Adrenal Gland

Adrenal Gland

1. Cortex

   • All of the hormones are produced are steroid hormones, mineral corticoids, glucocorticoids and androgens and they are all synthesised from cholesterol.
   • Zona Glomerulosa
     • The outermost section of the cortex minusing the capsule.
     • Aldosterone
       • Renin-angiostenin system acts strongly and the electrolyte system also acts strongly upon the adrenal cortex to stimulate aldosterone which maintain normal extracellular fluids and concentration of ions. When there are high K+ it activates. Inhibited by low K+ and High NA+
   • Zona Fasciculata and Zona Reticularis
     • Androgens are synthesised here, Stimulated by the adrenocorticotropic hormone (ACTH) from anterior pituitary glands In females it is a major source of androgens for sex drive. In males, majority of the androgens is supplied by the testis.
     • Cortisol
       • Physical/Emotional Stressors activates it. ACTH activates the release. It have the same efffects as glucagon. It has the highest concentration just after waking.
       • Dysfunction
         • Hypersecretion: Cushing's Syndrome. Adrenal defect or excessive secretion of ACTH from pituitary causes excessive glucose produciton and loss of muscle proteins. Abnormal fat deposits and hence muscle wastage. Hyposecretion: Addison's Disease Adrenal glands can't produce much glucocorticoids. Poor response to stress and hyperpigmentation and lethargy and apathy.

2. Medulla

   • Made up of post-ganglionic sympathetic cells Produces about 80% adrenaline and 20% noradrenaline (cathecholamines). Stored on vesicles. Act on alpha and beta adrenergic receptors and g-proteins.
   • Cathecholamines
     • Synthesized from tyrosine. Sympathetic nervous system stimulates this and increases flight or flight responses.