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Liver
- 8 lobes
- sits in RUQ
- Blood flow: blood from all abdominal organs --> mesenteric vein --> hepatic portal vein --> into individual lobes of liver (with hepatic artery) --> blood is "processed" --> hepatic veins (R, L, and middle) --> IVC
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Liver Functions
- Storage: blood (can be released with increased metabolic activity or hemorrhage) — can store up to a liter of blood; fat soluble vitamins — A, D, E, K, B12, iron
- Filter: detoxifies blood of toxins, drugs, bacteria, visues etc; filters and metabolises certain drugs and hormones
- -physical filter: Kupffer cells (macrophages); Pit cells (tumor factor defense); Stellate cells (remove foreign debris/bacteria)
- -biochemical filter: Phase 1: Cytochrome P450 — enzyme in hepatic cells that helps break down toxins and metabolites --> makes them water soluble --> can be filtered out by the kidneys; Phse 2: Esterification — hydrolises toxin/metabolite; go into blood and are excreted by kidney, or into bile and excreted by GI system
- Metabolism:
- -Carbs: broken down in liver into simple sugars like glucose and glycogen --> allows liver to buffer blood glucose levels, can store glycogen, can convert non-carbs into glucose via gluconeogenesis
- -Ammonia: only place in body that filters ammonia out, ammonia is formed in gut and can affect CNS, liver converts it to urea --> filtered out by kidneys
- -ETOH: broken down in liver, higher amounts of ETOH --> increased cytochrome P450 --> ETOH tolerance
- -Bilirubin: bilirubin comes from heme section of hemoglobin (conjugated is bound to albumin [lipid soluble], unconjugated is not [water soluble]) --> liver makes bilirubin become unconjugated --> excreted in bile or urine
- -Vitamin D: forms calcitrol (active vitamin D) --> regulated calcium and phosphorus levels
- -Fats: break down into glycerol and FFAs --> used to make ATP. Excessive amount of fat --> triglycerides released into blood --> picked up by adipose tissue
- Synthesis:
- -proteins: in particular albumin — regulates osmolarity of vasculature, high affinity for water, low albumin levels --> fluid into third space
- -fats: from protein and carbs
- -cholesterol
- -bile salts: help digestion
- Clotting factors: synthesizes all clotting factors related to K, breaks down activated clotting factors
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Bile
- Made in liver in hepatic cells
- Drains through bile ducts
- Bile acids, salts, and pigments
- Aids digestion of fats and buffers GI acids
- Stored in the gallbladder
- about 1 liter made/day
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Gallbladder
- Function: stores and concentrates bile
- not essential to digestion
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Liver Function Tests — LFTs
- Enzymes released by damaged hepatic cells
- ALT: Alanine Aminotransferase (SGPT); normal level: 5–35; specific to hepatic cell injury
- AST: Asparate Aminotransferase (SGOT); normal level: 8–20; detects inflammation, injury, or necrosis of hepatic cells, but is non specific (also found in skeletal muscle, kidney, brain, pancreas, lungs, and spleen)
- ALP: Alkaline Phosphatase "alk phos"; normal level 30–85; non specific marker of liver disease, bone disease, or hyperparathyroidism
- GGPT: Franctionated alk phos: liver specific alk phos; elevated with any dysfunction in biliary tree
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