Dorothy FarrarNeurohypophyse
The neurohypophysis is part of the pituitary gland and is also known as the posterior pituitary gland . The hormones adiuretin and oxytocin produced in the hypothalamus are transported to the neurohypophysis and released from there into the bloodstream.
Definition
The neurohypophysis is the back part of the pituitary gland, the pituitary gland. From an evolutionary point of view, the neurohypophysis is a part of the brain . Because it lies topographically behind the adenohypophysis, the anterior lobe of the pituitary gland, the neurohypophysis is also called the posterior pituitary gland (HVL). It releases two of the hormones produced in the hypothalamus into the blood .
Anatomy
The pituitary itself is about the size of a hazelnut. It sits at the base of the skull in the so-called Turkish saddle (Sella turcica), a bone structure on the inside of the sphenoid bone. The posterior pituitary is divided into a pituitary stalk and a neural lobe.
The tissue of the neurohypophysis consists of axons, i.e. nerve fibers , on the one hand, and pituicytes on the other. Pituicytes are special supporting tissue cells that influence the release of hormones from the posterior pituitary gland. The neurohypophysis is connected to the hypothalamus via the pituitary stalk (infundibulum).
The so-called eminentia mediana is also located near the pituitary stalk. It is a vascularized region that plays an important role in the release of the regulatory hormones of the hypothalamus. It forms the intersection between the nervous and endocrine systems.
The secretions of the hypothalamus, bound to carrier proteins, reach the neurohypophysis via the hypothalamophysial tract, a nerve fiber tract that runs through the pituitary stalk. Here they are stored in the neural lobe, split off from their transport protein if necessary and released into the blood.
Function
The neurohypophysis serves as a storage and transport medium for the hormones of the hypothalamus. Both hormones are initially bound to so-called neurophysins in the hypothalamus for transport purposes. In the posterior pituitary gland, hormones are stored together with the neurophysins. If there is now a need for one of the two hormones, the pituicytes of the neurohypophysis ensure that the neurophysins are split off and thus trigger the release of the required hormones.
The antidiuretic hormone, also known as vasopressin or adiuretin, is involved in the regulation of water balance. ADH has an antidiuretic effect, which means it promotes water reabsorption in the kidneys . In addition, the hormone leads to a narrowing of the arterial vessels. This is also referred to as vasoconstriction.
Adiuretin causes an increase in blood pressure through water reabsorption and vasoconstruction . Along with other hormones such as aldosterone or angiotensin II, ADH also influences drinking behavior.
Oxytocin is also known as the bonding hormone. It affects the bonding between mother and child, between sex partners, and also has an impact on normal social interactions. Research shows a link between oxytocin and feelings like love, calm and trust. In addition, the hormone has been proven to have a lust-increasing effect. After orgasm, oxytocin causes pleasant fatigue and relaxation. Oxytocin is increasingly released, especially with pleasant touches such as caressing, hugging or massages.
During childbirth, oxytocin causes the uterine muscles to contract, inducing labor. Oxytocin is also used in obstetrics as a labor drip. After birth, oxytocin causes the aftermath. These are important to avoid secondary bleeding and also promote the regression of the uterus.
Furthermore, the hormone together with prolactin stimulates milk production and milk evacuation. Oxytocin lowers blood pressure and cortisol levels . Oxytocin can also cause weight gain and fatigue. Research also shows that oxytocin has a regulatory effect on malignant new tissue formation.
Diseases
Diseases of the neurohypophysis are usually associated with reduced release of adiuretin. Disturbances in the hormone regulation of oxytocin are rare. The main cause of dysregulation of the neurohypophysis are tumors of the hypothalamus and the pituitary gland.
Inflammation or injuries to the pituitary stalk can also cause an adiuretin deficiency. The pituitary gland can also be affected by strokes, cerebral hemorrhages or radiation.
The adiuretin deficiency leads to increased water loss and thus to an increased amount of urine. In order to compensate for the loss of water via the kidneys, a strong feeling of thirst arises . Affected patients drink several liters of water a day, but excrete exactly the same amount. Urine volumes of ten to twenty liters per day are not uncommon in this disease, diabetes insipidus.
Typical symptoms of diabetes insipidus include high levels of urine and an increased feeling of thirst , fatigue , dry skin and low blood pressure . The constant loss of water also leads to disturbances in the electrolyte balance.
In particular, the sodium concentration in the blood increases. The consequences of this hypernatremia are seizures , coma , and disorientation. If there is a lack of ADH, the sufferers receive a synthetic form of the hormone in the form of tablets, injections or as a nasal spray.
Hello and welcome to my Health Guide & Encyclopedia! My name is Dorothy Farrar, and I'm the founder and main author of this platform.
My passion for health and wellness started at a young age when I became interested in the connection between the food we eat and the way we feel. This fascination led me to study nutrition and dietetics in college, where I learned about the importance of a balanced diet and the impact of various nutrients on the body.