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Liver: Cell Types Found in Liver Simplified

Overview of the Liver

The liver is the largest solid organ of the body, and the 4 major cells types found in the liver each have a unique role that allows the breakdown of proteins, carbohydrates, lipids, and vitamins. Due to the positioning of the liver between the digestive tract and the rest of the body, the liver also plays a role in filtering the blood by removing toxic substances and engulfing bacteria that made it past the defense mechanisms of the stomach and small intestine. For a simplified explanation of the liver I suggest your take a look at the main functions of the liver first.

Specialized Cell Types of the Liver

The location of the liver in humans.
Picture from Imageafter

Hepatocytes

The parenchymal or major cell type found in the liver are hepatocytes. The hepatocytes make up  75% of the liver, and carry out the major functions of the liver:

  1. Breakdown and store lipids, carbohydrates, and amino acids
  2. Produce bile which aids in the breakdown of food.
  3. Detoxify harmful chemicals
  4. Multiply rapidly to regenerate the liver when damaged

Hepatocytes are grouped into similar functional units and are similar in appearance, but they express different genes depending on their location. This compartmentalization allows the liver to carry out the multiple functions of the liver in different locations.

Every cell does not participate in the oxidation of proteins, detoxification of reactive oxygen species, and bile productions. These tasks would be given to different groups of hepatocytes depending on their location in the liver.

 

The rest of the cells are in compartments

The rest of the cells in the liver (collectively called non-parenchymal cells) are found in compartments between the massive number of hepatocytes.

1. Kupffer Cells

Kupffer cells are star shaped cells that have the crucial function of protection the liver from bacteria and other harmful antigens that escape the defenses of the stomach and small intestine. This is no easy journey from ingested bacteria since the acidic conditions of the stomach kill a majority of invading bacteria. If anything survives the acidic conditions of the stomach they must compete with the “friendly” bacteria of the small intestine to survive.

2. Stellate (Ito) Cells

One function of stellate cells is the storage of vitamin A also known as retinol. Vitamin A is a group of related molecules we need in small quantities. Vitamin A stored in Stellate cells have been shown to contribute to liver regeneration, fibrosis, and tumor formation.

3. Liver Sinusoidal Endothelial Cells

Endothelial cells line the sinuses (space between hepatocytes)  and regulate the passage of molecules from the blood vessels into the liver. The endothelial cells have extended processes and pores known as fenestrations that allow nutrients and other important molecules to pass from blood vessels through a region in the liver known as the Space of Disse.

The Space of Disse is like the troll birdge. Not everyone get to cross.
Image by Flickr user Aldeka

The Space of Disse is similar to the tale of a bridge with a troll protecting it and only allows travelers who pay to walk across. Likewise only molecules the liver needs are allowed to cross the Space of Disse where they will enter hepatocytes. When alcoholics develop liver fibrosis they show a disruption in the fenestrations spanning the endothelial cells. This results in disrupted solute uptake and impaired liver function.

 

The liver is the central unifying Organ

The liver is located in a pivotal location of the body and plays a crucial role that unifies concepts of metabolism, waste excretion, immune defense. The major cells that contribute to the liver’s functions are:

  1. Hepatocytes – carry out main functions of the liver such as glycolysis, gluconeogenesis, and bile production
  2. Kupffer cells -macrophages that protect the liver from invading organisms and destroy cancerous liver cells
  3. Stellate or Ito cells – store Vitamin A which helps regulate the immune system
  4. Liver Sinusoidal Endothelial Cells – cells that protect the bridge into the liver

 

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One comment

  1. Which of these cells carry out the synthetic work? ie building of coagulation proteins and Albumin