IPHY 4440 1st Edition Lecture 18Outline of Current Lecture II. ZonationI. Other zonesIII. Glucocorticoid secretionIV. Types of action (of glucocorticoids)Current LectureII. ZonationA. Zona glomerulosa: outermost region (smallest portion of cortex). – Secretes aldosterone but it is not controlled by ACTH aka Renin-Angiotensin System (RAS)B. Zona fasciculate: largest region. –Secretes cortisol (F) and/or corticosterone (B)- Controlled by ACTH, So remove ACTH and fasiculatashrinks away to almost non existence (atrophy) after surgery, ACTH tropic hormone stimulate secretion of other hormones like glucocorticoids and stimulate the growth of target endocrine organs, Lot of ACTH will enlarge the adrenal C. Zona reticularis: innermost region. –Secretes androstendione DHEA and DHEAS which are controlled by ACTH or LH and secretion peaks at puberty=adrenarche - Reticular: something that forms really complex network- Only one layer/zone is part of the HPA axis à zona fasiculata - But all three zones are steriodogenic, produce steroids of different types - Medulla: epi and norepià sympathetic NSIII. Other zonesA. The fetal zone: largest zone at birth in humans. Size of adult adrenal at birth. Shrinks rapidly after birth. Most prominent in fetus before birth These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Within first year after birth, fetal zone will shrink and after baby is a year old will be completely gone. Important for steroid (androgen) synthesis during pregnancy. If fetus that doesn’t have strong fetal zone then mothers pregnancy cannot be maintained, not good and possibility of death. - Progesterone (precursor) - Depends on which zone you are looking at, will see different enzymes- Zona glomerulosa: what enzyme what would you find? Both P450 and P450aldoIV. Glucocorticoid secretion: controlled by ACTH (tropic stimulation)A. Patterns of secretion: diurnal/circadian rhythms- ACTH peak before we wake up - And cortisol also peak in the morning- Pattern is not absolute it depends on whether your nocturnal or diurnal- For rats under ACTH and cortisol do not peak until the evening B. Lifetime pattern of adrenal androgens - Male (first one) androgen levels are quite low initially and grow as child gets older and peaks at puberty: adrenarche- Girl and boy reach from 13-17 depends on person- Peak before one year of age: fetal zone (and zona reticularis) has not completely gone away so still completely cranking out androgens - Accelerates at puberty à Remains high until middle age à Declines begin between 40 and 50 yrs= ADRENOPAUSEV. Types of action (of glucocorticoids)1) Metabolism (include permissive) 2) Immune 3) Reproduction & development 4) Brain function 5)Permissive for metabolism and a lot of other things A. Effects on metabolism 1) Inhibits glucose uptake by “peripheral” tissues= everything except CNS –Especially inhibits muscle uptake of glucose and may induce temporary hyperglycemia Side Notes: Chronic starvation/ fasting (gluco are going to skyrocket) very little glucose floating around - Most metabolically demanding cell type in body: neurons - Glucocorticoids hate muscles bc they are the last thing that you want to target unless starving - The glucose sparing effects: smart choices in what tissues should be using glucose2) Stimulates gluconeogenesis: formation of glucose from amino acids or fatty acids. Activates enzyme PEPCK in liver and ONLY in liver and kidneys!3) Alters amino acid metabolism, causes protein catabolism in muscle and increase plasma AA levels. Stimulates AA uptake by liver à more gluconeogenic substrate4) Enhances lipolysis caused by other hormones à increase NEFAS & glycerol in plasma, more gluconeogenic substrate, glucose- Action that is permissive: glucocorticoids don’t do it directly but must be there to help - NEFS: free fatty acids + glycerol 5) Alters immune functions: GCs can suppress inflammation & GCs can enhance