3 B Flashcards
What are the two purposes of aminostransferases or transaminases?
Deamination and synthesis of non-essential amino acids within liver hepatocytes.
What is the first step of amino acid catabolism in the liver?
Deamination (removal of an NH2)
What is the fate of the amine groups produced by amino acid catabolism?
They are first converted to NH3 or NH4 and then to urea where they are then excreted from the body
What can a build up of urea in the blood cause?
Uremia or azotemia (often a symptom of renal disease or renal failure)
Why would someone with renal disease or renal failure be put on a low protein diet?
To reduce the amount of urea they produce as they will have a hard time excreting it.
What are four things that increase BUN?
Impaired renal function Increased protein intake or catabolism GI bleeding (due to intestinal flora creating nitrogenous waste) Dehydration
What important liver hepatocyte enzyme is required for endogenous cholesterol synthesis?
HMG-CoA reductase
What is the only way the body can get rid of excess cholesterol?
Through the bile
What causes gall stones?
Excess cholesterol
Digestion of what causes gall stones?
Fat
What are the three causes of ketogenesis?
Fasting states, poorly controlled type I diabetes mellitus
What organ degrades all steroid hormones as well as T3 and T4?
The liver
What transports Iron from the stomach to the SI and releases it for absorption?
Gastroferritin
What carries Iron from the blood to the liver?
Transferrin
What binds Iron in the liver and stores it?
Apoferritin
What is the storage form of Iron in the liver called?
Ferritin
What three vitamins does the liver store in large quantities?
B12, A, D
What is the purpose of drug metabolism?
To make drugs less active and more water soluble and thus more readily excreted in the urine and bile.
What is phase I of drug metabolism marked by?
Cytochrome P 450
What is phase II of drug metabolism marked by?
Conjugation
What is the purpose of conjugation?
To make something more H2O (polar or hydrophilic) soluble by adding a metabolite.
What does CP450 inhibition do?
Decreases metabolic activity of CP 450 enzymes leading to decreased metabolism of the drug and increased effects of the drug
What does a CP450 inducer do?
It increases the activity of the CP450 enzymes leading to increased metabolism of the drug which decreases the effects of the drug.
What are the three major types of plasma proteins?
Albumins
Globulins
Fibrinogen
What are the major functions of the proteins synthesized by the liver?
Oncotic pressure (albumin)
Buffering capacity of the blood (albumin)
Transport of hormones (albumin and globulin)
Carriers (albumin and globulin)
Blood clotting (fibrinogen)
Immune response (gamma-globulin)
What are the organic constituents of bile?
Bile salts
Phospholipids
Cholesterol
Bile pigments (bilirubin)
What two primary bile acids are synthesized by hepatocytes?
Cholic acid
Chenodeoxycholic acid
Primary bile acids are converted by intestinal bacteria into what two secondary bile acids?
Deoxycholic acid
Lithocholic acid
What is the difference between bile acids and bile salts?
Bile salts are just bile acids that have the amino acids glycine or taurine conjugated to them
What property does conjugating bile acids give to bile salts?
It makes them amphipathic
What is the most common phospholipid found in bile?
Lecithin
What accounts for the majority of cholesterol breakdown in the body?
Conversion of cholesterol to bile acids.
Outline the breakdown of hemoglobin:
Heme- biliverdin- bilirubin- bile- feces
What are two other names for bilirubin and how is it transported in the blood?
Indirect bilirubin or unconjugated bilirubin
Carried in the blood attached to albumin
What form of bilirubin is excreted in the urine?
Urobilin
What enzyme is necessary for the conjugation of bilirubin?
Glucuronyl transferase
What are the three steps of bile synthesis?
- Hepatocytes actively secrete bile into the bile canals (canaliculi)
- Intrahepatic and extrahepatic ducts transport the bile and the cells that line the ducts secrete a watery HCO3 fluid
- Between meals 1/2 the bile is diverted to the gall bladder which stores the bile and removes salts and water
What are the two main functions of bile?
It provides the sole excretory route for many solutes that are not excreted by the kidneys
Secreted bile salts and lecithin are required for normal lipid digestion and absorption in the small intestine
