PHSI2006 Study Guide - Midterm Guide: Adrenal Medulla, Anterior Pituitary, Circadian Rhythm

• School: University of Sydney
• Department: Physiology
• Course: PHSI2006
• Professor: phsi2006

Document Summary

Adrenal gland: there are 3 layers in the cortex and also a medulla: the adrenal cortex secretes steroids. All of the steroids start from cholesterol and it depends what enzymes are in the tissue as to which steroid occurs. E. g. aldosterone and cortisol are most important: the adrenal medulla secretes catecholamines. And aldosterone, angiotensin, parathyroid hormone, vit d kick in to help this. Cortisol is a protein secreted from adrenal cortex: biosynthesis from cholesterol, made on demand and not stored, transported on corticosteroid-binding globulin (made in liver), half-life of 60-90 minutes. There is circadian rhythms of tonic secretion and stress enhances release: control pathway of cortisol: crh (hypothalamus)! Cortisol (adrenal cortex): steroid hormones act on the genes/at the cellular level it initiates transcription, translation and new protein synthesis. Takes longer to take an effect: negative feedback regulation to anterior pituitary and hypothalamus. The three main metabolites- the glycerol fatty acids, amino acids and glucose are all increased by glucocorticoids.