Chapter 42-Concept 42.1: Circulatory systems link exchange surfaces with cells through out the bodyDiffusion time is proportional to the square of the distanceSmall or thin animals can exchange material directly with its surround mediumMost animals, cells exchange materials with environment via fluid filled circulatory system-Central functions of Circulatory system1) Transport: Nutrients, gases (CO2 and O2) and waste products2) Communication: transport of hormones3) Fight infections: through transport of white blood cells and antibody proteins4) control body temp: transpiration of heat5) control of body pH: through transport of buffers-General properties of circulatory systemsA circulatory system hasCirculatory fluid (Blood or hemolymph)Set of interconnecting vessels (blood vessels)Muscular pump, the heart Can be open or closedOpen circulatory system: insects, other arthropods, and most mollusks blood bathe the organs directlyNo distinction between blood and interstitial fluid, this body fluid is called hemolymphClosed Circulatory System: confined to vessels and is distinct from the interstitial fluidMore efficient at transporting circulatory fluids to tissues and cellsAnnelids, cephalopods, and vertebrates-Organization of vertebrate circulatory systemCardiovascular system: humans and other vertebrates closed circulatorysystem3 types of blood vessels, Arteries, Veins, and CapillariesArteries branch into arterioles and carry blood away from the heart to capillariesCapillary beds: networks of capillaries are the sites of chemical exchange between the blood and interstitial fluidVenules: converge into veins and return blood from capillaries to the heartArteries and veins are distinguish by direction of blood flowIn the heart blood enters an atrium and is pumped out though a ventricle-Double circulationDouble circulation: oxygen poor and oxygen rich blood are pumped separately from the right and left sides of the heartAmphibians, reptiles and mammals have thisOxygen poor blood flows through the pulmonary circuit to pick up oxygen from the lungsOxygen rich blood delivers oxygen though the systematic circuitMammals and birds4 chamber hearts: 2 Atria, 2 ventriclesLeft side: Oxygen richRight Side: oxygen poor are endotherms (generate own heat) and require more oxygen than ectotherms-Concept 42.2 coordinated cycles of heart contraction drive double circulation in mammalsMammalian circulationBlood begins its flow with the Right Ventricle pumping blood to lungsThrough pulmonary trunk (divides into arteries)Oxygen rich blood from lungs enters left atrium and is pumped through aorta (largest artery) to the body tissues by the left ventricleCoronary arteries: Aorta provides blood to heartBlood returns to heart through superior vena cava (head neck, forelimbs)and inferior vena cava (blood from lower half)flow into right atrium-Heart Valves prevent backflow of bloodValves are located between atria and ventricles: Atrioventricular valveTricuspid valve: separates the right atrium from the right ventricleBicuspid Valve: separates the left atrium form left ventriclesValve located between the pulmonary trunk and right ventriclePulmonary Semilunar ValveAortic semilunar valve: valve located between aorta and left ventricleLup dup sound of heart beat is recoil of blood against the AV valves (lub) and then against the semilunar (dup) valvesHeart Murmur: When backflow occurs.Cardiac cycle: rhythmic cycle of heart contracting and relaxingSystole: contraction or pumping phaseDiastole: relaxing or filling phaseHeart Rate: Pulse or BPMStroke Volume: amount of blood pumped in a single contractioncardiac output: volume of blood pumped into systematic circulation per minute depends on both BPM and SV; BPM * SV-Maintaining the Heart’s Rhythmic BeatSinaerial (SA) node: pace makerAtrioventricular (AV) node: receives signals from SA node, delayed and travel to the purkinje fibers that make the ventricles contactElectrocardiogram(EKG or ECG): record impulse that travel through cardiac cyclePace maker is controlled by sympathetic and parasympathetic nervous systemsSN speeds it upPSN slows it downHormones and temp regulate pace makerEpinephrine and higher temps increase heart rate-Concept 42.3 patterns of blood pressure and flow reflect the structure and arrangement of blood vessels-Blood vessel structure and functionVessels cavity: Central lumenEndothelium: Epithelial layer that lines blood vessels, smooth and minimizes resistanceArteries are composed ofendothelium (Inner layer-lines central lumen)Smooth Muscle (middle layer-allows for vasoconstriction or vasodilation)Connective Tissue: (outer layer-protects the blood vessel)Arteries have thicker walls to accommodate the high blood pressure20 year old at rest, 120/70mmHg, systolic/diastolic-Changes in blood pressure during the cardiac cycleSystolic pressure: pressure in arteries during ventricular systole, it is the highest pressure in the arteriesdiastolic pressure: pressure in the arteries during diastole, lower than systolic pressurePulse: rhythmic bulging of artery wall with each heart beatArteriesArteriolesCapillariesCapillaries have thin walls, the endothelium plus its basal lamina, to facilitate the exchange of materialsSmallest of blood vesselssite of gas exchange and nutrient/waste exchangeO2 and nutrients diffuse from blood into interstitial fluidCO2 and organic waste diffuse from interstitial fluid to bloodblood goes CapillariesVenules(small veins)VeinsVeins have thinner-walls compared to arteries, muscle contraction drives blood flowOne way valves prevent backflowMovement of blood1) Smooth Muscle contraction of venules2) Skeletal muscle contraction3) Expansion of vena cava during inhalation-Blood Flow velocityVelocity of blood flow is slowest in capillary beds, as a result of the high resistance and large total cross-sectional areaBlood flow in capillaries is necessarily slow for exchange of materialsVelocity is fastest in arteries-Anatomy of Capillaries facilitate ExchangeExchange happens in capillaries because:1) Small diameter (slows blood flow)2) Thin porous walls (one cell wall thick)3) Numerous exchange is by diffusion and bulk transport across cells of the capillary wall and through
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