Liver physiology Flashcards
What are the functions of the liver?
- Clearance of rbcs and bacteria by phagocytosis
- Lipid and carbohydrate management
- Protein management and synthesis
- Biotransformation of toxin, hormones and drugs metabolism
- Vitamin and mineral storage
- Bile synthesis
How does the liver correct low blood glucose?
Glycogenolysis
-breaks down glycogen to glucose
-converts some amino acids and lactic acid into glucose
-converts other sugars (galactose, fructose) into glucose
the glucose is released into the blood stream
How does the liver correct high blood glucose?
Glycogenesis
- converts excess glucose into glycogen
- and into triglycerides for storage in liver
What is produced when the liver oxidises acids?
ATP
How does the liver deal with lipids it receives?
It receives chylomicrons from the duodenal villi
Hepatocytes synthesise VLDLS (very low density lipoproteins
LDLS are formed in plasma
HDLs are formed in liver
The liver synthesises cholesterol.
What is this used for in the liver?
Making bile salts
What does deamination mean?
The removal of the amino group (NH2) from an amino acid by hepatocytes
This leaves a ketoacid (which is used in Krebs to make ATP)
What is the benefit of deamination?
The ‘deaminated’ amino acids can be used for producing ATP, or being converted into carbohydrates or fats
What happens to the NH2 after deamination?
It becomes toxic ammonia (NH3) but then is combined with CO2 in urea cycle to make urea and water
What type of proteins do hepatocytes synthesise?
Albumin & clotting factors Factor I - fibrinogen Factor II - prothrombin Factors V, VI, VIII, IX, X, X Protein C, S Antithrombin
Is Von Willebrand factor produced in the liver?
No! In endothelial cells
What is special about factor VIII production?
It is produced in the liver AND the endothelial cells
Which vitamins are stored in the liver?
A, D, E, K, B12
Which cells carry out phagocytosis in the liver?
Kupffer cells - macrophages
Where are Kupffer cells found?
In sinusoids - types of blood vessels in liver with fenestrated endothelium
What doe Kupffer cells phagocytise?
Damaged RBCs and bacteria
They break down haem and globin and release bilirubin
Draw the bilirubin pathway!
:)
What do the phase 1 and 2 detoxification pathways do?
Convert fat-soluble chemicals into water soluble chemicals so they can be excreted from the body easily
Give some examples of toxins the liver removes.
Metabolic end products Micro-organisms Contaminants/pollutants Food additives Drugs Alcohol
What enzymes do the phase 1 reactions use?
Where are they found?
Cytochrome P450
On membranes of hepatocytes
What do the phase 1 reactions convert toxins into and how do they do it?
Convert toxic chemicals into less harmful chemicals
By various processes - oxidation, reduction, hydrolysis
What enzymes catalyse the phase 2 reactions?
Transferases such as UDP glucuronyl transferase (converts unconjugated bilirubin into conjugated bilirubin)
How does the phase 2 pathway detoxify molecules?
It does so by adding substances to a toxic chemical to render it less harmful.
This then makes the toxin water soluble so it can be excreted.
What is the reticularendothelial system?
Immune system of phagocyte cells located in reticular connective tissue.
