DIGESTIVE SYSTEM

Overview of the Digestive System

The digestive system consists of various organs that work together to process food, absorb nutrients, and eliminate waste.

Digestive Phases

  1. Ingestion

  2. Movement

  3. Mechanical and Chemical Digestion

  4. Absorption

  5. Elimination

Types of Digestion

  • Mechanical Digestion: Involves physical processes like chewing and grinding.

  • Chemical Digestion: Enzymatic breakdown of complex molecules into simpler forms:

    • Carbohydrates

    • Proteins

    • Dietary Lipids

Major Salivary Glands

  1. Parotid glands

  2. Submandibular glands

  3. Sublingual glands

  • Functions: Facilitate chewing, swallowing, speech, and taste perception.

Digestive Enzymes

  • Lipase: Digests fats.

  • Amylase: Converts starches to sugars.

  • Maltase: Breaks down maltose into glucose.

  • Trypsin: Breaks down proteins into amino acids.

  • Lactase: Breaks down lactose into glucose and galactose.

  • Pepsin: Digests proteins in the stomach.

Digestive System Organization

  • Gastrointestinal (GI) Tract: Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum.

Mouth Functions

  • Mechanical breakdown of food by teeth.

  • Mixing food with saliva by tongue.

  • Epiglottis prevents food from entering the trachea.

Esophagus

  • About 20 cm long.

  • Functions: Secretes mucus and moves food to the stomach via peristalsis.

Stomach

  • J-shaped muscular bag.

  • Stores and breaks down food, mixing it with digestive juices.

  • Chyme is the liquid food formed.

  • Pylorus controls chyme release to the small intestine.

Small Intestine Structure

  • Approximately 7 meters long.

  • Lined with villi for increased surface area.

Small Intestine Functions

  • Absorbs nutrients including water, vitamins, minerals, carbohydrates, proteins, and lipids.

Large Intestine

  • About 1.5 meters long.

  • Accepts unabsorbed nutrients and stores feces.

Functions of the Large Intestine

  • Bacterial digestion, further water absorption, and waste concentration.

Accessory Organs

  • Include: Liver, gallbladder, and pancreas (not part of food path but crucial for digestion).

Liver

  • Produces bile for fat digestion and regulates blood sugar.

Gall Bladder

  • Stores bile and releases it into the small intestine.

Pancreas

  • Produces digestive enzymes and regulates blood sugar through insulin production.