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The circulatory system Chapter 23 Internal transport Compare the mammalian system to that of a fish Function and location of organs Trace blood flow through the body Study the heart beat and cardiac cycle Diseases Announcements Exam next Thursday Pick up unclaimed papers outside my office Update your portfolio See your advisor for help with Fall course selection Next weeks lab is on Circulation The Circulatory System Overview The circulatory system transports gases nutrients and wastes Different body designs demand a heart for pumping blood to the tissues because gravity opposes blood circulation Muscles contract around the blood vessels and work together with valves to pump blood to the heart Skin and connective tissue keep blood vessels from enlarging Capillaries and diffusion Fig 23 5 Capillaries and diffusion Fig 23 1B The circulation reaches all cells Diffusion is insufficient for moving substances over large distances Capillaries are the smallest vessels and reach all cells RBC s exchange materials with the interstitial fluid O2 and nutrients diffuse to the tissues and wastes and CO2 diffuse to the blood Homeostasis is maintained in the blood by the liver and kidney Types of internal transport Fig 23 2 Types of Internal transport Gastrovascular cavity Digestion and respiration occur in the same cavity Intricately branched system that allows water to bathe the entire system fluid moved by flagella Not good in animals with thick multiple layers of cells Types of internal transport Fig 23 2 What other system is here but not shown Types of Internal transport Open circulatory system Found in Arthropoda and Mollusca Blood pumped by hearts through open ended vessels no interstitial fluid Fluid is called hemolymph Contracts heart pumps blood out of the sinuses Relaxes heart draws hemolymph into the circulatory system Closed Circulatory System Fig 23 2 Types of Internal transport Closed circulatory system Blood is confined to vessels keeping it separate from the interstitial fluid Arteries carry blood away from the heart veins carry blood to the heart Fish Gills gill capillaries two chambered heart atrium ventricle Evolution of cardiovascular systems Fish vs mammal Fish have a single circuit of blood flow with the heart receiving and pumping oxygen poor blood flow Mammals have two circuits a four chambered heart two atria and two ventricles Pulmonary right side blood to lungs Systemic left side to the body Double system rapid delivery of oxygen to support high activity A trip through the cardiovascular system A trip through the cardiovascular system Heart is size of fist composed of cardiac muscle cells are electrically connected by intercalated disks Atria are thin walled and receive blood ventricles are thick walled and pump blood AV valves separate the atria and ventricles Semilunar valves separate the heart and the circulation pulmonary and systemic Valves maintain flow in one direction Learn the flow Structure and function of blood vessels Structure and function of blood vessels Capillaries supply cells thin walled single layer of epithelial cells and a basement membrane Promotes diffusion of material to and from the interstitial fluid Arteries pressure vessels that are thick walled contain smooth muscle and connective tissue Arteioles small vessels that control flow by changing diameter Veins capacitance vessels hold much blood more elastic than arteries contain valves to prevent backflow of blood Cardiac cycle Cardiac Cycle The heart passively fills with blood then actively contracts pumping out blood Diastole blood fills the heart while it is relaxed all the valves are open Systole atria contact and force blood to ventricles ventricles contract next forcing the AV valves closed and semilunar valves open blood is pumped to the body Lubb closing of AV valve Dubb closing of semilunar valve Cardiac output amount of blood leaving heart each beat 75 ml per beat Pacemaker Pacemaker and heartbeat SA node or pacemaker maintains the heartrate in the wall of the right atrium Generates electrical signals that travel to the atria then to the ventricles The AV node delays the signal allowing the ventricles to fill before they contract The heart is regulated autonomically just like the lungs A slight decrease in blood pH increased heartrate Heart Attack Heart Attack Death of cardiac cells resulting from lack of blood delivered to the heart Coronary artery blockage Dietary influences narrow arteries blood clots block the arteries Angina Corrective surgery Coronary bypass Balloon angioplasty Blood pressure and flow in arteries Pressure declines Velocity declines Flow reduced from Friction area increased Garden hose analogy Blood pressure and flow in arteries Blood pressure force that blood exerts against the walls of blood vessels Pulse stretching of arteries causes by pressure of blood from the heart during systole Caused by pumping of heart against the resistance of the smaller blood vessels greatest in aorta then decreases with distance form the heart Blood flow velocity decreases with distance from the heart lowest in the capillaries This allows for maximum diffusion Blood flow in veins Blood flow in veins Pressure in the veins is near zero How does it return to the heart Skeletal muscle pumps the veins Valves allow the blood to flow only to the heart Breathing also helps by enlarging the veins around the heart Measuring blood pressure Measuring blood pressure Blood pressure varies throughout the body 120 70 120 systole and 70 during diastole Sphygomomanometer Cuff cuts off pressure systole pushes blood through when the pressure is reduced Diastole when turbulent sounds are no longer heard Hypertension a consistent BP of 140 90 or higher Pumping against greater resistance wears out the heart athlerosclerosis Figure 23 12 Atherosclerosis normal artery and artery with plaque Smooth muscle controls the distribution of blood Smooth muscle controls the distribution of blood Smooth muscle controls the distribution of blood Blood flow is constant to the heart and brain but varies in other tissues Constriction of the arterioles reduces flow to the capillaries it is controlled by nerves and hormones Precapillary sphincters control blood flow into capillary beds Meals capillary beds in the digestive tract receive more blood after eating Capillary transfer of substances Capillary transfer of substances Transfer of substances Movement across the membrane occurs by diffusion endocytosis osmosis


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FSU BIOL 130 - The circulatory system

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