Circulation Vital Signs Pulse Vital Signs Pulse Blood Pressure Anatomy Joke of the Day Tissue Perfusion blood flow through tissue Delivers oxygen and nutrients to tissues Removes wastes from Exchanges gases in tissues lungs Forms urine in kidneys Blood Velocity speed of blood flow Inversely related to cross sectional area of vessels Regulated locally by modifying diameter of arterioles Regulation of Blood Flow Low levels of nutrients or oxygen cause vasodilation and relaxation of precapillary sphincters called metablic regulation based on concentration of oxygen or nutrients in blood and tissue Changes in stretch of vessel causes response in smooth muscle of vessel myogenic regulation results in changes in stretch of blood vessel which causes a response in smooth muscle of blood vessel increased stretch vasoconstriction which slows flow of blood down for greater exchange Angiogenesis increases number and size of vessels Capillary Dynamics Respiratory gases and lipid soluble molecules pass via direct diffusion Water soluble solutes pass through intercellular clefts and fenestrations Large molecules pass through caveoli but still upper limit most everything but proteins can pass through Fluids pass through pinocytic vesicles Capillary Fluid Dynamics Fluid forced out through clefts at arterial end of capillary bed because under highest pressure and speed Most returns at venous end some goes into lymphatic system Flow regulated by balance between hydrostatic pressure and colloid osmotic pressure Hydrostatic Pressure Force exerted by fluid pressing against a wall Capillary hydrostatic pressure drops along length of capillary bed highest at arterial side drops because fluid drop out at arterial side Colloid Osmotic Pressure Force created by presence of large nondiffusible molecules Functions in opposition to hydrostatic pressure Does not vary along length of capillary bed its constant Net Filtration Pressure Interaction between hydrostatic and colloid osmotic pressures Determines if there is a net gain or loss of fluid from capillaries Portal Systems Veins to capillaries to veins Serves specific regional tissue needs Circulatory Shock any condition where blood cannot circulate normally typically due to loss of blood vol Hypovolemic shock massive hemorrhage Circulatory Shock Hypovolemic shock Vascular shock normal blood vol but poor circulation usually due to extreme vasodilation most extreme form is anaphylactic shock trouble getting energy because of vasodilation sunburn can cause vasodilation even hot water can do this Circulatory Shock Hypovolemic shock Vascular shock Cardiogenic shock reduction in ability of heart to pump heart attack Embryological Development Mesoderm cells form endothelial lining of blood vessels These collect as blood islands These connect to form vascular tubes Platelet derived growth factor signals mesenchymal cells to form muscular and fibrous coats and then devlopment of blood vessel Age related Changes Atherosclerosis this is the accumulation over life starts when we are young estrogen helps to prevent the deposition of plaque so lower occurrence in women Age related Changes Atherosclerosis Hypertension increased BP accumulates as we age many factors increased kidney tissue increased hypertension can hurt eyeballs