The human digestive system is a group of organs that break down food into simple nutrients. These nutrients are absorbed into the blood and used by the body for energy, growth, and repair. Undigested waste is removed from the body through the digestive tract.
Digestive System flowchart
Mouth
│
Pharynx
│
Esophagus
│
Stomach
│
Duodenum
│
Small Intestine
(Jejunum & Ileum)
│
Large Intestine
(Colon)
│
Rectum
│
Anus
Accessory Organs
Liver ──► Gallbladder ──► Small Intestine
           ▲
Pancreas ───┘.
Main Organs and Their Functions
1. Mouth
Digestion begins here.
Teeth chew food (mechanical digestion).
Saliva moistens food.
Salivary amylase starts digestion of starch.
Function
Chewing
Mixing food with saliva
Beginning carbohydrate digestion
2. Pharynx
Passage connecting the mouth to the esophagus.
Helps in swallowing.
3. Esophagus
A muscular tube about 25 cm long.
Pushes food to the stomach by peristalsis.
4. Stomach
J-shaped muscular organ.
Stores food for several hours.
Mixes food with gastric juice.
Gastric Juice Contains
Hydrochloric acid (HCl)
Pepsin
Mucus
Functions
Protein digestion begins.
Kills harmful bacteria.
Converts food into chyme.
5. Small Intestine
Length: About 6 meters
Parts
Duodenum
Jejunum
Ileum
This is the main site of digestion and absorption.
Functions
Completes digestion.
Absorbs nutrients through villi.
Nutrients enter the bloodstream.
6. Large Intestine
Length: About 1.5 meters
Functions
Absorbs water and minerals.
Forms feces.
Contains helpful bacteria that produce vitamins.
7. Rectum
Stores feces before elimination.
8. Anus
Controls the release of feces through sphincter muscles.
Accessory Digestive Organs
Liver
Largest gland in the human body.
Produces bile.
Functions
Produces bile for fat digestion.
Stores glycogen.
Detoxifies harmful substances.
Gallbladder
Stores and concentrates bile.
Releases bile into the small intestine.
Pancreas
Produces pancreatic juice containing:
Amylase
Lipase
Trypsin
Functions
Digests carbohydrates, fats, and proteins.
Produces insulin and glucagon.
Process of Digestion
Food enters the mouth.
Teeth chew the food.
Saliva starts starch digestion.
Food moves through the esophagus.
The stomach digests proteins.
Bile breaks large fat droplets into smaller ones.
Pancreatic enzymes digest proteins, fats, and carbohydrates.
Small intestine absorbs nutrients.
Large intestine absorbs water.
Waste leaves through the anus.
Types of Digestion
Mechanical Digestion
Chewing
Churning in the stomach
Chemical Digestion
Enzymes break food into simple molecules.
Intresting facts
The digestive tract is about 9 meters long.
The liver is the largest internal organ.
The small intestine is longer than the large intestine.
The stomach produces acid strong enough to digest food but is protected by mucus.
Millions of villi in the small intestine greatly increase the surface area for absorption.
Frequently Asked Questions (FAQs)
Q1. What is the main function of the digestive system?
It breaks down food, absorbs nutrients, and removes waste.
Q2. Which organ produces bile?
The liver produces bile, and the gallbladder stores it.
Q3. Where does most digestion occur?
Most digestion occurs in the small intestine.
Q4. What is peristalsis?
Peristalsis is the wave-like movement of muscles that pushes food through the digestive tract.
Q5. Which organ absorbs most nutrients?
The small intestine.
Q6. What enzyme digests proteins in the stomach?
Pepsin.
Q7. What is the role of villi?
Villi increase the surface area of the small intestine for efficient nutrient absorption.