BIOH 370 1st Edition Lecture 12 Outline of Last Lecture Heart Part 3I. Cardiac Output ContinuedII. Help for Failing Heartsa. Heart Transplantb. Intra-Aortic Balloon Pumpc. Ventricular Assist Device (VAD)d. Coronary Bypass Surgerye. Stent in ArteryIII. Development of the HeartIV. Prenatal vs. Postnatal CirculationV. Congenital Heart Defectsa. Patent Foramen Ovaleb. Coarctation of the Aortac. Patent Ductus Arteriosusd. Tetralogy of FallotOutline of Current Lecture Blood VesselsI. Functional Differences between Arteries and VeinsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.II. Distinguishing Features of Blood VesselsIII. Precapillary SphinctersIV. Three Structural Types of Capillariesa. Continuous Capillariesb. Fenestrated Capillariesc. Sinusoidal CapillariesV. Dynamics of Capillary Exchange (Starling’s Law of Capillaries)a. Diffusionb. Transcytosisc. Bulk FlowVI. Velocity of Blood FlowVII. Movement of Venous Blood Flow back to Heart Occurs in 3 WaysVIII. Factors that Affect Blood PressureIX. Control Center of Blood Pressure and Blood FlowX. Short-term Neural Control of Blood PressureCurrent LectureBlood VesselsI. Functional Differences between Arteries and Veins- Arteries: have more structures associated with ito Lamina:stretch allowsarteries to have higherpressure insideo Veins: have valves= skeletalmuscle contraction pushes(a) ArteryTUNICA INTERNA:(b) VeinLumen LumenEndotheliumBasement membraneInternal elastic laminaSmooth muscleExternal elastic laminaTUNICA EXTERNATUNICA MEDIA:Valveveins together to move blood- valves allow blood to flow up and stopsbackflow of bloodArteries VeinsDelivery Blood pumped into single systemic artery—the aortaBlood returns via superior and interior venae cavae and the coronary sinusLocation Deep, and protected by tissues Both deep and superficialPathways Fairly distinct Numerous interconnectionsSupply/drainage Predictable supply Usually similar to arteries, except dural sinuses and hepatic portal circulationII. Distinguishing Features of Blood VesselsIII. Precapillary Sphincters- Regulate the flow of blood through capillary beds- Regulated by local chemical conditions and vasomotor nerves- Change depending on homeostatic imbalances- When in really cold places, the sphincters will shut off blood supply to extremities to focus on keeping internal organs warm- why get frostbite at extremities firstIV. Three Structural Types of Capillaries- Continuous Capillaries- Abundant in the skin and muscleso Tight junctions connect endothelial cellso Intercellular clefts allow the passage of fluids and small solutes- Continuous capillaries of the braino Tight junctions are complete, forming the blood-brain barrier- Very few holes in them- Fenestrated Capillaries- Some endothelial cells contain pores (fenestrations)= more permeable than continuous capillaries- Function in absorption or filtrate formation (small intestines, endocrine glands, and kidneys- Sinusoidal Capillaries- Fewer tight junctions, larger intercellular clefts, large lumens- Usually fenestrated- Allow large molecules and blood cells to pass between the blood and surrounding tissues=most leaky- Found in the liver, bone marrow, spleen-places where monitor pathogens=immune response, and in bone marrow where RBCs are made (hematopoiesis) V. Dynamics of Capillary Exchange (Starling’s Law of Capillaries)- Diffusion- O2, CO2, glucose, amino acids, and hormones- Transcytosis- Insulin- Maternal IgA antibodies through placenta- Bulk Flow- Filtration and absorption *20L of blood/day entercapillaries* 17L of blood/day leavecapillaries=3L/day don’t get to veins-instead go through lymphaticVI. Velocity of Blood Flow- Changes as it travels through the systemic circulation- Is inversely related to the total cross-sectional area- Is fastest in the aorta, slowest in the capillaries, increases again in veins- Slow capillary flow allows adequate time for exchange between blood and tissues- Autoregulation Is independent of MAP, which is controlled as needed to maintain constant pressure VII. Movement of Venous Blood Flow back to Heart Occurs in 3 Ways1. Pumping action of heart2. Contraction of skeletal muscles in lower limbs/valves in the veins3. Respiratory PumpVIII. Factors that Affect Blood PressureIX. Control Center of BloodPressure and Blood Flow- The medulla oblongatacontains a cardiovascular center,which is a group ofneurons that regulateheart rate, contractility, and blood vessel diameterX. Short-term Neural Control of Blood PressureBaroreceptors are important pressure-sensitive sensory neurons that monitor stretching of the walls of blood vessels and the atriao Baroreceptors taking part in the carotid sinus reflex protect the blood supply to the braino Baroreceptors taking part in the aortic reflex help maintain adequate blood pressure in the systemic circuitChemoreceptors respond to rise in CO2, drop in pH or O2o Increase blood pressure via the vasomotor center and the cardioacceleratory centerAre more important in the regulation of respiratory
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