Endocrine System

Introduction

The various physiological activities of animals are controlled by two systems-

• nervous system
• Endocrine System. In human beings and other mammals, ten different glands form the endocrine system.

These are ductless glands and secretes their respective hormones directly into the blood stream. These hormones are carried by the blood to different parts of the body where they produce specific physiological effects.

Hormones

Hormones are bio molecules, secreted by special glands, called endocrine glands. A hormone has a specific effect on a specific organ of the body, which is called the target organ.

Endocrine Glands in Human body

• Pituitary Gland: located between the roof of the mouth and floor of the brain. It is also known as 'master gland'.
• Pineal Gland: It is located between the two halves of the brain. This gland is related to biological clock of an organism.
• Thyroid gland: It is a bilobed gland and largest of all the endocrine glands. It is located behind the voice box (larynx) in the neck.
• Parathyroid Gland: Two pairs of small glands embedded in back side of the thyroid gland, are known as Parathyroid glands.
• Thymus Gland: This gland is present in infants and gradually degenerate in adults.
• Islets of Langerhans: Patches of special cells are found in Pancreas gland (digestive gland). These patches are called Islets of Langerhans after the name of Physiologist Langerhans.
• Adrenalin glands: each kidney has a cap like structure on it, which are called adrenal Glands. These glands are made up of outer cortex and inner medulla.
• Testes: testes produce testosterone hormone at puberty. This stimulates the secondary sexual characters like moustache, beard etc. in males.
• Ovary: Ova (eggs) in ovary produce estrogen hormone. This hormone, at puberty, switches on the development of secondary sexual characters (e.g., development of breasts) in females.