MEDI111 Lecture Notes - Lecture 8: Tunica Intima, Tunica Externa, Pulmonary Circulation
6 Aug 2018
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Document Summary
Arteries: divided into 3 groups based on size and function, elastic arteries located closer to heart, muscular arteries expand and recoil, arterioles. Amount of blood in different compartments of circulation. Resistance between flow, pressure and resistance: blood flow (f) is directly proportional to pressure gradient (delta p) If delta p increases, blood flow speeds up: blood flow is inversely proportional to peripheral resistance (r) If resistance increases, blood flow decreases, so: r is more important in influencing local blood flow because it is easily changes by altering blood vessel diameter. Systemic blood pressure: pumping action of the heart generates blood flow, pressure results when flow is opposed by resistance, systemic pressure is higher in aorta and declines throughout pathway, steepest drop occurs in arterioles. Venous blood pressure: changes little during cardiac cycle, small pressure gradient (only about 15mmhg) If vein is cut, low pressure of venous system causes blood to flow out smoothly.
