Hypothalamus

The hypothalamus is the mediator between the hormone and nervous system. Read more about hypothalamic function and anatomy!

Hypothalamus

Of the hypothalamus is the central regulatory site between the endocrine system and the nervous system. It controls autonomic functions of the organism, such as food and water intake, body temperature, circulation, sleep and sexual behavior. Read all important information about the hypothalamus: function, structure and important diseases!

What is the hypothalamus?

The hypothalamus is an area of โ€‹โ€‹the diencephalon. It consists of nerve cell collections (nuclei), which act as switching stations for the leading and trailing pathways to other parts of the brain: For example, information about the hypothalamus flows from the hippocampus, the almond body (amygdala), the thalamus, the striatum, the cerebral cortex of the limbic system, the middle and hindbrain and the spinal cord.

Outgoing information flows from the hypothalamus to the midbrain and thalamus as well as to the neurohypophysis (posterior pituitary gland).

In the hypothalamus, all known in the body periphery hormones can be detected.

What is the function of the hypothalamus?

The hypothalamus is the mediator between the hormone and the nervous system. The hypothalamic hormones control, for example, the sleep-wake rhythm, the feeling of hunger and thirst, but also the sex drive and pain sensations. The thermoregulation of the body also starts from the hypothalamus.

Information from various measuring stations in the body about blood sugar, blood pressure, temperature and much more converges in the hypothalamus, which can then send signals for the release of certain hormones for regulation. These hypothalamic hormones are divided into three groups:

Effektorhormone

The first group of hypopthalamic hormones, called effector hormones, include oxytocin and adiuretine. Oxytocin stimulates labor at birth as well as the injection of breast milk into the breast. Adiuretin is responsible for water reabsorption in the kidney. Both hormones are synthesized in the hypothalamic nuclei, then transported to the posterior pituitary, from where they are released into the systemic circulation.

control hormones

The second group of hypothalamic hormones are control hormones: various releasing (release) hormones stimulate the pituitary gland to synthesize and secrete various hormones. Inhibiting hormones inhibit the secretion of pituitary hormones.

Other hormones

Additional neuropeptides from the hypothalamic neurons, together with the first or second group, affect the function of the anterior pituitary or act as communicators between the hypothalamus and other areas of the brain.

Control circuits ensure order

The effects of hormones must always be precisely tailored to the needs of the organism. Therefore, the systems of synthesis, secretion, receptor, transport to the target organ and the metabolism of each hormone must be exactly matched. To do that, there are control loops that affect all of this, including, in particular, the hypothalamic-pituitary system.

Example: thermoregulation

In addition to many other regulatory circuits, thermoregulation is important to the organism to maintain a core temperature of about 37 degrees Celsius. The core temperature of the body must - within certain limits - always be constant. To achieve this, the body has "sensors" in the skin and in the organs - free nerve endings of sensitive nerve cells. Their information is transmitted to the thalamus and then to the hypothalamus.

If the body core temperature drops, a control loop for temperature regulation starts. The hypothalamus stimulates the anterior pituitary with a specific hormone to release the hormone TRH (thyrotropin releasing hormone). TRH secretes TSH into the pituitary gland via TRH, which in turn stimulates the secretion of thyroxine (T4) from the thyroid gland. T4 enters adipose tissue and skeletal muscle and is converted to triiodothyronine (T3). T3 causes an increase in the basal metabolic rate, leads to increased energy supply from the liver, increases the heart rate - with the result of an increase in temperature.

When the body core temperature rises, the hypothalamus reduces the sympathetic tone, which widens the vessels in the periphery and promotes sweat secretion - resulting in a cooling of the body.

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Where is the hypothalamus?

The hypothalamus is a small part in the anterior part of the diencephalon and is located below the thalamus. It consists of the side wall and the bottom of the third ventricle and contains in its central area, which faces the ventricle, several core areas. The nerve fibers from the core areas run to the pituitary stalk (infundibulum).

What problems can the hypothalamus cause?

The Hypothalamus contains the Essence Center and the Saturation Center. In the case of disturbances in the eating center, which may be genetically or psychologically caused, no more food is absorbed - those affected lose weight. On the other hand, if the satiety center is disturbed and the center is permanently active, hyperphagia, an overgrowth of obesity, develops.

A pituitary adenoma (benign tumor of the pituitary gland) may affect the function of the hypophysis itself as well as that of the hypothalamus. As a result, too many or too few hormones either. For example, an acromegaly (enlargement of the nose, chin, fingers and skull) is the result of overproduction of STH, and Cushing's disease is caused by overproduction of cortisol.

Tumors in the area of hypothalamus grow, are very rare and lead by changes in hormone production, for example, to a hypothalamic syndrome. It is characterized by severe obesity and short stature.


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