Introduction To Endocrine System

ENDOCRINE SYSTEM Glands are the secretory organs and are of two main types. 1. EXOCRINE GLANDS 2. ENDOCRINE GLANDS ENDOCRINE GLANDS These are glands of internal secretion and do not possess the duct. Endocrine glands secrete active substances known as hormones. Hormones are the informational molecules, transported through blood and acts only on the target organs. Hormones secreted by endocrine glands do not act as enzymes. Human endocrine system consists of following glands.

1. 2. 3. 4. 5. 6. 7. 8.

Hypothalamus- pituitary Thyroid Parathyroid Adrenal Testes (male), ovaries (females) Thymus Pineal Pancreas

Pituitary gland is a small pea shaped gland situated below the hypothalamus and connected to the brain by stalk. Neurons of the hypothalamic nuclei control the pituitary gland. The pituitary gland is divided into three lobes. 1. Anterior lobe 2. Posterior lobe 3. Intermediate lobe

FUNCTIONS 1. Secretion of the anterior pituitary hormones. Anterior lobe secretes six hormones which regulates. z Body growth z Thyroid secretion z Growth of hormones responsible for development of sex characters in male and female 2. Intermediate lobe hormones gives skin its characteristic color by synthesizing a pigment called melanin. 3. Secretion of posterior pituitary hormones.

4. Since the hormones from the pituitary gland controls the secretion of hormones from the other gland and controls the growth, development and other major activities, pituitary is also referred to as master gland.