Question

What is the role of Lacteals?

Answer 1

Hint: Lacteals are specialized lymph vessels present in the small intestine where maximum digestion and absorption of food occurs. These are located inside villi.

Complete answer:
Lacteals are vessel-like structures present in the space inside the intestinal villi. They provide a route through which fatty acids and glycerol are absorbed and drained into the blood through the lymphatic system. The main role of lacteals is the absorption of fatty acids and glycerol from the small intestine. These are filled with fatty liquid that continues to the lymphatic circulation and finally drains into the venous circulation of the body. This is required because fatty acids are large molecules and cannot be directly absorbed into the blood from the small intestine.

Additional Information:

The steps in human nutrition include ingestion, digestion, absorption, assimilation, and egestion.
Lacteals play a major role in the absorption of fatty acids and glycerol from digested food.

The steps in the absorption of fatty acids are as follows :

1) Triglycerides are broken down into fatty acids and glycerol inside the small intestine. These are absorbed by the epithelial cells known as enterocytes lining the villi.
2) The absorbed fatty acid and glycerol are again reformed into triglycerides by the endoplasmic reticulum inside the cell and are converted into chylomicrons.
3) Chylomicrons have a protein coating them and are filled with triglycerides, phospholipids, and cholesterol.
4) They leave the enterocyte by exocytosis and are absorbed by the lacteals, this fatty fluid inside the lacteal has a milky appearance and is known as chyle. The lacteals carry them and drain into the venous circulation.

Absorption into lacteals occurs by mechanism of simple diffusion and no special mechanisms like facilitated diffusion or active transport are required.

Waldmann’s Disorder is related to lacteals. It occurs when the lacteals get dilated and there is leakage of lymphatic fluid into the lumen of the small intestine.

Note: It should be remembered that lacteals only help in the absorption of fatty acids in our bloodstream, other products of digestion like monosaccharides and amino acids are directly absorbed into the bloodstream from the small intestine as they are smaller in size, unlike fatty acids. Lacteals are found specifically in the small intestine of the alimentary canal.