Relaxation of Detrusor occurs via which receptors-
Ans. is 'b' i.e., b-2 sympatheticEffects of Sympathetic system1. Heart - (due to pactions)i) | heart rate, (Positive chronotropic)ii) | force of cardiac contraction (Positive ionotropic)iii) Conduction velocity in the conductive tissues of heart is increased (Positive dromotropic)iv) Increased automaticity (positive bathmotropic)v) 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 time)2. 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.
b-1 sympathetic
b-2 sympathetic
a-1 sympathetic
a-2 sympathetic
Nervous System