Unit 10 - Liver/Gallbladder Flashcards
structure responsible for eliminating bacteria from the liver
Kupffer cells
functional unit of the liver
acinus
otherwise known as the liver lobule
functional unit of the liver
acinus
otherwise known as the liver lobule
where do sinusoids receive blood flow
hepatic artery
portal vein
where are Kupffer cells located
in sinusoids
collect bile produced by hepatocytes
bile canaliculi
SNS innervation of the liver
T3-T11
how are hepatocytes organized in acinus
in zones according to proximity to portal triad & central vein
what part of acinus are O2 and nutrient gradients the highest
zone 1
lowest in zone 3
what part of acinus is most susceptible to injury
zone 3
where in the acinus is the highest concentration of CYP450 enzymes
zone 3
how is bile produced
hepatocytes
stored in gallbladder
path of bile to duodenum
canniculi → bile duct → common hepatic duct → common bile duct → ampulla of Vater → duodenum
3 Key Functions of Bile:
1) Absorption of fat and fat-soluble vitamins (AEDK)
2) Excretory pathway for bilirubin and products of metabolism
3) Alkalinization of duodenum
where is Cholecystokinin produced
duodenum
how is CCK production stimulated
Eating fat and protein increases release
effect of CCK release
stimulates gallbladder contraction and ↑ flow of bile into duodenum
function of space of Disse
Lymph and proteins drain into before emptying into lymphatic duct
organ responsible for about ½ of lymph production in the body
liver
how much CO does liver receive
~30% of CO (1500 mL/min)
blood supply to liver
Dual blood supply from portal vein and hepatic artery
liver blood flow and O2 supply from portal vein
75% blood flow, 50% O2 supply
liver blood flow and O2 supply from hepatic artery
25% blood flow, 50% O2 supply
how does splanchnic vascular resistance affect portal vein blood flow
↑ splanchnic vascular resistance = ↓ portal vein blood flow (SNS stim, pain, hypoxia, hypercarbia)
Portal Perfusion Pressure =
Portal Vein Pressure – Hepatic Vein Pressure
portal vein and sinusoid pressure in portal HTN
portal vein: > 20-30 mmHg
sinusoid: > 5 mmHg
normal portal vein and sinusoid pressure
portal vein: 7-10 mmHg
sinusoid: 0 mmHg
physiologic consequences of portal hypertension
- esophageal varices, hemorrhage
- ascites
- spider angiomas
- hemorrhoids
- encephalopathy
compensation for reduced portal vein flow
hepatic arterial buffer response compensates by increasing flow through hepatic artery
why are pts with severe liver disease at increased risk for inadequate hepatic blood flow
Severe liver disease abolishes the hepatic arterial buffer response
portal vein flow is not autoregulated (and hepatic arterial flow can’t r
why are pts with severe liver disease at increased risk for inadequate hepatic blood flow
Severe liver disease abolishes the hepatic arterial buffer response
portal vein flow is not autoregulated (and hepatic arterial flow can’t r
how does anesthesia affect liver blood flow
Both GA & neuraxial anesthesia reduce MAP and CO = dose-dependent ↓ in liver blood flow
how does propranolol affect liver blood flow
↓ CO and increases splanchnic vascular resistance
(hepatic artery constriction)
how do intraabd surgeries affect liver blood flow
reduce d/t retraction and release of vasoactive substances
what 2 major blood vessels supply blood to the liver
- hepatic artery
- portal vein
celiac artery provides blood flow to which 3 organs
- liver
- spleen
- stomach
superior mesenteric artery provides blood flow to which 3 organs
- pancreas
- small intestine
- colon
1 organ that receives blood flow from inferior mesenteric artery
colon
4 examples of things that increase splanchnic vascular resistance
- SNS stim
- hypoxia
- pain
- propranolol
why is PT an early indicator of synthetic dysfunction
factor 7 has the shortest half life of all procoagulants
vitamin K dependent clotting factors
factors 2, 7, 9, 10
The absorption of vitamin K is dependent on:
bile in the gut
where is alpha-1 acid glycoprotein produced
liver
(hepatocytes)
where is von willebrand factor produced
vascular endothelial cells
where is factor 3 produced
vascular endothelial cells
where is factor 8 produced
liver sinusoidal cells and endothelial cells
the liver produces all plasma proteins except:
immunoglobulins
function of thrombopoietin
stim plt production
most abundant plasma protein
albumin
why are pts with liver failure at increased risk of hypoglycemia
Liver is an important regulator of serum glucose & clears insulin from circulation
body’s compensation for hyperglycemia
- insulin released from pancreatic beta cells (glycogenesis)
- glucose converted to glycogen for storage
body’s response to hypoglycemia
- release of glucagon from pancreatic alpha cells & epi from adrenal medulla (glycogenolysis & gluconeogenesis)
- glycogen from storage and non-carbohydrates (amino acids, pyruvate, lactate, glycerol) turned to glucose
what is amino acid deamination
allows the body to convert proteins to carbohydrates and fats. Some of these are utilized in the Krebs cycle to produce ATP
how is urea eliminated from the body
- liver converts ammonia to urea
- urea is eliminated by kidneys
MOA of hepatic encephalopathy
Failure to clear ammonia (hepatic failure or portosystemic shunting)
blood reservoir for acidic drugs
albumin
blood reservoir for basic drugs
alpha 1 acid glycoprotein
erythrocyte life cycle
120 days
where are old RBCs broken down
by the reticuloendothelial cells in the spleen
byproduct of hgb metabolism
bilirubin
how is unconjugated bilirubin transported to liver
bound to albumin
how is unconjugated bilirubin excreted
- lipophilic - transported to liver bound to albumin
- liver conjugates with glucuronic acid - increases water solubility
- conjugated bilirubin excreted into bile
how is conjugated bilirubin metabolized & eliminated
by intestinal bacteria
eliminated in stool
normal PT values
12-14 seconds
LFT very sensitive for acute injury
PT
how does vitamin K deficiency affect PT
prolongs
normal value for albumin
3.5-5 g/dL
half life of albumin
21days
poor indicator of acute liver injury
poor specificity for liver disease
causes of decreased albumin level
impaired synthesis or ↑ consumption
Conditions that ↓: infection, nephrotic syndrome, malnutrition, malignancy, burns
coagulation factors NOT synthesized in liver
vWF
factor 3
factor 4
what is glycogenesis
glucose stored as glycogen
what is glycogenolysis
glycogen cleaved into glucose
gluconeogenesis
glucose created from non-carb sources
what does marked elevation of both AST & ALT indicate
hepatitis
AST/ALT ratio > 2 suggests:
cirrhosis, alcoholic liver disease
normal values for AST & ALT
AST: 10-40 units/L
ALT: 10-50 units/L
LFTs that assess synthetic function
PT, albumin
LFTs that assess hepatocellular injury
AST, ALT
LFTs that assess hepatic clearance
bilirubin
LFTs that assess biliary tract obstruction
Alkaline phosphatase
Y Glutamyl transpeptidase
5’-Nucleotidase
most specific indicator of biliary obstruction
5’-NT
normal values:
Alkaline phosphatase
Y Glutamyl transpeptidase
5’-Nucleotidase
Alkaline phosphatase: 45-115 units/L
Y Glutamyl transpeptidase: 0-30 units/L
5’-Nucleotidase : 0-11 units/L
albumin levels assoc. with hepatocellular injury
acute injury: no change
chronic: decreased
causes of prehepatic liver injury
Hemolysis
Hematoma reabsorption
causes of hepatocellular injury
Cirrhosis
Alcohol abuse
Drugs
Viral infection
Sepsis
Hypoxemia
causes of cholestatic liver injury
Biliary tract obstruction
Sepsis
what aspect of hepatic function is assessed by alkaline phosphatase
cholestatic
(biliary duct obstruction)
Most common cause of liver cancer
hepatitis
most common indicator for liver transplantation in adults
hepatitis
etiologies of hepatitis
viruses, hepatotoxins, and autoimmune responses
also herpes simplex, CMV, Epstein-Barr