1 Chapter One Physiology is the science of biological function Function is closely related to structure Order of systems largest to smallest organ systems organs tissues cells human organism molecule atom Homeostasis is the maintenance of a constant internal environment despite external changes or changes caused by variation in biological activity within cells tissues and organs equilibrium conditions on inside of body change ex someone sprinting body adapts to increase blood supply and more oxygen will be supplied lactic acid is produced when body does not adapt no oxygen changes in external environment ex maintaining body temperature in cold environments Pathophysiology disease External causes of disease infection Internal causes of disease genetic mutations Understanding disease mechanisms also helps to develop a better understanding of normal physiological processes Changes in physiology associated with diseases genetic mutations infections environment factors Chapter Two Blood Blood is part of the circulatory system cardiovascular system Blood can be considered a type of connective tissue even though it is a fluid connects cells throughout the body as it continuously circulates within blood vessels 2 transports molecules such as oxygen glucose or carbon dioxide from one organ to another transports chemical signals such as hormones between cells within different regions of the body Cells are the basic units of life Diffusion is the mechanism for transport of respiratory gasses O2 and CO2 between blood plasma and the cytoplasm of RBCs Blood is a fluid in the body major component is water Blood will clot unless treated with an anticoagulant such as heparin Clotting is an initial step toward healing Blood has two major components cells most of which are red and plasma clear fluid in which the cells are suspended Hematocrit is the percentage of blood volume that is occupied by red blood cells RBCs usually 35 45 carrying O2 Cell types red blood cells RBCs white blood cells WBCs platelets cell fragments Plasma water electrolytes ions small molecules proteins chemical signals o hormones o some are proteins RBCs erythrocytes WBCs leukocytes o gasses O2 and CO2 o food molecules and metabolic wastes RBCs and WBCs are the two major classes of cells found in human blood 3 Platelets thrombocytes and cell fragments Hematocrit 45 for males 40 for females Red Blood Cells are specialized to transport Oxygen RBCs are the most numerous cells in the body have a distinct bi concave shape leads to short diffusion distance for O2 Spectrin is one of the main proteins in RBCs cytoskeleton that maintains its biconcave shape Diffusion is he net movement of molecules from regions of high concentration to regions of low concentration by the random motion of molecules colliding with other molecules There is no nucleus and thus no DNA in RBCs of humans and other mammals Absence of nucleus is significant for several reasons RBCs cannot divide and reproduce frees space within an RBC for more molecules of the oxygen binding protein hemoglobin Hb which increases the amount of oxygen it can carry RBCs contain substantial amounts of hemoglobin which accounts for most of the protein in an RBC Myoglobin binds 1 oxygen Hemoglobin binds 4 oxygen molecules binding 1 oxygen changes hemoglobin so it can bind more Each molecule of Hb is comprised of four nearly equivalent parts and each of these four parts is similar to one molecule of myoglobin each part consists of a protein portion and an iron containing heme group A heme group is an organized arrangement of carbon oxygen hydrogen and nitrogen atoms surrounding a single iron atom Hemoglobin Hb is the oxygen binding protein in RBCs Myoglobin is the oxygen binding protein in red muscles RBCs also participate in CO2 transport CO2 transport in blood dissolved in plasma band to Hb 4 Two proteins in RBCs that are involved in these transport functions Hemoglobin Hb Carbonic anhydrase Two gas molecules that transport RBCs O2 CO2 Enzymes are biological catalysts molecules that speed up chemical reactions Bicarbonate serves a second role in homeostasis as a pH buffer a molecule that minimizes changes in pH despite production such as lactic acid or use of protons Caron dioxide CO2 is transported in the blood primarily as carbonic acid H2CO3 and bicarbonate HCO3 Humans continuously generate new RBCs and other types of blood cells from stem cells located in the red marrow of bone Stem cells are not themselves specialized cells until they undergo the process of differentiation Erythropoiesis is the process of forming new RBCs hormone erythropoieitin EPO a glycoprotein hormone that is normally produced by the kidneys Cycle for RBC production 1 An individual RBC circulates in blood for only 3 4 months 2 New RBCs come from stem cells that divide replicate and specialize differentiate in RBCs a occurs in red marrow of bones b maturation takes about one week c RBC loses nucleus during maturation more room for Hb 3 Cells throughout body need O2 to make ATP energy 4 O2 transported in blood 5 Blood is 40 45 RBC p 16 for graph increasing the amount of EPO in the blood stimulates more stem cells in bone marrow to produce RBCs which normally increases hematocrit and O2 carrying capacity the shape of an RBC is normally determined by proteins of the cytoskeleton especially spectrin 5 Sickle cell disease is a genetically inherited disease It is caused by seemingly small change in DNA sequence that alters just one amino acid out of 140 amino acids in one of the polypeptides that assemble to form an HB molecule Individuals with sickle cell disease have Hb molecules in which to of the four polypeptides contain the altered amino acid Due to a mutation in Hb in change in shape of RBC White blood cells leukocytes are components of our immune system have a cell nucleus Several types of white blood cells created through differentiation 1 of blood volume Hematopoiesis hemopoiesis name for the process of formation of blood cells and platelets in bone marrow Platelets are cell fragments that are involved in clotting thrombocytes role in protection against blood loss produced from red marrow in bone as well thrombocytes produced from larger cells called megakaryocytes Plasma mostly water also many other types of ions and molecules ions that are either positively or negatively charged sodium Na chloride Cl and bicarbonate HCO2 contains dissolved gasses Oxygen and Carbon Dioxide Hormones are a chemically
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