Unit 2: Digestive System & Energetics

February 20, 2026

Semester 2
BP201T

Introduction to Digestive System & Energetics

Unit 2 focuses on how our body processes food to sustain life. It details the anatomy of the GI Tract and accessory organs like the Liver and Pancreas. You will learn the physiology of digestion (breaking down food) and absorption. The unit also covers ‘Energetics’, explaining how the body generates ATP and regulates metabolic rate (BMR).

Download PDF

Syllabus & Topics

  • 1Anatomy of GI Tract with special reference to anatomy and functions of stomach.
  • 2Acid production in the stomach, regulation of acid production (parasympathetic nervous system).
  • 3Pepsin role in protein digestion.
  • 4Small intestine and large intestine: Anatomy and functions.
  • 5Anatomy and functions of accessory glands: Salivary glands, Pancreas, and Liver.
  • 6Movements of GIT.
  • 7Digestion and absorption of nutrients.
  • 8Disorders of GIT.
  • 9Energetics: Formation and role of ATP.
  • 10Creatinine Phosphate and Basal Metabolic Rate (BMR).

Learning Objectives

Trace the Path: List the organs of the GI tract in order from mouth to anus.
Explain Digestion: Describe how Carbohydrates, Proteins, and Fats are chemically digested by enzymes.
Understand Acid Secretion: Explain the mechanism of HCl secretion in the stomach.
Calculate BMR: Define Basal Metabolic Rate and factors affecting it.
Describe ATP Formation: Explain the significance of ATP as the energy currency of the cell.

Frequently Asked Questions (FAQs)

Q1. What is the role of Bile?

Bile is produced by the liver and stored in the gallbladder. Its main function is to emulsify fats, breaking large fat globules into smaller droplets so that lipase can act efficiently.

Q2. How is Acid production regulated?

Gastric acid secretion is regulated by:

  • The parasympathetic nervous system (via the vagus nerve)

  • Hormones such as gastrin

  • Local mediators like histamine

Q3. What is BMR?

Basal Metabolic Rate (BMR) is the amount of energy expended by the body at rest in a neutral temperature environment, required to maintain vital body functions.

Q4. What are the enzymes involved in Protein digestion?

Protein digestion involves:

  • Pepsin (Stomach)

  • Trypsin, Chymotrypsin, Carboxypeptidase (Pancreas)

  • Peptidases (Small intestine)

Q5. What is the difference between Digestion and Absorption?

  • Digestion: Mechanical and chemical breakdown of food into simpler molecules.

  • Absorption: Movement of digested nutrients from the gastrointestinal tract into the bloodstream.