<prompt> Relaxation of Detrusor occurs via which receptors-b-1 sympatheticb-2 sympathetica-1 sympathetica-2 sympathetic  <response>: Ans. is b i.e., b-2 sympatheticEffects of Sympathetic system1. Heart - due to pactionsi heart rate, Positive chronotropicii force of cardiac contraction Positive ionotropiciii Conduction velocity in the conductive tissues of heart is increased Positive dromotropiciv Increased automaticity positive bathmotropicv Refractory Period RP of all type of cardiac cells is reduced. This makes sense, because with a fight or flight response, heart rate increases, as a consequence of: Conduction velocity Positive dromotropic Refractory period so that cardiac tissue becomes excitable in a shorter span on time2. Blood vessels Stimulation of cq receptors cause vasoconstriction. Stimulation of b2 receptors cause vasodilation. Vasoconstriction a1 receptors predominate in skin, mucosal, renal and sphlanchnic blood vessels. Dilatation b2 receptors predominate in skeletal muscles, liver and coronary blood vessels. The direct effect on cerebral vessels is not prominent - blood flow through this bed parallels change in BP. Renal vessels contain bothaI vasoconstriction and vasodilatiator receptor. Therefore sympathetic stimulation cause less increase in vascular resistance as compared to other sites where sympathetic stimulation causes vasconstriction.3. Urinary system Relaxation of detrusor b2 action and contraction of trigone a1 action - urinary retention.4. GIT Relaxation of smooth muscles by direct action of b2 receptors and indirect action of a2 receptors a2 receptors decrease the release of ACH by acting presynaptically on cholinergic neurons.5. Respiratory system Bronchial smooth muscles have b2 receptors but no sympathetic supply. b2 receptor agonists exogenous drugs can cause bronchodilation. There is vasoconstriction of mucosal blood vessels of respiratory tract - further increase in diameter of bronchus. Overall there is decrease in resistance.6. Eye Mydriasis - Due to contraction of radial muscles Dilator pupillae of iris by a7 receptors.7. Genital system Relaxation of uterus - b2 receptors Ejaculation - a1 receptors.8. Secretory glands Sweating is increased due to cholinergic sympathetic receptors M3.9. Metabolic Lipolysis - b3 receptors gluconeogenesis and glycogenolysis - b2 action. Hyperkalemia followed by hypokalemia - b2 action. insulin release from pancreas - a2 action. glucagon secretion - b2 action. Overall there is hyperglycemia, hyperlipidemia.10. Kidney renin release from JG cells - b1 receptors.11. b2 stimulation causes tremors. 