The endocrine system is made of glands that release hormones directly into the blood. Hormones control growth, metabolism and many body functions, making this an important exam topic.
Endocrine vs Exocrine Glands
Endocrine glands are ductless and pour hormones into the blood. Exocrine glands (like sweat and salivary glands) release through ducts.
Major Glands and Hormones
- Pituitary gland: the master gland; releases growth hormone.
- Thyroid gland: releases thyroxine; needs iodine.
- Pancreas: releases insulin to control blood sugar.
- Adrenal gland: releases adrenaline, the emergency hormone.
Important Hormones
- Insulin: lowers blood sugar.
- Thyroxine: controls metabolism.
- Adrenaline: prepares the body for fight or flight.
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Common Disorders
- Diabetes: caused by a lack of insulin.
- Goitre: swelling of the thyroid due to iodine deficiency.
- Dwarfism and gigantism: caused by growth hormone problems.
Important Facts
The pituitary gland is called the master gland because it controls other glands. The pancreas acts as both an endocrine and an exocrine gland. Adrenaline is also called the fight-or-flight hormone.
Quick Revision Points
- Pituitary is the master gland.
- Insulin is made by the pancreas and lowers blood sugar.
- Lack of insulin causes diabetes.
- Thyroxine needs iodine; deficiency causes goitre.
- Adrenaline is the emergency hormone.
- Endocrine glands are ductless.
- Pancreas is both endocrine and exocrine.