The endocrine system consists of tissues and organs that synthesize and secrete chemical substances (called hormones) into the bloodstream that then effect the activities of specific target cells in many organs the body.

Learning outcomes

Your knowledge of the histological features of the endocrine system should include

• identifying the following glands

1. pituitary gland – anterior and posterior.
2. adrenal gland – cortex and medulla.
3. thyroid gland – follicles, follicular cells and parafollicular cells.
4. parathyroid gland.
5. pancreas – pancreatic islets (islets of Langerhan).

• understanding the structural and functional specializations of each gland.

• understanding the structural/functional relationship of the hypothalamus and pituitary gland.

• understanding the structure/function of the hypothalamo-hypophyseal portal system.