Ch. 25 Liver Function - Part 1 Flashcards
Give the four major functions of the liver
Metabolism of carbohydrates, lipids, proteins, and bilirubin
Detoxification of harmful substances
Storage of essential compounds
Excretion/Secretion of substances to prevent harm
If the liver is nonfunctional for any reason, death will occur within approximately 24 hours due to _____
Hypoglycemia
Which of the following statements is/are TRUE:
The liver is
A. 1.2 to 1.5 kg in a healthy adult
B. located beneath and attached to the diaphragm
C. Protected by the lower rib cage
D. Held in pace by ligamentous attachments
All
Divides the liver into two unequal parts
Falciform ligament
The right lobe of the liver is 6x (larger/smaller) than the left lobe
Larger
Enumerate the liver’s two sources of blood
Hepatic artery
Portal vein
Which among the livers two sources of blood:
Is a branch of the aorta
Supplies oxygen-rich blood
Provides for 25% of the total blood supply to the liver
Hepatic artery
Which among the livers two sources of blood:
Supplies nutrient-rich blood from the digestive tract
Provides for 75% of total blood supply
Portal vein
Results from the merging of the Hepatic artery and the Portal vein
Hepatic sinusoid
The hepatic sinusoid is lined with _____ capable of removing potentially toxic substances from the blood
Hepatocytes
It is through this passage that blood leaves the liver
Central canal (Central vein)
The collecting system of veins that drain the approximately 1500 mL of blood from the liver empties into what vein
Hepatic vein
It is where the excretory system of the liver begins
Bile canaliculi
These are small spaces between the hepatocytes that form intrahepatic ducts, where excretory products of the cell can drain
Bile canaliculi
Microscopic and functional units of the liver
Lobules
They are responsible for all metabolic and excretory functions performed by the liver
Lobules
Two major cell types in the liver:
Hepatocytes
Kupffer cells
Each six-sided lobule of the liver has portal triads that contains
Hepatic artery
Portal vein
Bile duct
These make up 80% of the volume of the liver; large cells that radiate outward from the central vein in plates to the periphery of the lobule
Hepatocytes
Responsible for the regenerative properties of the liver.
Hepatocytes
These are macrophages that line the sinusoids of the liver. These acts as phagocytes capable of engulfing bacteria, debris, toxins, and other substances flowing through the sinusoids
Kupffer cells
The major heme waste product
Bilirubin
It is the only organ that has the capacity to rid the body of heme waste products
Liver
Principal pigment in bile. Derived from the breakdown of red blood cells
Bilirubin
Approximately _____ days after the emergence from the reticuloendothelial tissue, red blood cells are phagocytized and hemoglobin is released.
126
What is the composition of bile?
Bile acids or salts
Bile pigments
Cholesterol
Other substances extracted from the blood
The body produces approximately __L of bile per day and secretes __L of what is produced
3, 1
Degradation of Hemoglobin produces:
Heme
Globin
Iron
Among the three components produced from the degradation of hemoglobin, which would be bound by transferrin and returned to the liver or bone marrow for reuse?
Iron
Among the three components produced from the degradation of hemoglobin, which would be degraded to its constituent amino acids, which are then reused by the body?
Globin
Among the three components produced from the degradation of hemoglobin, which would be converted to bilirubin in 2 to 3 hours?
Heme
Before bilirubin is transported to the liver, what amino acid binds to it?
Albumin
Bilirubin bound to albumin is called _____. It is insoluble in water, and cannot be removed from the body until it is has been conjugated by the liver.
Unconjugated or Indirect bilirubin (B1)
What carrier protein picks up bilirubin once it has been separated from albumin and has flowed through the sinusoidal spaces of the liver
Ligandin
It carries the unconjugated bilirubin from the liver to the endoplasmic riticulum
Ligandin
Site where the conjugation (esterification) of bilirubin happens
Endoplasmic reticulum
The enzyme present during esterification; which transfers a glucuronic acid molecule to each of the two propionic acid side chains of bilirubin to form bilirubin diglucuronide
Uridyldiphosphate glucuronyl transferases (UDPGT)
The form of bilirubin that is water soluble and is able to be secreted from the hepatocyte into the bile canaculi. Once in the hepatic duct, it combines with secretions from the gallbladder through the cystic duct and is expelled through the common bile duct to the intestines.
Conjugated biirubin (B2)
Acts upon the conjugated bilirubin in the intestines and produces mesobilirubin
Intestinal bacteria
Mesobilirubin is reduced to form mesobilirubinogen and then _____ (a colorless product).
Urobilinogen
Roughly 80% of the formed urobilinogen is oxidized to an orange colored product called _____, which is then extcreted in feces
Urobilin/Stercobilin
The substance that gives stool its brown color
Stercobilin
The majority of the remaining 20% of urobilinogen will be absorbed by _____ to be recycled through the liver and re-excreted
Extrahepatic circulation
What will happen to the lesser fraction of the remaining 20% of urobilinogen in the liver?
The lesser fraction of the remaining 20% of urobilinogen will enter systemic circulation and will subsequently be filtered by the kidney and excreted in the urine.
Approximately how many mg of bilirubin is produced per day?
200 to 300 mg
Almost all the bilirubin formed is eliminated in the _____
Feces
What is the usual level of total bilirubin in the serum of a healthy adult?
0.2 - 1.0 mg/dL
When carbohydrates are ingested and absorbed, the liver can do three things which are:
- Use the glucose for its own cellular energy requirements
- Circulate the glucose for use at the peripheral tissues
- Store glucose as glycogen
Principal storage form of glucose
Glycogen
It is the major player in maintaining stable glucose concentrations due to its ability to store glucose and degrade glycogen
Liver
The term used to describe the storing of glucose in the form of glycogen
Glycogenesis
Degrading glycogen to obtain glucose; could occur at times where there is an increased need for glucose (fasting or stress). Breakdown of glycogen to glucose for use as energy.
Glycogenolysis
The process wherein the liver creates glucose (Glucose-6-phosphate) from nonsugar carbon substrates like pyruvate, lactate, and amino acid.
Gluconeogenesis
The liver metabolizes lipids and lipoproteins and gathers free fatty acids from the diet, and those produced by the liver itself. These are then broken down to form _____, which can enter several pathways to form triglycerides, phospholipids, or cholesterol
Acetyl-CoA
The greatest source of cholesterol in the body comes from _____
What is produced by the liver, not from dietary sources.
TRUE/FALSE. All proteins are synthesized by the liver. Explain
False. Immunoglobulins and adult hemoglobin are not synthesized in the liver
It is one of the most important proteins synthesized by the liver
Albumin
This results in the exchange of an amino group on one acid with a ketone group on another acid.
Transamination (via Transaminase)
After transamination, _____ degrades them to produce ammonium ions that are consumed in the synthesis of urea and urea is excreted by the kidneys
Deamination
This serves as a gatekeeper between substances absorbed by the gastrointestinal tract and those released into systemic circulation.
Liver
The process wherein every substance that is absorbed in the gastrointestinal tract must first pass through the liver is referred to as:
First pass
What are the body’s two mechanisms for detoxification of foreign materials (drugs and poisons) and metabolic products (bilirubin and ammonia)
- Bind the material reversibly so as to inactivate the compound
- Chemically modify the compound so it can be extcreted
The most important mechanism in the liver; responsible for the detoxification of many drugs through oxidation, reduction, hydrolysis, hydroxylation, carboxylation, and demethylation.
Drug-metabolizing system
Many of the drug-metabolizing systems take place in the liver microsome via what isoenzyme?
Cytochrome P-450 isoenzymes
Metabolism of glucose to lactate or pyruvate for production of energy
Glycolysis
What are the processes by which the liver detoxifies drugs?
oxidation, reduction, hydrolysis, hydroxylation, carboxylation, and demethylation.
Many of the detoxification processes of the liver takes place in the _____ via the cytochrome P-450 isoenzyme.
Liver microsome