N3 Anatomy and Physiology AY 2024-2025

1. How does the food change in consistency and form?
Food undergoes mechanical digestion through chewing and chemical digestion by salivary enzymes in the mouth, forming a soft, swallowable mass called a bolus. The bolus moves to the stomach, where gastric juices and enzymes break it down further (chemical digestion) while churning turns it into a semi-liquid substance called chyme. In the small intestine, chemical digestion by pancreatic enzymes and bile breaks down food into nutrients for absorption. In the large intestine, water absorption hardens the chyme into fecal matter, which is then expelled.

2. How does the body absorb nutrients from food?
Nutrient absorption occurs after mechanical and chemical digestion transform food into its simplest forms. The bolus, formed in the mouth, and chyme, produced in the stomach, are broken down by enzymes from the stomach and pancreas, along with bile from the liver, into glucose, amino acids, and fatty acids. In the small intestine, the microvilli increases surface area for efficient absorption, allowing nutrients to enter the bloodstream or lymphatic system. The large intestine absorbs water and leaves undigested material for elimination.