10.07 Liver & Gallbladder

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Outline

Overview

  1. Liver – largest gland, 3-4 lbs
    1. Location – upper quadrants of abdominal cavity
    2. External structure
      1. Anterior
        1. Right lobe
        2. Falciform ligament (used to be umbilical cord)
        3. Left lobe
      2. Posterior
        1. Left lobe
        2. Right lobe proper
          1. Subdivisions of right lobe of liver
            1. Caudate
            2. Quadrate
    3. Blood supply
      1. Hepatic artery → liver sinusoids
      2. Hepatic portal vein → liver sinusoids
      3. Sinusoids → hepatic veins
      4. Sinusoids → inferior vena cava
  2. Gallbladder and associated ducts
    1. Lower right lobe of liver
    2. Cystic duct – drains bile out of gall bladder
    3. Hepatic duct
      1. Out of right lobe of liver
      2. Formed from interlobular bile ducts
      3. Drains liver
    4. Common bile duct
      1. Fusion of cystic and hepatic ducts
      2. Fuses with pancreatic duct and enters duodenum
      3. Delivers bile and pancreatic secretions into the duodenum

Nursing Points

General

  1. Tissue structure
    1. Liver lobule – basic unit of function
      1. Central vein – middle of lobule
      2. Arterial periphery
        1. Branches of hepatic portal vein
        2. Branches of hepatic artery
        3. Interlobular bile duct
      3. Hepatocytes (liver cells) present in plates
        1. Sinusoids – large spaces lined by endothelium with Kupffer cells
          1. Connect hepatic artery and hepatic portal vein to central vein
        2. Bile canaliculi
          1. Tubes connect interlobular bile duct
          2. Moves bile to hepatic duct then to gallbladder
  2. Functions of Liver
    1. Intermediary metabolism – processing of glucose
      1. Glucogenesis = glucose → glycogen
      2. glycogenolysis = glycogen → glucose
      3. gluconeogenesis = FAT/PRO → glucose
    2. Storage
      1. Glycogen
      2. Iron – to bone marrow for hemoglobin synthesis
      3. Vitamins – A, D, E, K, B complex, B12
      4. Bile – bile salts + bile pigments – sent to gallbladder for storage
    3. Synthesis
      1. Plasma proteins
        1. Alpha-1, alpha-2, beta globulins
        2. serum albumin
        3. Fibrinogen
        4. Prothrombin
        5. Angiotensinogen
      2. Bile components – salts and pigments
      3. Heparin – prevents intravascular clotting
    4. Secretion
      1. Secretes bile
        1. Cholecystokinin (CCK) secreted from small intestine
          1. CCK ➝ contraction of GB to release bile into small intestine
        2. Chemical digestion of fat
        3. Absorption into lacteals of small intestine
    5. Excretion
      1. Kupfer cells in sinusoids (contain macrophages)
        1. Engulf, destroy and eliminate bacteria, old RBC’s, and dead tissues from liver blood
      2. Bile pigments are the product of heme destruction of old dying RBC’s
        1. Bilirubin – no significant function…therefore excreted in feces
      3. Drugs, medications
        1. Liver cells contain enzymes which modify drugs and medications so that they can be sent to blood then to kidney and then out through urine
      4. Urea production
        1. AA’s → urea → blood → kidneys → urine → out
      5. Uric acid production
        1. Nucleic acids → uric acid → blood kidneys → urine → out

Transcript

In this lesson we’re going to take a look at the liver and gallbladder

What are looking at the structure of the liver and gallbladder, recognize that they are two different organs.

The liver is the largest gland and it usually weighs about 3 to 4 lb. When are looking at the liver anteriorly, but you will recognize it there right and left lobe, and they are separated by something called the falciform ligament. The posterior view you have a left lobe that you can see, but there are also two other lobes that are part of the right lobe and those are the caudate and the quadrate lobe. It’s not that you need to be able to specifically identify them but just know that the right lobe is much larger.

We were talking about blood supply to the liver, there is something called a portal venous system which will get into it a minute. But the main thing that you need to recognize that they have hepatic artery comes from the aorta and it actually brings in oxygenated blood. There Is also blood flow from the portal system which comes directly from the digestive tract, and it is deoxygenated, but it carries all of the absorbed nutrients and minerals from the GI tract. It also will include any drugs that a person may be taking

Once the blood reaches the liver, the blood travels down something called liver sinusoids, which essentially empty into hepatic veins and the inferior vena cava. The inferior vena cava is the last place that the blood travels from the liver before it goes back to the heart.

The gallbladder is a hollow organ and it is located to the lower right lobe of the liver. There is something called the cystic duct which drains bile directly from the gallbladder. Then there’s the hepatic duct, which runs out of the right liver lobe and drains the liver and they are formed by interlobular bile ducts. Now where the cystic duct and the hepatic ducts come together is called the common bile duct. They actually fused with pancreatic duct in an empty out into the duodenum. This is going to deliver bile and pancreatic secretions into the duodenum.

In the liver, there are these functional units called liver lobules. And they are hexagonal units, and in the middle of there is a central vein and this is where blood is delivered to the hepatocytes, or the liver cells which are formed in plates. At the end of each one of these liver lobules is something called a portal Triad. It consists of a portal venule, a portal arteriole, and a bile duct. Once the blood is delivered to the parasites from the central vein, they’ll travel through the sinusoids and they’ll be delivered to back to the portal Triads. Once there, they leave the liver via the sinusoids to the inferior vena cava and back to the heart for circulation.

Now the sinusoids are really important because they are special capillaries. Inside these capillaries are the special types of macrophages called Cooper cells. We’ll get into the specifics of what they do in a minute, but what they do is they connect the hepatic artery in the portal vein to a central vein. There’s there’s also these other important vessels called bile canaliculi. They connect the interlobular bile ducts, and that moves bile from The hepatic duct to the gallbladder

Now the liver has a lot of important functions, one of the primary ones being glucose metabolism. It’s responsible for gluconeogenesis, glucogenolysis, and gluconeogenesis. Glucogenesis is the conversion from glucose to glycogen. Glycogenolysis is the conversion from glycogen to glucose. And then gluconeogenesis is the conversion a fat or proteins to glucose.

The liver is also responsible for storage of certain things. Obviously is responsible for glycogen storage, but it’s also important for iron storage, and the storage of certain vitamins. These vitamins are a, d, e, k, B complex, and b12. It’s also responsible for the storage of bile In smaller amounts. Bile is made up of bile salts and bile pigments. Once large quantities get created they’re sent to the gallbladder for storage.

Liver is also responsible for synthesis of several different types of things. The first thing that is responsible for the formation of plasma proteins. This includes Alpha One, Alpha 2, and beta globulins. It’s also responsible for albumin, fibrinogen, prothrombin, and the formation of angiotensinogen. It’s also responsible for the synthesis of Heparin.

The liver and gallbladder are also responsible for the processes of secretion and excretion. When we talked about the secretion of bile what happens is that this duodenum in the jejunum release something called cholecystokinin, and that stimulates a reaction from the gallbladder to contract into dump bile into the small intestine for the absorption of fat. This absorption is going to find those fat molecules to the bile and it’s going to be absorbed in the lacteals in the small intestine. Go check out the small intestine lesson for more information on that.

The other important part of their process is the excretion portion. Now like I discussed in the tissues a few minutes ago, these Kupffer cells are these specialized macrophages. They are responsible for engulfing and eliminating bacteria, and also for getting rid of old red blood cells and destroying dead tissues that are in the liver.

The liver is also responsible for getting rid of bile pigments that are the byproduct of heme destruction. These get processed in the liver and are eliminated via the feces. It’s also the responsibility of the liver to kick out drugs that are in the body. The liver enzymes modify the drugs so that they are send to the blood, utilize, and then kicked out through the kidneys. The liver is also responsible for urea and uric acid production.Enzymes in the liver convert amino acids to urea and those are transferred to the blood where they kicked out via the kidneys in the urine. Similarly uric acid is broken out from nucleic acids to uric acid, and that’s into the blood and then kicked out from the kidneys into the urine.

Okay so let’s recap.

The liver has two main lobes, mostly separated by falciform ligament. It depends on which angle you’re looking at but for the most part they’re two primary lobes, right and left low.

The gallbladder is located below the right lobe, it’s a hollow organ that stores bile for the fat absorption.

The hepatic blood supply is really important because the aorta delivers oxygen rich blood to the liver, and the pool system delivers those nutrients that have been absorbed from the small Intestine to utilize nutrients.

The liver has a lot of functions, in that it stores in synthesizes glucose, stores vitamins, and it synthesizes proteins.

The liver is responsible for filtering blood for pathogens, drugs, and their production of those waste by-products there then kicked out to the blood and excreted from the body via the kidneys

That’s it for a lesson on the liver and gallbladder. Make sure you check out all the resources attached to this lesson. Now go out, and be your best self today, and as always, happy nursing!