HEPATIC PORTAL VEIN

  Portal Vein (Hepatic Portal Vein)

The hepatic portal vein drains blood from the abdominal part of the Gastrointestinal tract from the lower third of the esophagus to halfway down the anal canal. It also drains blood from the spleen, pancreas, and gallbladder. The hepatic portal vein enters the liver and breaks up into sinusoids, from which blood passes into the hepatic veins that join the inferior vena cava. The portal vein is about 2 inch (5 cm) long and forms behind the neck of the pancreas by the union of the superior mesenteric and splenic veins. It ascends to the right, behind the first part of the duodenum, and enters the lesser omentum. It then runs upward in front of the opening into the lesser

sac to the porta hepatis, where it lies behind the bile duct and the hepatic artery. Finally, it divides into right and left terminal branches.

Tributaries of the Hepatic portal vein

Splenic vein: 

Splenic vein leaves the hilum of the spleen and passes to the right in the splenorenal ligament. It unites with the superior mesenteric vein behind the neck of the pancreas to form the portal vein. It receives the short gastric, left gastro-omental, inferior mesenteric, and pancreatic veins.

Inferior mesenteric vein: 

Inferior mesenteric vein ascends on the posterior abdominal wall and joins the splenic vein behind the body of the pancreas. It receives the superior rectal veins, the sigmoid veins, and the left colic vein.

Superior mesenteric vein: 

Superior Mesenteric vein ascends in the root of the mesentery of the small intestine. It passes in front of the third part of the duodenum and joins the splenic vein behind the neck of the pancreas. It receives the jejunal, ileal, ileocolic, right colic, middle colic, inferior pancreaticoduodenal, and right gastro-omental veins.

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Left gastric vein: 

Left gastric vein drains the left portion of the lesser curvature of the stomach and the distal part of the esophagus. It opens directly into the portal vein.

Right gastric vein: 

Right gastric vein drains the right portion of the lesser curvature of the stomach and drains directly into the portal vein.

Cystic veins: 

Cystic veins either drain the gallbladder directly into the liver or join the portal vein.

Clinical Notes on Hepatic Portal Vein

Portal–Systemic Anastomoses

Under normal conditions, the portal venous blood traverses the liver anddrains into the inferior vena cava of the systemic venous circulation by way of the hepatic veins. This is the direct route. However, other, smaller communications exist between the portal and systemic systems, and they become important when the direct route becomes blocked.

These communications are as follows:

Gastroesophageal anastomosis.

 At the lower third of the esophagus,the esophageal branches of the left gastric vein (portal tributary) anastomose with the esophageal veins draining the middle third of the esophagus into the azygos veins (systemic tributary).Anorectal anastomosis. Halfway down the anal canal, the superior rectal veins (portal tributary) draining the upper half of the anal canal anastomose with the middle and inferior rectal veins (systemic tributaries), which are tributaries of the internal iliac and internal pudendal veins, respectively.

Paraumbilical anastomosis. 

The paraumbilical veins connect the left branch of the portal vein with the superficial veins of the anterior abdominal wall (systemic tributaries). The paraumbilical veins travel in the falciform ligament and accompany the ligamentum teres.

Retroperitoneal anastomoses. 

The veins of retroperitoneal organs (duodenum, pancreas, ascending colon, and descending colon), plus the liver (portal tributaries), anastomose with the renal, lumbar, and phrenic veins (systemic tributaries). 

Portal Hypertension

Portal hypertension is a common clinical condition that influences the portal–systemic anastomoses just described. Enlargement of the portal–systemic connections is frequently accompanied by congestive enlargement of the spleen. Portacaval shunts for the treatment of portal hypertension mayinvolve the anastomosis of the portal vein, because it lies within the lesser omentum, to the anterior wall of the inferior vena cava behind the entranceinto the lesser sac. The splenic vein may be anastomosed to the left renal vein after removing the spleen.

Blood Flow through Portal Vein and Malignant Disease

The portal vein conveys about 70% of the blood that enters the liver. The remaining 30% is oxygenated blood, which passes to the liver via the

hepatic artery. The wide angle of union of the splenic vein with the superior mesenteric vein to form the portal vein leads to streaming of the blood flow in the portal vein. The right lobe of the liver receives blood mainly from the intestine, whereas the left lobe plus the quadrate and caudate lobes receive blood from the stomach and the spleen. This distribution of blood may explain the distribution of secondary malignant deposits in the liver.

IONIZATION ENERGY

  What is Ionization energy?

Ionization energy is the minimum amount of energy required to remove the most loosely bounded electron from an isolated gaseous atom in its ground state.

CHEMISTRY| ORGANIC CHEMISTRY

 What is Organic Chemistry ?

Organic chemistry is the branch of  Chemistry that deals with the study of structure, composition, chemical reactions, and other physical and chemical properties of hydrocarbons and their derivatives. 

What are hydrocarbons and their derivatives? 

Hydrocarbons are the compounds of purely carbon and hydrogen e.g alkanes, alkenes, alkynes and aromatic compounds like benzene, napthalene, anthracene and many others. Not the atom of any other element is present in them. If any other atom is attached with these hydrocarbons, then these compounds are called as the derivatives of hydrocarbons. They may contain elements like Oxygen, Nitrogen, Halogens, Sulphur, Phosphorus, and some metals like magnesium, potassium, copper,iron etc. For example alcohols(R-OH), Amines (R-NH2), Alkyl halides (R-X), Carboxylic acids(R-COOH), Phenols, substituted aryls, Nitro benzene, Grignard reagents(R-Mg-X)and  many others. These compounds are called as derivatives because they are formed by the substitution of a group in a hydrocarbons. 

What are the classes of organic compounds? 

Organic compounds are divided into different classes on the basis of the functional group attached to the hydrocarbons. There are too many classes of organic compounds, a few of them are listed below. 

Some common classes of organic compounds with general structures and class name.

How do we study organic compounds? 

About 900 million organic compounds exists in the today's world and they are increasing  exponentially. These compounds may be naturally occurring or synthesized artificially in the laboratory for commercial purposes. As, it would be quite impossible to study these organic compounds individually. So, to simplify the study of organic compounds, these are classified or divided into homologous series. 

What are homologous series? 

Homologous series is a series of organic compounds having same general formula (the length of carbon chain increases but have the same functional group), chemical properties , show similar chemical reactions and have comparable methods of preparation. The successive members of the homologous series vary from each other by a CH2  group. The members of homologous series differ from each other because of their chain length. 

For example, the hydrocarbons having OH- group attached to the carbon atom, form a homologous series of compounds called as Alkanols (alcohols). The chemical formula and chain length of the adjacent members of this series differ from each other by -CH2 (methyl group). 

Definition of chemistry | Matter | Substance | Mixture

WHAT IS CHEMISTRY? 

Chemistry is the branch of science that deals with the study of matter ( substance and mixture), their chemical and physical properties, the chemical reactions and the conditions that govern these reactions. 

FLAVONOIDS

 FLAVONOIDS 

Flavonoids are plant's secondary metabolites and have a polyphenolic structure. These are an important class of natural products. These are present abundantly in fruits, vegetables, cereals, tea, wine, and many others. They have many biochemical effects associated with them, which attributes them important biological activities like anti-oxidant, anti-inflammatory, anti-cancerous, neuro protective and cardiovascular protective etc.