Liver A & P Learning Objectives (Val)

- Located in the upper right abdomen beneath the diaphragm

- 4 lobes: right, left, caudate, quadrate

- organized into hexagonal lobules with a central vein and portal triad

- Supported by the falciform ligament

Gross Anatomy of the liver

- liver lobules

- portal triad

- sinusoids

- kupffer cells

- stellate cells

microscopic anatomy of the liver

- optimize nutrient delivery and toxin clearance through blood-hepatocyte exchange

- functional unit

hexagonal structure

liver lobule

-fenestrated capillaries

- blood filtration

- direct blood-hepatocyte exchange

sinusoids

- specialized macrophages

- anchored to the sinusoidal endothelium

- immune surveillance

- macrophage activity

- attached to sinusoidal endothelial cells

kupffer cells

- fibrogenic if activated by injury

- store vitamin A

- maintain normal matrix

satellite cells

arranged in cords radiating from a central vein

hepatocytes

- at each lobule corner

- Branch of portal vein

- Branch of hepatic artery

- Bile duct

portal triad

dual

the liver has a ____ blood supply

- Oxygen-rich blood from celiac trunk

- 25%

Hepatic artery

- Nutrient-rich, partially deoxygenated blood from GI tract & spleen

- 75%

portal vein

- Blood flows through sinusoids → central vein → hepatic veins

- 3 hepatic veins (right, middle, left) drain into the inferior vena cava

how does blood get out of the liver

- carbohydrate metabolism

- lipid metabolism

- protein metabolism

- stores fat soluble vitamins and minerals

major metabolic functions of the liver

- Stores excess glucose as glycogen

- Releases glucose to maintain blood glucose between meals

Carbohydrate Metabolism

- Cholesterol synthesis & regulation

- Produces lipoproteins VLDL, HDL

- Converts excess cholesterol → bile acids

- Performs fatty acid oxidation for energy

Lipid metabolism

- Converts ammonia → urea (detoxification)

- Processes amino acids

Protein Metabolism

- vitamins (A, D, E, K)

- minerals (iron)

vitamin and mineral storage

- oxidation/hydroxylation via CYP450 enzymes

- Produces less lipophilic metabolites

Xenobotic metabolism (biotransformation) Phase 1

conjugation (e.g., glucuronidation, sulfation)

Xenobotic metabolism (biotransformation) Phase 2

- Excretion via bile (for fate digestion) or urine

- Removes substances like Bilirubin and Steroid hormones

waste elimination

- Produced by hepatocytes (~500 mL/day)

- Fat emulsification

- Excretion of lipid-soluble waste

- Undergoes enterohepatic circulation

bile production

some components are reabsorbed in the intestine and re-excreated by the liver

enterohepatic circulation

- Albumin

- Clotting factors

- Acute-phase proteins (e.g., CRP)

- Hormone-binding proteins

What plasma proteins the Liver Synthesizes

Maintains oncotic pressure

albumin

2, 7, 9, 10

clotting factors that are vit K dependent

- Edema (↓ albumin)

- Coagulation abnormalities

- Increased drug effects (less protein binding)

- Hormonal imbalances

Liver failure

- Located in sinusoids

- Perform immune surveillance

- Phagocytize Bacteria, Debris, and Damaged RBCs

- Liver acts as a blood filter

- Excess inflammation → liver injury (e.g., hepatitis)

Kupffer cells (liver macrophages)

- increased O2 concentration

- gluconeogensis

- oxidative energy metabolism

- urea synthesis

Zone 1

- glycolysis

- lipogenesis

- lots of CYP450

Zone 3

- billirubin

- biliverdin

what causes yellow color

- the liver takes glucose and stores it as glycogen

- when you've just eaten (high Blood sugar)

- insulin is active

glycogenesis

- breaks glycogen into glucose

- release glucose into blood

- when you haven't eaten for a while (low blood sugar0

- glucagon is active

glycogenolysis

- makes new glucose from amino acids and glycerol

- later or prolonged fasting

gluconeogenesis