hypertension notes.docx

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BIO 103
Mark Shrimpton

From the Lewis textbook, read pages 823-843 Hypertension: sustained elevated BP, 140/90 and above Normal Regulation of BP  BP is the force exerted by blood against the walls of the blood vessel and must be adequate for tissue perfusion.  CO + systemic vascular resistence= BP  Systemic vascular resistence is the force opposing the movement of blood within vessels. Eg. Radius  Short term regulation of BP: SNS, vascular endothelium (seconds) o SNS: increases HR and contractility, produces vasocontriction, promotes release of renin in kidneys, net effect is to increase BP by increasing CO and SVR  Baroreceptors sense changes in BP  Causes norepinephrine to be released activating SA node causing contractions o VE: single layer of cells lining bv  Produces enthothelin which is a vasoconstrictor  Long term regulation of BP: renal and hormonal o Renal: kidneys control Na+ excretion and extracellular fluid  Renin-angiotensin-aldosterone system  Renin converts angiotensinogen to angiotensin I and ACE converts I into II  II is a vasocontrictor also stimulates adrenal cortex to release aldosterone, causing Na+ & H2O rentention ^BP  Prostaglandins secreted by the renal medulla, vasodilate, >BP o Endocrine: hormones  Epinepherine increases CO by increasing HR and contractility  Activates B2 receptors causing vasodilation  Alpha 1 epinepherine causes vasocontriction Subtypes of Hypertension  Isolated Systolic: sustained elevation of SBP of 160 and above and a DBP <90 o Most common in elderly due to loss of elasticity of arterties o Treatment goal for elderly is to get SBP to 140  Psuedohypertesion: occurs due to sclerosis of large arteries o Sclerotic arteries dont collapse under the BP cuff and thus cause much higher cuff pressure reasings o Have to use intra-arethral catheter to measure BP Etiology  Primary Hypertension: elevated BP without a cause (90-95% of cases) o Can be causes by SNS activity, hormones, obesity, diabates.  Secondary Hypertension: elevated BP with a specific cause and can be treated (5-10%) o Causes include, narrowing of aorta, renal disease, endocrine disorders, neuro disorders, sleep apnea, meds, pregnancy Pathophysiology  Primary Hypertension o For arterial pressure to rise there has to be an increase in either CO or SVR o Hallmark is persistent high SVR o Can be hereditary, water and sodium rentention, altered renin-angiotensin mechanism, stress, increased SNS activity, insulin resistance, endothelial dysfunction Clinical Manifestations  Called silent killer  Usually asymptomatic  S&S includes, fatigue, dizziness, palpitations, angina, dyspnea  Complications include, heart disease, retina damage, and kidney damage Diseases  Coranary artery disease o Develop atherosclerosis o Response to injury theory  Left Ventricular hypertrophy o Increaed cardiac workload causes ventricle to hypertrophy o Heart cant meet requirements of body o Contractility is de
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