Hepatic System Flashcards
Describe the structure of Glisson’s capsule
Connective tissue covered by mesothelium layer.
- rich in nerve endings.
The liver has __ lobes, __ major and __ minor.
4 2 2
What is a liver lobule
Functional unit of the liver.
Describe the composition of the lobule
Central terminal hepatic venule
Interconnecting plates of hepatocytes
Peripherally arranged portal triad
State the 3 hepatocyte zones which differ by levels of ____
centrilobular, periportal, mid zone
oxidation
Describe the structure of a hepatic lobule
hexagonal
central vein
portal triad
plates of hepatocytes w sinusoids.
what are the 3 vessels of the portal triad
hepatic portal vein
hepatic artery
bile duct
Hepatic portal vein:
- state direction of blood flow.
- state function
blood to liver from digestive tract (75%)
filters toxins from digestive tract
Hepatic artery
- state direction of blood flow
oxygenated blood from aorta to liver (25%)
Which cells do sinusoids contain?
Kupffer cell lining
Hepatic stellate cells
What are the 2 main structures of the hepatobiliary system?
Bile canaculi & bile ducts
Describe the flow of blood & bile in the liver acinus (lobule)
OPPOSITE DIRECTION OF FLOW:
Blood flow towards central vein, bile away.
State functions of the liver
xenobiotic detoxification & metabolism erythrocyte decomposition & bilirubin excretion bile production cholesterol synthesis & lipogenesis carbohydrate metabolism protein synthesis hormone production storage
Which proteins are synthesised by the liver?
Albumin
Coagulation of fibrinogen, prothrombin, factors (V, VII, IX-XI), antithrombin
Which hormones are synthesised by the liver?
Thrombopoietin
Angiotensin
State the function of thrombopoietin
regulates platelet production by bone marrow
State the function of angiotensin
raises BP following renin activation
Which substances are stored by the liver?
Glycogen
Fat soluble vits A D E K
Water soluble vits B12
Iron, Copper
Glycogenolysis
stored glycogen -> glucose
Gluconeogenesis
State the 2 cycles involved
Exhausted glycogen store: non-carbohydrates -> glucose.
Cori & Alanine cycle
Glycogenesis
XS glucose -> glycogen storage
Describe the Cori Cycle
Anaerobic conditions.
Flow of lactate & glucose between active muscles & liver.
Describe the Alanine Cycle
Protein degradation -> glucose.
State the hormones which effect glucose regulation
insulin, glucagon, adrenalin, cortisol
Describe lipid metabolism in the liver.
- Glucose converted to fatty acids via acetyl-CoA
- VLDL formed.
- cholesterol synthesis
Cholesterol uses:
Synthesis of bile acids, cell membranes, hormones
XS cholesterol is converted to ___ ___ OR _____ with bile
bile acids
excreted
Bile is linked to ____ ____ to form bile salts
amino acids (Glycine or Taurine)
State a characteristic of bile acids
AMPIPATHIC (polar & apolar side)
Bile is produced by ____ (Cells) & passes into ___ _____ which carry bile back to ____ ____
hepatocytes, bile canaliculi, portal triad
Describe erythrocyte degradation to form bilirubin.
Erythrocyte phagocytosis -> haemoglobin released
Globin metabolised
Amino acids recycled
Iron bound to transferrin is returned to liver
Haem converted to bilirubin & bound to albumin.
In the liver: uptake of bilirubin by _____.
Bilirubin dissociates from ____ & enters ____.
Bilirubin conjugated with __ _____ ____ via ___-______ ______.
Conjugated bilirubin transported into ___ _____ and ____.
Intestinal bacteria degrade bilirubin to _______.
80% oxidised to ____ and excreted via ____.
20% enters ______ ______ and excreted via _____.
hepatocytes
albumin, hepatocytes
2 glucuronic acids, UDP-glucuronyl transferase
bile canalculi, bile
urobilinogen
stercobilin, faeces
extrahepatic circulation, urine
Describe the first pass effect.
Absorbed [drug] is reduced by liver before reaching the systemic circulation.
REDUCES DRUG BIOAVAILIBILITY
Describe the 2 phases of drug metabolism
PI: add/unmask func groups to convert compound to more POLAR (HYDROPHILIC) metabolite
PII: CONJUGATION to increase AQUEOUS SOLUBILITY.
State some phase I metabolism reactions.
OXIDATION (CYP450s), reduction, hydrolytic cleavage, alkylation
State some phase II metabolism reactions.
CONJUGATION by GLUCURONIDATION, sulfation, acetylation.
Hepatitis
Liver inflammation
Cirrhosis
Fibrous tissue in liver forms & replaces dead cells
Haemochromatosis
Excessive iron accumulation & liver damage
Wilson’s disease
Copper retention (hereditary)
Biliary cirrhosis
disease of bile ducts
Gilbert’s syndrome
bilirubin metabolism disorder (genetic)
Jaudice
Yellow skin, nail beds & sclera.
causes: hyperbilirubinemia -> deposition of bilirubin.
IMPORTANCE: marker of hepatic disease.
State 3 liver function assessment biomarkers (and their enzymes).
TRANSAMINASES (ALT, AST)
CHOLESTATIC enzymes (ALP, GGT)
BILIRUBIN
