Chapter 19: Blood PDF

Chapter 19: Blood Jessy Abraham ▪ Cardiovascular system consists of A pump (the heart) Series of conducting hoses (blood vessels) Fluid connective tissue (blood) 3 ▪ Blood  Specialized connective tissue  Contains cells s...

Chapter 19: Blood Jessy Abraham ▪ Cardiovascular system consists of A pump (the heart) Series of conducting hoses (blood vessels) Fluid connective tissue (blood) 3 ▪ Blood  Specialized connective tissue  Contains cells suspended in a fluid matrix ▪ Functions of blood  Transporting dissolved gases, nutrients, hormones, and metabolic wastes  Regulating pH, ion composition of interstitial fluids  Restricting fluid losses at injury sites  Defending against toxins and pathogens  Stabilizing body temperature 4 ▪ Characteristics of blood 38ºC (100.4ºF) High viscosity Slightly alkaline (pH of 7.35– 7.45) ▪ Blood volume (liters) = 7 percent of body weight (kilograms) A 75-kg (165-lb) person would have approximately 5.25 liters (1.38 gallons ) of blood 5 ▪ Fractionation Process of separating whole blood into plasma and formed elements ▪ Whole blood Plasma Fluid Formed elements Cells and cell fragments ▪ Formed elements Red blood cells ( erythrocytes) White blood cells –in buffy coat Cell fragments (platelets)- in buffy coat 6 WBC Cells Never Let Monkey Eats Banana Neutrophils, Lymphocytes, Monocytes, Eosinophils and Basophils ▪ Plasma Makes up about 55 percent of blood volume More than 90 percent of plasma is water Also contains dissolved plasma proteins and other solutes Similar in composition to interstitial fluid Because water, ions, and small solutes are exchanged across capillary walls 8 ▪ Plasma proteins  Albumins (60 percent) Major contributors to plasma osmolarity Transport fatty acids, thyroid hormones, some steroid hormones, etc.  Globulins (35 percent) Antibodies Transport globulins including hormone-binding proteins, lipoproteins, and steroid- binding proteins 9 ▪ Plasma proteins Fibrinogen (4 percent) Soluble protein that functions in clotting Converted to insoluble fibrin Conversion of fibrinogen to fibrin leaves serum (fluid) in blood sample Other plasma proteins (1 percent) Varying concentrations of enzymes and hormones Plasma and serum are both components of blood, but they differ in how they are obtained and what they contain. Serum is the liquid that remains after the blood has clotted. Plasma is the liquid that remains when clotting is prevented with the addition of an anticoagulant. 10 ▪ Origins of plasma proteins More than 90 percent made in liver Including all albumins, fibrinogen, most globulins, and various proenzymes Antibodies made by plasma cells Peptide hormones made by endocrine organs 11 ▪ Hemopoiesis Process of producing formed elements ▪ Formed elements Red blood cells White blood cells Cell fragments (platelets) 12 13 The Composition of Whole Blood 1 Red Blood Cells Red blood cells (RBCs), or erythrocytes (e-RITH-rō-sīts; erythros, red + -cyte, cell), are the most abundant blood cells. These specialized cells are essential for the transport of oxygen in the blood. 14 The Composition of Whole Blood 2 White Blood Cells White blood cells (WBCs), or leukocytes (LŪ-kō-sīts; leukos, white + -cyte, cell), play a role in the body’s defense mechanisms. There are five classes of leukocytes, each with Neutrophils Basophils slightly different functions that will be Lymphocytes explored later in the chapter. Eosinophils Monocytes 15 The Composition of Whole Blood 3 Platelets Platelets (PLĀT-lets) are small, membrane- bound cell fragments that contain enzymes and other substances important for clotting. ▪ Red blood cells (RBCs) Also called erythrocytes Make up 99.9 percent of formed elements Contain hemoglobin Red pigment that gives whole blood its color Binds and transports oxygen and carbon dioxide 16 ▪ Red blood cell count Number of RBCs per microliter of whole blood Adult male: 4.5–6.3 million Adult female: 4.2–5.5 million ▪ Hematocrit Packed cell volume (PCV) Percentage of formed elements in blood Adult male: 46 Adult female: 42 17 ▪ Structure of RBCs Small, highly specialized cells Biconcave discs Thin central region and thicker outer margin 18 ▪ Important effects of RBC structure on function  Large surface-area-to-volume ratio Quickly absorb and release oxygen  Form stacks called rouleaux /ru-loz/ Smooth blood flow through narrow blood vessels  Bend and flex when entering small capillaries 7.8-µm RBC can pass through a 4- µm capillary ▪ Mature RBCs  Anucleate (lack nuclei)  Lack mitochondria and ribosomes  Unable to divide, synthesize proteins, or repair damage  Live about 120 days 19 ▪ Hemoglobin (Hb or Hgb) Protein in RBCs that transports respiratory gases Normal hemoglobin Adult male: 14–18 g/dL( gram per deciliter) whole blood Adult female: 12–16 g/dL whole blood 20 ▪ Hemoglobin Complex quaternary structure Four globular protein subunits Two alpha (α) chains and two beta (β) chains Each with one molecule of heme ( 4) Each heme contains one iron ion Iron interacts with oxygen to form oxyhemoglobin, HbO2 Dissociate easily to form deoxyhemoglobin 21 ▪ Hemoglobin function  Each RBC contains about 280 million Hb molecules Each RBC can carry over a billion molecules of O2  In peripheral capillaries, where O 2 is low, hemoglobin Releases O2 Binds CO2, forming carbaminohemoglobin  At the lungs, where O2 is high, hemoglobin Binds O2 Releases CO2 ▪ Fetal hemoglobin  Form of hemoglobin in embryo or fetus  Binds oxygen more readily than does adult hemoglobin Takes up oxygen from maternal blood at placenta 22 ▪ Anemia Results when hematocrit or Hb content of RBCs is reduced Interferes with oxygen delivery to peripheral tissues ▪ RBC formation and turnover 1 percent of circulating RBCs are replaced per day About 3 million new RBCs enter bloodstream each second 23 ▪ Erythropoiesis Red blood cell formation In embryos, embryonic blood cells move from bloodstream to liver, spleen, thymus, bone marrow Differentiate into stem cells That divide to produce blood cells In adults, occurs only in myeloid tissue (red bone marrow) 24 ▪ Hemocytoblasts Also called hematopoietic stem cells (HSCs) Stem cells in myeloid tissue that divide to produce Myeloid stem cells Become RBCs and some WBCs Lymphoid stem cells Become lymphocytes 25 ▪ Hematologists (blood specialists) have identified several stages of RBC maturation: Myeloid stem cell Proerythroblast Erythroblast stages Reticulocyte Mature RBC 26 ▪ Erythropoietin (EPO) Hormone that stimulates erythropoiesis Secreted by kidneys and liver when oxygen in peripheral tissues is low (hypoxia) ▪ Blood doping A dangerous practice used by some athletes Re-infuse packed RBCs to elevate hematocrit ▪ Erythropoiesis requires amino acids, iron, folic acid, and vitamins B12 and B6 Lack of vitamin B12 leads to pernicious anemia 27 ▪ Hemoglobin recycling Macrophages of spleen, liver, and red bone marrow Engulf aged RBCs Remove Hb molecules from hemolyzed (ruptured) RBCs Break Hb into components Only the iron of each heme unit is recycled Hemoglobinuria Red or brown urine Due to abnormally high hemolysis in bloodstream Hematuria Whole RBCs in urine Due to kidney or blood vessel damage 28 ▪ Hemoglobin recycling cont.  Iron is removed from each heme unit, forming green biliverdin Converted to orange-yellow bilirubin  Bilirubin is excreted by liver in bile Jaundice is caused by buildup of bilirubin Converted by intestinal bacteria and oxygen to urobilins and stercobilins ▪ Iron recycling  Iron removed from heme Is bound and stored in phagocytic cell Or released into bloodstream  In bloodstream, iron is bound to transferrin Developing RBCs in red bone marrow absorb transferrins and use them to synthesize Hb Excess transferrins are removed in liver and spleen, storing iron in ferritin and hemosiderin 29  Events Occurring in the Red Bone Marrow 30 RBC formation Fe2+ transported in bloodstream by transferrin Average life span of RBC is 120 days New RBCs released into bloodstream In the bloodstream, the rupture of RBCs is called hemolysis. Hemoglobin that is not phagocytized breaks down, and the alpha and beta chains are eliminated in urine.  Events Occurring in Macrophages 31 Macrophages in spleen, liver, and red bone marrow Fe2+ Fe 2+ transported in bloodstream by transferrin Amino acids Heme Average life span of 90% RBC is 120 days Biliverdin Old and Bilirubin damaged 10% In the bloodstream, RBCs the rupture of RBCs is called hemolysis. Bilirubin bound to albumin in bloodstream Hemoglobin that is not phagocytized breaks down, and the alpha and beta chains are eliminated in urine.  Events Occurring in the Liver 33 Bilirubin bound Hemoglobin that is not to albumin in phagocytized breaks down, bloodstream and the alpha and beta chains are eliminated in urine. Liver Bilirubin Absorbed into the bloodstream Excreted in bile Large intestine Urobilins, Bilirubin stercobilins  Events Occurring in 34 Hemoglobin that is not the Kidney phagocytized breaks down, and the alpha and beta chains are eliminated in urine. Kidney Hb Absorbed into the bloodstream Urobilins Events Occurring in the Large Intestine Large intestine Urobilins, Bilirubin stercobilins Eliminated in urine Eliminated in feces Surface antigens  Substances on plasma membranes that identify cells to immune system  Normal cells are ignored and foreign cells are attacked ▪ Blood type  Determined by presence or absence of surface antigens on RBCs: A, B, and Rh (or D) ▪ Agglutinogens  Surface antigens on RBCs  Screened by immune system ▪ Agglutinins  Antibodies in plasma  Attack antigens on foreign RBCs Causing agglutination (clumping) of foreign cells 35 Blood Types ▪ Four blood types  Type A (surface antigen A)  Type B (surface antigen B)  Type AB (antigens A and B)  Type O (neither A nor B) ▪ Rh blood group  Based on presence or absence of Rh antigen  Rh positive (Rh+) Rh surface antigen is present (e.g., Type O+)  Rh negative (Rh–) Rh antigen is absent (e.g., Type O–) 36 Agglutinins (Antibodies in plasma) Type A blood Anti-B antibodies Type B blood Anti-A antibodies Type O blood Both anti-A and anti- B antibodies Type AB blood Neither anti-A nor anti-B antibodies Only sensitized Rh– blood has anti-Rh antibodies 38 ▪ Cross-reaction (transfusion reaction) May occur in a transfusion of blood or plasma from one person to another Occurs if donor and recipient blood types are not compatible Plasma antibody meets its specific surface antigen RBCs agglutinate and may hemolyze 39 ▪ Compatibility testing Performed in advance of transfusions Cross-match testing Reveals cross-reactions between donor’s RBCs and recipient’s plasma Type O– is the universal donor But cross-reactions can still occur Because at least 48 surface antigens exist besides A and B AB+ is the universal recipient Type O- and AB+ are universal blood groups 40 41 Blood Anti-A Anti-B Anti-Rh type A+ Clumping No clumping Clumping B+ No clumping Clumping Clumping AB+ Clumping Clumping Clumping O− No clumping No clumping No clumping  Hemolytic Disease of the Newborn 42 Rh− mother Rh+ fetus 1 During First Pregnancy Problems seldom develop during a first Maternal blood supply pregnancy, because and tissue very few fetal cells Rh− Rh− enter the maternal Rh− Rh− bloodstream then, and Placenta thus the mother’s Rh+ Rh+ immune system is not stimulated to produce Fetal blood supply anti-Rh antibodies. Rh+ and tissue Rh+ The most common form of hemolytic disease of the newborn develops after an Rh− woman has carried an Rh+ fetus. 45 4 White Blood Cells ▪ White blood cells (WBCs)  Also called leukocytes  Have nuclei and other organelles  Lack hemoglobin  WBC functions Defending body against pathogens Removing toxins and wastes Attacking abnormal or damaged cells ▪ Most WBCs are in  Connective tissue proper  Organs of lymphatic system ▪ A small fraction of WBCs circulates in blood  5000 to 10,000 per microliter 46 ▪ Characteristics of circulating WBCs  All can migrate out of bloodstream  All are capable of amoeboid movement  All are attracted to specific chemical stimuli Positive chemotaxis  Some are phagocytic ▪ Types of WBCs  Neutrophils  Eosinophils  Basophils  Monocytes  Lymphocytes Never Let Monkey Eat Banana 47 ▪ Neutrophils Also called polymorphonuclear leukocytes 50–70 percent of circulating WBCs Pale cytoplasmic granules containing Lysosomal enzymes Bactericidal (bacteria-killing) compounds 48 ▪ Neutrophils  Very active, phagocytic cells  Attack and digest bacteria  Degranulation Reduction in number of cytoplasmic granules Occurs when vesicle containing pathogen fuses with lysosomes containing enzymes and defensins  Release prostaglandins and leukotrienes  Live in bloodstream for 10 hours or less Dead neutrophils contribute to pus 49 ▪ Eosinophils (acidophils) 2–4 percent of circulating WBCs Engulf bacteria, protozoa, and cellular debris Attack large parasites by releasing toxic compounds Nitric oxide Cytotoxic enzymes Sensitive to allergens Release enzymes that reduce inflammation caused by mast cells and neutrophils 50 ▪ Basophils Less than 1 percent of circulating WBCs Cross capillary endothelium and accumulate in damaged tissues Release Histamine—dilates blood vessels Heparin—prevents blood clotting 51 ▪ Monocytes Large, spherical cells 2–8 percent of circulating WBCs Remain in bloodstream for 24 hours Then enter peripheral tissues to become macrophages Aggressive phagocytes that engulf large pathogens Release chemicals that attract other phagocytic cells and fibroblasts to injured area 52 ▪ Lymphocytes Slightly larger than RBCs 20–40 percent of circulating WBCs Continuously migrate in and out of bloodstream Mostly in organs of lymphatic system and connective tissues other than blood Part of body’s specific defense system 53 ▪ Three classes of lymphocytes T cells (T lymphocytes) Cell-mediated immunity Attack foreign cells or control other lymphocytes B cells (B lymphocytes) Humoral immunity Differentiate into plasma cells, which synthesize antibodies Natural killer (NK) cells Detect and destroy abnormal cells 54 ▪ Differential count of WBC population Can detect infection, inflammation, and allergic reactions ▪ WBC disorders Leukopenia Low WBC count Leukocytosis High WBC count Leukemia Cancer of WBCs indicated by extreme leukocytosis 55 ▪ Leukopoiesis WBC production Hemocytoblasts produce myeloid stem cells and lymphoid stem cells Myeloid stem cells Divide to produce progenitor cells Give rise to all formed elements except lymphocytes Lymphocytopoiesis Production of lymphocytes from lymphoid stem cells 56 ▪ WBC development Some lymphoid stem cells remain in red bone marrow Differentiate into B cells or natural killer cells Others migrate from red bone marrow to peripheral lymphatic tissues Thymus, spleen, and lymph nodes Produce lymphocytes T cells are produced in thymus 57 Platelets ▪ Platelets (thrombocytes) Cell fragments involved in clotting system Circulate for 9–12 days Removed by phagocytes, mainly in spleen 150,000 to 500,000 per microliter of blood One-third of platelets in body are stored in vascular organs like the spleen Mobilized during a circulatory crisis 58 ▪ Functions of platelets Release important clotting chemicals Temporarily patch damaged vessel walls Reduce size of break in vessel wall ▪ Thrombocytopoiesis Platelet production Occurs in red bone marrow ▪ Megakaryocytes Giant cells in red bone marrow Produce platelets by shedding membrane-enclosed packets of cytoplasm ▪ Hormonal control of platelet production Thrombopoietin (TPO) Interleukin-6 (IL-6) Multi-CSF 59 ▪ Hemostasis  Cessation of bleeding ▪ Hemopoiesis  Process of producing formed elements ▪ Thrombocytopoiesis  Platelet production ▪ Leukopoiesis  WBC production  Lymphocytopoiesis Production of lymphocytes from lymphoid stem cells ▪ Erythropoiesis  Red blood cell formation ▪ Hemostasis Cessation of bleeding Has three phases 1.Vascular phase 2.Platelet phase 3.Coagulation phase And 4.Clot retraction ▪ 1.Vascular phase A cut triggers vascular spasm Contraction of smooth muscle fibers of vessel wall Lasts about 30 minutes 61 ▪ Changes in endothelium during vascular phase Endothelial cells contract and expose basement membrane to bloodstream Endothelial cells release chemical factors and local hormones ADP, tissue factor, and prostacyclin Endothelins (peptide hormones) Cause smooth muscle contraction and cell division Endothelial plasma membranes become “sticky” Seal off tear and prevent blood flow 62  1 Vascular Phase The vascular phase of hemostasis lasts for 63 about 30 minutes after the injury occurs. The The Phases of Hemostasis endothelial cells contract and release (Vascular, Platelet, and endothelins, which stimulate smooth muscle Coagulation) and Clot contraction and endothelial division. The endothelial cells become “sticky” and Retraction adhere to platelets and each other. Knife blade Blood vessel injury Vascular spasm ▪ 2.Platelet phase Platelet adhesion Platelets attach to exposed surfaces Platelet aggregation Platelets stick to each other Begins within 15 seconds after injury Forms platelet plug that closes small breaks 65  2 Platelet Phase The platelet phase of hemostasis begins with the The Phases of Hemostasis 66 attachment of platelets to sticky endothelial surfaces, to the basement membrane, to exposed (Vascular, Platelet, and collagen fibers, and to each other. As they become Coagulation) and Clot activated, platelets release a variety of chemicals Retraction that promote aggregation, vascular spasm, clotting, and vessel repair. Release of chemicals (ADP, PDGF, Ca2+, clotting factors) Plasma in vessel lumen Platelet aggregation Platelet Endothelium adhesion to damaged vessel Basement membrane Vessel wall Platelet plug Contracted smooth may form muscle cells Interstitial Cut edge of fluid vessel wall ▪ 3.Coagulation phase (blood clotting)  Begins 30 seconds or more after injury  Depends on clotting factors  Ca2+ and 11 different proteins Highly regulated mechanism  Proenzymes (inactive enzymes) Converted to active enzymes that direct reactions in clotting response ▪ Coagulation phase  Involves chain reactions of three pathways A. Extrinsic pathway B. Intrinsic pathway C. Common pathway 67 ▪ A.Extrinsic pathway Damaged endothelial cells or peripheral tissues release Factor III (tissue factor) Enzyme complex activates Factor X ▪ B.Intrinsic pathway Begins with activation of proenzymes exposed to collagen fibers at injury site Enzyme complex activates Factor X ▪ C.Common pathway Begins with activation of Factor X Factor X activates prothrombin activator Converts prothrombin (proenzyme) to thrombin Thrombin converts fibrinogen to insoluble fibrin Producing a blood clot 69  3 Coagulation Phase Coagulation, or blood clotting, involves a complex sequence of steps leading to the The Phases of 70 conversion of circulating fibrinogen (a soluble protein) into fibrin (an insoluble protein). As the fibrin network grows, blood cells and additional platelets are trapped in the Hemostasis fibrous tangle, forming a blood clot that seals off the damaged portion of the vessel. (Vascular, Platelet, Extrinsic Pathway Common Pathway Intrinsic Pathway and Coagulation) Factor X and Clot Retraction Prothrombin Factor X Tissue factor activator activator complex complex Prothrombin Thrombin Factor Factors VII VIII and IX Fibrin Fibrinogen Ca 2+ Ca 2+ Platelet factor (PF-3) Factor III Activated Platelets proenzymes (usually Factor XII) Trapped Tissue RBC damage Fibrin network Blood clot containing SEM × 1300 Contracted smooth trapped RBCs muscle cells ▪ Calcium ions and vitamin K Essential to clotting process All three pathways require Ca2+ Vitamin K is required for synthesis of four clotting factors ▪ Bleeding and clotting extremes Thrombocytopenia- low platelets Hemophilia - an inherited bleeding disorder in which the blood does not clot properly. Thrombophilia- blood has an increased tendency to form clots. Deep vein thrombosis (DVT)-blood clot (thrombus) forms in one or more of the deep veins in the body, usually in the legs. 71 ▪ Clot retraction Pulls torn edges of vessel closer together Reduces residual bleeding Stabilizes injury site Reduces size of damaged area Making it easier for fibroblasts, smooth muscle cells, and endothelial cells to complete repairs 72  4 73 Clot Retraction The Phases of Hemostasis (Vascular, Once the fibrin Platelet, and meshwork has formed, Coagulation) and Clot platelets and red blood Retraction cells stick to the fibrin strands. The platelets then contract, and the entire clot begins to undergo clot retraction, a process that continues over 30–60 minutes. ▪ Fibrinolysis Gradual process of dissolving clot Thrombin and tissue plasminogen activator Activate plasminogen, producing plasmin Plasmin digests fibrin strands 74