The hypothalamus links the brain to the endocrine system. It tells the pituitary gland, which hangs just below it, which hormones to release and when.
The control center
The hypothalamus senses body temperature, water balance, stress and blood hormone levels. It sends releasing hormones through a small network of blood vessels to the anterior pituitary.
Anterior pituitary
The front lobe makes hormones that drive other glands: TSH for the thyroid, ACTH for the adrenal cortex, and FSH and LH for the ovaries and testes. It also makes growth hormone and prolactin.
Posterior pituitary
The back lobe stores and releases two hormones made in the hypothalamus. ADH tells the kidneys to keep water; oxytocin causes uterine contractions and milk let-down.
Negative feedback
When a target gland's hormone rises, it switches off the hypothalamus and pituitary. This loop keeps levels steady and explains why TSH rises when the thyroid is underactive.
| Hormone | Source | Main target |
|---|---|---|
| TSH | Anterior pituitary | Thyroid |
| ACTH | Anterior pituitary | Adrenal cortex |
| FSH and LH | Anterior pituitary | Ovaries and testes |
| Growth hormone | Anterior pituitary | Liver, bone and muscle |
| ADH | Posterior pituitary | Kidneys |
| Oxytocin | Posterior pituitary | Uterus and breasts |
At the bedside
Too little ADH causes large volumes of dilute urine and a high sodium; too much ADH holds water and lowers sodium. A pituitary tumor can press on the optic chiasm and cut off the outer visual fields.
Related guides
Written by Making Synapses. Topic reference: OpenStax, Anatomy and Physiology 2e (no text adapted).