Human Digestive System
The human digestive system consists of various organs that work together to break down food, absorb nutrients, and remove waste.
Parts of the Digestive System
Mouth and Buccal Cavity
- Food enters through the mouth.
- Teeth chew food into smaller pieces (mechanical digestion).
- Saliva contains enzymes (like amylase) that start the digestion of carbohydrates.
Esophagus
- A muscular tube that connects the mouth to the stomach.
- Moves food through peristalsis (wave-like muscle contractions).
Stomach
- A muscular sac that churns food and mixes it with gastric juices.
- Hydrochloric acid (HCl) kills bacteria and activates enzymes.
- Pepsin breaks down proteins into smaller peptides.
Small Intestine
- The longest part of the digestive system (around 6 meters).
- Divided into three parts: duodenum, jejunum, and ileum.
- The pancreas and liver secrete digestive enzymes and bile for further digestion.
- Absorption of nutrients occurs through tiny finger-like structures called villi.
Large Intestine
- Absorbs water and minerals from undigested food.
- Houses beneficial bacteria that help in digestion.
- Forms solid waste (feces).
Anus
- The final part of the digestive system.
- Expels waste materials (feces) from the body.
Functions of Each Organ
- Mouth: Chewing and mixing food with saliva.
- Esophagus: Transports food to the stomach.
- Stomach: Breaks down proteins and churns food.
- Small Intestine: Digests food and absorbs nutrients.
- Large Intestine: Absorbs water and forms waste.
- Anus: Removes waste from the body.
Process of Digestion
- Ingestion – Taking food into the mouth.
- Digestion – Breaking down food into smaller molecules (mechanically and chemically).
- Absorption – Nutrients are absorbed into the bloodstream from the small intestine.
- Assimilation – Nutrients are transported to body cells for energy and growth.
- Egestion – Removal of undigested food and waste products through the anus.