The hypothalamus is an important area of the brain that, as a higher-level control center, controls numerous vegetative body functions, such as food and fluid intake, circulatory regulation, maintenance of body temperature and the control of the salt and water balance.
In addition, it continues to determine emotional and sexual behavior. Compared to other brain areas, the hypothalamus is comparatively small. It is part of the diencephalon, lies below the thalamus, weighs about 15 grams and is about the size of a 5 cent piece. The pituitary gland, to which it is connected via the pituitary stalk (infundibulum), is attached to it.
$config[ads_text1] not found
The pituitary gland is about the size of a hazelnut and is located in the middle of the cranial fossa in a bony bulge at the level of the root of the nose, anatomically referred to as the sella turcica. It consists of two parts, the anterior pituitary lobe and the posterior pituitary lobe. Both parts are structured differently and differ in their function. However, the hypothalamus and the pituitary gland together form an important functional unit and synthesize hormones with which they can control and influence the vegetative functions of the body.
The hypothalamus is bounded above by the thalamus, towards the forehead by the optic chiasm (junction of the optic nerves) and towards the bottom by the midbrain (mesencephalon). The hypothalamus is connected to the hypophyseal stalk (infundibulum) Pituitary gland (Pituitary gland) connected. It consists of several core areas that have different functions. The posterior part of the hypothalamus contains the corpora mamillaria, nuclear areas that lead to the limbic system belong and play an important role in memory processing. The front part of the hypothalamus contains numerous smaller core areas that mainly produce hormones and belong to the vegetative system.
$config[ads_text2] not found
The hypothalamus is an important control center in our brain. As an exocrine gland he forms and places Hormones free, which mainly influence and control the vegetative processes. Via its core areas, which produce and release the hormones, the hypothalamus thus controls, among other things, the individual day-night rhythm, food and fluid intake, regulates the cardiovascular system, takes part in memory formation and ensures the maintenance of body temperature.
But the hypothalamus also produces hormones like Oxytocin, especially during the pregnancy is poured out and the Labor pains initiates, but also conveys a feeling of closeness and trust between two people. Another hormone that is made and secreted in the hypothalamus is the hormone Prolactin, which leads to the growth of the mammary glands during pregnancy and to the penetration of milk into the mother after birth. All of these hormones are subject to controlled loops that reinforce each other, but can also inhibit one another. This will now be discussed in more detail below.
There are diseases that affect the production of hormones in the hypothalamus or in the Pituitary gland can disturb. For example, a hematoma as a result of an operation in the head area can cause a Cerebral hemorrhage or after an accident, press on parts of the sensitive organs and compress them so much that they become functionless and hormone formation is no longer possible. Large hematomas must be removed surgically. In the case of smaller hematomas and few side effects, it is possible to wait for the hematoma to dissolve itself. But also an inflammation of the meninges (meningitis) or the brain itself (Encephalitis) can damage the hypothalamus or the pituitary gland so severely that adequate hormone production is no longer possible. In these cases, depending on which core areas and hormone-producing parts are affected, hormone deficiencies and failures would occur.
$config[ads_text3] not foundFirst of all, the growth hormone axis is usually affected by damage that is associated with a deficiency in growth hormones and can lead to dwarfism in children. Second, the sex hormone axis is mostly affected. A deficiency in FSH and LH manifests itself in women mainly as a lack of it Menstrual period and sexual aversion, especially in men Erectile dysfunction. The other axes only fail relatively late and rarely. A lack of Thyroid hormones is usually associated with fatigue, exhaustion, hair loss and weight gain. A lack of ACTH and cortisol leads to disturbances of the salt and water balance, the Blood sugar and des Blood pressure. One therapeutic option here is primarily hormone substitution.
The hypothalamus makes a variety of different hormones. Some of these hormones are called "releasing hormones". They act directly on them in a hormonal control loop Pituitary gland (Pituitary gland) and stimulate the formation of further hormones there, which in turn act directly on the target organs or trigger further hormone production.
In return, there are the "inhibiting hormones", which are also formed by the hypothalamus and which inhibit the release of hormones from the pituitary gland and the periphery (to the target organs). The most important releasing hormones of the hypothalamus are CRH (Corticotropin-releasing hormone) that TRH (Thyrotropin-releasing hormone), the growth hormone-releasing hormone (also called somatotropin or STH labeled) and that GnRH (Gonadotropin-releasing hormone). The CRH stimulates the formation of in the pituitary gland ACTH (Adrenocorticotropic hormone). The ACTH in turn acts on the Adrenal gland, whereupon more glucocorticoids, mineral corticoids and androgens are formed. Glucocorticoids, their main representatives Cortisol act mainly on the metabolism, with an increase in blood pressure and blood sugar, and on the immune system, with an anti-inflammatory effect. The main stimuli for the release of cortisol are stress and pain, but also lower levels Blood pressure or one too low Blood sugar.
$config[ads_text4] not found
Mineral corticoids such as Aldosterone, regulate the body's salt and water balance. Androgens, which are also produced in the adrenal gland, have an anabolic metabolic effect, building up muscles and bones. If enough androgens, mineral corticoids or glucocorticoids have been produced by the body, they inhibit the further release of CRH and ACTH from the hypothalamus and the pituitary gland via negative feedback regulation. This prevents too many hormones from being produced peripherally (in the adrenal gland).
Another control cycle is the formation of TRH. Via the TRH, the hypothalamus stimulates the formation of TSH (Thyroid-stimulating hormone) in the pituitary gland, which in turn directly affects the thyroid acts and there to an increase in thyroid hormones (T3 / T4) leads. The main stimuli for the formation of TRH are severe cold and stress. The thyroid hormones T3 and T4 mainly affect the circulation and metabolism, and lead to a general Increase in the basal metabolic rate. They also increase the breakdown of fats, proteins and carbohydrates, and increase that Heart rate, temperature and blood pressure. To prevent overproduction of thyroid hormones, there is also a negative feedback mechanism in which the formation of T3 and T4 prevents the further formation of TSH.
The growth hormone releasing hormone (also known as somatotropin or STH), which is produced in the hypothalamus, plays a central role in the growth and regulation of the metabolism. It in turn stimulates the formation of growth hormone (synonym: growth hormone) in the pituitary gland, which in turn affects cells in the liver that produce a hormone (IGF-1) that promotes growth during childhood, and later in adulthood mainly results in anabolic metabolic regulation. This mechanism is inhibited by the hormone somatostatin, which is also produced in the hypothalamus. Via the GnRH (gonadotropin-releasing hormone) the hypothalamus stimulates the release of the two hormones LH and FSH in the pituitary gland. FSH and LH play a central role in the formation of sex hormones and the development of the gonads. In women, FSH causes egg cells to mature and form Estrogens, as well as the maturation of sperm cells in men. LH promotes ovulation and the formation of estrogens and progesterone in women and testosterone in men, with the development of the respective sexual characteristics during puberty. This control loop is also subject to you negative feedback mechanism.
The most important inhibiting hormones that are formed in the hypothalamus are for example Somatostatin, which inhibits the release of growth hormone in the pituitary gland, and Dopamine, the Prolactin inhibits. Other hormones that are formed in the hypothalamus and act directly on the target organ (e.g. kidney, uterus, breast) are, for example ADHwhich, in addition to the mineral corticoids, also regulates the body's salt and water balance via the kidneys, Oxytocin, which is released mainly during pregnancy to induce labor and Prolactinwhich leads to the penetration of milk into the female mammary glands. Disturbances in the respective circulatory system usually lead to serious illnesses that are associated with either a deficiency or an oversupply of hormones. Consequences are mostly Developmental disorders, infertility or a lack of adaptation of the body to different environmental situations and stresses.
Tumors can also be parts of the hypothalamus or the Pituitary gland compress so much that adequate hormone formation is no longer guaranteed. Tumors that only originate from the hypothalamus itself are rather rare. Most often it concerns with hypothalamus tumors Gliomas - that is, tumors that originate from certain brain tissue cells and can appear anywhere in the brain. According to WHO, they are in four degrees divided.
Grade I are mostly benign tumors that can be easily removed surgically. Grade IV are very malignant tumors with a poor prognosis. Many tumors start from the pituitary gland, for example the craniopharyngioma. It is a benign tumor that starts from the pituitary gland and presses on surrounding structures. The tumor can Visual disturbances and cause impaired hormone production. Treatment options are usually surgery, with subsequent radiation if necessary. Missing hormones, however, need to be regular and lifelong be substituted. Some tumors can also originate from the hormonal tissue itself and lead to increased hormone production. Tumors that originate from glandular tissue and produce hormones are called Adenomas designated.
This is a relatively common, hormone-producing tumor of the pituitary gland Prolactinomawhich is excessive Prolactin forms. Affected women often suffer from one Amenorrhea (Absence of menstruation), as well as milk leakage from the nipples. Certain drugs can be used for therapy here. If this is not enough, the tumor is usually removed by surgery. A tumor that produces growth hormones leads to the clinical picture of the during the growth phase Gigantismwhere there is excessive growth in size. However, if the tumor does not appear until adulthood, this tumor can have a Acromegaly cause. This is an enlargement of the hands and feet, the head and facial features such as the nose. Therapy options are surgery, with subsequent irradiation if necessary, if the entire tumor could not be removed.
