HN220 Lecture Notes - Lecture 22: Transcytosis, Pulse Pressure, Heme
Document Summary
Capillary pressure and exchange: map as the arterial branches become smaller and more numerous, pulse pressure also , steady pressure ~35 mmhg at precapillary sphincter. Venous system: less smooth muscle, venules: small, empty into veins (20. M: veins: low resistance vessels (~5mm, distensible can pool blood, one way valves prevent backward flow, skeletal muscle pump, respiratory pump. Increase in venomotor tone: contraction of smooth muscle in the wall of a vein, smooth muscle in walls of veins is innervated by sympathetic nervous system, norepinephrine acting at an adrenergic receptors causes venous constriction. Increases central venous pressure: decreases venous compliance. Q distribution: most tissues at expense of skeletal muscle, heart receives (though same relative amount, brain receives (though lower relative amount, brain cannot tolerate compromised supply. Initiating clot formation when a vessel is broken: offers defense against toxins and pathogens, white blood cells and antibodies, stabilization of body temperature.
