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PAT20 Study NotesWeeks 4 – HypertensionHYPERTENSION1)Blood Pressurea.Force on walls of arteries by the pulsing blood under pressure from <3; BP = CO x Rb.Blood flows from an area of high pressure (arterial sys.) to area of low pressure (venous sys.)c.Systolic = Blood ejected from L.ventricle to aorta under high pressure; max. pressure = ventricular contractiond.Diastolic = Relaxation of ventricle; minimal pressure on blood vessel walls; min. pressure = ventricular relaxatione.Pulse Pressure = Systolic – Diastolicf.Cardiac Output = How much your heart can generate (volume of blood); CO = HR x SVg.Systemic Vascular Resistance = Intrinsic (hormones) and extrinsic (sympathetic nerves, A-II, etc) factors influence SVR; i.e the Gardiner example = open up vascular resistence to make it easier for <3 to pumph.Blood Volume = Volume of blood in circ. sys. (5000ml for adults)i.Viscosity = Thickness of blood; determined by hematocrit and RBC content (the more = the thicker = the harder it is for the <3 to pump)j.Elasticity = Arterial walls are normally elastic; easily expands and contract to pump blood 2)Etiology of HTNa.Primary HTNi.90-95%; cause unknownb.Secondary HTNi.5-10%; have HTN due to1.Renal disease2.Endocrine disorders3.Other identifiable causes; remove the specific cause =cure HTN3)Stages of HTNa.Optimal = 120/80 or lessb.Pre-HTN = S: 121-130; D: 80-89c.HTN Stage 1 = S: 140-159; D: 90-99d.HTN Stage 2 = 160/100 or higher
4) SVRa.The resistance to blood flow offered by all of the systemic vasculatureb.All the vessels in the systemic system affects the <3 to pump bloodc.Although SVR is primarily determined by changed in blood vessel diameters, changes in viscosity also affect it d.Heart will manipulate certain things to maintain a certain CO; i.e SVR will ^to try to shunt blood back to where it needs to be e.SVR ^ = BP ^f.Heart beats = volume of blood ejected (sv)g.i.e 70ml x 70 = 4900ml = 4.9L/min; if 4.9 is a good CO, what would the HR be if sv was only 50/45/40/etc ml5)Factors Affecting BP6)Factors that Affect CO and SVRa.Sympathetic Nervous System (SNS)i.Activation of SNS = ^ HR & contractility = vasoconstriction in