In the stomach, two main types of chemical digestion occur: protein digestion and the beginning of fat digestion.
The primary enzyme responsible for protein digestion is pepsin, which is activated from its precursor, pepsinogen, by the acidic environment of the stomach created by gastric acid (hydrochloric acid). Pepsin breaks down large protein molecules into smaller peptides, making them easier for the body to absorb later in the digestive process.
Additionally, gastric lipase is another enzyme that begins the digestion of fats in the stomach, although this process is not as prominent as protein digestion. Gastric lipase helps to break down triglycerides into free fatty acids and glycerol, but most fat digestion occurs later in the small intestine.
Overall, the stomach plays a crucial role in initiating the chemical digestion of proteins and fats, preparing food for further digestion and absorption in the intestines.