Liver

Abstract

Gross anatomy

General structure

  • Largest gland in the body
    • Weight: ∼ 1.2–1.5 kg in adults (2.6–3.3 pounds)
  • Wedge-shaped
  • Consists of four lobes:
    • Right (largest)
    • Left
    • Quadrate
    • Caudate
  • Typically divided into 8 segments
  • Surrounded by the Glisson capsule
  • Porta hepatis structures

Location

Ligaments

Vasculature

Arteries
Veins
Lymphatics

As part of the liver's dual blood supply, the portal vein allows tissue to remain oxygenated and preserve function in the event of an obstructed hepatic artery.

Innervation

  • Glisson capsule and serosa: lower intercostal nerves
  • Parenchyma: hepatic plexus

Distention of the capsule results in well-localized, sharp pain, as seen in ascites, inflammation, or hepatic cancer.

References:[1][2][3]

Microscopic anatomy


References:[1][4][3]

Function

Energy metabolism
Synthesis
Regulation
  • Glucose homeostasis
Storage
Detoxification and clearance/excretion
Fetal

Also see “parameters of hepatocellular damage”, “parameters of cholestasis”, and “parameters of hepatic synthesis” in liver function tests.

Breakdown of ethanol

Example of zero-order elimination: A constant amount of alcohol is metabolized per unit time (∼ 1 ounce of alcohol per hour).

  1. Oxidation of ethanol to acetaldehyde by alcohol dehydrogenase (ADH): competitive inhibition of ADH by fomepizole; treatment of methanol or ethylene glycol poisoning to prevent the formation of toxic metabolites [5]
  2. Oxidation of acetaldehyde to acetate by acetaldehyde dehydrogenase
  3. Ligation of acetate and coenzyme A to acetyl-CoA by thiokinase under ATP consumption

When large quantities of alcohol are consumed, acetaldehyde builds up faster than it can be metabolized by ADH. Excess acetaldehyde plays a major role in hangover symptoms.

References:[7][5][6]

Embryology

References:[8]

Clinical significance

References:[9][10]

  • 1. Standring S. Gray's Anatomy: The Anatomical Basis of Clinical Practice. Elsevier Health Sciences; 2015.
  • 2. Kumar V, Abbas AK, Aster JC. Robbins & Cotran Pathologic Basis of Disease. Philadelphia, PA: Elsevier Saunders; 2014.
  • 3. Chung KW, Chung HM. Gross Anatomy. Philadelphia, PA: Lippincott Williams & Wilkins; 2012.
  • 4. Le T, Bhushan V,‎ Sochat M, Chavda Y, Zureick A. First Aid for the USMLE Step 1 2018. New York, NY: McGraw-Hill Medical; 2017.
  • 5. McMartin K, Jacobsen D, Hovda KE. Antidotes for poisoning by alcohols that form toxic metabolites. Br J Clin Pharmacol. 2016; 81(3): pp. 505–515. doi: 10.1111/bcp.12824.
  • 6. Goh ET, Morgan MY. Review article: pharmacotherapy for alcohol dependence - the why, the what and the wherefore. Aliment Pharmacol Ther. 2017; 45(7): pp. 865–882. doi: 10.1111/apt.13965.
  • 7. Hall JE. Guyton and Hall Textbook of Medical Physiology. Philadelphia, PA: Elsevier; 2016.
  • 8. Sadler TW. Langman's Medical Embryology. Philadelphia, PA: Wolters Kluwer Health; 2014.
  • 9. Kasper DL, Fauci AS, Hauser SL, Longo DL, Lameson JL, Loscalzo J. Harrison's Principles of Internal Medicine. New York, NY: McGraw-Hill Education; 2015.
  • 10. Goljan EF. Rapid Review Pathology. Philadelphia, PA: Elsevier Saunders; 2018.
last updated 12/09/2018
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