Hormonal regulation of metabolism and body functions
22 topics with concise breakdowns: definitions, key facts, and classroom questions.
This section focuses on the endocrine system and the molecular mechanisms of hormone action. Here we explore how biologically active substances control our body at the biochemical level — from cell receptor function to systemic responses.
The material covers key regulatory axes. You will study energy homeostasis during the absorptive and postabsorptive periods, metabolism during starvation, as well as the effects of peptide hormones, glucagon, and corticosteroids. A separate block is dedicated to water-salt metabolism (ADH, RAAS, atrial natriuretic peptide) and the regulation of calcium and phosphate levels.
In seminars and exams, pathochemistry is traditionally tested most rigorously: the molecular mechanisms of diabetes mellitus, adrenal dysfunction (regulation of cortisol synthesis), and hyper- and hypothyroidism resulting from iodothyronine pathway disruptions. Understanding these topics is your foundation for clinical endocrinology.
Why is the action of hormones in the body usually short-lived?
This is due to the fact that the synthesis and secretion of hormones are tightly regulated, and the circulating hormones themselves have a very high rate of inactivation (destruction).
What is the difference between liberins and statins?
Both groups of substances are hypothalamic releasing hormones. However, liberins stimulate the synthesis of pituitary hormones, while statins inhibit it.
Which hormones act via intracellular receptors?
This group includes steroid hormones and thyroxine. They cross the cell membrane and bind to receptors located in the cytosol or cell nucleus.
What happens to insulin inside secretory granules?
The preprohormone contains an N-terminal signal peptide (usually 26 amino acids), which is necessary for directing the molecule into the lumen of the ER. After its cleavage, a prohormone is formed, which then undergoes further cleavage by specific proteases.
In what form is glucagon initially synthesized?
In the form of an inactive precursor — preproglucagon, which is subsequently activated by partial proteolysis in pancreatic cells.
Where are iodothyronine receptors located?
Receptors for T3 and T4 are located intracellularly (in the nucleus). The hormones are lipophilic, cross the membrane, and directly regulate gene transcription.
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