Quan Flashcards
What is most of the oxygen usage commited to?
oxidative phosphorylation
What is activation of O2 mediated by at body temperature?
metal ions
___ ___ active metal ions are generally sequestered
Free redox
What are reactive oxygen species?
partially reduced, reactive forms of oxygen
What are the 3 ways of ROS formation?
- O2 with reactive metal
- Mitochondrial electron transfer reactions
- enzymatic reaction
What is oxidative stress balanced by?
ROS producing factors and antioxidants
Oxidative stress generated during ischemia/repurfusion results from?
the disruption of electron transfer chain
How does ROS damage cell membranes?
by interacting with polyunsaturated fatty acids to create lipid peroxide
How does ROS damage DNA
by causing DNA break
How does ROS damage protein function
oxidize amino acids
What is ROS important for?
production of bioactive molecules and for the killing of bacteria
What is a critical enzyme in bacterial killing?
myeloperoxidase
What three mechanisms is ROS defended by
prevention
repair
physical barrier
Name 6 antioxidant defenses
SOD catalase Vitamin A Vitamin C Vitamin E glutathione
liver serves as a ___ for all ____ ___
filter
digested materials
What has a broad range of synthetic and catabolic functions?
hepatocytes
Where is metabolic waste secreted into?
biliary tree
Where does the biliary tree drain into ?
Small intestine and excreted in feces
What can hepatic malfunction lead to
Increased: bilirubin glucose albumin prothrombin time urea cholesterol drug half-life bile acids
what does the portal vein drain?
metabolites of the gut to liver
What does glucose-6-phosphatase do
it is a key enzyme in the liver that permits the release of free glucose to the blood
What are 3 liver proteins?
albumin, coagulation factors and acute phase proteins
What does C-reactive protein (CRP) do?
critical phase protein that responds to inflammation or infection
What is the urea cycle essential for?
removal of nitrogen generated by amino acids, thereby preventing ammonia toxicity
What can cause brain damage?
Impaired clearance of ammonia
Function of Heme
O2 binding moiety in Mb, Hb, and cytochrome
What is the rate limiting step in heme synthesis?
production of 5-ALA from SCoA and Glycine
What happens at the final stage in heme synthesis
Fe2+ is added by ferrochelatase to protoporphyrin to form heme
How does Heme control the rate of its synthesis
inhibiting 5-ALA synthesis
what is the catabolic product of heme
Bilirubin
T/F bilirubin is soluble
F
T/F biliverdin is soluble
T
What is processed through the gut and excreted
Conjugated bilirubin
What is the imbalance between bilirubin production and excretion
hyperbilirbinemia
What is caused by increased bilirubin production
prehepatic jaundice
What is intrahepatic jaundice caused by?
impaired hepatic uptake, conjugation or secretion of bilirubin
What is posthepatic jaundice
obstruction of biliary drainage
What are the two phases that drugs are metabolized in the liver?
- addition of polar group
2. conjugation of organic group
What mediates addition of polar group?
cytochrome P-450
What mediates conjugation of organic group?
sulfation, acetylation, methylation
What does an overdose of acetaminophen lead to
production of free radical-mediated cytotoxicity
What is alcohol metabolized by?
alcohol dehydrogenase and acetaldehyde dehydrogenase
what does alcohol dehydrogenase and acetaldehyde dehydrogenase produce?
acetate
