BIO 3324 1nd Edition Lecture 13Outline of Last LectureI. ATPII. Power strokeIII. AutonomicIV. Control of movementV. visceraOutline of Current LectureI. circulatory systemII. flow of bloodIII. heart of four chambersIV. heart valvesV. atrial executionCurrent lecture:Circulatory system has 3 basic components• Heart – serves as the pump that imparts pressure to move the blood to the tissues• Blood vessels – the conveyance through which blood travelsThese notes represent a detailed interpretation of the professor’s lecture. Grade Buddy is best Used as a supplement to your own notes, not as a substitute.– Arteries carry blood away from the heart– Veins return blood to the heart• Blood – medium to transport materials long distance in the body– Nutrients, water & gases that enter the body– Materials that move from cell to cell in the body– Wastes that the cells eliminateHeart is a dual pump:• Located centrally in the thoracic cavity• Left and right halves divided by a septum - prevents blood from mixing from the two sides• Contains 4 chambers (2 upper, 2 lower) and is divided in left (O2-rich) and right (O2-poor) halves– Atria (upper chambers) – receive blood returning to the heart• Veins – carry blood to atria– Ventricles (lower chambers) – pump blood from the heart• Arteries – carry blood from ventricles• Pulmonary circulation – heart to lungs• Systemic circulation – heart to bodyFlow of blood:• Starting in right half of heart (O2-poor Blood)– Right Atrium – Right Venticle• To Pulmonary Circulation– Pulmonary arteries– Pulmonary capillaries (gas exchange: O2-poor to O2-rich blood)– Pulmonary veins• Return to left half of heart (O2-rich blood)– Left Atrium – Left Venticle• To Systemic Circulation– Aorta– Branching arteries– Systemic capillaries (gas exchange: O2-rich to O2-poor blood)– Systemic veins– Vena Cavae• Return to right half of heart• Hepatic portal vein carries blood from the digestive tract to the liver so absorbed nutrients can be processedBlood flow is dependent on pressure gradients and resistance:• Pressure gradient (DP) – difference in pressure between the beginning and end of the vessel– Blood flows from an area of high pressure to an area of low pressure• Heart is responsible for creating the high pressure– Pressure drops along the length of a blood vessel due to frictional lossesPressure physics:• Hydrostatic pressure is the pressure exerted by a non-moving fluid– Equally exerted in all directions• A moving fluid has two components– A flowing component representing its kinetic energy– And a lateral component that represents its hydrostatic pressure (& potential energy)• In a system with flow, pressure falls over distance as energy is lost• Pressure changes without changing volume– Contracting the wall of a fluid-filled container increases the pressure on the fluid without changing its volume– Expanding the wall of a fluid-filled container decreases the pressure on the fluidFlow & pressure gradients (DP):• Flow requires a pressure gradient• Pressure gradient is the difference in pressure between two ends of a tube• Direct relationship– The higher the pressure gradient the greater the flowResistance opposes flow:• Resistance (R) – The hindrance or opposition to blood flow due to friction between thefluid & vessel walls• Inverse relationship between flow and resistance– As resistance increases, flow decreases– 3 factors determine resistance– Vessel radius (r) – inverse relationship between R & r– Vessel length (L) – direct relationship– Viscocity (h) of the blood (determined by the # of circulating RBCs) – increased h = greater R• Changes in the radius of a vessel– Vasoconstriction – decrease in the radius; increases resistance– Vasodilation – increase in radius; decreases resistanceBlood flow:• Blood flow is directly proportional to the pressure gradient and indirectly proportional to the resistance of the vessel• Summarized by Poiseuille’s lawVelocity of flow:• Flow is the volume of blood passing a given point per unit time.– How much– Expressed as volume/unit time (L/min)• Velocity of flow is the distance a fixed volume of blood travels in a given unit of time– Velocity– Expressed as distance/unit time (cm/min)• Determined by equation:The heart: pericardium & myocardium• Heart is a muscular organ about the size of a fist located in the center of the thoracic cavity• Covered by the pericardium - a double walled sac enclosing the heart– Protect the heart– Anchor it to the surrounding structures– Prevents overfilling– Between the two layers is the pericardial cavity filled with serous fluid• Allows the two serous layers to slide without friction• Myocardium – composed of cardiac muscle bundles & a fibrous connective tissue network that forms a fibrous skeleton for the heart muscle– Spirally arranged around the circumference of the heart– Contraction, results in a wringing effect that pushes blood upward to the arteriesThe heart has four chambers:• Superior– 2 Atria (right & left)– The atria are the receiving chambers for blood returning from the circulation• Right atria receives blood from the systemic circulation (deoxygenated)• Left atria receives blood from the pulmonary circulation (oxygenated)– The contractions of the atria contribute very little to the propulsion of blood bythe heart• Inferior– 2 Ventricles (right & left)– The ventricles are the propelling chambers for the blood returning to circulation• Right ventricle pumps blood to the pulmonary circulation (deoxygenated)• Left ventricle pumps blood to the systemic circulation (oxygenated)• Septa divide the four chambers• Muscle wall on left side is much thicker– Pulmonary side = low pressure, low resistance– Circulatory side = high pressure, high resistanceBlood from to and from the heart:• Veins carry blood to the atria – Right atria receives blood from the systemic circulation (deoxygenated)• Superior vena cava• Inferior vena cava• Coronary sinus– Left atria receives blood from the pulmonary circulation (oxygenated)• Right pulmonary veins• Left pulmonary veins• Arteries carry blood from the ventricles – Right ventricle propels blood (deoxygenated) to the pulmonary circulation via the pulmonary arteries– Left ventricle propels blood (oxygenated) to the