NCERT Class 11 Biology Biology: Chapter 19 — Chemical Coordination and Integration
Chapter 23 of the NCERT Class 11 Biology textbook, titled "Chemical Coordination and Integration," introduces the endocrine system as a crucial counterpart to the neural system for regulating bodily functions. While the neural system offers rapid but short-lived coordination, the endocrine system provides continuous regulation through hormones. Hormones are defined as non-nutrient chemicals acting as intercellular messengers, produced in trace amounts. The chapter details the human endocrine system, including organized glands like the pituitary, pineal, thyroid, adrenal, pancreas, parathyroid, thymus, and gonads, as well as hormone-producing tissues in organs like the heart, kidney, and gastrointestinal tract. It begins by explaining the hypothalamus's role in regulating pituitary hormone secretion through releasing and inhibiting hormones. This chapter is essential for understanding how the body maintains homeostasis and coordinates complex physiological processes.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 11 |
| Subject | Biology |
| Book | Biology |
| Chapter | Chapter 19 — Chemical Coordination and Integration |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 3 minutes |
| Word count | 498 |
Learning outcomes
- Differentiate between neural and endocrine coordination.
- Define hormones and their role as intercellular messengers.
- Identify the major endocrine glands in the human body.
- Explain the regulatory role of the hypothalamus on the pituitary gland.
- Understand the basic mechanism of hormone action.
Vocabulary
| Word | Meaning |
|---|---|
| Coordination | The organization of the different elements of a complex body or activity so as to enable them to work together effectively. |
| Integration | The combination of different things in a way that produces a more effective result. |
| Hormones | Chemicals produced by endocrine glands that act as intercellular messengers. |
| Endocrine Glands | Ductless glands that secrete hormones directly into the bloodstream. |
| Intercellular messengers | Chemicals that transmit signals between cells. |
| Hypothalamus | A region of the forebrain that controls the pituitary gland and regulates many body functions. |
| Pituitary gland | A gland attached to the base of the brain that secretes hormones controlling growth and development. |
| Neurosecretory cells | Nerve cells that produce and secrete hormones. |
| Releasing hormones | Hormones produced by the hypothalamus that stimulate the secretion of pituitary hormones. |
| Inhibiting hormones | Hormones produced by the hypothalamus that inhibit the secretion of pituitary hormones. |
The complete chapter text is read in the official NCERT PDF viewer below (streamed from ncert.nic.in). This page provides NCERT Help study material — summary, vocabulary, practice questions, and FAQs — not a full reproduction of the textbook.
Read chapter online
This PDF is loaded from the official NCERT website (ncert.nic.in). Use the page buttons below to read — download is disabled on NCERT Help.
Read page by page below. PDF is streamed from the official NCERT website — no download button on this page.
Practice questions
- What is the main difference between neural coordination and endocrine coordination? Answer: Neural coordination is rapid and short-lived, while endocrine coordination is slower but provides continuous regulation.
- Define hormones according to the new scientific definition. Answer: Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts.
- Name at least five organised endocrine glands in the human body. Answer: Pituitary, pineal, thyroid, adrenal, pancreas, parathyroid, thymus, gonads.
- What is the function of the hypothalamus in relation to the pituitary gland? Answer: The hypothalamus produces releasing and inhibiting hormones that regulate the synthesis and secretion of pituitary hormones.
- How do hormones reach their target organs? Answer: Hormones are released into the blood and transported to distant target organs.
Frequently asked questions
What is the primary role of the endocrine system?
The endocrine system, along with the neural system, jointly coordinates and regulates the physiological functions in the body, providing continuous regulation through hormones.
What are hormones?
Hormones are non-nutrient chemicals that act as intercellular messengers and are produced in trace amounts by endocrine glands.
Which are the main organised endocrine glands in humans?
The main organised endocrine glands include the pituitary, pineal, thyroid, adrenal, pancreas, parathyroid, thymus, and gonads.
How does the hypothalamus control the pituitary gland?
The hypothalamus produces releasing and inhibiting hormones that stimulate or inhibit the secretion of pituitary hormones, respectively. It also directly regulates the posterior pituitary via neural pathways.
Are there any other organs besides endocrine glands that produce hormones?
Yes, organs like the gastrointestinal tract, liver, kidney, and heart also produce hormones.
What is the difference between releasing and inhibiting hormones from the hypothalamus?
Releasing hormones stimulate the pituitary to secrete its hormones, while inhibiting hormones prevent the pituitary from secreting certain hormones.
Related resources
Important topics
Topics covered
NCERT Class 11 Biology — Biology — Chapter 19 — Chemical Coordination and Integration. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.