27.24
Histologie der Leber
Die mikroskopische Anatomie der Leber ist ein komplexes und kompliziertes System, das aus zahlreichen Struktureinheiten besteht, die als Leberläppchen…
Die Leber besteht aus mehreren histologischen Komponenten wie Hepatozyten, Gallenkanälen und Sinusoiden.
Hepatozyten sind spezialisierte Epithelzellen, die in stark verzweigten, unregelmäßigen, dreidimensionalen Platten angeordnet sind, die als Leberlaminae bezeichnet werden.
Ihre Hauptfunktion besteht darin, die Blutentgiftung zu unterstützen und die Galle abzusondern.
Hepatozyten sezernieren Galle in kleine Gänge, die Gallenkanäle genannt werden. Von hier aus fließt die Galle in die Gallengänge und anschließend in größere Gallengänge.
Am Rand der Laminae befindet sich eine Ansammlung von Gallengängen, Ästen der Leberarterien und Leberportalvenen, die als Portaltriade bezeichnet werden.
Lebersinusoide, die zwischen den Hepatozytenreihen vorhanden sind, sammeln Blut aus den Pfortadertiaden und entleeren sich schließlich in die Zentralvene.
Das Blut gelangt aus den zentralen Venen in die Lebervenen, die in die untere Hohlvene münden.
Die sinusförmigen Wände haben auch sternförmige oder hepatische Makrophagen, die das Blut filtern, indem sie Ablagerungen und abgenutzte Blutzellen entfernen.
Es gibt viele anatomische Möglichkeiten, wie Hepatozyten, Portaltriade und Sinusoide angeordnet werden können, von denen der hepatische Acinus die am meisten akzeptierte ist.
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Q1: What are hepatocytes and what is their primary role in the liver?
Hepatocytes are specialized epithelial cells arranged in branched, irregular three-dimensional plates called hepatic laminae. They perform critical functions including blood detoxification and bile secretion. These versatile cells also store glucose as glycogen, produce plasma proteins from amino acids, and convert harmful ammonia into urea, making them essential for metabolic processing.
Q2: How does bile move through the liver after hepatocytes secrete it?
Hepatocytes secrete bile into small ducts called bile canaliculi. From there, bile flows into bile ductules and subsequently into larger bile ducts. This organized ductal system ensures efficient bile transport and delivery to the gallbladder and small intestine for digestive functions.
Q3: What structures make up the portal triad and where is it located?
The portal triad comprises three key structures: a branch of the hepatic artery, a branch of the hepatic portal vein, and a bile duct. Located at each corner of the liver lobule, the portal triad ensures delivery of oxygen-rich arterial blood and nutrient-laden venous blood to hepatocytes while facilitating bile drainage.
Q4: What role do liver sinusoids play in hepatic blood flow?
Liver sinusoids are enlarged, heavily fenestrated vessels positioned between hepatocyte plates that collect blood from the portal triads. Blood flows through these sinusoids and empties into the central vein, eventually reaching hepatic veins that drain into the inferior vena cava. This arrangement enables efficient nutrient and oxygen delivery to hepatocytes.
Q5: How do stellate macrophages contribute to liver function?
Stellate macrophages, also called hepatic macrophages or Kupffer cells, are star-shaped cells embedded in sinusoid walls. They filter blood by removing debris such as bacteria and worn-out blood cells, protecting the body from harmful substances and maintaining blood quality as it circulates through the liver.
Q6: What is the hepatic acinus and why is it significant?
The hepatic acinus is the most accepted anatomical arrangement of hepatocytes, portal triads, and sinusoids within the liver. This organizational model explains how the liver's structural components work together to facilitate blood detoxification, nutrient processing, and bile production in a coordinated, efficient manner.
Q7: How much bile do hepatocytes produce daily and what cellular structures enable this?
Hepatocytes secrete approximately 900 milliliters of bile daily. This high secretory capacity is supported by abundant cellular apparatus including rough and smooth endoplasmic reticulum, Golgi apparatus, peroxisomes, and mitochondria. These organelles provide the energy and synthetic machinery necessary for continuous bile production and other metabolic functions.