Chapter 1 Physiology the science of biological function Homeostasis the maintenance of a constant internal environment despite external changes or changes caused by variation in biological activity within cells tissues and organs Homeostatic mechanisms can be executed while running The demand for oxygen increases which means carbon dioxide production increases as well High altitudes can result in long term homeostatic changes because there are lower oxygen levels The body has to produce more oxygen carrying red blood cells RBCs Research of physiology pays off for society as a whole to prevent and treat disease Chapter 2 Blood part of the circulatory system Delivers oxygen and nutrients transports wastes to be removed distributes heat Blood is a connective tissue because it connects cells throughout our body Heals wounds and fights infections Blood must remain a fluid to be able to circulate through our blood vessels Blood drawn from the body will coagulate and clot unless treated with an anticoagulant such as heparin Clotting is important for limiting blood loss from wounds A sample of blood treated by heparin can be spun in a centrifuge tube During centrifugation red blood cells collect at the bottom of the tube Hematocrit is the percent volume of RBCs at the bottom of the tube in a blood sample Hematocrit can vary person to person due to disease or environmental changes Red blood cells and white blood cells WBCs are two major cells in the blood Platelets smaller fragments of cells are also present in blood RBCs also called erythrocytes Specialized for transporting oxygen Have a biconcave shape This shape helps oxygen molecules move in and out of the RBC by creating less distance for the oxygen molecule to travel There is no nucleus in RBCs With no nucleus RBCs do not divide and reproduce Humans continually generate new RBCs A nucleus would deform a RBCs structure RBCs contain a lot of hemoglobin Hb Hb accounts for most of the protein in an RBC and is responsible for the red color when oxygen is bound Each molecule of hemoglobin contains four heme groups or polypeptide subunits Each group can bind one molecule of oxygen So every Hb can bind up to four molecules of oxygen Hemoglobin is not to be confused with myoglobin which is the oxygen binding protein abundant in our reddest muscles However Hb and myoglobin are closely related The Hill Equation a mathematical description of oxygen binding to Hb RBCs play a role in transporting carbon dioxide Carbon dioxide is transported from metabolizing tissues to the lungs to be exhaled Carbonic anhydrase an enzyme in RBCs essential for the transportation of carbon dioxide Carbonic anhydrase does not transport the carbon dioxide rather it is an enzyme so it catalyzes a reaction between a carbon dioxide molecule and a water molecule This reaction forms some carbonic acid molecules and some bicarbonate molecules These reactions are easily reversed Bicarbonate and carbonic acid are converted back to carbon dioxide and water and exhaled by the lungs Humans generate new RBCs through stem cells found in the red marrow of bone Erythropoiesis the process of forming new RBCs The production of RBCs is controlled by hormones specifically erythropoietin EPO which is produced in the kidneys At higher altitudes there is lower amounts of atmospheric oxygen So our bodies increase EPO production Maturation of a RBC takes one week The nucleus of a RBC is lost during this first week An individual RBC circulates in the blood for 3 4 months Sickle cell disease affects the shape of a RBC making it crescent shaped The disease is genetically inherited It is caused by a change in DNA sequence that alters an amino acid and in turn alters a hemoglobin structure This disease can shorten the lifetime of a RBC People also experience painful blood vessel blockage due to abnormal sickle shaped cells WBCs also called leukocytes Components of our immune system Do not contain hemoglobin therefore do not have a red color They do have a nucleus WBCs make up about 1 of our blood volume There are different types neutrophils eosinophils basophils lymphocytes and monocytes Don t need to memorize every white blood cell Stem cells in the red marrow of bone also differentiate into WBCs Hematopoiesis the process of formation of blood cells and platelets in bone marrow This process includes erythropoiesis mentioned above Platelets cell fragments or thrombocytes Smaller than RBCs and WBCs Do not have a nuclei At the site of a cut platelets are activated to form a seal The same stem cells that produce RBCs and WBCs can also produce platelets through a specialized pathway In this pathway megakaryocytes white blood cells produce many platelets Blood Plasma if a person s hematocrit is 40 then their blood plasma makes up 60 of their blood volume Water is the most abundant molecule in plasma Electrolytes are next which include sodium chloride potassium bicarbonate calcium magnesium Dissolved gases are also a part of plasma The kidneys maintain blood plasma homeostasis by removing wastes and maintaining electrolyte A variety of small molecules such as food molecules are transported in the blood For example and others and water levels sucrose Chemical signals hormones are carried through the blood as well Proteins are found in blood plasma Major proteins are albumin globulin fibrinogen lipoprotein LDL and HDL Lipids are transported in blood plasma Blood clotting involves both platelets and fibrinogen This is a process called coagulation Platelets form a plug this plug is strengthened by fibrin strands Hemophilia an individuals blood cannot clot quickly can cause excessive bruising or or blood loss Blood that clots when not needed is dangerous to the organs Antibodies proteins that help protect against infection they circulate in the blood plasma Antibodies are globulins The antibodies bind to viruses and signal to WBCs that they should be removed destroyed Vaccination trains the immune system to fight infectious organisms Blood is involved in transporting heat and regulating body temperature In colder conditions blood flow to the surface of the body is reduced in order to conserve heat In warmer conditions blood flow to the surface increases in order to lose more heat Cancer some cells multiply abnormally resulting in a tumor of cancerous cells Leukemia cancers involve unusual numbers of WBC activity These cells affect blood function Metastasis cancer cells from a tumor in the body travel
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