PHSI 208 Lecture Notes - Lecture 5: Vascular Endothelial Growth Factor, Angiopoietin, Angiostatin
Document Summary
Veins are more numerous and have a larger volume, thinner walls, and more elastic tissue in comparison to arteries. This makes venous circulation the volume reservoir of the circulatory system. Angiogenesis (def): the formation of new blood vessels. Adult microcirculation is rather constant, with the exceptions of vessel growth during wound healing, endurance training, inflammation, tumor growth, and in the endometrium during the menstrual cycle. Angiogenic growth factors (mitogens) activate receptors on endothelial cells. Once activated, they produce proteases that degrade the basal lamina so it can move away from the parent vessel. Endothelial cells proliferate into the surrounding matrix and form sprouts towards the angiogenic stimulus in tandem. Sprouts then form loops to become a full-fledged vessel lumen as cells migrate to the site of angiogenesis. Ventricular contraction creates the force necessary to propel blood through the cv system. Contraction of the ventricles pushes blood into the elastic arteries, causing them to stretch.
