Digestive System And Associated Glands

Digestive System and Associated Glands

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 glands that secrete digestive enzymes and other substances to aid in digestion.

Major Components of the Digestive System

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.

Associated Glands

1. Salivary Glands

• Structure: There are three pairs of major salivary glands: parotid, submandibular, and sublingual glands.

• Function: Produce saliva, which contains enzymes like amylase to begin carbohydrate digestion and mucus to lubricate food.

2. Liver

• Structure: The largest internal organ, located in the upper right abdomen.

• Function:

  • Bile Production: Produces bile, which helps in the emulsification of fats.

  • Metabolism: Involved in the metabolism of carbohydrates, proteins, and fats.

  • Detoxification: Detoxifies harmful substances and stores vitamins and minerals.

3. Gallbladder

• Structure: A small, pear-shaped organ located under the liver.

• Function: Stores and concentrates bile produced by the liver, releasing it into the small intestine as needed for fat digestion.

4. Pancreas

• Structure: An elongated gland located behind the stomach.

• Function:

  • Exocrine Function: Produces digestive enzymes (e.g., amylase, lipase, proteases) and bicarbonate, which are released into the small intestine to aid in digestion.

  • Endocrine Function: Produces hormones like insulin and glucagon, which regulate blood sugar levels.