Blood power point 2022-1 (1).pptx

UNIVERSITY OF BELIZE COURSE CODE – ALHL2021 CARDIOVASCULAR SYSTEM: BLOOD WEEK FACULTY OF HEALTH SCIENCES 3 PATRICIA LOPEZ TIME FRAME (75 MINUTES) Copyright© 2020 University of Belize. All rights reserved Not to be reproduced or disseminated without permission from the University of Belize. O...

UNIVERSITY OF BELIZE COURSE CODE – ALHL2021 CARDIOVASCULAR SYSTEM: BLOOD WEEK FACULTY OF HEALTH SCIENCES 3 PATRICIA LOPEZ TIME FRAME (75 MINUTES) Copyright© 2020 University of Belize. All rights reserved Not to be reproduced or disseminated without permission from the University of Belize. Objectives • Describe general characteristics of blood • Describe components and functions of blood • Describe structure and function of RBC and WBC. • Describe process of hematopiesis and hemostasis • Describe the ABO and Rh blood groups and explain the basis of transfusion reactions Overview of blood circulation • Blood leaves the heart via arteries that branch repeatedly until they become capillaries • Oxygen (O2) and nutrients diffuse across capillary walls and enter tissues • Carbon dioxide (CO2) and wastes move from tissues into the blood Overview of blood • Oxygen-deficient blood leaves the capillaries and flows in veins to the heart • This blood flows to the lungs where it releases CO2 and picks up O2 • The oxygen-rich blood returns to the heart Composition of blood • Blood is the body’s only fluid tissue • It is composed of liquid plasma and formed elements • Formed elements include: – Erythrocytes, or red blood cells (RBCs) – Leukocytes, or white blood cells (WBCs) – Platelets • Hematocrit – the percentage of RBCs out of the total blood volume Components of whole blood Plasma (55% of whole blood) Buffy coat Erythrocytes (hematocrit) Physical characteristics of blood • Blood is a sticky, opaque fluid with a metallic taste • Color varies from scarlet (oxygen-rich) to dark red (oxygen-poor) • The pH of blood is 7.35–7.45 • Temperature is 38°C, slightly higher than “normal” body temperature • Blood accounts for approximately 8% of body weight • Average volume of blood is 5–6 L for males, and 4–5 L for females Functions of blood • Blood performs a number of functions dealing with: – Substance distribution – Regulation of blood levels of particular substances – Body protection Distribution • Blood transports: – Oxygen from the lungs and nutrients from the digestive tract – Metabolic wastes from cells to the lungs and kidneys for elimination – Hormones from endocrine glands to target organs Regulation • Blood maintains: – Appropriate body temperature by absorbing and distributing heat – Normal pH in body tissues using buffer systems – Adequate fluid volume in the circulatory system Protection • Blood prevents blood loss by: – Activating plasma proteins and platelets – Initiating clot formation when a vessel is broken • Blood prevents infection by: – Synthesizing and utilizing antibodies – Activating complement proteins – Activating WBCs to defend the body against foreign invaders Let’s Review • Describe the functions of blood by including specific examples under each function. Blood functions Protection Distribution of substances Regulation Blood plasma • Blood plasma contains over 100 solutes, including: – Proteins – albumin, globulins, clotting proteins, and others – Nonprotein nitrogenous substances – lactic acid, urea, creatinine – Organic nutrients – glucose, carbohydrates, amino acids – Electrolytes – sodium, potassium, calcium, chloride, bicarbonate – Respiratory gases – oxygen and carbon dioxide Formed elements • Erythrocytes, leukocytes, and platelets make up the formed elements – Only WBCs are complete cells – RBCs have no nuclei or organelles, and platelets are just cell fragments • Most formed elements survive in the bloodstream for only a few days • Most blood cells do not divide but are renewed by cells in bone marrow Erythrocytes • Biconcave discs, anucleate, essentially no organelles • Filled with hemoglobin (Hb), a protein that functions in gas transport • Contain the plasma membrane protein spectrin and other proteins that: – Give erythrocytes their flexibility – Allow them to change shape as necessary RBC RBC • Erythrocytes are an example of the complementarity of structure and function • Structural characteristics contribute to its gas transport function – Biconcave shape that has a huge surface area relative to volume – Discounting water content, erythrocytes are more than 97% hemoglobin – ATP is generated anaerobically, so the erythrocytes do not consume the oxygen they transport RBC function • Erythrocytes are dedicated to respiratory gas transport • Hemoglobin reversibly binds with oxygen and most oxygen in the blood is bound to hemoglobin • Hemoglobin is composed of the protein globin, made up of two alpha and two beta chains, each bound to a heme group • Each heme group bears an atom of iron, which can bind to one oxygen molecule • Each hemoglobin molecule can transport four molecules of oxygen Structure of hemoglobin Hemoglobin • Oxyhemoglobin – hemoglobin bound to oxygen – Oxygen loading takes place in the lungs • Deoxyhemoglobin – hemoglobin after oxygen diffuses into tissues (reduced Hb) • Carbaminohemoglobin – hemoglobin bound to carbon dioxide – Carbon dioxide loading takes place in the tissues Production of erythrocytes • Hematopoiesis – blood cell formation • Hematopoiesis occurs in the red bone marrow of the: – Axial skeleton and girdles – Epiphyses of the humerus and femur • Hemocytoblasts give rise to all formed elements Production of RBC • A hemocytoblast is transformed into a committed cell called the proerythroblast • Proerythroblasts develop into early erythroblasts • The developmental pathway consists of three phases – Phase 1 – ribosome synthesis in early erythroblasts – Phase 2 – hemoglobin accumulation in late erythroblasts and normoblasts – Phase 3 – ejection of the nucleus from normoblasts and formation of reticulocytes • Reticulocytes then become mature erythrocytes Production of RBC Hormonal control of erythropoiesis • Erythropoietin (EPO) release by the kidneys is triggered by: – Hypoxia due to decreased RBCs – Decreased oxygen availability – Increased tissue demand for oxygen • Enhanced erythropoiesis increases the: – RBC count in circulating blood – Oxygen carrying ability of the blood Dietary requirements of erythropoiesis • Erythropoiesis requires: – Proteins, lipids, and carbohydrates – Iron, vitamin B12, and folic acid • The body stores iron in Hb (65%), the liver, spleen, and bone marrow Fate and destruction of erythrocytes • The life span of an erythrocyte is 100–120 days • Old erythrocytes become rigid and fragile, and their hemoglobin begins to degenerate • Dying erythrocytes are engulfed by macrophages • Heme and globin are separated and the iron is salvaged for reuse Fate and destruction of erythrocytes • Heme is degraded to a yellow pigment called bilirubin • The liver secretes bilirubin into the intestines as bile • The intestines metabolize it into urobilinogen • This degraded pigment leaves the body in feces Leukocytes • Leukocytes, the only blood components that are complete cells: – Are less numerous than RBCs – Make up 1% of the total blood volume – Can leave capillaries via diapedesis – Move through tissue spaces • Leukocytosis – WBC count over 11,000 per cubic millimeter – Normal response to bacterial or viral invasion Granulocytes • Granulocytes – neutrophils, eosinophils, and basophils – Contain cytoplasmic granules that stain specifically (acidic, basic, or both) with Wright’s stain – Are larger and usually shorter-lived than RBCs – Have lobed nuclei – Are all phagocytic cells Neutrophils • Neutrophils have two types of granules that: – Take up both acidic and basic dyes – Give the cytoplasm a lilac color – Contain peroxidases, hydrolytic enzymes, and defensins (antibiotic-like proteins) • Neutrophils are our body’s bacteria slayers Eosinophils • Eosinophils account for 1–4% of WBCs – Have red-staining, bilobed nuclei connected via a broad band of nuclear material – Have red to crimson (acidophilic) large, coarse, lysosome-like granules – Lead the body’s counterattack against parasitic worms – Lessen the severity of allergies by phagocytizing immune complexes Basophils • Account for 0.5% of WBCs and: – Have U- or S-shaped nuclei with two or three conspicuous constrictions – Are functionally similar to mast cells – Have large, purplish-black (basophilic) granules that contain histamine • Histamine – inflammatory chemical that acts as a vasodilator and attracts other WBCs (antihistamines counter this effect) Agranulocytes • Agranulocytes – lymphocytes and monocytes: – Lack visible cytoplasmic granules – Are similar structurally, but are functionally distinct and unrelated cell types – Have spherical (lymphocytes) or kidneyshaped (monocytes) nuclei Lymphocytes • Account for 25% or more of WBCs and: – Have large, dark-purple, circular nuclei with a thin rim of blue cytoplasm – Are found mostly enmeshed in lymphoid tissue (some circulate in the blood) • There are two types of lymphocytes: T cells and B cells – T cells function in the immune response – B cells give rise to plasma cells, which produce antibodies Monocytes • Monocytes account for 4–8% of leukocytes – They are the largest leukocytes – They have abundant pale-blue cytoplasms – They have purple-staining, U- or kidneyshaped nuclei – They leave the circulation, enter tissue, and differentiate into macrophages Monocytes • Macrophages: – Are highly mobile and actively phagocytic – Activate lymphocytes to mount an immune response Summary of formed elements Summary of formed elements Formation of leukocytes • All leukocytes originate from hemocytoblasts • Hemocytoblasts differentiate into myeloid stem cells and lymphoid stem cells • Myeloid stem cells become myeloblasts or monoblasts • Lymphoid stem cells become lymphoblasts • Myeloblasts develop into eosinophils, neutrophils, and basophils • Monoblasts develop into monocytes • Lymphoblasts develop into lymphocytes Formation of leukocytes Leukocytes disorders • Leukemia refers to cancerous conditions involving white blood cells • Leukemias are named according to the abnormal white blood cells involved – Myelocytic leukemia – involves myeloblasts – Lymphocytic leukemia – involves lymphocytes • Acute leukemia involves blast-type cells and primarily affects children Leukemia • Immature white blood cells are found in the bloodstream in all leukemias • Bone marrow becomes totally occupied with cancerous leukocytes • The white blood cells produced, though numerous, are not functional • Death is caused by internal hemorrhage and overwhelming infections • Treatments include irradiation, antileukemic drugs, and bone marrow transplants Platelets • Platelets are fragments of megakaryocytes with a blue-staining outer region and a purple granular center • Their granules contain serotonin, Ca2+, enzymes, ADP, and platelet-derived growth factor (PDGF) • Platelets function in the clotting mechanism by forming a temporary plug that helps seal breaks in blood vessels Development of platelets Let’s review again! • • • • Where are elements of blood made? What is the role of RBC’s? Name the 2 categories of WBC’s. What is the role of neutrophils? Lymphocytes? • What is the function of platelets? Hemostasis • A series of reactions designed for stoppage of bleeding • During hemostasis, three phases occur in rapid sequence – Vascular spasms – immediate vasoconstriction in response to injury – Platelet plug formation – Coagulation (blood clotting) Platelet plug formation • Platelets do not stick to each other or to the endothelial lining of blood vessels • Upon damage to blood vessel endothelium (which exposes collagen) platelets: – With the help of von Willebrand factor (VWF) adhere to collagen – Are stimulated by thromboxane A2 – Stick to exposed collagen fibers and form a platelet plug – Release serotonin and ADP, which attract still more platelets • The platelet plug is limited to the immediate area of injury by PGI2 Coagulation • A set of reactions in which blood is transformed from a liquid to a gel • Coagulation follows intrinsic and extrinsic pathways • The final three steps of this series of reactions are: – Prothrombin activator is formed – Prothrombin is converted into thrombin – Thrombin catalyzes the joining of fibrinogen into a fibrin mesh Coagulation Detail events of coagulation Hemostasis disorders • Thrombus – a clot that develops and persists in an unbroken blood vessel – Thrombi can block circulation, resulting in tissue death – Coronary thrombosis – thrombus in blood vessel of the heart Hemostasis disorders • Embolus – a thrombus freely floating in the blood stream – Pulmonary emboli can impair the ability of the body to obtain oxygen – Cerebral emboli can cause strokes Prevention of undesirable clot • Substances used to prevent undesirable clots include: – Aspirin – an antiprostaglandin that inhibits thromboxane A2 – Heparin – an anticoagulant used clinically for pre- and postoperative cardiac care – Warfarin – used for those prone to atrial fibrillation Blood transfusion • Whole blood transfusions are used: – When blood loss is substantial – In treating thrombocytopenia • Packed red cells (cells with plasma removed) are used to treat anemia Human blood group • RBC membranes have glycoprotein antigens on their external surfaces • These antigens are: – Unique to the individual – Recognized as foreign if transfused into another individual – Promoters of agglutination and are referred to as agglutinogens • Presence or absence of these antigens is used to classify blood groups Blood groups • Humans have 30 varieties of naturally occurring RBC antigens • The antigens of the ABO and Rh blood groups cause vigorous transfusion reactions when they are improperly transfused • Other blood groups (M, N, Dufy, Kell, and Lewis) are mainly used for legalities ABO blood group • The ABO blood groups consists of: – Two antigens (A and B) on the surface of the RBCs – Two antibodies in the plasma (anti-A and anti-B) • An individual with ABO blood may have various types of antigens and spontaneously preformed antibodies • Agglutinogens and their corresponding antibodies cannot be mixed without serious hemolytic reactions ABO Blood Group Rh Blood Group • There are eight different Rh agglutinogens, three of which (C, D, and E) are common • Presence of the Rh agglutinogens on RBCs is indicated as Rh+ • Anti-Rh antibodies are not spontaneously formed in Rh– individuals • However, if an Rh– individual receives Rh+ blood, anti-Rh antibodies form • A second exposure to Rh+ blood will result in a typical transfusion reaction Hemolytic disease of newborn • Hemolytic disease of the newborn – Rh+ antibodies of a sensitized Rh– mother cross the placenta and attack and destroy the RBCs of an Rh+ baby • Rh– mother becomes sensitized when Rh+ blood (from a previous pregnancy of an Rh+ baby or a Rh+ transfusion) causes her body to synthesis Rh+ antibodies • The drug RhoGAM can prevent the Rh– mother from becoming sensitized • Treatment of hemolytic disease of the newborn involves pre-birth transfusions and exchange transfusions after birth Transfusion reaction • Transfusion reactions occur when mismatched blood is infused • Donor’s cells are attacked by the recipient’s plasma agglutinins causing: – Diminished oxygen-carrying capacity – Clumped cells that impede blood flow – Ruptured RBCs that release free hemoglobin into the bloodstream • Circulating hemoglobin precipitates in the kidneys and causes renal failure Blood typing • When serum containing anti-A or anti-B agglutinins is added to blood, agglutination will occur between the agglutinin and the corresponding agglutinogens • Positive reactions indicate agglutination Blood typing Blood type being tested RBC agglutinogens Serum Reaction Anti-A Anti-B AB A and B + + B B – + A A + – O None – – References • Marieb, E. N., & Hoehn, K. (2013). Human Anatomy and Physiology ( 9th ed.). San Francisco, CA: Benjamin Cummings. The End Recorded Lecture Policy: Students who are unable to attend virtual classes or consultation sessions have the right to download and view recorded lectures and consultation sessions for their personal study only. Lectures recorded for this purpose may not be shared with other people without the consent of the instructor. The recorded lectures may not be published without the express consent of the instructor and without giving proper identity and credit to the instructor. Students who use screen-recording softwares are required to adhere to the recording guidelines stated above. Copyright© 2020 University of Belize. All rights reserved Not to be reproduced or disseminated without permission from the University of Belize.