BMS 420 Lecture Notes - Perfusion, Ventricular Fibrillation, Diastole
Document Summary
2 receptors vasodilation (epinephrine at low concentration) Veins do not have 2 receptors do not vasodilate. Active hyperemia: bf due to metabolism metabolites. Reactive hyperemia: bf following an occlusion of artery. Myogenic autoregulation is the other major mechanism involved in control locally and we have discussed it several times. Aorta coronary sinus right atrium but also some drainage into chambers of heart via arterioluminal vessels, arteriosinusoidal vessels and the thebesian veins. Venous blood in body 75% saturated (does not apply to coronary vessels) In heart, about 75% of o2 extracted in single circulation. Heart rate must increase for heart to receive more o2. Left ventricular myocardial pressure is greatest near the endocardium. Endocardium: greater flow in diastole than in systole. Less tone in endocardial region and most prone to ischemia. Fairly equal flow distribution between epicardium and endocardium throughout entire cycle. Ventricular fibrillation ineffective pumping, metabolism , blood flow .
