About this course
Digestive System
The digestive system is a complex network of organs and structures responsible for breaking down food, absorbing nutrients, and eliminating waste. It consists of the alimentary canal (gastrointestinal tract) and associated organs.
Major Components and Functions
1. Mouth
Structure: The mouth includes teeth, tongue, and salivary glands.
Function:
Teeth: Chew and break down food into smaller pieces.
Saliva: Secreted by salivary glands, containing enzymes like amylase that begin the breakdown of carbohydrates.
Tongue: Helps in mixing food with saliva and forming a bolus for swallowing.
2. Pharynx and Esophagus
Structure: The pharynx is a muscular tube that connects the mouth to the esophagus. The esophagus is a muscular tube that connects the pharynx to the stomach.
Function:
Pharynx: Acts as a pathway for the movement of food from the mouth to the esophagus.
Esophagus: Transports food to the stomach through peristaltic movements.
3. Stomach
Structure: A muscular, J-shaped organ with gastric glands lining the inner walls.
Function:
Mechanical Digestion: The stomach muscles churn and mix food with gastric juices.
Chemical Digestion: Gastric glands secrete hydrochloric acid (HCl) and enzymes like pepsin, which begin protein digestion.
4. Small Intestine
Structure: A long, coiled tube divided into three parts: duodenum, jejunum, and ileum. It has villi and microvilli that increase the surface area for absorption.
Function:
Digestion: Enzymes from the pancreas and bile from the liver and gallbladder are released into the duodenum, aiding in the digestion of fats, proteins, and carbohydrates.
Absorption: Nutrients are absorbed into the bloodstream through the villi and microvilli.
5. Large Intestine
Structure: A broader tube including the cecum, colon, rectum, and anus.
Function:
Water Absorption: Absorbs water and electrolytes from the remaining indigestible food matter.
Formation and Elimination of Feces: Compacts waste into feces, which are stored in the rectum and eliminated through the anus.
6. Accessory Organs
Liver: Produces bile, which helps in the emulsification of fats.
Gallbladder: Stores and concentrates bile, releasing it into the small intestine as needed.
Pancreas: Produces digestive enzymes and bicarbonate, releasing them into the small intestine to aid in digestion.
