Consider the statement: “Hormones are chemical messengers that are secreted and regulated by the endocrine system.” How should this statement be classified?

Introduction / Context:
The endocrine system is one of the two major communication systems in the body, along with the nervous system. It uses hormones to coordinate and regulate many physiological processes such as growth, metabolism, reproduction and stress responses. Understanding what hormones are and which system secretes and controls them is fundamental in human physiology. This question asks you to classify a statement that describes hormones as chemical messengers secreted and regulated by the endocrine system.

Given Data / Assumptions:

The statement under evaluation is: “Hormones are chemical messengers that are secreted and regulated by the endocrine system.” We know that hormones are typically produced by endocrine glands and transported via the bloodstream. Options allow us to classify the statement as correct or incorrect with different explanations. We assume standard definitions of hormones and endocrine glands.

Concept / Approach:
Hormones are organic chemical substances produced in small quantities by endocrine cells or glands. They are secreted directly into the bloodstream (or other body fluids) and travel to target tissues, where they bind to specific receptors and alter cellular activity. The endocrine system includes glands such as the pituitary, thyroid, adrenal glands and endocrine pancreas, which secrete hormones and are themselves regulated by feedback mechanisms. Although some non classical tissues also produce hormones, the overall regulation and integration of hormonal signalling is handled by the endocrine system in close partnership with the nervous system. Therefore, describing hormones as chemical messengers secreted and regulated by the endocrine system is essentially correct.

Step-by-Step Solution:
Step 1: Confirm that hormones are indeed chemical in nature, often peptides, steroids or amines. Step 2: Recall that endocrine glands are ductless and secrete hormones directly into the bloodstream. Step 3: Recognise that the endocrine system includes these glands and the regulatory feedback loops that control hormone levels. Step 4: Compare this with the wording of the statement, which says hormones are chemical messengers secreted and regulated by the endocrine system. Step 5: Conclude that the statement is correct and select the option that affirms this with proper explanation.

Verification / Alternative check:
Standard physiology textbooks define hormones as chemical messengers produced by the endocrine system. They list classical endocrine glands and describe how hormones like insulin, adrenaline and thyroxine are secreted into the blood and regulated by feedback mechanisms involving the hypothalamus and pituitary. In contrast, exocrine glands secrete substances like enzymes and mucus into ducts, not hormones. These textbook distinctions support the statement's accuracy and align with option a.

Why Other Options Are Wrong:
Option b is wrong because hormones are definitely chemical in nature and not purely physical or mystical substances. Option c incorrectly states that hormones are secreted only by exocrine glands, which actually release substances through ducts to body surfaces or cavities, not into the bloodstream. Option d wrongly claims that the nervous system alone secretes all hormones; while the nervous and endocrine systems work together, hormone secretion is primarily the role of endocrine glands. Option e confuses hormones with digestive enzymes, which are usually exocrine secretions, not the regulated chemical messengers described in the statement.

Common Pitfalls:
Students sometimes mix up endocrine and exocrine glands because both secrete substances. Another pitfall is thinking of hormones as restricted only to so called hormone glands and forgetting that many tissues also secrete hormone like factors, which can blur the definition if not carefully considered. For exam purposes, however, it is safe and correct to state that hormones are chemical messengers secreted and regulated by the endocrine system. Keeping the distinction clear between endocrine (ductless, hormones) and exocrine (ducted, enzymes, mucus) helps avoid confusion.

Final Answer:
The statement is correct: hormones are chemical messengers secreted into the blood by endocrine glands and regulated by the endocrine system.