Biochem2 lecture 6- Organs and metabolism

winniesmith1's version from 2017-06-07 21:00

Section 1

Question Answer
Describe the liver Largest gland in mammals; uniform histology across species; secretory, protective, & synthetic functions; capable of considerable regeneration.
Why is the liver functionally placedBlood supply; portal vein 80% hepatic artery 20%. Most of the blood comes from the gut venous drainage. First organs to see blood from GI tract. Ideally positioned to modify it
What are the functions of the liverDetoxification, Storage, Bio-transformation, synthesis, phagocytosis
How does the liver do bio transformationchemically modify numerous compounds and dietary components
What does the liver synthesiseplasma proteins, sugars, clotting factors, urea, lipids, bile.
What does the liver storeCarbohydrate storage and control of carbohydrate metabolism. -iron breakdown products.
What does the liver use phagocytosis forsenescent erythrocytes. other particulate materials.

Section 2

Question Answer
Describe carbohydrate metabolismGlucose, fructose and galactose arrive via hepatic portal vein from intestines. The liver stabalizes the blood glucose level at apporx 90 mg/dl
What does the liver contain for carbohydrate metabolismGlucose transport system in the plasma membrane.
A glucokinase with high Km.
Glucose-6-phosphatase (gluconeogenesis)
What is glucogensisfructose and galactose are converted to glucose.
What is glycogenesisGlucose is polumerised producing glycogen that is stored in the liver
What is glucogenolysisGlycogen is hydrolyzed releasing glucose into the bloodstream
What is gluconeogenesisSynthesis of glucose from protein or from lipid

Section 3

Question Answer
Describe lipid metabolism in the liver triglycerides, fatty acids and glycerol arrive via the hepatic artery from the general circulatory system
What is ketogenesisformation of ketone bodies from fatty acids. (glycerol--> fatty acids--> beta oxidation --> Acetyl groups --> Ketone bodies
What are ketone bodies used forin cellular respiration (esp. by cardiac muscle & kidneys)
What is lipogenesissynthesis of triglycerides that can be stored or converted to other lipids
Describe protein metabolismAmino acids arrive via the hepatic portal vein from the intestine.
What is deaminationremoval of amine group (NH3) from amino acids and proteins; can produce ketoacids & other organic acids
What is decarboxylationremoval of carboxyl (-COOH) from amino acids & proteins
What is urea synthesis removal of excess amine groups
What is protein synthesisformation of blood proteins occurs in the liver

Section 4

Question Answer
how is glycogen storedanimal starch, stored in the liver (muscle tissue can also store glycogen)
What does the liver store glycogen, lipids, vit.A,D,E,K & B12
how is lipids storedfats, a high-fat diet or high alcohol consumption--> fatty liver (appears yellow & greasy macroscopically)
how are vitamins storedA,D,E,K & B12. fat-soluble vitamins; the concentration can be so great that liver is toxic (happens in polar bears)
what minerals are storedcopper & iron

Section 5

Question Answer
How is bile produced in liverAqueous solution of sodium salts or cholic acid (forms from cholesterol)
What do emulsifying agents of digestion dophysical breakdown of lipids that exposes a greater surface area to lipases.
What is the structure of bile salts synthesized from cholesterol so have a steroid structure (4-ring) in the carbon skeleton
What pigments bilebilirubin and biliverdin
What does bilirubin dopigment that forms from hemoglobin breakdown. Metabolized by intestinal bacteria to urobilinogen that colors feces brown.
What does biliverdin doformed from hemoglobin breakdown, then transformed into bilirubin
What electrolytes are in bilesame amounts & kinds of ions as blood plasma
What makes up lipidscholesterol and lecithin
What does enterohepatic circulation meanentero (from intestines) hepatic (to liver)
What are the normal levels of bile salts in the bodyabout 4 grams bile salts, utilized 2 to 10 times/day; loss of about 1/2 gram/day in feces, synthesis replaces. Bile salts that have been reabsorbed into the hepatic portal system of veins are recycles; 80% of amount produced.
What does abnormal increase in bile salts in blood result inextraction by sweat glands (intense itching in skin- pruritis) and interferes with absorption of water & salt--> watery diarrhea

Section 6

Question Answer
What is detoxification?Conversion of a toxic metabolic byproducts to less toxic substances
What produces ammonia in the intestines?deamination and metabolism by intestinal bacteria
Which blood vessel contains the highest concentration of ammonia (NH3)?Hepatic Portal Vein, 4 to 50 times the usual amount
Which blood vessel contains the least amount of ammonia?Hepatic Vein
How does the liver convert ammonia to urea?combining it with CO2, CO2+2NH3 --> NH2-CO-NH2 + H2O
Why does the liver ammonia to urea?Ammonia is toxic whereas urea is less toxic
How is alcohol removed via oxidation, enzymes needed are on the smooth ER of the liver cells (alcohol, acetaldehyde and acetate are all capable of causing tissue damage.
Equation for alcohol detoxificationethyl alcohol -> acetaldehyde -> acetate -> carbon dioxide + water
How is the hydrogen disposed in alcohol detoxificationvia diversion of pyruvate to lactate (interrupting normal cellular respiration). -Lactic acidosis develops. Reduces gluconeogenesis from AA in fasting state: results in hypoglucemia. High lactic acid interferes with excretion of uric acid; hyperuricemia results, gout may result.
How might alcoholics develop liver disease (even with adequate diet) STAGE 1Significant increase in fat deposition in the liver (fatty liver) enlargement and distortion of mitochondria in cells, increase in amount of smooth ER.
How might alcoholics develop liver disease STAGE 2Alcoholic hepatitis- death of liver cells with inflammation
How might alcoholics develop liver disease STAGE 3Cirrhosis- after 5 to 25 years of steady drinking, fibrous scars form, disrupting normal architecture of the lobules. (sig. impairment of normal circulation results (esophageal varices develop) -loss of normal liver function, blood clotting disorders develop, blood pressure disorders develop.