Fig 006 Endocrine Glands

Endocrine Glands

Endocrine glands secrete their hormones into the blood where they are transported to other tissues. They bind with receptors on target cells and alter their function. The major endocrine glands are:

• Pituitary Gland - situated at the interface between the brain and the rest of the body and secretes numerous hormones affecting many aspects of physiology
• Pineal Gland - secretes melatonin which modulates sleep patterns
• Thyroid Gland - secretes hormones that primarily influence the metabolic rate, protein synthesis and calcium metabolism
• Parathyroid Glands - secretes parathyroid hormone that causes increase Ca²⁺ blood levels
• Adrenal Glands - secretes a variety of hormones including adrenaline and the steroids aldosterone and cortisol
• Pancreatic Islets (or islets of Langerhans) - secrete hormones that regulate glucose and lipid metabolism
• Ovary - secrets the steroids estrogen and progesterone that regulate changes in menstrual cycle and during pregnancy
• Testis - secretes the steroid testosterone that regulate the development of male characteristics

Many other tissues have isolated single cells or groups of cells with endocrine functions.