Anatomy of the Liver

liverThe Liver weights approximately three pounds. The second largest organ in the body is the liver. Only the skin is a larger and heavier organ. The liver has many critical functions such as digestion, immunity, metabolism and storage for essential nutrients in the body. These functions make the liver a very vital organ, which the tissues of the body, would die if they do not receive the nutrients and energy. However, the liver can regenerate dead or damaged tissues. It is also possible to grow as quickly as a cancerous tumor to restore it to normal function and size.

Anatomy of the Liver
Gross Anatomy
The liver is approximately a triangular organ that extends across the entire abdominal cavity inferior to the diaphragm. Most of the live’s mass is found on the right side of the body where it slopes inferiorly toward the right kidney. The liver is made of very soft, brown and pink tissues shielded by attached tissues capsules. This capsule is further covered and bolstered by the peritoneum of the abdominal cavity, which preserves the liver and holds it in place inside the abdomen.

The peritoneum attached the liver in four locations; the coronary ligament, the right and left triangular ligaments, as well as the falciform ligament. These attachments are not are not exactly ligaments in the anatomical sense; rather they are condensed regions of a peritoneal membrane that hold the liver.

Liver_04_Couinaud_classification
The wide coronary ligament attaches the superior central portion of the liver to the diaphragm.
Positioned on the lateral borders of the left and right lobes, respectively, the left and right triangular ligaments attach the superior ends of the liver to the diaphragm.
The falciform ligament runs inferiorly from the diaphragm across the anterior edge of the liver to its interior border. At the inferior edge of the liver, the falciform ligament structures the round ligament (ligament teres) of the liver and joins the liver to the umbilicus. The round ligament is a remnant of the umbilical view that carries blood into the body during fetal growth.liver 6

The liver consists of four different lobes, the right, left, caudate, and quadrate lobes.
The liver right and left lobes are the largest lobes and are distributed by the falciform ligament. The right lobe is about five to six times larger than the tapered left lobe. The small caudate lobe expands to form the posterior side of the right lobe and encompassing the inferior vena cava.
The small quadrate lobe is lower than the caudate lobe and stretches from the poster side of the right lobe and binds around the gallbladder.


Bile Ducts

The tubes that carry bile from the liver and gallbladder are called bile ducts and form a branched formation known as the biliary tree. Bile created by liver cells drain into microscopic canals known as bile canaliculi. Multiple bile canaliculi connect into many larger bile ducts found throughout the liver.

These bile ducts join to form the larger left and right hepatic ducts, which carry bile from the right and left lobes of the liver. Those two hepatic ducts join to form the common hepatic duct that drains all bile away from the liver. The common hepatic duct eventually joins with the cystic duct from the gallbladder to form the common bile duct, taking bile to the duodenum of the small intestine. Most of the bile produced by the liver is pushed back up to the cystic duct by peristalsis to emerge in the gallbladder for storage until it is required for digestion.CDR765897-750

Blood vessels
The blood supply of the liver is unusual among all organs of the body due to the hepatic portal via the system. Blood traveling to the stomach, spleen, pancreas, intestines and pancreas through capillaries in this organ and is collected from the hepatic portal vein. The hepatic portal vein then passes this blood to the tissues of the liver where the contents of the blood are separated into smaller vessels and processed before being crossed on to the rest of the body. Blood leaving the tissues of the liver gathers into the hepatic veins that lead to vena cava and return to the heart. The liver also has it own system of parties and arterioles that provide oxygenated blood to its tissues just like any other organ.

Lobules
The internal composition of the liver is made of nearly 100,000 small hexagonal functional units known as lobules. Each lobule consists of a central view surrounded by six hepatic portal veins and six hepatic arteries. These blood vessels are attached by many capillary-like tubes referred to as sinusoids, which spread from the portal veins and arteries to meet the central vein like spoke on a wheel.

Each sinusoid passes through liver tissue containing two primary cell types: Kupffer cells and hepatocytes.2423_Microscopic_Anatomy_of_Liver

Kupffer cells are a kind of macrophage that recovers and break down old and worn out red blood cells crossing within the sinusoids.
Hepatocytes are cuboidal epithelial cells that overlay the sinusoids and make up the bulk of cells in the liver. Hepatocytes perform most of the liver’s functions such as bile production, digestion, metabolism, and active. Tine bile collection vessels called bile canaliculi run parallel to the sinusoids on the another side of the hepatocytes and empty into the bile ducts of the liver.

Physiology of the Liver

Digestion

The liver performs an operating role in the manner of digestion through the generation of bile. Bile is a blend of water, bile salts, cholesterol, and the pigment bilirubin. Hepatocytes in the liver create bile, which then carries through the bile ducts to be stored in the gallbladder. When food containing fats reach the duodenum, the class of the duodenum releases the hormone cholecystokinin to incite the gallbladder to release bile. Bile moves through the bile ducts and is sealed into the duodenum where it emulsifies large masses of fat. The emulsification of fats by bile becomes the large clumps of fat into smaller pieces that have more surface and are therefore easier for the body to digest.

Bilirubin, in bile, is a product of the liver’s digestion of exhausted red blood cells. Kupffer cells in the liver capture and destroy old, exhausted red blood cells and pass their components on to hepatocytes. Hepatocyte metabolizes hemoglobin, the red oxgen0carrying pigment of red blood cells. Kupffer cells in the liver catch and destroy old, worn-out red blood cells and pass their elements on to hepatocytes. Hepatocytes metabolize hemoglobin, the red oxygen-carrying pigment of red blood cells, into the elements heme and globin. Globin protein is further broken down and utilized as an energy source of the body. The iron -containing heme group cannot be recycled by the body and is transformed into the pigment bilirubin and appended to bile to be excreted from the body. Bilirubin gives bile its distinctive greenish color. Intestinal bacteria further turn bilirubin into the brown pigment stercobilin, which gives feces its brown coloration.

liver inferior view
The hepatocytes of the liver have many critical metabolic functions that support the cells of the body. Due to all the blood leaving the digestive system passing via the hepatic portal vein, the liver is responsible for metabolizing its carbohydrates and proteins into biologically usable materials.

The digestive

The hepatocytes of the liver are tasked with many of important metabolic jobs that support the cells of the body. Because all of the blood exiting the digestive system moves through the hepatic portal vein, the liver is responsible for metabolizing carbohydrate, lips, and proteins into biologically useful materials.

Our digestive system breaks down carbohydrates into the monosaccharide glucose which cells are as a primary energy source. Blood entering the liver trough the hepatic portal vein is very rich in glucose from digested food, Hepatocytes consume much of this glucose and stock it as the macromolecule glycogen, a branched polysaccharide that provides the hepatocytes for packing away significant amounts of glucose and quickly releasing glucose between meals. The absorption and release and release of glucose by the hepatocytes help to support homeostasis and protect the rest of the body from serious spikes and drops in the blood glucose level.

Fatty acids in the blood crossing through the liver are used by hepatocytes and metabolized to create energy in the form of ATP. Glycerol, another lipid component, is transformed into glucose by hepatocytes through the process of gluconeogenesis. Hepatocytes can also produce lips like cholesterol, lipoproteins that used by other cells through the body, and phospholipids. Much of the cholesterol provided by hepatocytes gets eliminated from the body as a component of bile.
Dietary proteins are broken down into their amino acids by the digestive system before being passed on the hepatic portal vein. Amino acids entering the liver need metabolic processing before being used as an energy source. Hepatocytes first extract the amine groups of the amino acids and transform them into ammonia and ultimately urea. Urea is less noxious than ammonia and can be excreted in urine as an excess product of digestion. The ending parts of the amino acids can be broken down into ATP or turned into new glucose molecules via the process of gluconeogenesis.

Detoxification

As blood from the digestive organs passes through the through the hepatic portal circulation, the hepatocytes of the liver keep track of the contents of the blood and eliminate many potentially toxic materials before they can spread to the rest of the body. Enxyme in hepatocytes metabolize many f these toxins such as alcohol and drugs into their inactive metabolites, And in orde to keep hormone levels within homeostatic limits, the liver also metabolizes and removes from circulation hormones produced by the own body glands.

Storage

The liver provides storage of many important nutrients, minerals, vitamins obtained from blood passing through the hepatic portal system. Glucose is carried into hepatocytes under the control of the hormone insulin and deposited as the polysaccharide glycogen. Hepatocytes also consume and store fatty acids from digested triglycerides. The storage of this nutrient allows the liver to maintain the homeostasis of blood glucose. Our liver also stores minerals and vitamins, such as vitamin A, D E, K and B12 and minerals iron and copper, to provide a constant supply of these essential substances of the tissues of the body.

Production
The liver is accountable for the production of various vital protein components of blood plasma: albumins, fibrinogen, prothrombin. Fibrinogen and Thrombin are coagulation factors involved in the formation of blood clots. Albumins are proteins that principal the isotonic environment of the blood so that cells of the body do not add or lose water in the presence of body fluids.

Immunity
The liver function as an organ of the immune system through the function Kupffer cells that line the sinusoids. Kuppffer cells are the type of fixed macrophage hat form part of the mononuclear phagocyte system as well as macrophages in the spleen and lymph nodes. Kupfer cells play an important role by capturing and digesting bacteria, parasites, fungi, worn out blood cells, and cellular debris. The high volume of blood moving through the hepatic portal system and the liver provides Kupffer cells to clean large volumes of blood very quickly.


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Health Life Media Team