Welcome to GattPrep!
Have you ever wondered what happens to that delicious bowl of rice and stew after you swallow it? Your body goes on a complex journey to break it down and absorb nutrients—and that journey takes place in the digestive system.
The digestive system is like your body’s kitchen and waste management unit. It breaks down food, absorbs nutrients, and gets rid of the leftovers. In this lesson, you’ll learn how food travels through your body, the major organs involved, the process of digestion, and how to take care of this important system.
The digestive system is a group of organs that work together to break down food into nutrients your body can use, and to eliminate undigested waste.
The main processes include:
Ingestion: Taking in food
Digestion: Breaking food into smaller parts
Absorption: Taking nutrients into the blood
Egestion: Removing waste
| Organ | Function |
|---|---|
| Mouth | Starts digestion by chewing (mechanical) and saliva (chemical) |
| Esophagus | Pushes food to stomach using peristalsis |
| Stomach | Churns food and adds digestive juices |
| Small Intestine | Absorbs nutrients into the bloodstream |
| Large Intestine | Absorbs water and forms feces |
| Rectum and Anus | Stores and removes waste |
| Organ | Function |
|---|---|
| Liver | Produces bile to help digest fats |
| Gallbladder | Stores bile from the liver |
| Pancreas | Produces enzymes that break down food in the small intestine |
| Type | Description | Example |
|---|---|---|
| Mechanical | Physical breakdown of food | Chewing in the mouth |
| Chemical | Enzymes break down food molecules | Saliva breaking starch into sugar |
| Enzyme | Acts On | Found In |
|---|---|---|
| Amylase | Starch → Sugar | Saliva, pancreas |
| Protease | Proteins → Amino acids | Stomach, pancreas |
| Lipase | Fats → Fatty acids + glycerol | Pancreas, small intestine |
The small intestine is lined with villi—tiny finger-like projections that increase surface area for absorption.
Nutrients like glucose, amino acids, and vitamins pass through villi into blood vessels.
| Problem | Cause | Symptoms | Prevention |
|---|---|---|---|
| Constipation | Lack of fiber or water | Difficulty passing stool | Drink water, eat fiber |
| Diarrhea | Infection, food poisoning | Loose, watery stool | Hygiene, clean food |
| Ulcers | Acid damage to stomach lining | Stomach pain | Avoid spicy food, treat infections |
| Indigestion | Overeating or stress | Bloating, discomfort | Eat slowly, avoid overeating |
🧠 Problem: Ama eats a meal rich in starch, proteins, and fats. What enzymes will break down each of these nutrients and where?
✅ Step-by-Step Solution:
Starch → broken down by amylase (in saliva and small intestine)
Proteins → broken down by protease (in stomach and pancreas)
Fats → broken down by lipase (in pancreas and small intestine)
✔️ Answer:
Starch: Amylase
Proteins: Protease
Fats: Lipase
(a) The enzyme that digests protein is called __________.
(b) The organ that absorbs most nutrients is the __________.
Answers:
(a) protease
(b) small intestine
| Organ | Function |
|---|---|
| (i) Liver | A. Churns and digests food with acid |
| (ii) Stomach | B. Produces bile |
| (iii) Large Intestine | C. Absorbs water and forms feces |
Answers:
(i) → B
(ii) → A
(iii) → C
Q: Why does the small intestine have many villi?
A: To increase surface area for absorption of nutrients into the blood.
Let’s go over what we’ve learned:
The digestive system breaks food down, absorbs nutrients, and removes waste.
It includes organs like the mouth, stomach, small and large intestines, and anus.
Supporting organs like the liver and pancreas help digestion.
Enzymes break down food: amylase (starch), protease (proteins), lipase (fats).
The small intestine is the main site of nutrient absorption.
Think about the last meal you ate. Can you explain how your body digested it—starting from the mouth all the way to the anus?
Write a short paragraph or draw a simple diagram in your science journal!
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