Villi are tiny, finger-like projections found in various parts of the body, most notably lining the small intestine. Their primary function is to significantly increase the surface area of the membrane where they are located, thus enhancing absorption.
Intestinal Villi: The Nutrient Absorbers
In the small intestine, villi play a crucial role in nutrient absorption. These microscopic, vascular projections are richly supplied with blood vessels. As digested food passes through the small intestine, the villi absorb nutrients from the food and transport them into the bloodstream. This efficient absorption is vital for the body's proper functioning. The structure of the villi, with their numerous folds and microvilli (even smaller projections on the surface of the villi), maximizes the contact area with digested food, allowing for maximum nutrient uptake. Verywell Health describes them as "tiny finger-like projections located in your small intestine, [that] absorb nutrients from the food you eat and move them into…" the bloodstream.
- Location: Inner lining of the small intestine.
- Function: Nutrient absorption.
- Structure: Small, slender, vascular projections.
Chorionic Villi: Prenatal Diagnostics
Chorionic villi are also found in the placenta during pregnancy. These villi are part of the fetal component of the placenta and play a crucial role in nutrient and gas exchange between the mother and fetus. A procedure called chorionic villus sampling (CVS) utilizes these villi to obtain a sample for prenatal genetic testing. Johns Hopkins Medicine describes CVS as a prenatal test "used to test for chromosomal abnormalities and other genetic problems."
- Location: Placenta.
- Function: Nutrient and gas exchange between mother and fetus; used in prenatal testing.
In summary, while the term "villi" refers to a variety of small, finger-like projections in different anatomical locations, their fundamental role revolves around increasing surface area to facilitate absorption or exchange of substances. The specific function varies depending on their location. The Merriam-Webster definition defines villus as "a small slender often vascular process" which neatly captures this general function. Merriam-Webster
