1. Ingestion: The process begins with eating, taking food into the mouth.
2. Mechanical Digestion:
* Mouth: Teeth break down food into smaller pieces, and saliva (containing enzymes) starts the breakdown of carbohydrates.
* Stomach: Muscles churn and mix food with gastric juices, breaking it down further.
3. Chemical Digestion:
* Mouth: The enzyme salivary amylase begins breaking down carbohydrates into simpler sugars.
* Stomach: The enzyme pepsin breaks down proteins into smaller peptides.
* Small Intestine: The majority of chemical digestion occurs here. Enzymes from the pancreas (e.g., trypsin, lipase, amylase) break down proteins, fats, and carbohydrates into even simpler molecules.
4. Absorption:
* Small Intestine: The small intestine has finger-like projections called villi, which increase surface area and allow for efficient absorption of nutrients into the bloodstream.
* Large Intestine: Water and electrolytes are absorbed here.
5. Elimination:
* Large Intestine: Waste products that were not absorbed are compacted into feces and eliminated through the rectum.
What Happens to the Absorbed Nutrients?
* Carbohydrates: Broken down into glucose, which is the primary energy source for the body.
* Proteins: Broken down into amino acids, used to build and repair tissues, enzymes, hormones, and other proteins.
* Fats: Broken down into fatty acids and glycerol, used for energy storage, insulation, and hormone production.
* Vitamins and Minerals: Absorbed and used for various bodily functions.
Important Note: This is a simplified explanation. Digestion is a complex process involving multiple organs, enzymes, and hormones working together to break down food and deliver the necessary nutrients to the body.
