Is the small intestine semi permeable?

The small intestine is semi-permeable, meaning that it allows some substances to pass through while blocking others. This allows the body to absorb nutrients from the food we eat while preventing harmful substances from entering the bloodstream. The small intestine is lined with a layer of epithelial cells that have tiny pores called tight junctions. These tight junctions allow small molecules, such as water and glucose, to pass through while blocking larger molecules, such as proteins and fats. The small intestine also contains a network of blood vessels that help to absorb nutrients into the bloodstream.