Published August 13, 2023 by

Hypothalamus। Definition, Location, Functions, Hormone Productions & Pathology

Hypothalamus is a region of the brain located below the thalamus and which acts in the regulation of body temperature, hunger, thirst and sexual behavior.

Hypothalamus is a region of the brain located just below the thalamus. It is a small region, but with great importance for the proper functioning of the organism, being considered the integrating link between the endocrine and nervous systems. The hypothalamus regulates thirst, appetite, temperature and blood pressure

It is also responsible for producing hormones that stimulate and inhibit the action of the pituitary gland, acting, therefore, indirectly, on different structures of our body. The hypothalamus also produces hormones that are released by the neurohypophysis, antidiuretic hormone and oxytocin. The antidiuretic hormone ensures greater reabsorption of water by the kidneys, while oxytocin is related to the ejection of milk by the mammary glands and uterine contraction.

Summary about Hypothalamus 

• It is a small structure of the brain. 

• It performs a number of important functions in the body, such as regulating hunger, temperature and blood pressure. 

• It produces hormones that will be secreted by the neurohypophysis and inhibition and release hormones that will act by controlling the secretion of hormones by the pituitary. 

• Antidiuretic hormone and oxytocin are the hormones made by the hypothalamus and released by the neurohypophysis. 

• The antidiuretic hormone promotes an increase in the concentration of urine, as it ensures greater reabsorption of water by the kidneys. 

• Oxytocin promotes contraction of the uterus at the time of childbirth and promotes milk ejection.

Functions of the Hypothalamus 

The hypothalamus is a region of the brain that has a number of important functions, being considered the integrating link between the endocrine system and the nervous system. Among the functions that can be attributed to the hypothalamus, we can highlight: 

• cardiovascular regulation (increase and decrease in blood pressure and increase and decrease in heart rate); 

• regulation of appetite and energy expenditure; 

• regulation of body water (controls the excretion of water in the urine and provides a feeling of thirst); 

• body temperature regulation; 

• acts on the biological clock; 

• regulates milk ejection and uterine contraction at the time of childbirth; 

• plays a role in sexual and mating behavior; 

• initiates fight-or-flight response; 

• stimulates and inhibits the secretion of hormones by the pituitary gland.

Hormone Productions  

The hypothalamus is a brain structure that produces hormones that act to control pituitary secretion and hormones that are released by the pituitary. Initially, we will talk about the hormones synthesized by the hypothalamus and which control the action of the pituitary gland. These hormones are known as hypothalamic releasing and inhibitory hormones and are synthesized by special neurons in the hypothalamus. They are:

Thyrotropin-releasing hormone (TRH): acts by stimulating the secretion of thyroid-stimulating hormone (TSH) and prolactin. 

Corticotropin Releasing Hormone (CRH): Promotes the release of adrenocorticotropic hormone (ACTH). 

Growth Hormone Releasing Hormone (GHRH): It works by ensuring the release of growth hormone. 

Growth hormone inhibitory hormone (GHIH) (somatostatin): causes inhibition of growth hormone release. 

Gonadotropin-releasing hormone (GnRH): triggers the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). 

Dopamine or prolactin inhibitory factor (PIF): acts by inhibiting the release of prolactin.

In addition to the releasing and inhibitory hormones, the hypothalamus produces: the antidiuretic hormone or vasopressin and oxytocin. Despite being synthesized by the hypothalamus, the two hormones will be released by the pituitary, more precisely by the neurohypophysis. Both hormones are polypeptides that contain nine amino acids. See, below, the functions that can be attributed to these two hormones. 

Antidiuretic hormone (ADH) or vasopressin: it is responsible for decreasing the volume of urine and increasing its concentration. This happens because this hormone promotes an increase in the permeability of the tubules and collecting ducts, causing a greater amount of water to be reabsorbed. 

Oxytocin: acts in the contraction of the uterus at the time of childbirth, in addition, it promotes the ejection of milk by the mammary glands, a process that is stimulated by the baby's suction.

Hypothalamus and Pituitary 

The hypothalamus is directly connected to the hypophysis (also called the pituitary) from a stalk called the infundibulum. The communication between these two regions is called the hypothalamic-pituitary axis, whereby the hypothalamus establishes control of the pituitary gland and the latter, in turn, establishes control of other glands in the body through the production of hormones. 

The pituitary is divided into two regions, the neurohypophysis and the adenohypophysis, which are anatomically united, but synthesize different hormones. Hormones secreted by the neurohypophysis (or posterior pituitary) are synthesized in the hypothalamus region and then transported to the neurohypophysis region. 

This region secretes the antidiuretic hormone (ADH), responsible for increasing the reabsorption of water by the kidneys, participating in the control of blood pressure, and also the hormone called oxytocin, which stimulates the ejection of milk in the mammary glands and uterine contractions during childbirth.

The adenohypophysis (or anterior pituitary), unlike the neurohypophysis, produces its own hormones, in addition to storing and secreting them into the bloodstream. Among the hormones produced in the anterior pituitary are: 

Adrenocorticotropic hormone (ACTH): stimulates cells in the adrenal cortex to synthesize their corticoid hormones. 

Thyroid-stimulating hormone (TSH): stimulates the thyroid to produce its T3 and T4 hormones. 

Follicle stimulating hormones (FSH) and luteinizing hormones (LH): act on the gonads to produce sex steroid hormones. 

Growth hormone (GH) or somatotropin: acts on various tissues, such as bones, stimulating their growth. 

Prolactin (PRL): acts on the mammary gland, stimulating milk production. The secretion of anterior pituitary hormones is controlled by the hypothalamus, through hypothalamic hormones.

Diseases related to the Hypothalamus 

The hypothalamus is related to the regulation of several activities, and any disorder that compromises the proper functioning of this region can affect the functioning of the activities that are regulated by it. 

Among some diseases related to the hypothalamus, there is acromegaly, which can be developed by a dysfunction in the functioning of the hypothalamus and which is triggered when levels of growth hormone (GH) are above normal. 

Another related condition is gonadotropin deficiency, which can lead to low levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which in turn will affect the production of sex steroid hormones. Furthermore, there is the occurrence of pituitary tumors, which trigger changes in the production of several hormones.