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55 Cards in this Set
- Front
- Back
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What are the 2 important functions of Stellate Ito cells found in the Space of Disse in the liver?
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1. Store Vitamin A
2. Produce reticular fiber |
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What are the functions of the Smooth Endoplasmic Reticulum in the liver epithelial cells?
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1. Glycogen metabolism (glucose 6 phosphatase)
2. Detoxification of lipid soluble drugs |
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Where is the highest concentration of glycogen in the body?
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The liver
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How is the liver the central regulator of blood nutrients?
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The Liver Maintains Homeostasis of Nutrients by:
1. Assuring there is a supply of glucose in the blood for neurons to use 2. distributes fatty acid carbons in the form of KETONES or packaged as TRIGLYCERIDES in very low density lipoproteins (VLDLs) |
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How does the liver make sure we have a storehouse full of glucose to use later on when glucose might not be readily available?
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1. The liver stores glucose in the form of glycogen (when glucose is readily available)
2. Glucose is released via the processes of GLYCOGENOLYSIS & GLUCONEOGENESIS |
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What is the process of converting carbons from other chemicals (primarily amino acids, but also glycerol) into glucose molecules?
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GLUCONEOGENESIS
This glucose will be used by neurons during the "bad times" of fasting |
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Where do you find the most glycogen in the body?
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Skeletal muscle
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What cells hold the highest concentrations of glycogen in the body?
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hepatocytes
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How do hepatocytes participate in lipid regulation?
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Hepatocytes synthesize & release:
1. VLDLs (fatty acid distribution) 2. HDLs (cholesterol scavenging) 3. Ketones ("soluble" fatty acid analogs) |
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What is the purpose of very low density lipoproteins (VLDL)?
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Fatty Acid Distribution
VLDLs are made by hepatocytes, which package triglycerides (also made by hepatocytes) to be sent out into the blood for distribution of the fatty acids to various cells of the body. |
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What is the purpose of high density lipoproteins (HDLs)?
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Cholesterol scavaging
HDLs are made by hepatocytes and they scavenge cholesterol from the blood and peripheral tissues as well as providing a circulating reservoir of apoproteins for activating VLDLs and chylomicrons |
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What is the purpose of ketones?
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Soluble Fatty Acid Analogs
Hepatocytes make ketones from fatty acid metabolism. Ketones are water soluble whereas fatty acids are poorly soluble. This allows the liver to distribute fatty acid carbons to cells throughout the body during the "Bad Times", something that would be difficult to do w/fatty acids alone |
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What are 3 types of ketones?
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Ketones:
1. Acetoacetate 2. 3-OH-butyrate 3. Acetone (worthless cousin) |
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How is the relationship of the liver and amino acid handling in the body significant?
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1. The liver primarily uses amino acids from skeletal muscle proteolysis during the "Bad Times" to make glucose via gluconeogenesis
2. Hepatocytes are primarily responsible for the ability to synthesize a number of amino acids; hence the term Non-essential Amino Acids |
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What is the Pneumonic for the Essential amino acids?
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PVT TIM HALL
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*What enzyme creates urea?
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Arginase converts arginine to urea
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Why is the liver the primary producer of urea?
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The removal of the amine groups from amino acids by hepatocytes during gluconeogenesis is the reason that the liver is the primary organ for producing urea
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What nutrients do the liver store?
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a. Glycogen (glucokinase in hepatocytes allow the liver to synthesize glycogen during the "Good Times")
b. Lipids (stored in the form of triglycerides & cholesterol) |
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Why does the liver tend to synthesize and store cholesterol?
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To facillitate bile salt synthesis
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What are 2 groups of plasma proteins of particular significance made by hepatocytes?
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1. Clotting Factors
2. Albumin |
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What are the clotting factors synthesized by the liver?
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1. Fibrinogen
2. Prothrombin 3. Factor VII others... |
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What does the liver require to synthesize several of the clotting factors?
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Vitamin K
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What would be the consequences of a Vitamin K shortage or liver dysfunction?
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Prolonged bleeding
(K is for Koagulation in german) |
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What is the most abundant of the plasma proteins?
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Albumin
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What is a good non-specific, reversible binder of hydrophobic compounds?
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Albumin
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What are the properties of albumin?
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1. non-specific reversible binder of hydrophobic compounds (helps distribute a broad variety of steroid hormones, drugs, & other hydrophobic compounds throughout the body)
2. Determines osmolality of the plasma (critical in fluid movement between capillaries & interstitium) |
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How would liver dysfunction affect plasma osmolality?
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Plasma osmolality would decrease and would result in edema formation throughout the body
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What is albumin good at sucking out of the blood?
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Albumin is good at sucking plasma back out of the blood
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What are the polar components of bile salts/acids (taurocholate or glycocholate)?
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Taurine or Glycine
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What is the non-polar component of bile salts/acids (taurocholate or glycocholate)?
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Cholesterol
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What property allows bile salts/acids to form micelles in the digestive tract with dietary fats occupying the core of the micelle?
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Bile salts/acids have a bipolar property thanks to a polar (taurine or glycine) & nonpolar (cholesterol) component
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How do the bile salts/acids ability to form micelles benefit digestion?
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The bile salts/acids increase the surface area to volume ratio of fat globules by forming micelles around chunks of fat. This allows greater efficiency of chemical digestion by pancreatic lipases
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What is a waste product of heme catabolism?
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bilirubin
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How is heme catabolism accomplished?
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Macrophages release the iron from the heme group.
The remaining compound is converted to biliverdin and then bilirubin. Bilirubin is bound to albumin and transported to the liver Liver conjugates the bilirubin w/glucuronate and/or sulfate before being excreted in bile |
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What are the 2 primary functions of drug metabolism in the liver?
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1. The drug becomes more hydrophilic (facilitating excretion by the kidneys)
2. Most drugs become less active or inactive when they are metabolized (although some become more active - levodopa to dopamine - or remains active - diazepam to nordiazepam) |
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What are the general types of reactions used to metabolize drugs & hormones?
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Phase I rxn - takes place at the SER, oxidations by cytochrome P-450 oxidases, (also include reductions or hydrolyses)
Phase II rxn - makes the drug even more polar (hydrophilic) by conjugation w/compounds like glucuronate |
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What type of reactions are Phase I reactions?
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Biotransformations of the drug to make it more polar (and therefore more hydrophilic). The rxns take place at the SER and most commonly are oxidations by the cytochrome P-450 (mixed function) oxidases, but also include reductions or hydrolyses.
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What type of reactions are Phase II reactions?
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For some drugs all that occurs is Phase I, while others proceed directly to Phase II. The Phase II rxns make the drug even more polar by conjugation with compounds such as glucuronate, acetate, glutathione, glycine, sulfate, or a methyl group.
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Why do people build a tolerance to some drugs when used over long term?
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Cytochrome P-450 activity increases resulting in inactivation of the drug, requiring a higher dosage in the future to produce the same effect
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What is the term for the process when drugs are absorbed in the small intestine and immediately pass throught the portal system. Meaning they are exposed to inactivation before ever having a chance to circulate throughout the body?
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First-pass metabolism
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What vitamins can the liver store?
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Vitamin A (as long as 10 months)
Vitamin D (as long as 4 months) Vitamin B12 (over a year) |
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Where is most of the iron found in the body?
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Hemaglobin
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Where is the 2nd largest amount of iron in the body?
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The liver serves as a reservoir of iron by reversibly binding it to the liver protein APOFERRITIN.
Apoferritin + iron = ferritin |
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How does ferritin benefit the body?
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Ferritin stores iron so that it can be used later on by the body
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What do somatomedins do?
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Somatomedins act to increase chondrocyte and osteoblast cell activity and cell number as well as promoting conversion of chondrocytes to osteogenic cells
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What are somatomedins also referred to as?
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Insulin-Like Growth Factors (IGF)
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How is blood cleansed of bacteria in the hepatic portal system?
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Kupffer cells are phagocytic macrophages which line the hepatic venous sinuses
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What are the functions of the liver?
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1. Maintain homeostasis of nutrients
2. Store nutrients 3. Synthesize and release plasma proteins 4. Synthesize & release bile 5. Process and excrete bilirubin 6. Detoxification & excretion of drugs, hormones & toxins 7. Storage of vitamins A, D (including processing) & B12 8. Iron storage (Fe bound to apoferritin) 9. Synthesize and release somatomedins (HGH) 10. Blood cleansing of bacteria |
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What does the Portal Area contain? (Formerly known as the portal triad)
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1. Hepatic Artery
2. Hepatic Portal Vein 3. Bile duct 4. Lymphatic |
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What is significant regarding blood flow in hepatic sinusoids?
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Each sinusoid is exposed to two different kinds of blood coming from the hepatic artery and hepatic portal vein
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Which cells are involved in filtration of the blood in the liver?
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Kupffer cells - they arrive from marrow (as monocytes) and enter the liver and settle there
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What are the significance of Stellate Ito cells?
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Stellate Ito Cells
1. Store vitamin A 2. Produce reticular fibers |
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What are a type of NK cell found in the Space of Disse?
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Pit cells are NK cells found in the space of Disse
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What is in the space of Disse?
(or perisinusoidal space) |
The space of Disse is located between a hepatocyte and a sinusoid. It contains:
1. Plasma from blood 2. microvilli of hepatocytes 3. Ito cells (vitamin A & reticular fibers) 4. Reticular collagen (structural) 5. Pit cells (NK cell) |
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What are the SER functions in liver?
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Glycogen metabolism (glucose 6 phosphatase)
Detoxification of lipid soluble drugs |
