Anatomy and Physiology II Practice Test

Which lymphatic structure is found in the walls of the small intestine?

1. Veins

2. Lacteals

3. Thoracic duct

4. Capillaries

The correct answer is: Lacteals

Lacteals are specialized lymphatic vessels located in the walls of the small intestine, specifically within the intestinal villi. They play a crucial role in the absorption of dietary fats and fat-soluble nutrients. When food is digested, fats are emulsified and packaged into chylomicrons, which are subsequently absorbed by the lacteals. This process allows these nutrients to be transported via the lymphatic system instead of directly entering the bloodstream through the capillaries. The significance of lacteals extends to their unique structure, which facilitates the uptake of larger molecules, such as fatty acids and monoglycerides, that would not easily pass through standard blood capillaries. Once absorbed, the chyle— the creamy fluid containing digested fats—travels through the lymphatic system, eventually draining into larger lymphatic vessels and ultimately into the bloodstream. While veins are responsible for returning deoxygenated blood to the heart, and capillaries serve as the site of exchange between the blood and tissues, they do not specifically relate to the absorption of dietary fats in the intestines. The thoracic duct, a major lymphatic vessel, plays a role in draining lymph from various parts of the body, but it is not located in the