Unit 4: Endocrine System

February 20, 2026

Semester 2
BP201T

Introduction to Endocrine System

Unit 4 explores the body’s chemical messaging system: The Hormones. It covers the major endocrine glands (Pituitary, Thyroid, Adrenal, Pancreas, etc.) and the hormones they secrete. Understanding how these hormones regulate metabolism, growth, and reproduction is crucial for understanding disorders like Diabetes and Hypothyroidism.

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Syllabus & Topics

  • 1Classification of hormones.
  • 2Mechanism of hormone action.
  • 3Pituitary gland: Structure and functions (Anterior & Posterior).
  • 4Thyroid gland.
  • 5Parathyroid gland.
  • 6Adrenal gland (Cortex and Medulla).
  • 7Pancreas (Islets of Langerhans).
  • 8Pineal gland.
  • 9Thymus gland.
  • 10Disorders of endocrine glands.

Learning Objectives

Classify Hormones: Differentiate between Steroid and Peptide hormones and their mechanism of action.
Master the Master Gland: List the hormones of the Anterior and Posterior Pituitary.
Explain Blood Glucose: Describe the roles of Insulin and Glucagon.
Understand Stress Response: Explain the role of Adrenal Cortex (Cortisol) and Medulla (Adrenaline) hormones.
Thyroid Function: Describe the synthesis and function of T3 and T4.

Frequently Asked Questions (FAQs)

Q1. What is the difference between Endocrine and Exocrine glands?

Endocrine glands are ductless and release hormones directly into the bloodstream.
Exocrine glands have ducts and release their secretions onto a surface or into a cavity (e.g., sweat glands).

Q2. How do hormones work?

Hormones act by binding to specific receptors on target cells.

  • Lipid-soluble hormones (e.g., steroids) bind to intracellular or nuclear receptors.

  • Water-soluble hormones bind to receptors on the cell membrane and act through secondary messengers.

Q3. What is a negative feedback loop?

A negative feedback loop is a regulatory mechanism in which the output of a system suppresses or inhibits its own production. For example, high T3 levels inhibit TSH secretion.

Q4. Which hormones are secreted by the Posterior Pituitary?

The posterior pituitary secretes:

  • Oxytocin – stimulates childbirth and milk ejection

  • ADH (Antidiuretic Hormone / Vasopressin) – regulates water balance by promoting water retention

Q5. What causes Diabetes Mellitus?

Diabetes Mellitus occurs due to either:

  • Insulin deficiency (Type 1)

  • Insulin resistance (Type 2)

Both conditions result in elevated blood glucose levels.