients, gases, hormones, wastes, proteins, inorganic ions – Plasma proteins are most abundant solutes Albumin: makes up 60% of plasma proteins – Functions as carrier of other molecules, as blood buffer, and contributes to plasma osmotic pressure © 2016 Pearson Education, Ltd.  Formed Elements Formed elements are RBCs, WBCs, Leukocytes and platelets Only WBCs are complete cells Erythrocytes – RBCs have no nuclei or other organelles Platelets – Platelets are cell fragments Most formed elements survive in SEM of blood (1800×, artificially colored) bloodstream only few days Most blood cells originate in bone Erythrocytes Platelets marrow and do not divide Neutrophil Eosinophil Monocyte Lymphocyte Photomicrograph of a human blood smear, Wright’s stain (610×) © 2016 Pearson Education, Ltd.  17.3 Erythrocytes Structural Characteristics Erythrocytes are small-diameter (7.5 µm) cells that contribute to gas transport Cell has biconcave disc shape, is anucleate, and essentially has no organelles Filled with hemoglobin (Hb) for gas transport Superb example of complementarity of structure and function Three features make for efficient gas transport: – Biconcave shape offers huge surface area relative to volume for gas exchange – Hemoglobin makes up 97% of cell volume (not counting water) – RBCs have no mitochondria ATP production is anaerobic, so they do not consume O2 they transport © 2016 Pearson Education, Ltd.  Function of Erythrocytes RBCs are dedicated to respiratory gas transport Hemoglobin binds reversibly with oxygen Normal values: Males 13–18g/100ml; Females: 12–16 g/100ml Hemoglobin consists of red heme pigment bound to the protein globin – Globin is composed of four polypeptide chains Two alpha and two beta chains – A heme pigment is bonded to each globin chain Gives blood red color Each heme’s central iron atom binds one O2 © 2016 Pearson Education, Ltd.  Function of Erythrocytes (cont.) Each Hb molecule can transport four O2 Each RBC contains 250 million Hb molecules O2 loading in lungs – Produces oxyhemoglobin (ruby red) O2 unloading in tissues – Produces deoxyhemoglobin, or reduced hemoglobin (dark red) CO2 loading in tissues – 20% of CO2 in blood binds to Hb, producing carbaminohemoglobin © 2016 Pearson Education, Ltd.  Regulation and Requirements of Erythropoiesis Erythropoiesis: process of formation of RBCs that takes about 15 days Too few RBCs lead to tissue hypoxia Too many RBCs increase blood viscosity > 2 million RBCs are made per second Balance between RBC production and destruction depends on: – Hormonal controls – Dietary requirements © 2016 Pearson Education, Ltd.  Regulation and Requirements of Erythropoiesis (cont.) Hormonal control – Erythropoietin (EPO): hormone that stimulates formation of RBCs Always small amount of EPO in blood to maintain basal rate Released by kidneys (some from liver) in response to hypoxia – Decreased RBC numbers due to hemorrhage or increased destruction – Insufficient hemoglobin per RBC (example: iron deficiency) – Reduced availability of O2 (example: high altitudes or lung problems such as pneumonia) © 2016 Pearson Education, Ltd. Figure 17.6 Erythropoietin mechanism for regulating erythropoiesis. Slide 1 Homeostasis: Normal blood oxygen levels 1 Stimulus: Hypoxia (inadequate 5 O2-carrying O2 delivery) due to ability of blood Decreased rises. RBC count Decreased amount of hemoglobin Decreased availability of O2 4 Enhanced erythropoiesis 2 Kidney (and liver to increases RBC count. a smaller extent) releases 3 Erythropoietin erythropoietin. stimulates red bone marrow. © 2016 Pearson Education, Ltd.  Clinical – Homeostatic Imbalance 17.1 Some athletes abuse artificial EPO – Use of EPO increases hematocrit, which allows athlete to increase stamina and performance Dangerous consequences: – EPO can increase hematocrit from 45% up to even 65%, with dehydration concentrating blood even more – Blood becomes like sludge and can cause clotting, stroke, or heart failure © 2016 Pearson Education, Ltd.  17.4 Leukocytes General Structure and Functional Characteristics Leukocytes, or WBCs, are only formed element that is complete cell with nuclei and organelles Function in defense against disease Leukocytosis: WBC count over 11,000 per µl – Increase is a normal response to infection Leukocytes grouped into two major categories: – Granulocytes: contain visible cytoplasmic granules – Agranulocytes: do not contain visible cytoplasmic granules; two types © 2016 Pearson Education, Ltd. Figure 17.9 Types and relative percentages of leukocytes in normal blood. Differential WBC count (All total 4800– Formed 10,800/µl) elements (not drawn to scale) Platelets Granulocytes Neutrophils (50–70%) Leukocytes Eosinophils (2–4%) Basophils (0.5–1%) Erythrocytes Agranulocytes Lymphocytes (25–45%) Monocytes (3–8%) © 2016 Pearson Education, Ltd.  Granulocytes Granulocytes: three types – Neutrophils, eosinophils, basophils Larger and shorter-lived than RBCs Contain lobed, rather than circular, nuclei © 2016 Pearson Education, Ltd. Table 17.2-1 Summary of Formed Elements of the Blood © 2016 Pearson Education, Ltd. Table 17.2-2 Summary of Formed Elements of the Blood (continued) © 2016 Pearson Education, Ltd.  17.1 Blood Functions – Internal ofTransport Blood System Learning Objectives: Blood Define hemostasis and describe its three major steps (i.e., vascular spasm, platelet plug formation, and coagulation). List the cell surface antigens and corresponding antibodies for each ABO blood type. Apply your understanding of cell surface antigens and plasma antibodies to predict which blood types are compatible for transfusion, and which blood types can serve as universal donors or universal recipients © 2016 Pearson Education, Ltd.  17.6 Hemostasis Hemostasis: fast series of reactions for stoppage of bleeding Requires clotting factors and substances released by platelets and injured tissues Three steps involved Step 1: Vascular spasm Step 2: Platelet plug formation Step 3: Coagulation (blood clotting) Positive feedback cycle: as more platelets stick, they release more chemicals, which cause more platelets to stick and release more chemicals © 2016 Pearson Education, Ltd. Figure 17.13 Events of hemostasis. Slide 1 1 Vascular spasm Smooth muscle contracts, causing vasoconstriction. 2 Platelet plug formation Injury to lining of vessel Collagen exposes collagen fibers; fibers platelets adhere. Platelets release chemicals that make nearby platelets sticky; platelet plug forms. Platelets 3 Coagulation Fibrin forms a mesh that traps red blood cells and platelets, forming the clot. Fibrin © 2016 Pearson Education, Ltd.  17.7 Blood Transfusions Cardiovascular system minimizes effects of blood loss by: 1. reducing volume of affected blood vessels 2. stepping up production of RBCs Body can compensate for only so much blood loss Loss of 15–30% causes pallor and weakness Loss of more than 30% results in potentially fatal severe shock – Whole-blood transfusions are used only when blood loss is rapid and substantial – Infusions of packed red blood cells, or PRBCs (plasma and WBCs removed), are preferred to restore oxygen-carrying capacity – Human blood groups of donated blood must be determined because transfusion reactions can be fatal – Blood typing determines groups © 2016 Pearson Education, Ltd.  Blood Typing (cont.) Human blood groups – Everyone has an ABO blood type (A, B, AB, or O) and an Rh factor (positive or negative). – Just like eye or hair color, our blood type is inherited from our parents. – Each biological parent donates one of two ABO genes to their child. The A and B genes are dominant and the O gene is recessive. For example, if an O gene is paired with an A gene, the blood type will be A.. – Mismatched transfused blood is perceived as foreign and may be agglutinated and destroyed Potentially fatal reaction Antigens of ABO and Rh blood groups cause most vigorous transfusion reactions; therefore, they are major groups typed © 2016 Pearson Education, Ltd.  Transfusing Red Blood Cells (cont.) – ABO blood groups – RBC membranes bear different many antigens RBC antigens are referred to as agglutinogens because they promote agglutination Based on presence or absence of two agglutinogens (antigens) (A and B) on surface of RBCs – Type A has only A agglutinogen – Type B has only B agglutinogen – Type AB has both A and B agglutinogens – Type O has neither A nor B agglutinogens Blood may contain preformed anti-A or anti-B antibodies (agglutinins) – Act against transfused RBCs with ABO antigens not present on recipient's RBCs © 2016 Pearson Education, Ltd. Table 17.4 ABO Blood Groups © 2016 Pearson Education, Ltd.  Transfusing Red Blood Cells (cont.) Transfusion reactions – Occur if mismatched blood is infused – Donor’s cells are attacked by recipient’s plasma agglutinins Agglutinate and clog small vessels Rupture and release hemoglobin into bloodstream – Result in: Diminished oxygen-carrying capacity Decreased blood flow beyond blocked vessel Hemoglobin in kidney tubules can lead to renal failure – Type O universal donor: no A or B antigens – Type AB universal recipient: no anti-A or anti-B antibodies – A patient can only receive blood from a person who has the same antigens on their red blood cells or no antigens on their red blood cells. © 2016 Pearson Education, Ltd.  Activity 1: BLOOD TYPING (ABO) intro Fundamentals of anatomy and physiology 9th ed Activity : BLOOD TYPING Question: A patient who is blood type O needs a blood transfusion. This patient can receive blood from a person whose blood type is/are: a. AB and O b. O and A c. only O d. only AB  Transfusing Red Blood Cells (cont.) – Rh blood groups 52 named Rh agglutinogens (Rh factors) C, D, and E are most common Rh+ indicates presence of D antigen Anti-Rh antibodies are not spontaneously formed in Rh– individuals – Anti-Rh antibodies form if Rh– individual receives Rh+ blood, or Rh– mom is carrying Rh+ fetus Second exposure to Rh+ blood will result in typical transfusion reaction © 2016 Pearson Education, Ltd.  Clinical – Homeostatic Imbalance 17.3 Hemolytic disease of newborn, also called erythroblastosis fetalis only occurs in Rh– mom with Rh+ fetus First pregnancy: Rh– mom exposed to Rh+ blood of fetus during delivery; first baby born healthy, but mother synthesizes anti-Rh antibodies Second pregnancy: Mom’s anti-Rh antibodies cross placenta and destroy RBCs of Rh+ baby Baby treated with prebirth transfusions and exchange transfusions after birth RhoGAM serum containing anti-Rh can prevent Rh– mother from becoming sensitized © 2016 Pearson Education, Ltd.  17.8 Diagnostic Blood Tests Examination of blood can yield information on persons health: – Low hematocrit seen in cases of anemia – Blood glucose tests check for diabetes – Leukocytosis can signal infection Microscopic examination of blood can reveal any variations in size or shape of RBCs – Abnormal size, shape, or color could indicate anemia © 2016 Pearson Education, Ltd.