3/6/14 Kin 470 class notes- Hypertensiono Resting blood pressure greater than 140/90mmHgo Primary (“essential”) hypertension Cause unknown 90% cases of hyper tensiono secondary hypertension result of some other condition or diseaseo Risk factor for: Left ventricular hypertrophy Atherosclerosis and heart attack Kidney damage Stroke- Effective treatment of high blood pressureo Medications Diuretics, beta-blockers, etc.o Regular physical activityo Weight losso Stress managemento Decreased sodium intakeo Decreased alcohol consumption- Electrical activity of the hearto Heart doesn’t need a CNSo Contraction of the heart depends on electrical stimulation of the myocardiumo Impulse is initiated in the right atrium and spreads throughout the entire hearto May be recorded on an electrocardiogram (ECG)- Conduction system of the hart- ECG interpretationo Records the electrical activity of the hearto P wave Arterial depolarizationo QRS complex Ventricular depolarization and arterial repolarizationo T wave Ventricular repolarization- Relationship between electrical events and the ECG- Diagnostic use of the ECG During Exerciseo S-T segment depression Suggests MI occurred Reduced blood flow to myocardiumo Result of atherosclerosis Fatty plaque that narrows coronary arteries- Impaired cardiac blood supplyo Impaired flow- Rate pressure product:o An estimate of myocardial worko Rate pressure product: SBP * HR = RPPo A commonly used measure of myocardial work- Myocardial Oxygen Useo At rest, myocardium uses ~70-80% available oxygeno During exercise, flow must increase 5-7 fold to meet oxygen demand- Vasodilation byo Adenosineo Hypoxiao Sympathetic nervous system hormones- Myocardial metabolism: Substrate
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