Biopsychology: The Endocrine System - Hormones

The hypothalamus is connected to the pituitary gland and is responsible for stimulating or controlling the release of hormones from the pituitary gland. Therefore, the hypothalamus is the control system which regulates the endocrine system.

The pituitary gland is sometimes known as the master gland because the hormones released by the pituitary gland control and stimulate the release of hormones from other glands in the endocrine system. The pituitary gland is also divided into the anterior (front) and posterior (rear) lobes (see right), which release different hormones.

A key hormone released from the posterior lobe is oxytocin (often referred to as the ‘love hormone’) which is responsible for uterus contractions during childbirth. A key hormone released from the anterior lobe is adrenocortical trophic hormone (ACTH) which stimulates the adrenal cortex and the release of cortisol, during the stress response.

The main hormone released from the pineal gland is melatonin, which is responsible for important biological rhythms, including the sleep-wake cycle.

The thyroid gland releases thyroxine which is responsible for regulating metabolism. People who have a fast metabolism typically struggle to put on weight, as metabolism is involved in the chemical process of converting food into energy.

The adrenal gland is divided into two parts, the adrenal medulla and the adrenal cortex. The adrenal medulla is responsible for releasing adrenaline and noradrenaline, which play a key role in the fight or flight response. The adrenal cortex releases cortisol, which stimulates the release of glucose to provide the body with energy while suppressing the immune system.

Males and females have different sex organs, and in males the testes release androgens, which include the main hormone testosterone. Testosterone is responsible for the development of male sex characteristics during puberty while also promoting muscle growth. In females, the ovaries release oestrogen which controls the regulation of the female reproductive system, including the menstrual cycle and pregnancy.