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Hormone

A hormone is a chemical messenger produced by an endocrine gland and carried by blood to target organs.

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Student-friendly explanation

Hormones help control growth, metabolism, development, and many body functions. They are released in small amounts, travel through blood, and act only on specific target organs that can respond to them. Unlike nerve impulses, hormones work more slowly but their effect may last longer. This makes hormonal control useful for long-term regulation in the body.

How to write this in exams

  1. 1

    Start with the exact idea

    A hormone is a chemical messenger produced by an endocrine gland and carried by blood to target organs.

  2. 2

    Then show how to use it

    1. Identify the gland that releases the hormone. 2. Show that the hormone enters blood. 3. Name the target organ. 4. State the specific action on the body. 5. Mention that the response is usually slower but longer lasting.

  3. 3

    Add one concrete example

    Insulin helps control blood sugar level, and thyroxine helps regulate body metabolism.

  4. 4

    Avoid this incomplete answer

    A common wrong answer is that hormones travel through neurons. That is wrong because hormones use blood as the transport medium.

Definition

A hormone is a chemical messenger produced by an endocrine gland and carried by blood to target organs.

Example

Insulin helps control blood sugar level, and thyroxine helps regulate body metabolism.

Rule to remember

Rule: hormone is secreted by an endocrine gland, carried in blood, and acts on a target organ.

Sequence to remember

Rule: hormone is secreted by an endocrine gland, carried in blood, and acts on a target organ. A flow diagram can show endocrine gland>
blood>
target organ>
response. 1. Identify the gland that releases the hormone. 2. Show that the hormone enters blood. 3. Name the target organ. 4. State the specific action on the body. 5. Mention that the response is usually slower but longer lasting

Memory hook

Hormone means blood-borne chemical message.

Examples and method

Worked example

When blood sugar rises after a meal, the pancreas releases insulin into the blood. Insulin reaches body cells and helps lower the blood sugar level.

Method to apply

1. Identify the gland that releases the hormone. 2. Show that the hormone enters blood. 3. Name the target organ. 4. State the specific action on the body. 5. Mention that the response is usually slower but longer lasting.

Diagram support

A flow diagram can show endocrine gland → blood → target organ → response.

How CBSE asks it

Questions may ask for the definition of a hormone, the difference between hormones and nerves, or the role of a particular endocrine gland.

Avoid common mistakes

Common confusion

Students often think hormones travel through nerves like electrical signals. They do not. Hormones travel through blood.

Common wrong answer

A common wrong answer is that hormones travel through neurons. That is wrong because hormones use blood as the transport medium.

Exam tip

If a question says chemical messenger, blood transport, target organ, or slow action, it is usually asking about hormones.

Quick check

Why are hormones called chemical messengers rather than nerve signals?

Hormones are called chemical messengers because they are chemicals released by glands and carried by blood to target organs. They do not travel as nerve impulses, and they usually act more slowly than nerve signals.

Answer writing and exam use

1-mark answer

A hormone is a chemical messenger produced by an endocrine gland and carried by blood to target organs.

2-mark answer

A hormone is a chemical messenger produced by an endocrine gland and carried by blood to target organs. Rule: hormone is secreted by an endocrine gland, carried in blood, and acts on a target organ. Insulin helps control blood sugar level, and thyroxine helps regulate body metabolism.

3-mark answer

Hormones help control growth, metabolism, development, and many body functions. They are released in small amounts, travel through blood, and act only on specific target organs that can respond to them. Unlike nerve impulses, hormones work more slowly but their effect may last longer. This makes hormonal control useful for long-term regulation in the body. Rule: hormone is secreted by an endocrine gland, carried in blood, and acts on a target organ. When blood sugar rises after a meal, the pancreas releases insulin into the blood. Insulin reaches body cells and helps lower the blood sugar level. Questions may ask for the definition of a hormone, the difference between hormones and nerves, or the role of a particular endocrine gland. A common wrong answer is that hormones travel through neurons. That is wrong because hormones use blood as the transport medium.
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