The diagram given below represents an endocrine gland in the human body. Study the diagram and answer the following questions: The diagram given below represents an endocrine gland in the human body. Study the diagram and answer the following questions:
Explain the term ‘Hormone’. What is the role of Tropic hormones in the human body?
Topic: Hormone and tropic hormones
Answer
A HORMONE is a chemical substance secreted in small quantities by an ENDOCRINE (ductless) gland, poured DIRECTLY INTO THE BLOOD, and carried to a distant TARGET ORGAN where it regulates a specific physiological activity.
TROPIC HORMONES are those whose target is ANOTHER ENDOCRINE GLAND. They stimulate that gland to secrete its own hormone — as TSH stimulates the thyroid and ACTH the adrenal cortex — and so coordinate the whole endocrine system.
Four elements make a complete definition of a hormone, and each is where a mark can be lost: a CHEMICAL from an ENDOCRINE gland, released DIRECTLY INTO THE BLOOD, acting on a distant TARGET ORGAN, needed in MINUTE quantities.
Hormones are sometimes called CHEMICAL MESSENGERS.
THE CONTRAST with nervous control, which examiners like: nervous coordination is FAST and SHORT-LIVED, travelling along nerves to a precise point; hormonal coordination is SLOWER but longer-lasting and widespread, travelling in the blood to the whole body.