ANATOMY AND PHYSIOLOGY:
10.DIGESTIVE SYSTEMS
The digestive system is a complex series of organs and structures responsible for the breakdown
of food into nutrients that can be absorbed by the body. It involves several organs, each playing a
specific role in digestion and nutrient absorption:
1. Mouth:
• Function: Mechanical and chemical digestion begin here.
• Mechanical Digestion: Chewing breaks down food into smaller pieces, increasing its
surface area for enzyme action.
• Chemical Digestion: Salivary glands secrete saliva containing enzymes (like amylase)
that start breaking down carbohydrates.
2. Pharynx and Esophagus:
• Pharynx: Common passageway for food and air.
• Esophagus: Muscular tube that transports food from the pharynx to the stomach through
peristalsis, a wave-like muscle contraction.
3. Stomach:
• Function: Stores and churns food while continuing digestion.
• Gastric Juices: Produced by gastric glands, containing hydrochloric acid and pepsinogen
(converted to pepsin), breaking down proteins.
• Mechanical Digestion: Muscular contractions mix food with gastric juices, forming
chyme.
• Limited Absorption: Some water, alcohol, and certain drugs can be absorbed in the
stomach.
4. Small Intestine:
• Duodenum, Jejunum, Ileum: Three parts of the small intestine.
• Major Site of Digestion and Absorption: Most chemical digestion and nutrient
absorption occur here.
• Pancreatic Enzymes: Pancreatic juices containing enzymes (lipase, protease, amylase)
further break down fats, proteins, and carbohydrates.
• Bile: Produced by the liver and stored in the gallbladder, aids in fat digestion and
absorption.
• Absorption: Nutrients (amino acids, fatty acids, glucose) are absorbed through the
intestinal lining into the bloodstream.
5. Large Intestine (Colon):
10.DIGESTIVE SYSTEMS
The digestive system is a complex series of organs and structures responsible for the breakdown
of food into nutrients that can be absorbed by the body. It involves several organs, each playing a
specific role in digestion and nutrient absorption:
1. Mouth:
• Function: Mechanical and chemical digestion begin here.
• Mechanical Digestion: Chewing breaks down food into smaller pieces, increasing its
surface area for enzyme action.
• Chemical Digestion: Salivary glands secrete saliva containing enzymes (like amylase)
that start breaking down carbohydrates.
2. Pharynx and Esophagus:
• Pharynx: Common passageway for food and air.
• Esophagus: Muscular tube that transports food from the pharynx to the stomach through
peristalsis, a wave-like muscle contraction.
3. Stomach:
• Function: Stores and churns food while continuing digestion.
• Gastric Juices: Produced by gastric glands, containing hydrochloric acid and pepsinogen
(converted to pepsin), breaking down proteins.
• Mechanical Digestion: Muscular contractions mix food with gastric juices, forming
chyme.
• Limited Absorption: Some water, alcohol, and certain drugs can be absorbed in the
stomach.
4. Small Intestine:
• Duodenum, Jejunum, Ileum: Three parts of the small intestine.
• Major Site of Digestion and Absorption: Most chemical digestion and nutrient
absorption occur here.
• Pancreatic Enzymes: Pancreatic juices containing enzymes (lipase, protease, amylase)
further break down fats, proteins, and carbohydrates.
• Bile: Produced by the liver and stored in the gallbladder, aids in fat digestion and
absorption.
• Absorption: Nutrients (amino acids, fatty acids, glucose) are absorbed through the
intestinal lining into the bloodstream.
5. Large Intestine (Colon):
