Stages of Digestion

Four Stages of Digestion

• Ingesting• Digesting • Absorbing• Eliminating

Stage 1:Ingesting

• The starting point of the digestion process.

Stage 2: Digesting• Mouth: Mechanical and Chemical digestion begins.• Mechanical digestion is the chewing and breaking food

down into smaller pieces• Each small piece of food is a bolus• Saliva lubricates the food, and contains an enzyme, called

amylase. • Chemical digestion occurs when amylase begins to break

down complex carbohydrates.

• Esophagus: as food passes through the pharynx, the epiglottis covers the airway tube.

• The food moves on to the esophagus.

• The esophagus is a tube that connects the pharynx and the stomach.

• The esophagus is long and muscular

• The bolus is pushed through the esophagus in a process called peristalsis.

Stomach

• Your stomach is like a stretchable muscular bag.

• Inside the stomach is gastric juice, which is very acidic.

• The stomach walls are lined with mucus, that protects the tissue.

• Pepsin is an enzyme which breaks down protein, and needs an acidic environment.

• The bolus breaks down into a liquid called chyme.

Small Intestine

• Once the chyme leaves the stomach, it empties into the small intestine.

• The first metre is called the duodenum. Digestion is complete after foods leaves.

• Within the first 30 cm are ducts that connect to other organs.

• Pancreas: produces enzymes

• Liver: produces bile.