Liver H.4.1-H.4.7

H.4.1 Blood flow through liver The liver receives blood from the hepatic portal vein This blood is coming from the small intestine and varies in quantity of nutrients depending on what one has eaten and when This blood is low in oxygen. This blood is low pressure because it has already been through a capillary bed

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The hepatic artery (a branch of the aorta) also brings blood to the liver. This blood is oxygenated The hepatic artery (a branch of the aorta) also brings blood to the liver. This blood is oxygenated Blood leaves the liver through the hepatic vein. This blood has been “treated” by the liver so its nutrient content is more stable. Blood leaves the liver through the hepatic vein. This blood has been “treated” by the liver so its nutrient content is more stable. Blood in the hepatic vein is also low pressure and low in oxygen Blood in the hepatic vein is also low pressure and low in oxygen

While in the liver the blood is transported by capillaries of the liver called sinusoids. These drain into the hepatic vein. While in the liver the blood is transported by capillaries of the liver called sinusoids. These drain into the hepatic vein. The sinusoids are where exchange of nutrients and gases take place in the liver The sinusoids are where exchange of nutrients and gases take place in the liver

How do sinusoids differ from capillaries? Sinusoids are wider Sinusoids are wider Sinusoids are lined by endothelial cells with gaps between them Sinusoids are lined by endothelial cells with gaps between them The gaps allow large molecules to be exchanged between liver cells and the bloodstream The gaps allow large molecules to be exchanged between liver cells and the bloodstream Hepatocytes (liver cells) are in direct contact with blood making exchange more efficient. Hepatocytes (liver cells) are in direct contact with blood making exchange more efficient.

Sinusoids contain Kupffer cells that breakdown and recycle red blood cells via phagocytosis Sinusoids contain Kupffer cells that breakdown and recycle red blood cells via phagocytosis Blood from sinusoids drains into hepatic vein. Blood from sinusoids drains into hepatic vein.

H.4.2 Nutrient Regulation Part of maintaining homeostasis is making sure that the levels of dissolved solutes in the blood remain fairly constant Part of maintaining homeostasis is making sure that the levels of dissolved solutes in the blood remain fairly constant As blood flows through the liver, excess nutrients are removed by hepatocytes and stored. Ex.) glucose  glycogen As blood flows through the liver, excess nutrients are removed by hepatocytes and stored. Ex.) glucose  glycogen Stored materials may be released if blood levels become too low. Stored materials may be released if blood levels become too low.

Vitamin A H.4.3 Storage

Glucose can affect the osmotic concentration of the blood. Hypertonic blood due to sugar absorption in the gut could be damaging particularly to the brain. Glucose can affect the osmotic concentration of the blood. Hypertonic blood due to sugar absorption in the gut could be damaging particularly to the brain. Salts can affect the osmotic concentration of the blood and are controlled for the same reason. Salts can affect the osmotic concentration of the blood and are controlled for the same reason. Amino acids can affect the osmotic concentration of blood but also amino acids cannot be stored like carbohydrate and therefore excess amino acids need to be regulated and detoxified. Amino acids can affect the osmotic concentration of blood but also amino acids cannot be stored like carbohydrate and therefore excess amino acids need to be regulated and detoxified. Vitamins & Minerals must be regulated because these are crucial for enzyme function, skeletal development, vision and a variety of other essential functions. Vitamins & Minerals must be regulated because these are crucial for enzyme function, skeletal development, vision and a variety of other essential functions.

H.4.4 Synthesis The liver synthesizes plasma proteins The liver synthesizes plasma proteins Albumin – regulates osmotic pressure of fluids in the body. It binds water, fatty acids, cations, and hormones. Albumin – regulates osmotic pressure of fluids in the body. It binds water, fatty acids, cations, and hormones. Fibrinogen – a blood clotting protein which is soluble in blood plasma. Will be converted to fibrin when clotting is required Fibrinogen – a blood clotting protein which is soluble in blood plasma. Will be converted to fibrin when clotting is required Globulins – include gamma globulins (antibodies) as well as carrier/transport proteins Globulins – include gamma globulins (antibodies) as well as carrier/transport proteins

The liver also synthesizes cholesterol The liver also synthesizes cholesterol Cholesterol is used to synthesize bile. Some cholesterol also is carried to the bloodstream to be incorporated into cell membranes or to be used to synthesize steroid hormones. Cholesterol is used to synthesize bile. Some cholesterol also is carried to the bloodstream to be incorporated into cell membranes or to be used to synthesize steroid hormones.

H.4.5 Detoxification The liver can detoxify ethanol (alcohol), preservatives in food, pesticides, and herbicides. The liver can detoxify ethanol (alcohol), preservatives in food, pesticides, and herbicides. It also detoxifies ammonia which is a by- product of protein metabolism in our bodies. It also detoxifies ammonia which is a by- product of protein metabolism in our bodies.

The liver converts ammonia to urea and sends it to the kidneys for excretion. The liver converts ammonia to urea and sends it to the kidneys for excretion.

H.4.7 Alcohol Damage The hepatic portal vein brings alcohol to the liver. The liver removes what it can the rest returns to the liver sinusoids over and over again. The hepatic portal vein brings alcohol to the liver. The liver removes what it can the rest returns to the liver sinusoids over and over again. This continuous exposure to alcohol damages the liver in a number of ways if an individual is a habitual drinker. This continuous exposure to alcohol damages the liver in a number of ways if an individual is a habitual drinker.

Cirrhosis – scar tissue where hepatocytes, blood vessels and ducts have been exposed to alcohol. This tissue does not function Cirrhosis – scar tissue where hepatocytes, blood vessels and ducts have been exposed to alcohol. This tissue does not function Fat accumulation – damaged areas may build up fat in place of healthy tissue Fat accumulation – damaged areas may build up fat in place of healthy tissue Inflammation – swelling due to alcoyolic exposure (AKA alcoholic hepatitis) Inflammation – swelling due to alcoyolic exposure (AKA alcoholic hepatitis)

Scroll down to see the biochemical pathway for alcohol breakdown. Learn this! Scroll down to see the biochemical pathway for alcohol breakdown. Learn this! Alcoholic females more susceptible to liver damage than males Alcoholic females more susceptible to liver damage than males Damage may repair itself if not too sever and patient gives up drinking. Damage may repair itself if not too sever and patient gives up drinking.

H.4.6 RBC breakdown etc… RBC’s have no nucleus therefore have a lifespan of just 4 months (120 days) RBC’s have no nucleus therefore have a lifespan of just 4 months (120 days) As they age the cell membrane ruptures and hemoglobin is released As they age the cell membrane ruptures and hemoglobin is released Kuppfer cells in liver ingest hemoglobin molecules in sinusoids via phagocytosis then disassembles it into it’s components Kuppfer cells in liver ingest hemoglobin molecules in sinusoids via phagocytosis then disassembles it into it’s components

What happens:

Hemoglobin is composed of 4 globulin proteins and a heme group Hemoglobin is composed of 4 globulin proteins and a heme group

The globulins are broken into amino acids and are sent to the bloodstream to be used in protein synthesis The globulins are broken into amino acids and are sent to the bloodstream to be used in protein synthesis The heme group has the iron removed from it. The iron is stored in the liver and is sent to the bone marrow to make new RBC’s The heme group has the iron removed from it. The iron is stored in the liver and is sent to the bone marrow to make new RBC’s The rest of the heme group is bilirubin which is absorbed by hepatocytes and is used to make bile. The rest of the heme group is bilirubin which is absorbed by hepatocytes and is used to make bile.