Hypothalamus

Hypothalamus
The highlighted area shows the hypothalamus. The hypothalamus is a complex area of the brain with a number of important functions. One of the most important is to link the nervous system to the endocrine system via the pituitary gland. Credit: Roger Harris/Science Photo Library/Getty Images

What Is the Hypothalamus?

About the size of a pearl, the hypothalamus directs a multitude of important functions in the body. It is the control center for many autonomic functions of the peripheral nervous system. Connections with structures of the endocrine and nervous systems enable the hypothalamus to play a vital role in maintaining homeostasis. Homeostasis is the process of maintaining bodily equilibrium by monitoring and adjusting physiological processes.

Blood vessel connections between the hypothalamus and pituitary gland allow hypothalamic hormones to control pituitary hormone secretion. Some of the physiological processes regulated by the hypothalamus include blood pressure, body temperature, cardiovascular system functions, fluid balance, and electrolyte balance. As a limbic system structure, the hypothalamus also influences various emotional responses. The hypothalamus regulates emotional responses through its influence on the pituitary gland, skeletal muscular system, and autonomic nervous system.

Hypothalamus Function

The hypothalamus is involved in several functions of the body including:

  • Autonomic Function Control
  • Endocrine Function Control
  • Homeostasis
  • Motor Function Control
  • Food and Water Intake Regulation
  • Sleep-Wake Cycle Regulation

Hypothalamus Location

Directionally, the hypothalamus is inferior to the thalamus. It is posterior to the optic chiasm and bordered on the sides by the temporal lobes and optic tracts.

The location of the hypothalamus, specifically its close proximity to and interactions with the thalamus and pituitary gland, enables it to act as a bridge between the nervous and endocrine systems.

Hypothalamus Hormones

Hormones produced by the hypothalamus include:

  • 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.

Hypothalamus Structure

The hypothalamus consists of several nuclei that may be divided into three regions. These regions include an anterior, middle or tuberal, and posterior component. Each region can be further divided into areas that contain nuclei responsible for a variety of functions.

Region     Functions
Hypothalamus Regions and Functions
AnteriorThermoregulation; releases oxytocin, anti-diuretic hormone, and gonadotropin-releasing hormone; controls sleep-wake cycles.
Middle (Tuberal)Controls blood pressure, heart rate, satiety, and neuroendocrine integration; releases growth hormone-releasing hormone.
PosteriorInvolved in memory, learning, arousal, sleep, pupil dilation, shivering, and feeding; releases anti-diuretic hormone.

Connections with various parts of the central nervous system allow the hypothalamus to influence various functions. It has connections with the brainstem, the part of the brain that relays information between the peripheral nerves and spinal cord to the upper parts of the brain. The brainstem includes the midbrain and portions of the hindbrain. The hypothalamus also connects to the peripheral nervous system. These connections enable the hypothalamus to be involved in many autonomic functions. In addition, the hypothalamus has connections with other limbic system structures including the amygdala, hippocampus, thalamus, and olfactory cortex.

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More Information:

For additional information on the hypothalamus, see:

  • Functional Anatomy of the Hypothalamus and Pituitary Gland

Divisions of the Brain

  • Forebrain - encompasses the cerebral cortex and brain lobes.
  • Midbrain - connects the forebrain to the hindbrain.
  • Hindbrain - regulates autonomic functions and coordinates movement.