2 - Liver Flashcards
The basic functional unit of the liver is the ______
lobule
How many lobules does the average liver contain?
50,000 - 100,000
The liver has ____ blood flow and _____ vascular resistance
high
low
What is the blood flow per minute in the liver?
1350 ml/min
What is NASH?
Non-alcoholic steatohepatitis
cirrhosis from excess fat accumulation in the liver and subsequent inflammation
What is Fatty Liver Disease?
A less severe form of NASH
most common cause of liver disease
associated with obesity and DM2
Why does cirrhosis cause portal HTN?
The vascular resistance is EXTREMELY low in the liver, and it has to be
pressure in the portal vein is usually around 9, and pressure in the hepatic vein that dumps into the vena cava is zero.
Any increase in vascular resistance in the liver will cause decreased flow through the sinusoids
A sudden blockage of the portal vein d/t clot can lead to death within a few hours. Why?
excessive loss of fluid from the capillaries into the lumens and walls of the intestines
When pressure is high in the RA, the liver can expand to hold up to _______ L of extra blood
0.5-1
Compared to capillaries in other tissues, hepatic sinusoids are (more/less) permeable
More!
Have huge openings that even plasma proteins flow through
Lymph draining from the liver has a protein concentration that is _______ compared to the plasma
almost the same as plasma
this is a testament to its extreme porosity
How much lymph does the liver create?
About half the lymph in the body is from the liver
what degree of portal hypertension can cause ascites?
an increase of only 3-7 mmHg
Where does ascites come from?
liver sweat
excess fluid that transudes into the lumph and leaks through the outer surface of the liver capsule directly into the abdominal cavity
Pretty much pure plasma
AND
leakage from the gut wall and capillaries
What substance is responsible for liver regeneration?
Hepatocyte growth factor
Where is hepatocyte growth factor produced?
NOT by hepatocytes
produced by mesenchymal cells in the liver and other tissues
Blood levels of HGF spark after liver resection, but the effects are only seen in the liver
Blood returning from the intestines is rich in colonic bacteria. How is this bacteria filtered out?
Kupffer cells (massive macrophages that line the hepatic sinuses)
Less than 1% of the bacteria entering the portal blood from the intestines succeeds in passing through the liver into the systemic circulation
What are the liver’s four function in carbohydrate metabolism?
- storage of large amounts of glycogen
- conversion of galatcose and fructose to glucose
- Gluconeogenesis
- Formation of chemical compounds from intermediate byproduts of carb metabolism
What is the liver’s role in fat metabolism?
- Oxidation of fatty acids to supply energy
- Synthesis of large quantities of cholesterol, phospholipids, and most lipoproteins
- Synthesis of fat from proteins and carbs
Describe how the liver facilitates fat use for energy
- Fat is split into glycerol and fatty acids
- fatty acids split by beta oxidation into two Acetyl CoA
- Acetyl-CoA enters citric acid cycle
- Whatever the liver can’t use is released into the bloodstream as acetoacetic acid
- Tissue cells use acetoacetic acid to form acetyl CoA
Describe how the liver facilitates fat storage
synthesizes fats from carbs and proteins
transported as lipoproteins
taken up by adipose tissue and stored
What are the most important functions of the liver in protein metabolism?
- deamination
- formation of urea
- formation of plasma proteins
- reconversion of amino acids into other compounds
How does the liver respond when plasma protein levels are low?
causes rapid mitosis of hepatic cells and growth of the liver to a larger size
How is iron stored in the body?
transferred in the blood via transferrin
stored in the liver as ferritin (the product of apoferritin from the liver and iron from the blood)
This is a reversible reaction, so when iron levels are low it functions as a blood iron buffer as well as a storage medium
In hemolytic jaundice, there is excess ______ bilirubin
In obstructive jaundice, there is excess ______ bilirubin
Why?
unconjugated
conjugated
In hemolytic, the liver is overwhelmed, so it can’t conjugate bilirubin fast enough
in obstructive, it actually is conjugating, the bilirubin just can’t get out and winds up bursting into the lymph
How can you tell if jaundice is caused by conjugated or unconjugated bilirubin?
When an obstruction is present, no bilirubin reaches the intestines to be cnverted into urobilinogen by bacteria, and therefore there is no urobilinogen in the urine
when hemolytic processes are at fault, an excess of urobilinogen is being formed and excreted in the urine
The liver produces all of the plasma proteins except for ____
immunoglobulins
Which coagulation factors are NOT produced in hepatocytes?
Von Willebrand (endothelium)
Factor III (endothelium)
Factor VIII (sinusoidal cells)
The most common indication for liver transplant is:
Hepatitis C
What is the acinus of the liver?
Liver tissue served by a single terminal branch of the hepatic artery
