liver Flashcards
(39 cards)
how are lipoprotiens made?
apoprotien a is synthasised in teh RER
• Microsomal TAG transfer protien adds the lipid to the ApoB proten to make a lipoprotien
• These are transported to the golgi aperatis where the protien part is glycosated
how are lipids brought to the liver
tryglycerides and lipoprotiens
Sometimes they are brought in as fatty ascids bounf to albumin
how to triglycerides move into cells
broken down by lipoprotein lipase into glycerol and fatty acids which can differ though
what are chylomicrons
chylomicrons are emulsification fo fat made by bile that can bipass the liver when it is overloaded
how are ketones made?
• When there is an abundance of acetyl CoA due to fatty acid catabolism
• 2 Acetyl CoA molecuels are bound together to form acetoacetyl CoA
• The CoA groups are then removed which makes acetoacetate
• This can be converted into betahydroxybuterate
This is used by the brain for fuel when there is no glucose left
How are ketones used as fuels?
converted into teh ketone acetoacetate
then succincyl CoA donates its CoA and becomes succinate, making Acetoacetate CoA
thsi can then be cleaved into two acetyl Co A molecuels that can go striaght into the krebbs cycle
where are ketones used as fuels
predominatly the brain when tehre is no glucose left, cant be used in the liver as it lacks the enzyme succinyl CoA transferase to make the Acetyl CoA, however the liver does make the ketone bodies
how do fatty acids get into the mitochondrial membrane?
- Fatty acids longer than 12 cant diffuse across the mitochondial membrane son have to use the carnitine shuttle
- The chains are broken down into ACYL CoA
- This is converted to ACYL carnitine (by carnatineacyl transferase 1 enzyme) and moved acorss the membrane
- Then it is reformed by carnatineacyltransferase 2 into ACYL CoA
- Carnitine can go back and shuttle more though
how are fatty acids metabolised inside of the mitochondria?
s the sequential removal of 2 carbon units by
oxidation – the second (hence beta) carbon is cleaved
• Each round of beta oxidation produces 1NADH, 1FADH2 and 1 acetyl coA
There can then do into the krebbs cycle or oxidative phosphorilation
what is transaminiation
the amino group being removed from an amino acid and added to another
what is an example of transaminiation
alphaketogluterase accepts the amino group from alanine to form glutamate (AKG) and pyruvate (from the alanine).
what is oxidative deaminiation
when the amino group is hydrolysed to form NH3 and a deaminiated amino acid
what is an example of oxidative deaminiation
glutamate is hydrolysed (water is added) to form alpha ketogluterase and NH3 (amonia)
what is the citric acid cycle
citrulline (in NH3), arginine (out urea), ornithine (in NH3 +CO2)
how much albmunin is made a day
9-12g
what are the two ways protines are degraded
protasomeal - in the cell cytoplpams and smalll proties bind to the protine and signal that it needs to be broken down then enzymes come and break it down
Lysosomal - lysosome vesticles fusing with it and breaking ti down
what is the glucose alanine cycle
• IN the muscle cell, the glucose is broken down into pyruvate via glycolysys
• The pyruvate is then converted into the amino acid alanine via transamination from glutame (which then turns into alpha ketogluterate - AKG)
• The alanine can then travel to the liver
• At the liver alanine is reconverted into pyruvate via transamination of AKG
The pyruvate then can be converted into glucose
• The Glutamate formed in the liver can undergo deaminiation to form urea and AKG
what is teh purpose of teh glucose alanine cycle
to make glucose
to get rid of excess amonia
what are xenobiotics
forign suubstances with no nutritional value that need to be excreted, for exapmle durgs
what are two ways xenobiotics can damage the body?
• They cane cause damage to protiens and act as carciogens by binding to DNA
They can react with O2 and release free oxygen radicals
how are xenobiotics excreted
they are made more soluble so they can be peed out. this happens through phase 1 and then 2 reactions
what is a phase 1 reaction
addiing a hydrophillic group such as OH, amine and carboxyl groups
• There are three tyoes of phase one reactions:
- Oxidation, which is addign OH groups, remocing hydrophobic side
- Reduction - adding H groups to make unsatureated bonds saturated
- Hydrolysis - splitting up amide and ester bonds to make the melecles smaller
what is a phase two reaction?
phase 2 involves conjugation of froming hydophillic metabolites
• This is by adding molecules to the xenobiotic such as sulphate, gluceronic acis
• This causes a large increase in hydrophilicity
what are the 4 steps of pharmakokinetics
absprption, distrabution, metabolism and elimination
