Question

liver sinusoids are lined by
A. Parenchymal cells
B. Endothelial cells
C. Kupffer cells
D. Both B and C

Answer 1

Hint: Liver is the largest gland in the human body. The lining of various tissues and organs contains epithelial cells. Liver sinusoids are special capillaries found in the livers. The Lining of these capillaries them special and unique.

Complete Answer:
The largest gland in the human body is the liver. Sinusoid is a type of capillary which contains discontinuous endothelium. This discontinuity helps in the mixing of oxygen rich blood coming through the hepatic artery with the nutrient rich blood coming from the portal vein.
- These capillaries consist of a special endothelium known as the liver endothelium which consists of endothelial cells along with the kupffer cells. These cells are scavenging in nature and thus are porous. The kupffer cells in the capillaries perform the functions of phagocytosis. They are also known as stellate macrophages.
- Presence of open pores or fenestrae which lacks diaphragm and a basal lamina under the endothelium makes them special and unique from other capillaries. The fenestre helps in the filtration of fluids, solutes and particles. Another important function of the epithelium is endocytosis. The endocytosis is performed by various endocytotic vesicles.
- The presence of endocytotic vesicles, fenestrae and absence of regular basal lamina makes them different and unique from other cells. So, the liver sinusoidal epithelial cells are regarded as selective sieve and scavengers
- Parenchymal cells form the lining of tissues and organs where they perform the biological functions such as in lungs, they are lined to perform gaseous exchange. In the liver, they help in cleaning of blood. The liver sinusoids are lined by endothelial cells along with Kupffer cells.

So, the correct answer is option (D).

Note: Liver sinusoids are a special type of capillaries found in livers. Their function and the endothelium makes them unique and different from other types of similar capillaries. The endothelium along with the kupffer cells perform unique functions in the liver sinusoids.