BIOL 460 1st Edition Lecture 25Outline of Last Lecture I. Exchange of Fluid between Capillaries and Tissue a. Starling Forcesb. EdemaII. Regulation of Blood by Kidneys a. ADHb. Aldosterone c. Renin secretion Outline of Current Lecture I. Regulation of Blood by Kidneys a. ANPII. Blood Flow III. Regulation of Blood Flow in ANSIV. Paracrine Regulation of Blood Flow V. Autoregulation Current LectureRegulation of Blood by Kidneys1. Atrialnatriuretic Peptide (ANP)a. Natri (salt) uresis (urine production)b. Aldosterone antagonistc. Excretion of salt and water in equivalent amountsd. Secreted by L atrium (some right) as a result of increase dblood volumee. Strectch receptors in atria, aorta, and carotid arteryf. Causes secretion of ANPg. Stretch receptors also cause lower ADH secretionh. Antagonizes Angiotensin IIBlood Flow1. Dependent on P (pressure change)Δa. Mean arterial pressure (MAP) = 100mmHgThese 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.b. Blood pressure in right atrium = 0mmHgc. P=100mmHg (drives blood through blood vesselsΔ2. Blood flow proportional to PΔ3.BF ≈Δ PPR4. PR – peripheral resistancea. Resistance to blood flowb. Caused byi. Length of blood vesselsii. Viscosity of bloodiii. Diameter of blood vessels (r=radius) c.PR ≈LVr45. Pouiselle’s Lawa.BF =∆ P r4π8 LV6. P= mean arterial pressureΔa. 120/80 in normal, healthy adultb. Systole-diastole = pulse pressure (40)c. MAP = diastolic pressure + ½*pulsepressureOrgan systems are in parallel, not in series1. Not usually one after the next2. If that was the case, vasoconstriction and dilation would have a huge effect downstream3. Two seriesa. Kidneys (hepatic portal)b. Liver (cleans blood)Regulation of blood flow by ANS1. Alpha 1 andrenergic receptors in sympathetic ANS cause vasoconstriction of vessels in skin and viscera2. Beta 1 receptors speed up heart rate and contractility, affecting ΔP3. Muscarinic cholinergic receptors innervated to vasodilate blood vessels of skeletal muscle (IPSP)4. Muscarinic cholinergic receptors slow HR in parasympathetic division of ANS, no effect on contractility5. Parasympathetic innervation to blood vessels of viscera – not a huge effectParacrine Regulation of Blood Flow1. NO2. Prostacyclin3. Causes vasodilationAutoregulation1. Myogenic control mechanismsa. Walls of small arterioles contain stretch recedptorsb. Receptors are mechanically gated ion channelsc. Ex: vessel supplying kidney and braini. Need relatively constant BPii. Stretch opens ion channel epsp vasoconstrictioniii. Pressure decreases, vessel vasodilatesiv. Smooth flow of blood to kidneys and brain2. Metabolic Control Mechanismsa. Increase in CO2b. Decrease in O2c. Decrease in pHd. Tissue needs adequate blood supply to prevent CO2 buildupe. CO2 + H2O H2CO3 (H+ and HCO3-)f. Decrease in pH causes vasodilation to increase blood flow to an organ3. Reactive Hyperemiaa. Excess of blood in a body partb. Blood pressure cuff example4. Active hyperemiaa. CO2 generated very quickly at start of intense exerciseb. Heart and vessels haven’t caught up yetc. Causes
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