Question

4.) Describe the functional structure of the small intestine for absorption? Draw and label the parts.

Answer 1

The functional structure of small intestine is villi. The villi is the foldings of visceral epithelium whose deep portions are termed as crypts. Villus, plural villi, in anatomy any of the small, slender, vascular projections that increase the surface area of a membrane. Important villous membranes include the placenta and the mucous-membrane coating of the small intestine. The villi of the small intestine project into the intestinal cavity, greatly increasing the surface area for food absorption and adding digestive secretions. The villi number about 10 to 40 per square millimetre (6,000 to 25,000 per square inch) of tissue. They are most prevalent at the beginning of the small intestine and diminish in number toward the end of the tract. They range in length from about 0.5 to 1 mm (about 0.02 to 0.04 inch).The large number of villi give the internal intestinal wall a velvety appearance. Each villus has a central core composed of one artery and one vein, a strand of muscle, a centrally located lymphatic capillary (lacteal), and connective tissue that adds support to the structures. The blood vessels are thought to transport proteins and carbohydrates absorbed by the cells of the villi, while the lymphatic capiLlary  removes droplets of emulsified fat (chyle). The muscle strand allows the villi to contract and expand; it is believed that these contractions empty the contents of the lacteal into larger lymphatic vessels.