Liver Function Overview

Liver Function Overview

• Liver functions include storage (glycogen), detoxification (harmful substances), excretion (waste), and detailed processes like ethanol metabolism, fatty liver, cirrhosis, urea formation, and more.

Ethanol Metabolism

• Ethanol is absorbed in the stomach, transported to the liver, metabolized by alcohol dehydrogenase to ethanal (acetaldehyde).
• Ethanal is further converted to ethanoic acid (acetic acid).
• NAD+ reduces to NADH during both ethanol breakdown steps.
• Excessive ethanol leads to a fatty liver due to prioritized ethanol oxidation over fatty acid breakdown.

Fatty Liver

• Characterized by fat accumulation in the liver, potentially progressing to cirrhosis.

Cirrhosis

• Liver scarring due to chronic, excessive alcohol consumption.
• Results from the liver's overload in processing alcohol.

Urea Formation

• Amino acids from proteins enter the liver via the hepatic portal vein.
• Excess amino acids are deaminated, forming ammonia.
• The ornithine cycle converts ammonia into urea, a less toxic substance.
• Urea is excreted in urine.

Liver Excretion and Blood Flow

• Hepatic portal vein connects the digestive tract to the liver, carrying nutrient-rich but potentially deoxygenated blood.
• Hepatic vein carries blood from the liver to the body.
• Hepatic artery brings oxygenated blood.
• Most liver blood originates from the low-pressure hepatic portal vein.
• Sinusoids in the liver are large, permeable capillaries allowing large molecule transfer.
• Bile ducts connect with the gall bladder for storage and release.

Deamination

• Removal of an amino group from amino acids.
• Results in ammonia, converted to urea for elimination.

Carbon Dioxide Transport and Acidosis

• CO2 buildup forms carbanino-haemoglobin, reducing oxygen affinity in blood.
• High bicarbonate levels can also impair oxygen transport.
• Impaired CO2 removal (transport) can cause respiratory acidosis.

Egestion

• Removal of undigested matter through defecation.

Liver Cells and Structure

• Kupffer cells (liver sinusoids) eliminate bacteria and decompose red blood cells.
• Hepatocytes perform diverse functions, like detoxification, bile production, and breaking down harmful products.
• Sinusoids, specialized liver capillaries, enable hepatocyte-blood interaction and filtering.
• Hepatic portal vein transports blood from the digestive system to the liver.
• Bile ducts transport bile out of the liver for release or storage.

Handwritten Notes Summary

• Deamination: Amino acids become keto acids and ammonia.
• Keto acids are used for energy release or fat storage.
• Ornithine cycle converts ammonia and CO2 into urea.
• Urea is removed via the kidneys.
• Ammonia conversion to urea lowers toxicity and prevents pH change.
• Hepatic portal vein delivers low-pressure blood from the digestive system to the liver.
• Liver structure: Lobes then lobules.
• Sinusoids connect hepatic artery and portal vein to central veins for hepatocyte filtering.
• Blood flows: Sinusoids → Central Vein → Hepatic Vein.
• Bile flows opposite to blood flow, via canaliculi connecting to bile ducts.