Chapter 15 The Liver Flashcards
What is the gross structure of the liver?
Split into (2) main lobes
Each lobe contains hexagonal shaped lobules
2 blood vessels- hepatic portal vein and hepatic artery
Blood vessels at each corner of the lobule
What is the structure of a lobule?
At each corner, there is a hepatic arteriole, hepatic portal venue, and bile duct
The sinusoid is the space in which the blood mixes, and it contains phagocytic cells called Kuppfer cells to clean blood
Bile is secreted by hepatocytes but sealed in its bile caniculi
Blood flows to the central hepatic venue, to go back to the heart
How can you tell the blood vessels in the lobule apart?
At the ends, where there are two vessels, the larger one is the hepatic portal venule. The small one is the hepatic arteriole
The one by itself is the hepatic venule
The bile duct is sealed
How does the structure of the liver allow as much blood to flow past hepatocytes as possible?
Extensive branching of blood vessels
Formation of lobules with vessels at each corner
What type of blood (what it contains) is in the hepatic portal vein?
Contains digestive waste products as from the intestines/rectum/colon/stomach
What is excretion?
The removal of waste products of metabolism from the body
What are the main functions of the liver?
Storage- of glycogen and vitamins KEDA
Detoxification- deamination, ornithine cycle, alcohols, RBCs, H2O2
Synthesis- bile, lipids, protein
Metabolism
What is bile and what is its function?
Made by hepatocytes. Alkaline. Contains bile pigments from disposed of erythrocytes, and cholesterol, and bile salts
Travels from biliary trees to bile caniculi to the gall bladder until needed
Neutralises gastric acid
Allows lipid emulsification to take place, starts to break them down into smaller globules
What is special about hepatocytes?
Packed full of organelles including lots of SER, RER, Golgi apparatus, mitochondria, and peroxisomes
Can divide, undergo mitosis
Very active
How do hepatocytes break down RBCs?
Senescent RBCs removed by Kupffer cells or Haemoglobin released when cell ruptures
Protein element hydrolysed into amino acids
Haem group- iron recycled, poryphrin rings turns into bile pigments
What is the process of deamination and give an equation?
The removal of NH2 from excess amino acids
NH2-CH- R-COOH + 1/2 O2 —/ RCO-COOH + NH3
Ketoacid used in the Krebs Cycle, ammonia transferred to ornithine cycle
What is the process of the ornithine cycle?
- Ornithine + CO2 + NH3 + ATP —-/ Citrilline + Water
- Citrilline + NH3 —/ Arginine + Water
- Arginine + Water —-/ Ornithine + Urea
What is the process of hepatocytes breaking down Hydrogen Peroxide?
H2O2 is formed as a by product in some metabolic pathways
Hepatocytes contain peroxisomes, with contain catalyse enclosed
Catalyses breakdown into oxygen and water
And also breaks down medicines and non-toxic hormones
What is the process of breaking down alcohol? Why is this bad?
Ethanol— / Ethanal using Alcohol dehydrogenase and NAD+
Ethanal —/ Ethanoate using aldehyde dehydrogenase and NAD +
Ethanoate with acetylCoA for respiration
Using NAD+ from Krebs cycle, should be used to metabolise fats, but it doesn’t .so fatty acids build up, fatty liver disease, cirrhosis
What is transamination?
The process of converting one amino acid into another