What are the endocrine glands in the human body?

The mysteries of the human body have not yet been fully understood, but the structure of the human body has apparently been studied very thoroughly in medicine. For example, how many bones does the human body have and what specific functions does each one have? For example, what organs are there in the human body and what is the function of each organ. In addition, there are some endocrine glands in the human body. So what are the endocrine glands in the human body?

Endocrine glands

The endocrine glands of the human body include the pituitary gland, thyroid gland, pancreatic islets, adrenal glands, parathyroid glands, thymus and gonads. In addition, the pineal gland and endocrine cells distributed in the gastrointestinal mucosa, as well as certain nerve cells in the hypothalamus, also have endocrine functions. The following is some additional information about endocrine glands and the hormones they secrete.

pituitary

The pituitary gland hangs at the base of the brain, so it is also called the pituitary gland or hypopituitary gland. It is oval in shape, about the size of a pea, and connected to the lower part of the thalamus (also called the hypothalamus) by a short stalk. The pituitary gland can be divided into two parts: the adenohypophysis and the neurohypophysis. Adenohypophysis is a glandular tissue while neurohypophysis is a neural tissue.

The pituitary gland secretes growth hormone, prolactin, etc. Growth hormone acts directly on tissue cells, increasing the volume and number of cells and promoting human growth.

The pituitary gland also secretes thyroid-stimulating hormone, adrenocorticotropic hormone, and gonadotropin, which are collectively called trophic hormones. On the one hand, trophic hormones regulate the synthesis and secretion of hormones in the corresponding glands, and on the other hand, they maintain the normal growth and development of the corresponding glands.

Because the pituitary gland has the function of regulating and managing other endocrine glands, some people in the past called it the king of endocrine glands. The results of modern medical research show that the adenohypophysis does not independently command other glands, but its activities are controlled by various pituitary-stimulating hormones secreted by neurosecretory cells in the hypothalamus. Specifically, after the various hormones (collectively called neurohormones) secreted by certain nerve cells in the anterior hypothalamus are transported to the adenohypophysis, they can promote or inhibit the secretion of certain adenohypophysial hormones. For example, growth hormone-releasing hormone secreted by the hypothalamus can promote the secretion of growth hormone; growth hormone-inhibiting hormone can inhibit the secretion of growth hormone. Therefore, it now seems that the crown of king of endocrine glands should belong to the hypothalamic neurosecretory cells.

The neurohypophysis does not have the function of synthesizing hormones. The antidiuretic hormone (vasopressin) and oxytocin it releases are secreted by certain cells in the hypothalamus, sent to the neurohypophysis along nerve fibers, and then released into the blood under the regulation of the nervous system. Antidiuretic hormone can promote the reabsorption of water by the renal tubules and collecting ducts, thereby reducing urine volume. We often have this experience in life: when we drink less water or lose water due to sweating, the amount of urine will decrease. This is because in this case, the secretion of antidiuretic hormone increases, thereby promoting the reabsorption of water by the renal tubules and reducing the amount of urine. Antidiuretic hormone can cause constriction of small arteries throughout the body and increase blood pressure, so it is also called vasopressin. In general, vasopressin has antidiuretic and blood pressure-increasing effects. Oxytocin also has two physiological effects. One is to strongly stimulate uterine contraction, and the other is to promote milk discharge.

To sum up, the pituitary gland is the most important endocrine organ in the human body. It has a complex structure, secretes many types of hormones, has a wide range of effects, and can regulate the activities of other endocrine glands.