Anatomy and Physiology
Anatomy and Physiology BIOH 113 - 01
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BIOH 112 - 01
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This 5 page Bundle was uploaded by Meaghan Raw on Tuesday February 23, 2016. The Bundle belongs to BIOH 113 - 01 at University of Montana taught by Heather Dawn Labbe (P) in Spring 2016. Since its upload, it has received 32 views. For similar materials see Human Form and Function II in Biological Sciences at University of Montana.
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Date Created: 02/23/16
BIOH 113 Chapter 18 February 18 to February 23 Blood Blood is composed of Connective Tissue (CT) Its function is to regulation, distribution, and protect o 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 o 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 o Protection Blood prevents blood loss by: Activating plasma proteins and platelets Initiating clot formation when a vessel is broken Blood prevents infection by: o Synthesizing and utilizing antibodies o Activating complement proteins o Activating WBCs to defend the body against foreign invaders Blood Circulation o Blood leaves the heart through arteries and into capillaries o Oxygen (O2) and nutrients diffuse across capillary walls and enter tissues o Carbon dioxide (CO2) and wastes move from tissues into the blood o Oxygen-deficient blood leaves the capillaries and flows in veins to the heart o This blood flows to the lungs where it releases CO2 and picks up O2 o The oxygen-rich blood returns to the heart Characteristics o Blood is a sticky, opaque fluid with a metallic taste o Color varies from scarlet (oxygen-rich) to dark red (oxygen-poor) o The pH of blood is 7.35–7.45 o Temperature is 38 degrees Celsius, which is slightly higher than “normal” body temperature o Blood accounts for approximately 8% of body weight o Average volume of blood is 5–6 L for males, and 4–5 L for females Composition of Blood o Blood is the body’s only fluid connective tissue o It is composed of liquid plasma and formed elements o Formed elements include: Erythrocytes, or red blood cells (RBCs) Leukocytes, or white blood cells (WBCs) Platelets o Hematocrit: the percentage of RBC’s out of the total blood volumes Blood Plasma o Blood plasma contains over 100 solutes, including: Proteins – albumin, globulins, clotting proteins (fibrinogens), 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 o Erythrocytes, leukocytes, and platelets make up the formed elements o Only WBCs are complete cells o RBCs have no nuclei or organelles, and platelets are just cell fragments o Most formed elements survive in the bloodstream for only a few days o Most blood cells do not divide but are renewed by cells in bone marrow Erythrocytes o Biconcave discs, anucleate, essentially no organelles o Filled with hemoglobin (Hb), a protein that functions in gas transport o Contain the plasma membrane protein spectrin and other proteins that: Give erythrocytes their flexibility Allow them to change shape as necessary o Erythrocytes are an example of the complementarity of structure and function o Structural characteristics contribute to its gas transport function o Biconcave shape that has a huge surface area relative to volume o Discounting water content, erythrocytes are more than 97% hemoglobin ATP is generated anaerobically, so the erythrocytes do not consume the oxygen they transport Erythrocyte Function o Erythrocytes are dedicated to respiratory gas transport o Hemoglobin reversibly binds with oxygen and most oxygen in the blood is bound to hemoglobin o Hemoglobin is composed of the protein globin, made up of two alpha and two beta chains, each bound to a heme group o Each heme group bears an atom of iron, which can bind to one oxygen molecule o Each hemoglobin molecule can transport four molecules of oxygen Hemoglobin o Oxyhemoglobin – hemoglobin bound to oxygen o Oxygen loading takes place in the lungs o Deoxyhemoglobin – hemoglobin after oxygen diffuses into tissues (reduced Hb) o Carbaminohemoglobin – hemoglobin bound to carbon dioxide o Carbon dioxide loading takes place in the tissues Hematopoiesis o Hematopoiesis – blood cell formation o Hematopoiesis occurs in the red bone marrow of the: o Axial skeleton and girdles o Epiphyses of the humerus and femur o “Pluripotent” stem cells give rise to all formed elements o Erythropoiesis – red blood cell formation o Polycythemia – abnormally high hematocrit o Anemia – abnormally low hematocrit o Leukopoiesis – white blood cell formation o Leukocytosis – abnormally high WBC count o Leukopenia – abnormally low WBC count o Thrombopoiesis – formation of platelets o Thrombocytosis – abnormally high platelet count o Thrombocytopenia – abnormally low platelet count Regulation and Requirements for Erythropoiesis o Circulating erythrocytes – the number remains constant and reflects a balance between RBC production and destruction o Too few red blood cells leads to tissue hypoxia o Too many red blood cells causes undesirable blood viscosity o Erythropoiesis is hormonally controlled and depends on adequate supplies of iron, amino acids, and B vitamins Hormonal Control of Erythropoiesis Erythropoietin (EPO) release by the kidneys is triggered by: o Hypoxia due to decreased RBCs o Decreased oxygen availability o Increased tissue demand for oxygen Enhanced erythropoiesis increases the: o RBC count in circulating blood o Oxygen carrying ability of the blood Fate and Destruction of Red Blood Cells o live 100-120 days because they dont have a nucleus which means they cant do what a normal cell needs to do in order to survive o cells get stuck in the spllen because of its structure "graveyard" this is a good place because other cells there are able to break down the cells and reuse what can be reused Erythrocyte Disorders o Anemia – blood has abnormally low oxygen-carrying capacity It is a symptom rather than a disease itself Blood oxygen levels cannot support normal metabolism Signs/symptoms include fatigue, paleness, shortness of breath, and chills Can be due to low hematocrit, low Hb, abnormal Hb o Polycythemia – excess RBCs that increase blood viscosity Can be pathologic both if natural causes or “induced” Leukocytes (WBCs) o Leukocytes, the only blood components that are complete cells: o Are less numerous than RBCs o Make up 1% of the total blood volume o Can leave capillaries via diapedesis o Move through tissue spaces o Granulocytes Neutrophils – 60-70% - phagocytize bacteria Eosinophils – 2-4% - kill worms, destroy antigen antibody complexes Basophils – .5-1% - initiate inflammation, contain heparin and histamine 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 o Agranulocytes Lymphocytes – 20-25% - mount immune response Monocytes – 3-8% - phagocytosis, develop into macrophages Agranulocytes – lymphocytes and monocytes: Lack visible cytoplasmic granules Are similar structurally, but are functionally distinct and unrelated cell types Have spherical (lymphocytes) or kidney-shaped (monocytes) nuclei o Leukopoiesis Stem cells 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 o Leukocyte Disorders Leukemia refers to cancerous conditions involving white blood cells 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 o Platelets (Thrombocytes) Platelets are fragments of megakaryocytes with a blue staining outer region and a purple granular center Their granules contain chemicals necessary for clotting to occur Platelets function in the clotting mechanism by forming a temporary plug that helps seal breaks in blood vessels Platelets not involved in clotting are kept inactive by other chemicals including Nitric Oxide (NO) o 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) o Coagulation A set of reactions in which blood is transformed from a liquid to a gel Coagulation follows intrinsic and extrinsic pathways which use clotting factors (enzymes and chemicals) The final three steps of this series of reactions are: 1. Prothrombinase is formed 2. Prothrombin is converted into thrombin 3.Thrombin catalyzes the joining of fibrinogen into a fibrin mesh o Human 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 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) Rh Blood Groups 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
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