PHYSL402 Lecture Notes - Lecture 23: Afferent Nerve Fiber, Vascular Permeability, Splenectomy
7 Nov 2016
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In response to fall in map, no reflex increase in hr: if have excess anp. Vasodilator (in most, but not all, vascular beds): recall: constricts at renal efferent. Inhibits sympa nerve activity through increased vagal afferent nerve activity (brain does not know there has been a fall in bp): Fall in map primarily due to reduced co. Dilates splanchnic capacitance vessels (blood pooled in veins): in gut. Increases lymphatic system capacitance (lymph pooled in ducts) Inhibits lymphatic duct pumping (lymph pooled in ducts) Reduced tone blood pools = storage site and can be rapidly mobilized. Spleen may be major site of fluid movement out of the vasculature. Anp increases filtration of cell-free fluid out of the splenic vasculature. Splenic vasculature permeable to proteins no oncotic p gradient. Fluid efflux controlled solely by hydrostatic p gradient across capillary wall. Effect of anf on splenic resistance arteries and veins. Anf constricts splenic venules more than splenic arterioles.
