Physiopathology for Biomedical Sciences: Endocrinology

The endocrine system relies on different endocrine axis to assure homeostasis and the control of reproduction, growth and metabolism. Several internal secretory glands function as different endocrine axis: the pituitary, the pineal gland, the thymus gland, the thyroid, four parathyroid glands, two adrenals, two gonads, the endocrine pancreas, the gastrointestinal endocrine cells, the adipose tissue and their specific secretions known as hormones.
Endocrine glands present with high vascularization in order to secrete the hormones into circulatory system. They also receive regulatory signals (negative and positive feedbacks) from hormones and other signals (glucose, electrolytes, etc…).
Hormones are chemical messengers secreted by endocrine glands, acting in autocrine, paracrine, or endocrine manner. These molecules may derive from aminoacids (for instance thyroid hormones, serotonin or melatonin), peptides (like insulin or thyrotropin hormone), steroids (mineralocorticoids, glucocorticoids and sexual steroids) or eicosanoids (such as prostaglandins). Their cellular actions depend on the binding of transmembrane or intracellular receptors, to bring about the effects on metabolism. The physiology and pathology of the endocrine system are the result of increased or decreased production of various hormones: these constitute hyper or hypofunction endocrine syndromes. It must also be taken into account the mass and distant effects caused by gland tumors and, rarely, their metastasis. We will review in this course differents aspects of endocrine physiopathology.