Question

Particles that enter circulation often accumulate in the liver and spleen. Describe the function of the liver and spleen, including the location and function of resident macrophages. Describe two mechanisms for accumulation of particles in the liver. Provide references.

Answer 1

Liver is locatedin the upper part of abdomen.It controls the chemical levels in the blood.It helps carry waste and also breaks down fats during digestion process.It makes some protein and cholestrol.Liver is the organ that stores and releases glucose and stores iron.Regulates blood clotting.Fights infections and other harmful factors in the blood using macrophages.
Spleen is located in the left upper side of abdomen.It produces blood cells during fetal life.Spleen produces opsonins and tuftsins that helps in immune system. It filters blood when antigens,microorganisms or other particles from blood.It stores macrophages that helps fight forein bodies entering the body.

Macrophages are important type of white blood cells that belongs to the immune system that are formed when there is infection,foreign substance or microbes or any particles that does not belong to a healthy body.It is formed from monocytes.They are usually accumulated in the Kupffer cells in the liver.In the spleen they are located in two areas of spleen.They are located in red pulp area as well as white pulp area.When there is an infection ,tissue damage or any particle that has to be removed from blood the monocytes leaves the bloodstream and then enter the affected area to change to macrophages and can ingest the foreign materials.It plays a vital role in regulation of immune responses and to develop inflammation.These macrophages then integrates this antigen to the to present it to helper T cells that produces antibodies.

The mechanism of accumulation of particles in the liver is done by using Kupffer cells located in the liver.It can recognize nanoparticles as a foreign material.One mechanism is using hepatocytes that eliminates the particles by endocytocis.In this mechanism particles traverse the hepatic sinusoid.Then particles depending on the size enters the bile duct via canaliculi and it travels through hepatic ducts and collected.If particles are lesser in size then it can be accumulated and cleared by kupffer cells.If its a large sized particle it is taken by monocytic phygocyte system ,that is using macrophages.