Around the size of a pea and located just below the hypothalamus, this tiny gland has a powerful effect on the body. This master gland makes hormones that control other endocrine glands, such as the thyroid and adrenals, and receives its information from the hypothalamus, for example a change in temperature.

The pituitary is divided into two parts:

• The anterior lobe regulates the thyroid, adrenals and reproductive glands.
• The posterior stores and releases the hormones from the hypothalamus
  without making any hormones itself. For example the antidiurectic
  hormone is released as it prevents excess water being excreted by the kidneys.

The pituitary gland also secretes endorphins that act on the nervous system to respond to pain as well as secreting the hormone FSH and luteinizing hormone that are vital for reproduction.