Organs Liver (Detail)

Right Lobe Segment 1

Segment I is the caudate lobe situated posteriorly around the IVC and different to the other 7 segments. It may receive its supply from both the right and the left portal vein and is drained directly into the IVC by one or more small hepatic veins. segments II and III are to the left of the left hepatic vein and falciform ligament with II superior and III inferior to the portal plane. Source

Right Lobe Segment 2

Units II and III lie medial to the falciform ligament with II superior to the portal venous supply and III inferior.

Right Lope Segment 3

Units II and III lie medial to the falciform ligament with II superior to the portal venous supply and III inferior.

Right Lobe Segment 4

Segment IV lies between the left and middle hepatic veins. https://radiopaedia.org/articles/couinaud-classification-of-hepatic-segments

Left Hepatic Vein

The hepatic veins carry oxygen-depleted blood from the liver to the inferior vena cava. They also transport blood that has been drained from the colon, pancreas, small intestine, and the stomach, and cleaned by the liver. These veins originate from the core vein of the liver lobule, but they do not have any valves. They can be segregated into the lower group and the upper group veins. The lower group veins originate from the lower parts of the right or caudate lobe. They are smaller in size than the upper group veins and vary in number from person to person. The upper group usually consists of three large veins that originate from the backside of the liver and drain the right, middle, and left lobes of the liver. The oxygen-depleted blood from these veins empty into the inferior vena cava. From here, the blood is delivered back to the heart, where the re-oxygenation process of the blood takes place. In that respect, the liver performs the role of a filtering organ for blood that is on its way back to the heart. Any impediment in the outflow of blood from the hepatic veins may result in a serious condition known as Budd-Chiari syndrome, which can cause liver damage. Source

Umbilical Vein (Remnant)

The umbilical vein is a vein present during fetal development that carries oxygenated blood from the placenta into the growing fetus. The umbilical vein provides convenient access to the central circulation of a neonate for restoration of blood volume and for administration of glucose and drugs. The unpaired umbilical vein carries oxygen and nutrient rich blood derived from fetal-maternal blood exchange at the chorionic villi. More than two-thirds of fetal hepatic circulation is via the main portal vein, while the remainder is shunted from the left portal vein via the ductus venosus to the inferior vena cava, eventually being delivered to the fetal right atrium.

Hepatic Duct

The duct formed by the junction of the right hepatic duct (which drains bile from the right half of the liver) and the left hepatic duct (which drains bile from the left half of the liver). The common hepatic duct then joins the cystic duct coming from the gallbladder to form the common bile duct. Source

Inferior Vena Cava

The inferior vena cava is the largest vein in the human body. It collects blood from veins serving the tissues inferior to the heart and returns this blood to the right atrium of the heart. Although the vena cava is very large in diameter, its walls are incredibly thin due to the low pressure exerted by venous blood. The inferior vena cava forms at the superior end of the pelvic cavity when the common iliac veins unite to form a larger vein. From the pelvis, the inferior vena cava ascends through the posterior abdominal body wall just to the right of the vertebral column. Along its way through the abdomen, blood from the internal organs joins the inferior vena cava through a series of large veins, including the gonadal, renal, suprarenal and inferior phrenic veins. The hepatic vein provides blood from the digestive organs of the abdomen after it has passed through the hepatic portal system in the liver. Blood from the tissues of the lower back, including the spinal cord and muscles of the back, enters the vena cava through the lumbar veins. Many smaller veins also provide blood to the vena cava from the tissues of the abdominal body wall. Upon reaching the heart, the inferior vena cava connects to the right atrium on its posterior side, inferior to the connection of the superior vena cava. The inferior vena cava and its tributaries drain blood from the feet, legs, thighs, pelvis and abdomen and deliver this blood to the heart. Many one-way venous valves help to move blood through the veins of the lower extremities against the pull of gravity. Blood passing through the veins is under very little pressure and so must be pumped toward the heart by the contraction of skeletal muscles in the legs and by pressure in the abdomen caused by breathing. Venous valves help to trap blood between muscle contractions or breaths and prevent it from being pulled back down towards the feet by gravity. Source

Branch of Hepatic Vein

Hepatic veins are blood vessels which transport the liver’s deoxygenated blood and blood which has been filtered by the liver (this is blood from the pancreas, colon, small intestine, and stomach) to the inferior vena cava. The hepatic veins originate in the liver lobule’s central vein. Hepatic veins are unusual in that they do not have valves. Source

Central Vein

The central veins of liver (or central venules) are veins found at the center of hepatic lobules (one vein at each lobule center). They receive the blood mixed in the liver sinusoids and return it to circulation via the hepatic veins. The central vein of the lobules will converge to form two hepatic veins, which will carry blood from the liver to the inferior vena cava. In the middle of each lobule is a central vein and at the periphery of each lobule are branches of the hepatic portal vein and hepatic artery, opening into spaces between hepatic plates. Arterial blood and portal venous blood, containing nutrient molecules absorbed in the gastrointestinal tract mix as the blood flows from the periphery of the lobule to the central vein. Source

Interlobular Arteriole

The interlobular artery gives off branches called the afferent arteriole, which forms the glomerulus, which is this network of capillaries contained within the glomerular capsule. This is called a Bowman’s capsule or glomerular capsule. The stellate veins join to form the interlobular veins, which pass inward between the rays, receive branches from the plexuses around the convoluted tubules, and, having arrived at the bases of the renal pyramids, join with the venae rectae. The interlobar arteries travel along the bases of the pyramids where they are called the arcuate arteries. The arcuate arteries give off branches that ascend in the cortex called cortical radiate arteries. The afferent arterioles branch off the cortical radiate arteries (a.k.a. interlobular arteries) and bring blood to the glomerulus. Sou rce

Disse Space

The perisinusoidal space (or space of Disse) is a location in the liver between a hepatocyte and a sinusoid. It contains the blood plasma. Microvilli of hepatocytes extend into this space, allowing proteins and other plasma components from the sinusoids to be absorbed by the hepatocytes. Fenestration and discontinuity of the endothelium, as well as its basement membrane, facilitates this transport. This space may be obliterated in liver disease, leading to decreased uptake by hepatocytes of nutrients and wastes such as bilirubin. The perisinusoidal space is the thin and narrow space between a hepatocyte and a liver sinusoid. It is filled with the blood plasma. Source

Sinusoids

A liver sinusoid is a type of sinusoidal blood vessel (with fenestrated, discontinuous endothelium) that serves as a location for mixing of the oxygen-rich blood from the hepatic artery and the nutrient-rich blood from the portal vein.

Liver Cell Plates

The hepatocytes (epithelial cells of the liver) form branching plates of cells, often only one cell thick, between a system of capillary sinusoids that connect the portal tracts to the central vein. Source

Stellate Cells

Stellate cells are any neuron that have a star-like shape formed by dendritic processes radiating from the cell body. Hepatic stellate cells reside between the hepatocytes and small blood vessels in the liver. They are characterised by the presence of lipid droplets and thin protrusions extending around the blood vessels. Their activation in damaged liver leads to secretion of collagen and formation of scar tissue, leading to chronic fibrosis or cirrhosis. Source

Left Lobe Segment 1

Left Lobe Segment 2

Units II and III lie medial to the falciform ligament with II superior to the portal venous supply and III inferior.

Left Lobe Segment 3

Units II and III lie medial to the falciform ligament with II superior to the portal venous supply and III inferior.

Left Lobe Segemtn 4

Segment IV lies between the left and middle hepatic veins. https://radiopaedia.org/articles/couinaud-classification-of-hepatic-segments

Right Hepatic Vein

The hepatic veins are the veins that drain de-oxygenated blood from the liver into the inferior vena cava. There are usually three upper hepatic veins draining from the left, middle, and right parts of the liver. These are larger than the group of lower hepatic veins that can number from six to twenty. All of the hepatic veins drain into the inferior vena cava. They are one of two sets of veins connected to the liver, the others are the portal veins. The large hepatic veins arise from smaller veins found within the liver, and ultimately from numerous central veins of the liver lobules. None of the hepatic veins have valves.

Middle Hepatic Vein

The middle hepatic vein runs at the middle hepatic fissure and drains segments IVa, IVb, V and VIII. The vertical plane of the middle hepatic vein separates the segments V and VIII (posterolateral to this plane) from segments IVa and IVb (anteromedial to this plane).

Portal Vein

The hepatic portal vein is a vessel that moves blood from the spleen and gastrointestinal tract to the liver. the portal vein splits into left and right veins before entering the liver. The right vein then branches off into anterior and superior veins. The portal vein supplies approximately 75 percent of blood flow to the liver. The portal vein is not a true vein, which means it does not drain into the heart. Instead, it brings nutrient-rich blood to the liver from the gastrointestinal tract and spleen. Once there, the liver can process the nutrients from the blood and filter out any toxic substances it contains before the blood goes back into general circulation. Source

Hepatic Artery

The common hepatic artery is a short blood vessel that supplies oxygenated blood to the liver, pylorus of the stomach, duodenum and pancreas.

Bile Duct

The bile ducts carry bile from the liver and gallbladder through the pancreas to the duodenum, which is a part of the small intestine. Bile is a dark-green or yellowish-brown fluid secreted by the liver to digest fats. After you eat, the gallbladder releases bile to help in digestion and fat absorption. Bile also helps clear the liver of waste products. Source

Branch of Portal Vein

The portal vein or hepatic portal vein is a blood vessel that carries blood from the gastrointestinal tract, gallbladder, pancreas and spleen to the liver. This blood contains nutrients and toxins extracted from digested contents. Approximately 75% of total liver blood flow is through the portal vein, with the remainder coming from the hepatic artery proper. The blood leaves the liver to the heart in the hepatic veins. The portal vein is not a true vein, because it conducts blood to capillary beds in the liver and not directly to the heart. It is a major component of the hepatic portal system, one of only two portal venous systems in the body – with the hypophyseal portal system being the other. The portal vein is usually formed by the confluence of the superior mesenteric and splenic veins and also receives blood from the inferior mesenteric, gastric, and cystic veins.

Distributing Vein

The veins that drain into the hepatic portal vein include the superior mesenteric v., inferior mesenteric v. and splenic v. This blood is nutrient-rich but oxygen-poor. Oxygen-rich blood is delivered to the liver by the hepatic artery proper. This arrangement allows the liver to perform its processing and storage functions. Source

Inlet Venule

A venule is a small blood vessel in the microcirculation that allows deoxygenated blood to return from capillary beds to larger blood vessels called veins. Venules range from 8 to 100μm in diameter and are formed when capillaries come together. Many venules unite to form a vein. Venule walls have three layers: an inner endothelium composed of squamous endothelial cells that act as a membrane, a middle layer of muscle and elastic tissue, and an outer layer of fibrous connective tissue. The middle layer is poorly developed so that venules have thinner walls than arterioles. Venules are extremely porous so that fluid and blood cells can move easily from the bloodstream through their walls Venules are small blood vessels in the microcirculation that connect capillary beds to veins. Venule walls have three layers: an inner endothelium composed of squamous endothelial cells that act as a membrane, a middle layer of muscle and elastic tissue, and an outer layer of fibrous connective tissue. A venule is a small blood vessel in the microcirculation that allows deoxygenated blood to return from capillary beds to larger blood vessels called veins. Venules range from 8 to 100μm in diameter and are formed when capillaries come together. Many venules unite to form a vein. Source

Hepatocyte

The liver performs many essential functions related to digestion, metabolism, immunity, and the storage of nutrients within the body. These functions make the liver a vital organ without which the tissues of the body would quickly die from lack of energy and nutrients. Fortunately, the liver has an incredible capacity for regeneration of dead or damaged tissues, it capable of growing as quickly as a concerous tumor to restore its normal size and Function. Hepatocytes are cuboidal epithelial cells that line the sinusoids and make up the majority of cells in the liver. Hepatocytes perform most of the liver’s functions — metabolism, storage, digestion, and bile production. Tiny bile collection vessels known as bile canaliculi run parallel to the sinusoids on the other side of the hepatocytes and drain into the bile ducts of the liver. Source

Kupffer Cells

Kupffer cells are a type of macrophage that capture and break down old, worn out red blood cells passing through the sinusoids. also known as stellate macrophages and Kupffer-Browicz cells, are specialized macrophages located in the liver, lining the walls of the sinusoids that form part of the mononuclear phagocyte system. Source

Lymph Vessel

Lymphatic vessels are structures of the lymphatic system that transport fluid away from tissues. Lymphatic vessels are similar to blood vessels, but they don’t carry blood. The fluid transported by lymphatic vessels is called lymph. Lymph is a clear fluid that comes from blood plasma that exits blood vessels at capillary beds. This fluid becomes the interstitial fluid that surrounds cells. Lymph vessels collect and filter this fluid before directing it toward blood vessels near the heart. It is here that lymph re-enters blood circulation. Returning lymph to the blood helps to maintain normal blood volume and pressure. It also prevents edema, the excess accumulation of fluid around tissues. It’s a thin-walled vessels structured like blood vessels, that carry lymph. As part of the lymphatic system, lymph vessels are complementary to the cardiovascular system. Lymph vessels are lined by endothelial cells, and have a thin layer of smooth muscle, and adventitia that bind the lymph vessels to the surrounding tissue. Lymph vessels are devoted to the propulsion of the lymph from the lymph capillaries, which are mainly concerned with absorption of interstitial fluid from the tissues. Lymph capillaries are slightly larger than their counterpart capillaries of the vascular system. Lymph vessels that carry lymph to a lymph node are called afferent lymph vessels, and those that carry it from a lymph node are called efferent lymph vessels, from where the lymph may travel to another lymph node, may be returned to a vein, or may travel to a larger lymph duct. Lymph ducts drain the lymph into one of the subclavian veins and thus return it to general circulation.

Canaliculs

This is a thin tube that collects bile secreted by hepatocytes. The bile canaliculi merge and form bile ductules, which eventually become common hepatic duct.