1. Chapter 3 section 5
Digestion and pH

2. Key Concepts Why must your body digest food?
How does pH affect digestion?

3. Key terms
Digestion
Mechanical Digestion
Chemical Digestion

4. What is digestion
Foods must be broken down into simpler substances that your body can use for raw materials and energy.
Digestion: the process which breaks down the complex molecules of foods into smaller molecules.
Mechanical Digestion: The physical process in which large pieces of food are torn and ground into smaller pieces.
Chemical Digestion: the chemical process of breaking down molecules into smaller ones.
Digestive enzymes.
Some digestive enzymes work at low pH, and others need higher pH to work.

5. pH in the Digestive System
Your mouth
Your teeth chew (mechanical digestion) and mixes with saliva.
Saliva = amylase…amylase breaks down starches into simpler sugar molecules
pH of saliva is around 7.0
Your stomach
Folds in your stomach churn your food (mechanical digestion) and enzymes along with hydrochloric acid (chemical digestion) break down proteins.
Pepsin is an enzyme that breaks down proteins into amino acids
The pH is around 2
Your small intestines
Digestive fluids containing bicarbonate ions (HCO3) surround and create a slightly basic solution with a pH of about 8