Food undergoes physical and chemical processes in the mouth, wherein teeth grind them into smaller particles, while saliva, rich in enzymes, moistens and forms a bolus. The bolus moves through the esophagus through peristaltic waves, guided by the lower esophageal sphincter. It will reach the acidic stomach environment. Gastric acid breaks down the bolus into chyme, and is further processed by enzymes in the small intestine, wherein nutrient absorption occurs. The large intestine focuses on water reabsorption, forming feces, and specialized bacteria in the colon aid in complex carbohydrate breakdown. Finally, feces is expelled through the anus, thus completing the digestive journey.
How could the body absorb the nutrients from the foods we eat?
The small intestine and large intestine play crucial roles in nutrient absorption. In the small intestine, enzymes break down complex molecules into simpler forms. The small intestine's large surface area facilitates absorption through villi and microvilli. Nutrients like amino acids, fatty acids, and monosaccharides are absorbed into blood vessels or lymphatics. Moreover, the large intestine absorbs water and electrolytes from the remaining indigestible material, forming feces. While it doesn't play a primary role in nutrient absorption, water absorption is crucial for maintaining fluid balance. The absorbed nutrients eventually enter the bloodstream, which provides the body with the essential components needed for energy, growth, and maintenance.