Topic overview

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The overview follows six sources of endocrine signals. It links pineal melatonin with circadian rhythm and light exposure, and thymic thymosin with T-cell development in early life. Gastrointestinal hormones are distinguished by their main actions: gastrin increases acid secretion, CCK supports bile and pancreatic enzyme release, secretin increases bicarbonate, GIP promotes insulin secretion, and motilin supports motility between meals. Kidney hormones connect erythropoietin to red blood cell production, renin to RAAS activation, and calcitriol to calcium and phosphate absorption. The topic also introduces atrial natriuretic peptide in blood pressure regulation and adipose hormones involved in appetite and insulin sensitivity.