The Hypothalamus

Written by Robert M. Sargis MD, PhD

The Hypothalamus Essentials

• The portion of the brain that maintains the body’s internal balance (homeostasis).
• The hypothalamus is the link between the endocrine and nervous systems.
• The hypothalamus produces releasing and inhibiting hormones, which stop and start the production of other hormones throughout the body.

The hypothalamus plays a significant role in the endocrine system. It is responsible for maintaining your body’s internal balance, which is known as homeostasis. To do this, the hypothalamus helps stimulate or inhibit many of your body’s key processes, including:

• Heart rate and blood pressure
• Body temperature
• Fluid and electrolyte balance, including thirst
• Appetite and body weight
• Glandular secretions of the stomach and intestines
• Production of substances that influence the pituitary gland to release hormones
• Sleep cycles

The hypothalamus is involved in many functions of the autonomic nervous system, as it receives information from nearly all parts of the nervous system. As such, it is considered the link between the nervous system and the endocrine system. You can learn more by reading a SpineUniverse article about the nervous system.

 

 Anatomy of the Hypothalamus

The hypothalamus is located below the thalamus (a part of the brain that relays sensory information) and above the pituitary gland and brain stem. It is about the size of an almond.

 
 Hormones of the Hypothalamus

The hypothalamus is highly involved in pituitary gland function. When it receives a signal from the nervous system, the hypothalamus secretes substances known as neurohormones that start and stop the secretion of pituitary hormones.  

 

Primary hormones secreted by the hypothalamus include:

• Anti-diuretic hormone (ADH): This hormone increases water absorption into the blood by the kidneys.
• Corticotropin-releasing hormone (CRH): CRH sends a message to the anterior pituitary gland to stimulate the adrenal glands to release corticosteroids, which help regulate metabolism and immune response.  
• Gonadotropin-releasing hormone (GnRH): GnRH stimulates the anterior pituitary to release follicle stimulating hormone (FSH) and luteinizing hormone (LH), which work together to ensure normal functioning of the ovaries and testes.
• Growth hormone-releasing hormone (GHRH) or growth hormone-inhibiting hormone (GHIH) (also known as somatostain): GHRH prompts the anterior pituitary to release growth hormone (GH); GHIH has the opposite effect. In children, GH is essential to maintaining a healthy body composition. In adults, it aids healthy bone and muscle mass and affects fat distribution.
• Oxytocin: Oxytocin is involved in a variety of processes, such as orgasm, the ability to trust, body temperature, sleep cycles, and the release of breast milk.
• Prolactin-releasing hormone (PRH) or prolactin-inhibiting hormone (PIH) (also known as dopamine): PRH prompts the anterior pituitary to stimulate breast milk production through the production of prolactin. Conversely, PIH inhibits prolactin, and thereby, milk production. Thyrotropin releasing hormone (TRH): TRH triggers the release of thyroid stimulating hormone (TSH), which stimulates release of thyroid hormones, which regulate metabolism, energy, and growth and development. 

Hypothalamic Disease
A disease or disorder of the hypothalamus is known as a hypothalamic disease. A physical injury to the head that impacts the hypothalamus is one of the most common causes of hypothalamic disease.

Hypothalamic diseases can include appetite and sleep disorders, but because the hypothalamus affects so many different parts of the endocrine system, it can be hard to pinpoint whether the root cause of the disorder is actually related to another gland.

In particular, the hypothalamus and pituitary gland are so tightly connected that it’s often difficult for doctors to determine whether the condition is associated with the hypothalamus or pituitary gland. These are known as hypothalamic-pituitary disorders. However, there are hormone tests that help shed light on which part of the body is the root cause.

The hypothalamus is arguably the most essential of the endocrine system. By alerting the pituitary gland to release certain hormones to the rest of the endocrine system, the hypothalamus ensures that the internal processes of your body are balanced and working as they should.