Where does diffusion take place in digestive system?

The primary site of diffusion within the digestive system is the small intestine. The small intestine is the longest portion of the digestive tract and is structurally designed to maximize the diffusion of nutrients into the bloodstream. Here's where diffusion occurs in the small intestine:

1. Villi: The inner surface of the small intestine contains millions of finger-like projections called villi. Villi are covered with numerous microscopic projections called microvilli, which further increase the surface area available for diffusion.

2. Microvilli: Microvilli are tiny brush-border projections that cover the surface of the epithelial cells lining the small intestine. They provide a vast surface area for the diffusion of nutrients across the intestinal epithelium into the bloodstream.

3. Tight Junctions: The epithelial cells of the small intestine are held together by specialized junctions called tight junctions. These tight junctions create a semipermeable barrier that allows the diffusion of small molecules, such as nutrients, ions, and water, while restricting the passage of harmful substances.

4. Concentration Gradient: The small intestine maintains a concentration gradient, with a higher concentration of nutrients in the intestinal lumen and a lower concentration within the epithelial cells. This gradient facilitates the movement of nutrients across the intestinal wall by diffusion.

Through the process of diffusion, essential nutrients, such as glucose, amino acids, vitamins, and minerals, are absorbed from the digested food into the bloodstream through the villi and microvilli. Diffusion plays a critical role in nutrient absorption and helps provide the body with the necessary building blocks for growth, energy production, and various physiological processes.