quiz 7 Flashcards
what are the 4 dietary lipids?
TAG
FSV
Cholesterol and CEs
phospholipids (PL)
describe TAG digestion in the stomach
TAG clumps together in the stomach and the exterior is digested by gastric lipase.
it removes one FA to create DAG.
describe TAG digestion in the small intestine
cck is secreted when chyme enters
the pancrease releases pancreatic lipase and colipase, which acts on the gallbladder to secrete bile
what are the lipids broken down into
emulsification droplets
describe emulsification droplets
lipids make up the center and bile salts make up the exterior
what binds to the droplet? why
pancreatic colipase, so lipase can access the lipids
what does pancreatic lipase remove
2 FAs from TAG and 1 FA from DAG
what is the end product of TAG digestion
MAGs and FAs, which need to get absorbed
what do droplets become after absorption
bile salts micelles
how are the products of digestion transported to the ER
fatty acid binding proteins
define reesterification
fatty acids recombining with MAGs
describe chylomicrons
what TAGs are packaged in
help with lipid transport
where do lipids first enter after the small intestine?
the lymphatic system
what are TAGs broken down to in the ruminant
1 glycerol and 3 FAs
what is glycerol converted to
VFAs
why is too much fat a problem
it can be toxic to animals
why are PUFAs more toxic
they contain double bonds
define bihydrogenation
removes double bonds in PUFAs
FAs can/can not cross the brush border
can
can lipid transport freely occur?
no
describe very low density lipoproteins
instead of going to the lymphatic system, it goes to the liver
what makes up density
lipid:protein
define apolipoproteins
proteins associated with lipoproteins
what are the functions of lipoproteins
structural, cofactor for enzymes, and/or ligands for receptors
what does apoB100 do
acts as a ligand
what does apoE do
acts as a structure and cofactor
what does apoC2 do
acts as a cofactor
what does chylomicron contain
apoB48
what does chylomicron react with in the bloodstream
apoC2
what does chylomicron do
binds to enzymes in the capillary walls and releases lipids
what is chylomicron a cofactor for
lipoprotein lipase
what are lipoprotein lipases broken down into
glycerol and FAs
where does glycerol go
the liver
where do FAs go
into tissue for energy or storage
what happens when 80% of the TAGs are released
apoC2 dissociates from chylomicrons
define chylomicron remnant
what remains when apoC2 dissociates from chylomicrons
when does chylomicron remnant get removed from the bloodstream
when apoB48 binds to the receptor on liver cells
what do VLDLs use
apoB100 and apoE
what do VLDLs associate with in the bloodstream
apoC2
how many TAGs are initially released with VLDLs
50%
what is created when apoC2 is dissociated from VLDL
intermediate density lipoprotein
what do IDLs become
LDLs
what does LDL transfer
cholesterol from the liver into the body
what do LDLs use for transferring
apoB100
describe the LDL steps
travels through the bloodstream
binds to apoB100 on capillary walls
cholesterol is diffused into tissues
how long to LDLs stay in circulation
2 days
where do LDLs go when cholesterol is absorbed
back to the liver
what do HDLs do
the reverse of cholesterol transport: transport cholesterol from tissue using apoA1
what are the steps of HDLs
binds to apoA1 receptors on capillary walls
cholesterol is desorbed from tissue
returns to liver with cholesterol
what are the 4 roles of lipid metabolism
energy source
structural components
lubricants
signaling molecules
what are the only two places that synthesize fat
adipose tissue and the liver
