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Liver anatomy and physiology

High Yield Notes
6 pages
Transcript

Your liver lies just below your diaphragm in the right upper quadrant of your abdominal cavity. And it does a wide range of things - from helping to manage the body’s metabolism, detoxification, and bile production.

The surface of the liver is covered by a serous membrane called the visceral peritoneum.

The visceral peritoneum folds over on itself, and it suspends the liver from the abdominal wall and the diaphragm.

There are five of these peritoneal folds and they’re referred to as ligaments.

There’s the falciform ligament, which attaches the liver to the anterior wall of the abdominal cavity.

There’s the round ligament of the liver, which is a fibrous cord found in the free margin of the falciform ligament.

There’s the coronary ligament, which attaches the liver to the inferior surface of the diaphragm.

There’s the right triangular ligament, which is a small triangular fold which attaches the right lateral surface of the liver to the diaphragm.

And lastly there’s the left triangular ligament, which attaches the upper left surface of the liver to the diaphragm.

Now, viewed from above, the liver is divided by the falciform ligament into two main lobes: the larger right lobe and the smaller left lobe.

When viewed from below, the liver has two additional lobes between the right and left lobe--the posterior caudate lobe and the anterior quadrate lobe. These two lobes are separated by the porta hepatis, which literally means “the gate to the liver”.

Now the porta hepatis contains the hepatic artery, the hepatic portal vein, and the common hepatic duct.

The hepatic artery delivers oxygen-rich arterial blood from the heart to the liver, while the hepatic portal vein delivers nutrient-rich venous blood from the gastrointestinal tract, but also from the spleen, and pancreas.

Lastly, the common hepatic duct drains bile from the liver into the gallbladder.

Now let’s take a closer look inside a section of the liver, which shows the functional units of the liver called hepatic lobules.

Each hepatic lobule looks like a tiny hexagon.

At the periphery of the hepatic lobule, there are portal triads which are made up of a branch of the hepatic artery, a branch of the portal vein and one or two small bile ducts.

Now, these branches of the hepatic artery and the portal vein both drain into very porous blood vessels called sinusoids which carry blood towards the center of the lobule and drain into the central vein.

From central veins, the blood flows into the hepatic veins and eventually drain into the inferior vena cava.

Now, back in the sinusoids, oxygen and nutrients are able to get through pores in the sinusoids and enter the underlying hepatocytes.

Hepatocytes take in oxygen and nutrients and deposit carbon dioxide into the blood, like all other cells in the body. But in addition, they also pick up and detoxify harmful substances like drugs or alcohol.

Hepatocytes help maintain a normal blood glucose level.

When blood glucose levels are high like after eating a meal, hepatocytes convert glucose into a storage molecule called glycogen using a process called glycogenesis.

Sources
  1. "Medical Physiology" Elsevier (2016)
  2. "Physiology" Elsevier (2017)
  3. "Human Anatomy & Physiology" Pearson (2018)
  4. "Principles of Anatomy and Physiology" Wiley (2014)
  5. "THE STRUCTURE OF THE LIVER OF VERTEBRATES" Cells Tissues Organs (1952)
  6. "Anatomy of the hepatic hilar area: the plate system" Journal of Hepato-Biliary-Pancreatic Surgery (2000)