The Journey of Food Through the Digestive System
The digestive process begins in the mouth and continues through various organs, each playing a specific role in breaking down food and absorbing nutrients.
Mouth and Esophagus
Digestion starts in the mouth with mechanical breakdown by teeth and chemical breakdown by salivary enzymes. The esophagus then uses peristalsis to push food towards the stomach.
Vocabulary: Peristalsis - wave-like muscle contractions that move food through the digestive tract.
Stomach
The stomach is a muscular bag that mixes food with acid and enzymes. It contains pepsin, which begins protein digestion.
Definition: Pepsin - an enzyme that breaks down proteins into smaller peptides.
Small Intestine
The small intestine is where most digestion and nutrient absorption occurs. Bile from the liver creates an environment for enzyme action.
Example: Carbohydrase breaks down starch into sugar, protease breaks down proteins into amino acids, and lipase breaks down lipids into glycerol and fatty acids.
Large Intestine and Excretion
The large intestine reabsorbs water and stores solid waste before it's excreted through the rectum and anus.
Highlight: The digestive system process involves both physical and chemical digestion, working together to efficiently break down food and absorb nutrients.