D3 Functions of liver Flashcards
1
Q
what is the movement of blood in liver? (3)
A
- receives oxygenated blood from hepatic artery (sustains hepatocytes-> liver cells)
- receives nutrient-rich blood from gut via portal vein
- deoxygenated blood transported via hepatic vein
2
Q
what are the function of liver? (4)
A
- storage and controlled release of key nutrients
- detoxification of harmful ingested material
- produce plasma proteins that maintain sustainable osmotic conditions in bloodstream
- breakdown of red bl0od cells and bile salt production
3
Q
what is the structure of the liver? (5)
A
- composed of small histological structures (lobules)
- each lobule surrounded by branches of hepatic artery (O2) and portal vein (nutrients)
- vessels into sinusoids (like capillaries) - exchange material directly with hepatocytes
- sinusoids drain into central vein which feeds deoxygenated blood into hepatic vein
- hepatocytes produce bile which is transported by canaliculi (vessels) to bile duct which surround lobule
4
Q
what is the structure of sinusoids? (3)
A
- increase permeability
- surround diagram (basement membrane) has discontinuous in sinusoid
- endothelial layer contains large intercellular gaps and fewer tight junctions (allow passage of larger molecules)
5
Q
what is carbohydrate metabolism in liver? (4)
A
- excess glucose in bloodstream is taken up by liver and exported to body tissue
- when blood glucose level drops, liver breaks down glycogen into glucose and exports to body tissues
- when hepatic glycogen reserves become exhausted the liver synthesised glucose from other sources (eg fat)
- metabolic processes are coordinated by pancreatic hormones (insulin and glucagon)
6
Q
what is protein metabolism in the liver? (5)
A
- body can’t store amino acids and must be broken down when excess
- amino acid breakdown release amine group (NH2) - can’t be used by body and toxic
- liver removes amine group (deamination) and converts into harmless product
- amine group is converted into urea by liver (excreted within urine by kidneys)
- liver can synthesise non-essential amino acids from surplus stock (transamination)
7
Q
what is fat metabolism in the liver? (6)
A
- liver converts excess carbohydrates and proteins into fatty acids and triglycerides
- responsible for synthesis of large quantities of phospholipids and cholesterol
- these are stored by liver or exported to cells
- LDL transports cholesterol to cells for use n cell membrane and steroid synthesis
- HDL transports excess cholesterol from cells back to liver
- surplus cholesterol is converted by liver into bile salts which can be eliminated via bowel
8
Q
what is the first detoxification chemical pathway? (3)
A
- toxins are converted into less harmful chemicals via oxidation, reduction and hydrolysis
- the reactions are mediated by enzymes (cytochrome P450 enzyme group)
- the conversion produce free radicals (damaging) which are neutralised by antioxidants in liver
9
Q
what is the second detoxification chemical pathway? (3)
A
- converted chemical is attached to another substance via conjunction reaction
- renders compound less harmful and makes it water soluble
- water soluble compounds are then excreted from body within urine by kidneys
10
Q
where are plasma proteins produced in the liver?
A
by rough ER in hepatocytes and exported via Golgi complex
11
Q
what are the 3 types of plasma proteins and functions?
A
- albumins - regulate osmotic pressure of blood (and of body fluids)
- globins - immune system and act as transport protein
- fibrinogen - clotting process
12
Q
what does liver do to red blood cells?
A
- breaksdown and recycles components
13
Q
how does liver breakdown RBC? (4)
A
- liver has kupffer cells (phagocytes) which engulf RBC and break them down into globin and iron containing heme groups
- globin is digested by peptidase to produce amino acids (recycled or metabolised by liver)
- heme group are broken down into iron and bilirubin (bile pigment)
14
Q
what happens to released iron after RBC is broken down? (3)
A
- complexed within a protein to stop oxidation into ferric state
- irons can be stored by lier within protein shell, ferritin
- iron can be transported to bone marrow (where new haemoglobin is produces) within transferrin
15
Q
what is jaundice?
A
condition caused by excess of bile pigment (bilirubin)
