PHGY 214 Lecture Notes - Lecture 4: Adrenal Cortex, Adrenal Medulla, Circadian Rhythm
28 Apr 2016
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Document Summary
Two, embedded above each kidney in a capsule of fat. Composed of two endocrine organs: adrenal cortex. Secretes 3 types of steroid hormones, half life of hours: adrenal medulla. Secretes catecholamines (mostly epinephrine, some norepinephrine), half life of seconds. The 3 layers are responsible for synthesizing of the 3 different steroids. The enzymes neede to synthesize he steroids are different in each layer. Mineralocorticoids: mainly aldosterone, influence mineral balance, specifically na+ and k+ balance, sodium absorption relies on potassium secretion, not regulated by hypothalamic-pituitary axis. Stimulates hepatic gluconeogenesis: stimulates liver cells to produce glucose. Inhibits glucose uptake and use by many tissues, but not the brain: brain doesn"t function well without glucose, prevents certain tissues from taking all the glucose to make sure the brain gets enough. Stimulates protein degradation in muscle: amino acids become available. Facilitates lipolysis: breakdown of lipids, glycolysis, fatty acids can be used as alternative energy source.
