IMED3004 Lecture 4: L4 Endocrine Control Systems II
1 Nov 2020
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Star has thus far been found in all tissues that can produce steroids, (adrenal cortex, gonads, the brain) Star transports cholesterol molecules into mitochondria p450scc. Regulated by camp (receptors for acth, atii, fsh, Then, it goes, it goes it just goes : well, sort of, most other enzymes are also regulated too, but are less rate-limiting". Corticosteroids: mineralocorticoids: cortex hormones that regulate minerals (sodium) Sex hormones: very low activity precursors to sex hormones. All regulated by different trophic hormones acting on cells with different enzymes (+ different routes!) Steroids are lipophilic = they diffuse between adjacent cells! Switching it on: cholesterol pregnenolone: need cholesterol = ldl receptors. P450scc (cyp11a1) = cholesterol side chain cleavage = rate limiting step. All steroids require these 2 enzymes: making it specific: pregnenolone all other steroids. Different strokes for different folks: adrenal cortex. Aldosterone = requires cyp11b2 (aldosterone synthase [corticosterone aldosterone]) Testosterone = 17 hsd (androstenedione testosterone: ova.
