The pituitary gland and hypothalamus
Pituitary gland and hypothalamus
The pituitary gland and the hypothalamus are a very important part of the endocrine system of the human body. This system includes all organs (called endocrine glands), but also individually scattered cells that produce different hormones (chemical messengers), which significantly influence the functions of target tissues. Hormones get to them by blood. The pituitary gland and hypothalamus are located in the brain and the hormones they produce control the release of hormones from other endocrine glands (e.g. thyroid, adrenal glands). The term hypothalamic-pituitary axis implies that the hormones of the hypothalamus are functionally superior to the pituitary hormones, which in turn directly affect other glands.
The hypothalamus is located in the lower part of the brain around the temples. It is divided into a front, middle and rear part. The functions of this organ are truly diverse, in addition to the control of the release of chemical messengers it is a center for thermoregulation, center for hunger, thirst and food intake, center for management of the function of the vegetative nervous system, sexual function, etc. Hormones are produced by the hypothalamus in the front and middle part. In the front part is produced oxytocin (which is essential for women for childbirth and lactation) and vasopressin (or antidiuretic hormone that reduces urine production in the kidneys). They are further transferred through nerve fibers to the pituitary gland, where they are stored. In the central part are produced liberins - releasing factors that promote secretion of pituitary hormones, and statins - inhibitory factors, which in turn reduces the secretion of these hormones. They get to the pituitary gland by blood through the hypothalamic-pituitary blood network. Liberins include: thyreoliberin (TRH), gonadotropin releasing hormone (GnRH), corticoliberin and growth-hormone-releasing hormone (GHRH) and statins include: prolactin-inhibiting hormone (PIH), dopamine and somatostatin (GHIH).
Pituitary gland or hypophysis is located below the hypothalamus; it is stored in the so-called Turkish saddle, which is a depression in the sphenoid bone. An average human pituitary gland measures around 1 cm and weighs about 0.5 grams. Despite its small size, it has a crucial role in the control of other endocrine glands, for which it is called the conductor of the endocrine system. It is divided into two lobes - the front the adenohypophysis and the back neurohypophysis. In the adenohypophysis are produced pituitary hormones that are regulated via the blood circulation by factors of the hypothalamus. They are somatotropin (GH, growth hormone), prolactin (PRL, essential during lactation in women), adrenocorticotropic hormone (ACTH, affecting the function of the adrenal gland), thyrotropin (TSH related to the function of the thyroid gland), gonadotropins (luteinizing hormone and follicle-stimulating hormone influencing the activity of the gonads) and endorphins. In the neurohypophysis hormone production does not occur. The lobe is connected to the hypothalamus by a stem leading nerve fibers, through which the neurohypophysis receives oxytocin and vasopressin from the hypothalamus. These hormones are stored here and, if necessary, they are just released into the large circulation.
The role of pituitary gland and hypothalamus in the organism
The pituitary gland as well as the hypothalamus has an undoubtedly essential and irreplaceable role in maintaining the correct operation of the human body due to the fact that so many other organs depend on their activity. Their function may be adversely affected by accidents or cancer.