BSCI440 Chapter 14 Notes Exam 2 Study Guide Cardiovascular I Chapter 14 Cardiovascular Physiology Cardiovascular system closed system heart blood vessels and blood Cardiovascular system transports materials throughout the body nutrients water and gases that come from the environment materials that move from cell to cell within the body wastes that cells eliminate i e CO2 oxygen enters the body at the exchange surface of the lungs nutrients and water are absorbed across the intestinal epithelium oxygen is necessary for cell life i e if oxygen delivery stops for 5 10 minutes permanent brain damage Heart Blood Vessels and Blood Arteries blood vessels that carry blood away from heart Veins blood vessels that carry blood towards heart aka venous return Valves in blood vessels ensure blood moves in one direction Heart is divided by a central wall called the septum splits heart in right and left halves II Each half of the heart functions as a separate pump atrium and ventricle Atrium receives blood returning to heart from veins and ventricles pump blood Right side of heart receives blood from tissues and sends it to the longs for Left side of heart receives newly oxygenated blood from lungs and pumps into into the arteries oxygenation tissues of the body Right Atrium right ventricle pulmonary arteries pulmonary capillaries lungs pulmonary veins left atrium left ventricle aorta descending arteries capillaries trunk liver GI kidneys pelvis and legs ascending veins vena cava right atrium blue pulmonary circuit red systemic circuit In systemic circuit capillaries are where oxygen diffuses into tissues and the blood moving into the veins is now deoxygenated Coronary arteries and veins nourish the heart blood flows from coronary arties into capillaries into coronary veins then empty into right atrium at coronary sinus Ascending branches of the aorta go to the arms and abdominal aorta supplies blood to trunk legs and internal organs Pressure Volume Flow and Resistance Pressure gradient blood moves from high pressure to low pressure Heart creates high pressure when it contracts blood flows of the heart into closed loop blood vessels high low As blood moves pressure is lost due to friction between the fluid and blood vessel Highest pressure in the aorta and systemic arteries lowest pressure in the vena walls cava before entering right atrium Pressure measured in mmHg III 1 Pressure changes in liquids without a change in volume if the walls of a fluid filled container contract the pressure exerted on the fluid in the container increases Driving pressure forces blood from ventricle to blood vessels high low When the heart relaxes and expands pressure in fluid filled chambers decreases Vasodilation pressure decreases vasoconstriction pressure increases Flow is proportional to the pressure gradient F proportional to P where P P1 P2 so the higher the pressure gradient the greater the fluid flow Resistance tendency of the cardiovascular system to oppose blood flow Increase resistance decrease flow F proportional to 1 R Influenced by 3 components R radius of tube L length of tube and n viscosity of fluid Poiseuille s Law R 8 L n pi r 4 o Resistance of flow offered by a tube increases as length of tube increases viscosity of fluid increases and tube s radius increases o Radius has the largest effect on resistance i e radius of 2 resistance decreases flow increases by 16 fold o Decrease in blood vessel diameter vasoconstriction and decreases blood flow increase in blood vessel diameter vasodilation and increases blood flow Flow is proportional to P and inversely proportional to Flow refers to flow rate the volume of blood that passes a given point in the system per unit time L min or mL min Velocity of flow the distance a fixed volume of blood travels in a given period of time v Q A v velocity of flow Q flow rate A cross sectional area of tube smaller tube means higher flow rate larger tube means smaller flow rate Arteries act as a pressure reservoir during the heart s relaxation phase maintaining mean arterial pressure MAP that is the primary driving force of blood flow MAP Cardiac Output Peripheral Resistance Cardiac Muscle and the Heart Point apex of heart angles down to the left side of the body while the broader base sits just under the opening of the main blood vessels Heart muscle myocardium Heart valves ensure one way flow in the heart Atrioventricular valves AV valves between atria and ventricles o Tricuspid valve between right atrium and right ventricle o Bicuspid mitral valve between left atrium and left ventricle o Chordae tendinae and papillary muscles provide stability for the valves when a ventricle contracts blood pushes against bottom side of AV valve and forces it upward into closed position and chordae tendinae prevent it from being pushed too far back into the atrium Semilunar valves between ventricles and arteries o Aortic valve between left ventricle and aorta o Pulmonary valve between right ventricle and pulmonary trunk Most cardiac muscle is contractile but 1 are specialized to generate action potentials spontaneously gives the heart the ability to contract without outside signals myogenic 2 IV Autorhythmic cells pacemakers set the rate for heartbeat smaller and contain fewer contractile fibers no sarcomeres so do not contribute to the contractile force of the heart Gap junctions electrically connect cardiac muscle cells to one another allow wave depolarization to spread rapidly from cell to cell Myocardial SR is smaller than skeletal muscle reflecting the fact that cardiac muscle depends in part on extracellular Ca2 to initiate contraction Calcium Entry is a Feature of Cardiac EC Coupling Ca2 induced Ca2 release CICR 1 Action potential enters contractile cell membrane 2 Voltage gated L type Ca2 channels in cell membrane open 3 Ca2 enters cell and opens ryanodine receptor Ca2 release channels RyR in V 4 RyR channels now open stored Ca2 flows out of the SR and into cytosol SR creating a Ca2 spark 5 Multiple sparks from different RyR channels sum to create a Ca2 signal 6 Ca2 diffuses through cytosol to contractile elements where the ions bind to troponin ad initiate crossbridge cycling 7 Relaxation cytoplasmic Ca2 concentrations decrease Ca2 unbind to troponin myosin releases from actin and relaxation occurs Ca2 is transported back into SR by SERCA Ca2 ATPase Ca2 is also removed from the cell in exchange for Na via the Na Ca2 exchanger NCX 1 Ca2 for 3 Na entering the cell this Na