The hepatic portal system PDF

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Hepatic portal system The two main blood vessels on the right lobe that supply the liver are; hepa7c artery and the portal vein. The hepa7c artery is a blood vessel that supplies oxygenated blood and carries the blood from the aorta to the liver. The hepa7c portal vein located in the abdominal cavity formed by both the superior mesenteric and splenic veins which channel blood from the gastrointes7nal tract and spleen. These two main blood vessels subdivide into capillaries that lead to the lobule. There are four lobes that make up the liver, which are: le?, right, caudate and quadrate. From then the lobes divides further into lobules (each lobule is made up of millions of hepa7c cells which become metabolic cells of the liver. (Lumen Candela, n.d). The hepa7c portal system is formed by veins (superior and inferior mesenteric veins, the splenic vein, gastric vein and the cys7c vein) that drains the diges7ve organs, spleen, and pancreas and delivers nutrient-rich blood and toxins through the short hepa7c portal vein to the liver for processing. Slowly blood flows through the liver to where some nutrients are stored or processed before it is allowed to enter the systemic circula7on. The hepa7c veins that enter the inferior vena cava drains the liver. To ensure that the liver maintains the proper glucose, fat and protein level, the system makes the blood have a “detour” for processing the substances as well as processing drugs and toxins that are absorbed from the stomach and intes7nes. (Marieb, 2012). The inferior mesenteric vein drains the terminal parts of the large intes7ne and drains into the splenic vein, which itself drains the spleen, pancreas and the le? side of the stomach. The splenic vein and superior mesenteric vein drain the small intes7ne and the first part of the colon to form the hepa7c portal vein. The le? gastric vein drains the right side of the stomach, drains directly into the hepa7c portal vein. (Marieb, 2019). The hepa7c portal system is to ensure that the blood from the portal vein (venous blood supplies 75% of the liver’s blood) drains the diges7ve system and carries the nutrients from the gastrointes7nal tract (the stomach, intes7nes, spleen and pancreas) to pass through the liver before entering the rest of the circula7on. The hepa7c portal system also ensures to connect capillaries of the gastrointes7nal tract with the capillaries within the liver. Before the substances get exposed to the rest of the body, the liver ensures that they store and detoxifies the nutrients. Carbohydrates and amino acids can be stored or to help make new proteins and carbohydrates. (Lumen Candela, n.d)

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! Hepa&c!portal!circula&on:!The!circula&on!in!which!the!hepa&c!portal!vein!carries! dissolved!nutrients!from!the!diges&ve!tract!to!the!liver!for!processing.!–!Essen&als!of!Human! Anatomy!and!Physiology! The!hepa&c!portal!system!is!composed!of!two!capillary!beds!separated!by!a!vein!between! the!arterial!supply!and!the!venous!damage.!The!first!capillary!bed!drains!the!diges&ve! organs,!spleen!and!pancreas!and!delivers!this!blood!containing!nutrients!and!toxins!through! the!short!portal!vein!to!the!liver!for!processing.!Some!nutrients!are!stored!or!processed!in! various!ways!for!later!release!in!blood.!Blood!flows!slowly!through!the!liver!sinusoids!which! cons&tute!the!second!capillary!bed.!The!liver!is!drained!by!the!hepa&c!veins!that!enter!the! inferior!vena.!This!system!allows!the!blood!to!take!a!“detour”!to!ensure!processing!of! absorbed!substances,!as!the!liver!is!a!key!organ!that!is!involved!in!maintaining!the!proper! glucose,!fat!and!protein!level,!as!well!as,!processing!of!drugs!and!toxins!absorbed!from! stomach!and!intes&nes.!(Powerpoints)! Hepa&c!portal!circula&on.! The!veins!of!the!hepa&c!portal!circula&on!drain!the!diges&ve!organs,!spleen,!and!pancreas! and!deliver!this!blood!to!the!liver!through!the!hepa&c!portal!vein.!When!you!have!just!eaten,! the!hepa&c!portal!blood!contains!large!amounts!of!nutrients.!Because!the!liver!is!a!key!body! organ!involved!in!maintaining!the!proper!glucose,!fat!and!protein!concentra&ons!in!the! blood,!this!system!“takes!a!detour”!to!ensure!that!the!liver!processes!these!substances! before!they!enter!the!systemic!circula&on.!As!blood!flows!slowly!through!the!liver,!some!of! the!nutrients!are!removed!to!be!stored!or!processed!in!various!ways!for!later!release!to!the! blood.!The!liver!is!drained!by!the!hepa&c!veins!that!enter!the!inferior!vena!cava.!Like!the! portal!circula&on!that!links!the!hypothalamus!of!the!brain!and!the!anterior!pituitary!gland,! the!hepa&c!portal!circula&on!is!a!unique!and!unusual!circula&on.!Normally,!arteries!feed! capillary!bed,!which!in!turn!drain!into!veins.!! The!major!vessels!composing!the!hepa&c!portal!circula&on!include!the!inferior!and!superior! mesenteric!veins,!the!splenic!vein,!and!the!leP!gastric!vein.!The!inferior!mesenteric!vein,! draining!the!terminal!part!of!the!large!intes&ne,!drains!into!the!splenic!vein,!which!itself! drains!the!spleen,!pancreas,!and!the!leP!side!of!the!stomach.!The!splenic!vein!and!superior! mesenteric!vein!(which!drains!the!small!intes&ne!and!the!first!part!of!the!colon)!join!to!form! the!hepa&c!portal!vein.!The!L.!gastric!vein,!which!drains!the!right!side!of!the!stomach,!drains! directly!into!the!hepa&c!portal!vein.!! The!hepa&c!portal!circula&on!is!formed!by!veins!draining!the!diges&ve!organs,!which!empty! into!the!hepa&c!portal!vein.!The!hepa&c!portal!vein!carries!the!nutrient-rich-blood!to!the! liver,!where!it!is!processed!before!the!blood!is!allowed!to!enter!the!systemic!circula&on.! (Marieb,!N.!E.!(2012).!Essen&als!of!Human!Anatomy!and!Physiology!ed.!10.)! What!is!the!func&on!of!the!hepa&c!portal!circula&on?!In!what!way!is!a!portal!circula&on!a! “strange”!circula&on?!!! Hepa&c!portal!circula&on:! -Is!the!circula&on!concerned!with!the!liver,!where!the!liver!cells!get!in!contact!with!the! venous!blood!coming!from!the!intes&nes!and!the!spleen.!! -The!venous!blood!in!the!portal!circula&on!drains!the!stomach,!intes&nes,!spleen,!and! pancreas!and!passes!through!the!portal!vein!to!enter!the!liver.!This!blood!carriers!the! products!of!diges&on!to!the!liver.!!

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-The!portal!vein!divides!repeatedly!inside!the!liver!to!end!in!the!liver!sinusoids.!These! sinusoids!lead!to!the!hepa&c!veins!which!join!the!inferior!vena!cava!(IVC).!ThereaPer,!the! blood!in!the!IVC!enters!the!right!atrium!of!the!heart.! Func&on!of!the!hepa&c!portal!circula&on:! 1.Supplies!blood!rich!in!nutrients!to!the!liver!(from!GIT)!for!storage!and!metabolism! 2.Ensure!that!foreign!bodies!in!the!blood!coming!from!the!GIT!are!removed!by!the! Kupffer!cellss!of!the!liver!sinusoids!(Macrophages)!before!entering!into!general! circula&on.!! 3.Detoxifica&on!of!drugs!and!toxic!substances!by!the!liver!cells!before!entering!the! general!circula&on.! Portal!circula&on!is!a!strange!circula&on:! Because!a!capillary!bed!pools!into!another!capillary!bed!through!veins!without!first!going! through!the!heart!(i.e:!the!blood!passes!through!two!beds!of!capillaries!connected!by!veins! without!passing!through!the!heart).! The!hepa&c!portal!circula&on!func&ons!to!ensure!that!all!blood!draining!the!diges&ve! system,!and!carrying!nutrients!from!a!recently!diges&ve!meal,!will!pass!through!the!liver! before!entering!the!rest!of!circula&on.!This!allows!the!liver!to!store!nutrients!and!detoxify! substances!before!they!are!exposed!to!the!rest!of!the!body.!This!circula&on!is!strange! because!it!consists!of!veins!feeding!the!capillaries!of!an!organ!which!is!usually!a!job!for!the! arteries.!(Internet!-!Sadler)! Hepa&c!portal!circula&on:! -Drains!nutrients-rich!blood!from!diges&ve!organs.!Delivers!it!to!the!liver!for!processing.! Hepa&c!portal!system!basic! -Blood!leaving!capillary!beds!in!the!walls!of!the!gut!passes!through!the!hepa&c!portal! vein!before!reaching!the!capillary!beds!in!the!liver! Hepa&c!portal!vein! -Located!in!the!lesser!omen&n!dorsal!to!bile!duct! -Extends!to!the!right!lobe!of!the!liver!‘receives!three!tributaries:!the!gastric,!pancrea&c! mesenteric,!and!the!lien!mesenteric!veins.! Gastric!vein! -Most!interior!to!the!tributaries! -Branches!on!the!walls!of!the!ventral!protein!of!the!stomach! pancrea&c!mesenteric!vein:! -This!tributary!is!a!con&nua&on!of!the!anterior!intes&nal!vein! -Passes!across!the!ventral!surface!of!the!intes&ne,!just!breath!the!caudal!border!of!the! ventral!lobe!of!the!pancreas!and!enters!the!lesser!omen&n.! Anterior!intes&nal!vein:! -Vessel!ascending!along!the!right!side!of!the!intes&ne!collec&ng!blood!from!the!annular! veins! Anterior!splenic!vein:! -Enters!the!pancrea&c!mesenteric!vein!just!before!it!enters!the!lesser!omen&n.! -Drains!deoxygenated!blood!from!the!spleen! intes&nal!vein:! -Leaves!the!intes&ne!adjacent!to!the!point!at!which!the!corresponding!artery!enters! Pyloric!vein! -Drains!the!pylorus! lien!mesenteric!vein:!

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-The!middle!tributary!of!the!hepa&c!portal!vein! -Begins!as!the!posterior!intes&nal!vein!which!branches!from!the!rectal!gland,!ascends! along!the!leP!side!of!the!intes&ne!collec&ng!from!annular!tributes! -Near!the!middle!of!the!intes&ne,!the!posterior!intes&nal!vein!passes!to!the!leP!across! the!body!cavity!to!pancreas!where!it!receives!the!short!posterior!splenic!vein!from!the! spleen.! the liver is supplied by two main blood vessels on its right lobe: the hepatic artery and the portal vein. The portal vein brings venous blood from the spleen, pancreas, and small intestine so that the liver can process the nutrients and byproducts of food digestion.

the liver is connected to two large blood vessels, the hepatic artery and the portal vein. the hepatic artery carries blood from the aorta to the liver, whereas the portal vein carries blood containing the digestive nutrients from the entire gastrointestinal tract, and also from the spleen and pancreas to the liver. These blood vessels subdivide into capillaries that then lead to a lobule.

The liver is divided into four lobes: left, right, caudate, and quadrate. The lobes are further divides into lobules, the functional units of the liver. Each lobule is made up of millions of hepatic cells that are the basic metabolic cells of the liver.

in the hepatic portal system, the liver receives a dual blood supply from the hepatic portal vein and the hepatic arteries. key points: • the hepatic portal vein supplies 75% of the blood to the liver, while the hepatic arteries supply the remaining 25% • approximately half of the liver’s oxygen demand is met by the hepatic portal vein and half is met by the hepatic arteries. • the hepatic portal system connects the capillaries of the gastrointestinal tract with the capillaries in the liver. Nutrient-rich blood leaves the gastrointestinal tract and is first brought to the liver for processing before being sent to the heart.

key terms: 1.the hepatic arteries: A blood vessel that supplies oxygenated blood to the liver

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2.The hepatic portal vein: A vessel located in the abdominal cavity that is formed by the union of the superior mesenteric and splenic veins that channel blood from the gastrointestinal tract and spleen to the capillary beds in the liver. Cofactors: A substance, especially a coenzyme or a metal, that must be present for an enzyme to function. In the hepatic portal system, the liver receives a dual blood supply from the hepatic portal vein and hepatic arteries. The hepatic portal vein carries venous blood drained from the spleen, gastrointestinal tract and its associated organs; it supplies approximately 75% of the liver’s blood. The hepatic arteries supply arterial blood to the liver and account for the remainder of its blood flow. Oxygen is provided from both sources; approximately half of the liver’s oxygen demand is met by the hepatic portal vein, and half is met by the hepatic arteries. Blood flows through the liver tissue and empties into the central vein of each lobule. The central veins coalesce into hepatic veins that collect the blood leaving the liver and bring it to the heart. A portal system is a venous structure that enables blood from one set of capillary beds to drain into another set of capillary beds, without first returning this blood to the heart. The majority of capillaries in the body drain directly into the heart, so portal systems are unusual. The hepatic portal system connects the capillaries of the gastrointestinal tract with the capillaries in the liver. Nutrient-rich blood leaves the gastrointestinal tract and is first brought to the liver for processing before being sent to the heart. Here, carbohydrates and amino acids can be stored or used to make new proteins and carbohydrates. The liver also removes vitamins and cofactors from the blood for storage, as well as filters any toxins that may have been absorbed along with the food. When any of these stored substances are needed, the liver releases them back into circulation through the hepatic veins. Lumen!Candela!(n.d).!Boundless!Anatomy!and!Physiology:!The!Liver.!haps:// courses.lumenlearning.com/boundless-ap/chapter/the-liver/!

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