Endocrine Glands and Hormones

Definition

Ductless glands that secrete chemical messengers called hormones directly into the bloodstream to regulate body functions such as growth, metabolism, and reproduction.

Key points

• The pituitary gland, at the base of the brain, is called the master gland because it controls many other endocrine glands and secretes growth hormone.
• The thyroid gland secretes thyroxine, which controls metabolism and needs iodine; its deficiency causes goitre and, in children, stunted growth (cretinism).
• The pancreas secretes insulin, which lowers blood sugar; its deficiency or ineffectiveness causes diabetes mellitus.
• The adrenal glands secrete adrenaline, the fight-or-flight hormone that raises heart rate and prepares the body for emergencies.
• Sex hormones include testosterone (testes) and oestrogen and progesterone (ovaries); endocrine glands lack ducts, unlike exocrine glands such as salivary and sweat glands that release through ducts.

Why it matters for CAPF

The master gland, thyroxine and iodine, insulin and diabetes, adrenaline, and the ductless nature of endocrine glands are recurring biology facts, and iodine deficiency disorders link to public-health questions.

Common confusion

Endocrine glands are ductless and pour hormones into blood, while exocrine glands (sweat, saliva) use ducts; the pancreas does both. Goitre is caused by iodine deficiency affecting the thyroid, not by a problem with insulin.

Related concepts

concept vitamins and deficiencies, concept human blood groups, concept enzymes

Parent note

human body and systems