Explain the process of digestion of food in the mouth, stomach, and small intestine in the human body.

(N/A) Digestion of food occurs in the following ways:
$(a)$ Mouth (Buccal cavity): Teeth crush food into small particles. Salivary glands secrete saliva, which moistens food. Salivary amylase breaks down starch:
$\text{Starch} \xrightarrow{\text{Salivary amylase}} \text{Maltose}$
$(b)$ Stomach: Gastric glands release:
$(i)$ $\text{Hydrochloric acid}$: Creates an acidic medium for pepsin.
(ii) $\text{Mucus}$: Protects the stomach lining from acid.
(iii) $\text{Pepsin}$: Digests proteins into peptones.
$\text{Proteins} \xrightarrow{\text{Pepsin}} \text{Peptones}$
$(c)$ Small intestine: Site of complete digestion. It receives:
$(i)$ $\text{Bile juice}$: From the liver, it emulsifies fats and makes the medium alkaline.
(ii) $\text{Pancreatic juice}$: Contains amylase (starch), trypsin (proteins), and lipase (fats).
(iii) $\text{Intestinal juice}$: Contains enzymes like maltase and lipase for final digestion into glucose, amino acids, and fatty acids.