Which of these is true of the endocrine system?

Concept:

• Exocrine glands: The glands which secrete substances on the epithelial surface through the ducts are called exocrine glands. Eg. sweat, salivary, mammary, ceruminous, lacrimal, sebaceous, prostate, and mucous glands.
• Endocrine glands: The glands which secrete hormones and other substances directly into the bloodstream are called endocrine glands. Eg. Pituitary, Pineal, Thyroid, Thymus, Gonads, etc.

​Explanation:

Endocrine Glands: 

• Endocrine glands lack ducts and are hence, called ductless glands. Their secretions are called hormones
• Hormones are non-nutrient chemicals that act as intercellular messengers and are produced in trace amounts
• The hormones are emptied directly into the bloodstream and then transported to target cells by blood
• The endocrine system regulates the metabolic activities of the body like body growth, sexual development & other biological processes
• The endocrine gland signalling is slow but its effects are prolonged 
• Some of the major endocrine glands are the Pituitary, Pineal, Thyroid, Thymus, Gonads, etc.

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