Liver Pathology Flashcards
Outline the main functions of the liver.
- Temporary nutrient store
- Removes toxins from the blood
- Removes old/ damaged RBCs
- Regulates nutrient and metabolite levels in the blood.
- Secretes bile into the small intestines via the bile ducts and gall bladder
What are the 4 lobes of the liver?
Major; left and right
Minor; caudate and quadrate
What are the different ducts of the liver?
- Common hepatic
- Cystic
- Common bile
Describe the structure of liver lobules.
Roughly hexagonal structures consisting of hepatocyte cells.
At each of the six corners there is a portal triad.
What is the purpose of the hepatic artery?
To supply oxygen-rich blood to the liver.
Describe the blood in the hepatic portal vein.
Nutrient-rich, toxin-ladened, oxygen-poor blood from the gut.
Describe blood in the hepatic portal artery.
Oxygen-rich
Where do the two supplies of blood in the liver (from the hepatic portal vein and artery) meet and describe each
Triad - Branches of three vessels; hepatic portal vein, hepatic artery along with the bile drainage ductless all run together to infiltrate all parts of the liver.
Sinusoids - Special liver capillaries where blood mixed with liver cells etc.
By-products leave as bile in canalicui which merge to form bile ducts.
Outline the functions of hepatocytes.
- Bilirubin metabolism
- Intermediary metabolism of carbohydrates, lipids, proteins and minerals
- Synthesis of plasma proteins
- Detoxification, inactivation or conversation of hormones and xenobiotics.
What cells produce bile?
Hepatocytes
What is bile?
A yellow, green alkaline solution containing bile salts, bile pigments, cholesterol, neural fats, phospholipids and a variety of electrolytes.
It is composed of water, ions, bile salts, bile acids and organic molecules.
How much bile does the liver produce daily ?
1/2 to 1 litres
How do bile salts emulsify fats?
Large fat globules enter the small intestines and are physically separated into millions of small fat droplets to be digested and absorbed.
What is the main component in Gallstones?
Cholesterol
What is the purpose of bile salts and when is this useful?
They emulsify fats and salts which allows absorption across the walls of the small intestines into the lacteal lymph capillaries.
Describe the structure of the gall bladder.
A thin-walled muscular sac on the inferior surface of the liver.
Describe how the gallbladder carries out its function.
When the muscular wall contracts, bile is expelled into the bile duct.
What does the gallbladder store?
Bile that is not immediately needed for digestion.
What does the gallbladder do to bile that it is storing?
Concentrates it
What is cholesterol needed for?
Cell membranes Vitamin D Hormones (progesterone and testosterone) Myelin Components of bile salts
Describe where different %’s of bile in the body come from
85% endogenous or manufactured by our own cells (mostly in the liver).
15% from food we eat.
What substrate does the liver use to produce cholesterol?
Acetyl-CoA
What type of cholesterol is termed “bad”?
LDL - low density lipoproteins
What type of cholesterol is termed “good”?
HDL - high density lipoproteins
What dietary factors raise HDL levels?
Mono-unsaturated fats such as olive and canola oil
What dietary factors raise LDL levels?
Trans and saturated fats
What components does the liver metabolise?
Steroid and polypeptide hormones.
Drugs and foreign compounds.
Bilirubin.
What components does the liver store?
Iron
Glycogen
Vitamin A, D, E and B12
Outline how detoxification occurs within the liver.
Typically a 2 stage process whereby reactive groups are added to xenobiotes and then conjugates are added to make it soluble. This allows excretion via the kidneys.
What is the purpose of the liver carrying out detoxification?
Allows excretion via the kidneys.
Can detoxification in the liver create harmful substances?
Sometimes the original compound could be toxic, sometimes it could be the Phase I or Phase II metabolite. This process may convert unharmful substances to harmful products or vice versa.
What happens in detoxification Phase I in the liver?
Addition of a reactive group to a rug or xenobiotic molecule via oxidation, reduction or hydrolysis in order to render it more water soluble.
In terms of detoxification Phase I, what systems and molecules can be used if oxidation takes place?
- Cytochrome P450 monooxygenase system
- Flavin-containing monooxygenase system
- Alcohol dehydrogenase and aldehyde dehydrogenase
- Monoamine oxidase
In terms of detoxification Phase I, what systems and molecules can be used if reduction takes place?
NADPH-cytochrome P450 reductase
In terms of detoxification Phase I, what systems and molecules can be used if hydrolysis takes place?
Esterases and Amidase
Epoxide hydrolase
Describe what happens in Phase II of detoxification in the liver.
Conjugates a Phase I metabolite with a charged endogenous species to allow for efficient excretion via the kidney.
In Phase II of detoxification, what different ways can conjugation occur?
Methylation, sulphation, acetylation, glucoronidation, glutathione, glycine.
Which phase of detoxification in the liver is most likely to produce toxic metabolites ?
Phase I