SS-L Lecture Flashcards
What suspends the liver between the stomach & anterior abdominal wall?
Peritoneum via two peritoneal ligaments
What is the largest gland in the body?
Liver
What are the two peritoneal ligaments which suspend the liver b/w the stomach & anterior abdominal wall?
- Lesser omentum: b/w liver & stomach, contains hepatic blood vessels & bile ducts
- Falciform ligament: b/w liver & anterior abdominal wall; visceral peritoneum covers liver except bare area, top of liver attached to diaphragm & surrounded by coronal ligament
What are the lobes of the liver & how are they determined?
Right, left, quadrate & caudate
Demarcated by blood vessels & ligaments however, do not represent internal organization
Ligamentum teres is a vestige of what?
Umbilical cord carrying blood from placenta to fetus
What is the porta hepatis?
‘hilum’ of the liver containing bile ducts, hepatic artery & portal vein
The liver receives what percentage of CO?
29%
What are the 5 fxns of the liver?
- macrophages (kupffer cells) consume colonic bacteria
- metabolizes 3 major components of food
- CHO: stores as glycogen or secretes into circulation through gluconeogenesis
- lipids: synthesizes lipoproteins, cholesterol & phospholipids; oxidizes FAs; converts CHOs & proteins into fat
- proteins: synthesizes plasma proteins; forms urea - stores vitamins & iron
- detoxifies drugs, hormones, etc
- secretes bile
What are the 4 blood pathways in the liver?
- hepatic artery: brings oxygenated blood from the aorta via the celiac artery
- portal vein: brings nutrient-filled, deoxygenated blood from the gastric, splenic & mesenteric veins
- sinusoids: lined w/hepatocytes that detoxify, metabolize, store iron & vitamins, etc
- hepatic veins: brings blood out of superior aspect of liver into the IVC
What is the arrangement w/in the liver? (of the cells)
classic lobule, hexagonal
What is the functional unit of the liver? What do they contain?
- liver lobule
- triads; they contain the hepatic artery, portal vein & bile duct; central vein lies in the middle
What is the more functional unit of the liver?
Acinus
Hepatocyte efficiency depends on what? What are the differences between the different zones?
- proximity to blood supply; from hepatic and portal vessels out
- zone 1 receives highest concentration of oxygen & nutrients
- zone 3 receives least oxygen & nutrients, but is the primary site of alcohol & drug detoxification; susceptible to hypoxia & toxic damage
In terms of lymphatics, what is the structure which contains plasma & what space does this plasma flow into?
- plasma flows from sinusoids into space of Disse
- space of Disse b/w hepatocytes & endothelium of sinusoids
- lymph sent via channels to IVC or thoracic duct
How does Portal Hypertension happen?
-back pressure of blood into portal circulation due to flow obstruction: varicosities in portal-caval anastamoses (hemorrhoids, caput medusae & esophageal varices)
What are ascites?
- build of fluid into peritoneal cavity surrounding the liver due to an increase in portal hypertension–> increase in lymph flow into space of Disse–> lymph seeps through visceral layer of peritoneum= fluid build up
- drop in blood volume stimulates renal salt & H2O retention until blood volume is restored
Bile is secreted from what through what and towards what?
Bile is secreted from hepatocytes through the canaliculi towards the bile ducts
What are the constituents of bile?
- bile acids
- phospholipids
- cholesterol
- bicarbonate (from bile ducts & hepatocytes to neutralize stomach acid)
- bile pigments (bilirubin)
- melatonin (antioxidant to protect mucosa against damage)
The right and left hepatic ducts are for outflow from where?
bile outflow from the liver
The Common Hepatic Duct is what structurally?
junction of R and L hepatic ducts
The Cystic Duct is for outflow from where?
outflow from gall bladder
The Common Bile Duct is for outflow of what?
outflow of bile from gall bladder & liver
The Hepatopancreatic Ampulla is what structurally?
the junction of bile and pancreatic ducts
The main pancreatic duct is for outflow from where?
outflow from the pancreas
The Major Duodenal Papilla is for secretions of what into where?
bile and pancreatic secretion into duodenum
What are the functions of the gall bladder?
store & concentrate bile
What is the purpose of the choledochal sphincter of Oddi?
creates back flow to fill the gall bladder
What does the gall bladder release and into where?
- bile into the duodenum
- CCK released in response to fats, contracts GB wall
- vagus n. increases bile flow & contracts GB
What does CCK promote?
- GB emptying
- pancreatic secretion
- gastric slowing
- intestinal peristalsis
What does secretin promote?
-promotes HCO3- secretion from bile ducts, pancreatic ducts & Brunner’s glands
Gall stones are precipitates of what due to what?
precipitates of cholesterol due to:
- excess absorption of water
- excess secretion of cholesterol
- inflammation of epithelium
- stasis of gall bladder smooth muscle layer
- **Main one from SSL: reduction in terminal ileum reabsorption of bile salts
In regards to the triad of biliary lithogenicity, what do we want our bile salt vs cholesterol vs phosphatidylcholine concentrations to be (to avoid gall stones)?
- bile salts high (above 70%)
- cholesterol low (below 20%)
- phosphatidylcholine high (above 80%)
Bile is necessary for what?
- digestion & absorption of lipids
- elimination of endogenous products (cholesterol, bile pigments, etc) and exogenous substances (drugs, heavy metals)
What is the sequence of fat digestion?
- lipases hydrolyze TGs into FFAs
- digested FFAs transported into enterocytes via biliary micelles
- FFA reconverted to TGs
- TGs converted to chylomicrons
- chylomicrons transported to the blood
Bile emulsifies fat into what?
1 micrometer soluble droplets
Pancreatic lipases do what to TGs?
-hydrolyze TGs to glycerides & FAs
What does phospholipase A2 do?
hydrolyzes phospholipids
What does cholesterol esterase do?
hydrolyzes cholesterol
What is the structure of a micelle?
-bile acids, phospholipids & cholesterol form lipophilic center that emulsifies fats into a form digestible by lipases
What is the sequence of bile acids to bile salts? Starting with synthesis
- bile acids synthesized in the liver
- conjugated in liver to taurine or glycine to form bile salts
- deconjugaed in intestine to form bile acids
What do phospholipids align with? What makes cholesterol soluble?
- phospholipids align with bile acids
- cholesterol is solubilized by micelles
Micelles transport & facilitate what? What can pass through the unstirred layer?
- absorption of glycerides & FAs through mucosa
- LCFAs can pass through unstirred aqueous layer to reach enterocyte membrane
What do micelles transport and to where? What happens to them there? How, in contrast, is cholesterol absorbed?
- FAs & glycerides to enterocyte where they diffuse into cell
- once inside the enterocyte, FAs & glycerides are re-synthesized into TGs
- cholesterol is absorbed & processed in free form
What is enterohepatic circulation?
- bile acids & salts are recycled back to the liver
- most reabsorption is active transport in the ileum (less passive transport from rest of intestine)
- bile acids & salts are returned to the liver and reconjugated with taurine or glycine
What do chylomicrons transport? What are they formed from & coated with? Where are they transported to? Where are they stored?
- exogenous LCFAs into circulation
- TGs, cholesterol & phospholipids & coated with apoproteins
- transported into lacteals & thoracic duct
- stored in liver & adipose tissue
What happens to short/MCFAs?
-not converted to TGs–>transported directly into portal system of veins
What are the lipoproteins? Where is each one made? What does it transport?
- Chylomicrons: made in SI, transport fat into blood
- VLDL: made in liver, transport TG from liver to organs
- LDL: made in plasma, transport cholesterol esters from liver to organs or tissues (LDL cholesterol deposits in atherosclerosis)
- HDL: made in plasma, transport cholesterol from peripheral tissues to liver
Where is bilirubin derived from? What is it converted to and by what?
- derived from hemoglobin
- converted by colonic bacteria to urobilinogen, either: stercobilin= makes feces brown or excreted in urine= makes urine yellow
What is jaundice?
-excess bilirubin due to increased hemolysis, liver damage or bile duct obstruction
