Hepatobiliary and GI Function Flashcards
Progression steps of digestion
Mouth to anus
- Mouth: taste, chewing, bolus formation
- Esophagus: transport
- Stomach: Storage, grinding, mixing, digestion, acid secretion
- Small intestine: digestion, absorption
- Large intestine: fluid and electrolyte absorption
- Rectum: Storage and excretion
Accessory organs to digestions
Pancreas: Digestions and HCO3- buffer
Liver: Metabolism, detoxification, bile formation
Gallbladder: Bile Storage
Pancreas buffers stomach acid / Bile helps digest lipids
Transit time of food to excretion
- Esophagus transit time: 10 s
- Time to small intestine: 1-3 h
- Time to ileocecal valve: 7-9 h
- Time to decending colon: 25-30 h
- Excretion: 30 h
what are the 5 functions of the liver?
carb metabolism
synthesis of plasma proteins
synthesis of lipoproteins
immunity
inactivation of toxins
what is the liver triad?
- hepatic artery
- portal vein
- bile duct
what does the liver do for immunity?
kupffer cells produce lymph
liver blood supply
25% from celiac artery
75% from portal vein (drains from GI system)
how much blood pools in the liver
10%, 500mL
how much nutrients does the liver take (first pass)
1/3-1/2 of nutrients
not fat or suppositories
How to avoid first pass effect?
Different ways to administer drugs?
Topical
Inhaled
Sublingal
Injectable
Liver metabolism: Lipids
- Fatty acid oxidation: Acetyl-CoA
- Ketone formation: (Keto acidosis)
- Synthesize lipoproteins, cholesterol, phospolipids
Liver metabolism: Carbs
- Glucogenesis (Amino Acids)
- Glycogensis (glycogenolysis)
- Hormonal control of glucose release
Liver metabolism: Proteins
- Synthesizes plasma proteins
- Cirrhosis decreases albumin and clotting factors
- Increase of unbound fraction of drugs (larger impact systemically)
- Urea
Liver metabolism on anesthesia
Surgery is stressful. Relases of catecholamines, glucagon, and cortosol. Results in mobilization of carb and protein storage causing hyperglycemia and negative nitrogen balance
Iso and Sevo increase blood glucose levels, Propofol does not (lipid based)
Liver and Urea Recycling
- Deamination = Ammonia (NH3) [85% enters via portal circulation]
- Uptake and Ureagenesis
- GFR (75% of systemic flow after exit from liver)
- GI (25% of systemic flow after exit from liver) Ammonia and Ammonium Ion (NH4)
Liver detox
What toxins? MIDCAP-MF
Metabolic end products
Insecticides
Drugs
Contaminants / Pollutants
Alcohol
Pesticides
Mico-organisms
Food additives
*fat-soluble
Liver Detox: Phase 1
P450’s
Liver Detox: Phase 2
conjugation
ionize, to make water soluble
Liver Detox: Waste Products
Two paths of elimination
- Gallbladder→Bile→Stool
- Kidneys→Urine
Bilirubin production and excretion
- Hemoglobin degraded to bilirubin by the reticuloendothelial system
- Bilirubin is carried in circulation by albumin (bound to it)
- Hits liver: bilirubin is conjugated with glucuronic acid by UDP glucuronyl transferase
- Part of the conjugated bilirubin (glucuronide and bilirubin sulfate) is H2O soluble and excreted into bile
- In the intestine conjugated bilirubin is converted to urobilinogen
- 18% returned to the liver via the enterohepatic circulation then excreted in urine as urobilin (2%)
- 80% is excreted in feces as urobilin and stercobilin
Obstructive / Conjugated / Direct
Bulirubin in Plasma? Yes
Bilirubin in Urine: Yes
Hepatobiliary dx (Cholestasis)
obstruction of the bile ducts, can not be released into the digestive tract
Hemolytic / Unconjugated / indirect
Bilirubin in plasma? Yes
Bilirubin in Urine? No
Impaired conjuction or overproduction
Albumin and bilirubin
Unconjgated bilirubin tighhtly binds to albumin creating an excess in the system
Conjugated bilirubin does not bind as tightly therefore can be excreted in the urine
Markers of liver inflammation / injury
- Asparate transaminase (AST)
- Alanine transaminse (ALT)
- Alkaline Phosphatase (AP)