Size and Location of the Hypothalamus

The hypothalamus is a small almond sized area, located in the center of the brain.  It is below the thalamus and behind the optic chiasm. The pituitary gland hangs on a stalk directly below the hypothalamus.

What does the Hypothalamus Do?

The hypothalamus creates hormones to help stimulate or inhibit many different bodily functions in order to monitor and maintain the body’s internal balance (homeostasis).  The hypothalamus also serves as a bridge between other systems of the body, including the nervous and endocrine systems, as it receives and processes information about the body, including the following:

  • 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
  • Emotions
  • Sexual behavior
  • Memory

Hormones Created by the Hypothalamus:

  • Anti-Diuretic Hormone (Vasopressin) – regulates water levels and influence blood volume and blood pressure.
  • Corticotropin-Releasing Hormone – acts on the pituitary gland causing the release of hormones in response to stress.
  • Oxytocin – influences sexual and social behavior.
  • Gonadotropin-Releasing Hormone – stimulates the pituitary to release hormones that influence the development of reproductive system structures.
  • Somatostatin – inhibits the release of thyroid-stimulating hormone (TSH) and growth hormone (GH).
  • Growth Hormone-Releasing Hormone – stimulates the release of growth hormone by the pituitary.
  • Thyrotropin-Releasing Hormone – stimulates the pituitary to release thyroid-stimulating hormone (TSH). TSH regulates metabolism, growth, heart rate, and body temperature.
  • Dopamine – important signaling molecule in the hypothalamus.

What Happens if the Hypothalamus is Damaged:

The hypothalamus coordinates the functions of all endocrine glands in the body. The endocrine glands secrete their hormones (chemical messengers) directly into the blood. Damage to the hypothalamus, whether at birth, as a result of surgery, a tumor, or Traumatic Brain Injury (TBI), can lead to significant health issues. Such as:

  • Diabetes insipidus: A condition associated with passing large amounts of urine, but blood sugars are normal. A chemical called vasopressin is released from the hypothalamus. This vasopressin regulates the water reabsorption in the kidneys. In the absence of vasopressin, the reabsorption process does not take place, thus inducing rapid water loss from the body.
  • Precocious Puberty: Early onset of puberty symptoms, usually before age 8 in girls and age 9 in boys.
  • Insomnia: A part of the hypothalamus sets our sleep-wake cycle.
  • Fluctuations in body temperature
  • Hypothalamic Obesity: Signs and symptoms of hypothalamic obesity include excessive appetite, inability to feel ‘full’, and rapid weight gain. In addition, people with this condition have a low metabolic rate, decreased physical activity, and excessive daytime sleepiness. Hypothalamic Obesity can lead to other conditions like:
    • Sleep apnea
    • Mood disorders
    • Dyslipidemia – an abnormal amount of lipids in the blood
  • Hypopituitarism: It occurs when the pituitary glands do not produce sufficient hormones due to loss of control by the hypothalamus. Various hormones generated by the hypothalamus directly affect those created by the pituitary gland. Hypopituitarism can lead to:
    • Adrenal insufficiency – in individuals with HH it is called Secondary Adrenal Insufficiency
    • Hypothyroidism – diminished thyroid hormone production
    • Hypogonadism – diminished production of sex hormones
    • Growth hormone deficiency – low growth hormone production
    • Prolactin deficiency – inability to lactate
  • Sex gland deficiency: This can lead to:
    • Erection problems
    • Infertility
    • Problems with breastfeeding