Adrenal medulla

of 19/19
  • date post

  • Category


  • view

  • download


Embed Size (px)

Transcript of Adrenal medulla

Adrenal Medulla

Adrenal Medulla Dr.Yogesh Kumar Department Of PhysiologyAdrenal Medulla The adrenal medulla, which constitutes 28% of the mass of the adrenal gland, is made up of interlacing cords of densely innervated granule-containing cells that abut on venous sinuses Made of chromaffin cells 2 types Contains granules - 2 types Paraganglia cellsStained by pot dichromate 2The adrenal medulla is in effect a sympathetic ganglion The cells secrete when stimulated by the preganglionic nerve fibers Innervated by splanchnic nerves prepare the body for emergencies, the "fight-or-flight" responses

Catecholamines Adrenalin (epinephrine)Noradrenalin (norepinephrine)Dopamine Synthesis Of Catecholamines

Secretion Of Catecholamines Fight or flight reactions Pre-ganglionic ativation Exo-cytosis of granules mediated by ca influxPhysiological and psychological stimuli such Pain , anxiety , trauma , hypovolemia , hypoglycemia , hypothermia, severe exercise , emotional stimulus Metabolism

Table 1. Classification of Adrenergic Hormone Receptors ReceptorAgonistsSecondMessengerG proteinalpha1 (1)E>NEIP3/Ca2+; DAGGqalpha2 (2)NE>E cyclic AMPGibeta1 (1)E=NE cyclic AMPGsbeta2 (2)E>>NE cyclic AMPGsE = epinephrine; NE = norepinephrineAlpha adrenergic receptors - NE ,E major stimulatory (except intestine)Beta adrenergic receptors - E major inhibitory ( except myocardium)Receptors Alpha 1 , 2 Beta 1, 2 ,3 Up regulation Down regulationAdrenalin alpha 1,2 . Beta 1, 2 ,3Nor-adr alpha 1,2 . Beta 1 , poor beta activity

Actions Of Adrenal Medulla

Actions On Various Organs Metabolism o2 consumption co2 production

Carbohydrate MetabolismGluconeogenesis , glycogenolysis , glycogenesis , insulin inhibition , glucagon secretion , ACTH secretion

Lipid Metabolism lipolysis thro HSL Heart - beta 1Cns alertness , anxiety , tremors - beta Blood vessel blood pressure Respiration beta 2

Contd Skin arrector pili Urinary Bladder And GIT Eyes alpha - pupilary dilation , beta produces relaxation of ciliary muscle Blood increases rbc , coagulabilitySkeletal muscle contraction , increase blood supply , glycogeneolysis Smooth muscle - splenic capsule shpincters dilator pupillae uterus arrector piliContd Relaxation in non sphicteric gi muscles Urinary bladder Bronchioles Kidney renin secretion Sweat glands Lacrmal glands Salaivary glands Role In Secretion Of Other Hormones Insulin , somatostatin Glucagon Thyroxin , t4 t3 enhancement TRH Renin secretion

Regulation Acute sympathetic stimulationChronic sympathetic stimulationACTH increases enzymes of catecholCortisol - PNMT Epinephrine Exposure to cold Hypoglycemia Dopamine Produced by adrenal medulla and dopaminergic neurons Vasoconstriction Dilatation in mesentery Increase in heart rate and BPPheochromocytoma Endocrine hypertension Anxiety Chest painFever Headache Hyperglycemia Nausea and vomiting Polyuria , glucosuria Palpitations Sweating TachycardiaWt lossTest for pheochromocytoma