BIO201 – Topic 7: The Human Digestive System
Course Code: BIO 201
Course Name: Human Biology
© Lesuyai Organic Guides 2025
(Original | Educational | Professional | Plagiarism-Free | 2025 Edition | A4 Format)
7.1 Introduction
The digestive system is responsible for breaking down food into nutrients that the body can
absorb and use for energy, growth, and repair.
7.2 Definition and Function
The digestive system is a coordinated group of organs that mechanically and chemically
process food. Its functions include ingestion, digestion, absorption, assimilation, and egestion.
7.3 Structure of the Human Digestive System
The digestive system includes the alimentary canal and associated organs:
• Mouth – Mechanical breakdown and saliva secretion.
• Pharynx and Esophagus – Transport food.
• Stomach – Secretes gastric juices and begins protein digestion.
• Small Intestine – Completes digestion and absorbs nutrients.
• Large Intestine – Absorbs water and forms feces.
• Liver, Pancreas, and Gall Bladder – Produce bile and enzymes for digestion.
7.4 Digestive Enzymes and Their Roles
Enzymes speed up digestion:
• Amylase – Converts starch to maltose.
• Pepsin – Breaks proteins into peptides.
• Lipase – Converts fats to fatty acids and glycerol.
• Trypsin – Continues protein breakdown.
• Maltase, Sucrase, Lactase – Convert sugars into monosaccharides.
7.5 Absorption and Assimilation
Absorption occurs in the small intestine through villi and microvilli, increasing surface area.
Assimilation involves the transport and utilization of absorbed nutrients by cells.
7.6 Common Digestive Disorders
Common disorders include ulcers, constipation, diarrhea, indigestion, and gallstones. Healthy
eating, hydration, and hygiene help prevent these issues.
7.7 Summary
The digestive system is essential for nutrient supply and body maintenance. Understanding its
functions helps in maintaining overall health.
Course Code: BIO 201
Course Name: Human Biology
© Lesuyai Organic Guides 2025
(Original | Educational | Professional | Plagiarism-Free | 2025 Edition | A4 Format)
7.1 Introduction
The digestive system is responsible for breaking down food into nutrients that the body can
absorb and use for energy, growth, and repair.
7.2 Definition and Function
The digestive system is a coordinated group of organs that mechanically and chemically
process food. Its functions include ingestion, digestion, absorption, assimilation, and egestion.
7.3 Structure of the Human Digestive System
The digestive system includes the alimentary canal and associated organs:
• Mouth – Mechanical breakdown and saliva secretion.
• Pharynx and Esophagus – Transport food.
• Stomach – Secretes gastric juices and begins protein digestion.
• Small Intestine – Completes digestion and absorbs nutrients.
• Large Intestine – Absorbs water and forms feces.
• Liver, Pancreas, and Gall Bladder – Produce bile and enzymes for digestion.
7.4 Digestive Enzymes and Their Roles
Enzymes speed up digestion:
• Amylase – Converts starch to maltose.
• Pepsin – Breaks proteins into peptides.
• Lipase – Converts fats to fatty acids and glycerol.
• Trypsin – Continues protein breakdown.
• Maltase, Sucrase, Lactase – Convert sugars into monosaccharides.
7.5 Absorption and Assimilation
Absorption occurs in the small intestine through villi and microvilli, increasing surface area.
Assimilation involves the transport and utilization of absorbed nutrients by cells.
7.6 Common Digestive Disorders
Common disorders include ulcers, constipation, diarrhea, indigestion, and gallstones. Healthy
eating, hydration, and hygiene help prevent these issues.
7.7 Summary
The digestive system is essential for nutrient supply and body maintenance. Understanding its
functions helps in maintaining overall health.
