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Biochem Lipid Digestion
KYCOM Block 3
70
Biochemistry
Graduate
10/30/2012

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Term
describe the solubility of lipids
Definition
hydrophobic, non-polar, water insoluble
Term
what does the solubility of lipids cause the molecules to do
Definition
compartmentalize
Term
how can you dissolve lipids
Definition
non-polar solvents
Term
what are the major functions of lipids
Definition
provide hydrophobic barriers for cell membranes and subcellular compartments, source of energy
Term
what are the minor functions of lipids
Definition
coenzyme or regulatory, regulating homeostasis
Term
what lipids have coenzyme functions
Definition
fat soluble vitamins
Term
what lipids have functions in regulation of homeostasis
Definition
prostaglandins
Term
what has increased intake in saturated FA and cholesterol been shown to cause risk of, what form of fat does not
Definition
dementia, fish
Term
what is the optimal pH for acid lipase
Definition
4-6
Term
what are the enzymes in the stomach that digest lipids
Definition
acid lipase, lingual lipase, gastric lipase
Term
what is an example of something that acid lipase digests
Definition
milk fat
Term
what enzyme is important in neonates for milk digestion
Definition
acid lipase
Term
what does acid lipase target
Definition
short and medium chain FA (<12 C)
Term
where is lingual lipase secreted
Definition
glands at back of tounge
Term
where is gastric lipase secreted
Definition
gastric mucosa
Term
in general what processes emulsify dietary lipids
Definition
complimentary actions: mechanical agitation and secretion of bile salts
Term
what causes mechanical digestion, what does it accomplish
Definition
peristalsis increases surface area of lipid droplets
Term
what do bile salts do
Definition
make smaller particles, detergent stablizes particles so they dont stick back together
Term
where are bile salts made
Definition
liver
Term
where are bile salts stored
Definition
gallbladder
Term
where are bile salts secreted
Definition
small intestines
Term
what do proteolytic enzymes in the small intestines digest
Definition
TAG, cholesterol esters, phospholipids
Term
what digests TAGs in the small intestine
Definition
pancreatic lipase
Term
what does pancreatic lipase cleave TAGs into
Definition
2-monoacylglycerol and FA
Term
what percent of the pancreatic secretion is pancreatic lipase
Definition
2-3%
Term
what does pancreatic lipase need for it to work
Definition
colipase
Term
what does colipase do
Definition
binds pancreatic lipase at a 1:1 ratio moving it to aqueous barrer where inhibitor bile acids are present so enzymes can get to the TAG
Term
ih what form is most dietary cholesterol
Definition
free
Term
what digests cholesterol esters in the small intestines
Definition
pancreatic cholesterol esterase
Term
what does pancreatic cholesterol esterase turn cholesterol esters into
Definition
cholesterol and FA
Term
what activates pancreatic cholesterol esterase
Definition
bile salts
Term
in general how are phosphilipids digested
Definition
aequential removal of FA
Term
what is the process of phospholipid digestion
Definition
1. phospholipase A2 removes FA from position 2 makes lysophorpholipid and FA
2. lisophospholipase removes FA from position one making glycerophosphoryl and FA
3. glycerylphosphorly base is absorbed, digested, or excreted
Term
what conteols pancreatic enzymes
Definition
CCK and secretin
Term
what is CCK secreted from
Definition
mucosal cells of lower duodenum and jejunum
Term
what is CCK released in response to
Definition
lipids, partially digested proteins
Term
what does CCK cause
Definition
contraction of gall bladder releasing bile salts, phospholipids, free cholesterol. exocrine cells of pancreas to secrete hydrolytic enzymes, decreases gastric motility, reducing release of gastric contents into the small intestines
Term
what type of hormone is secretin
Definition
peptide
Term
what makes secretin
Definition
intestinal cells
Term
what does secretin respond to
Definition
low pH of chime entering intestine
Term
what does secretin cause
Definition
bicarbonate release from liver and pancreas, gives appropirate pH for enzyme function
Term
after being digested what happens to the lipid particles
Definition
they form into micelles along with soluble vitamins and bile salts, micelles go to brush border of the membrane of enterocytes and are absorbed
Term
what does lipid digestion in the small intestines generate in the end
Definition
Fa, cholesterol, 2-monoacylglycerol
Term
how do long chain fatty acids get absorbed into brush border
Definition
broken down and put into micelles
Term
how do short and medium chain fatty acids get absorbed into brush border
Definition
they can go right through
Term
once in the enterocytes, what happens to long chain FA
Definition
converted to acyl-Coa at the ER
Term
once in the enterocytes, what happens to 2-monoacylglycerol, what helps
Definition
TAG synthase sequentially adds FA using acyltransferase activities
Term
once in the enterocytes, what happens to lysophospholipids
Definition
reacylated by acyltransferases to form phospholipids
Term
once in the enterocytes, what happens to cholesterol
Definition
esterified
Term
once in the enterocytes, what happens to short and medium chain FA
Definition
not activated, released into portal circulation and carried by serum albumin
Term
what needs to happen to TAG and cholesterol esters before the can leave the enterocyte
Definition
need to be packaged into chylomicrons
Term
what is a chylomicron made of
Definition
TAG and cholesterol esters with a layer of phospholipids, cholesterol, and Apo B48 around the outside
Term
where are chylomicrons made
Definition
ER of enterocytes
Term
once made, what happens to the chylomicron
Definition
exocytosed into the lacteal making the lumph chyle
Term
what is a lacteal
Definition
lymph capillary in the SI villi
Term
what happens when the chylomicron makes chylo
Definition
it is passed into the lymphatic system to thoracic duct to left subclavian then blood
Term
what happens to a chylomicron once it reaches a tissue
Definition
lipoprotein lipase degrades TAG into FA and glycerol
Term
where is lipoprotein lipase secreted
Definition
mostly muscle and adipose but also heart, lung, kidney, liver
Term
what does lipoprotein lipase associate with
Definition
lumen endothelial cells of capillary bed
Term
what happens for FA in circulation
Definition
they are usually taken up immediatly by adjacent muscle or adipose if they dont, they will circulate on albumin until they are
Term
what happens to glycerol after being released into blood
Definition
it is taken up by liver and used to make glycerol-3-phosphate for glycolysis or gluconeogenesis
Term
what remains after the contents of a chylomicron are used by the tissues
Definition
phospholipids, cholesterol esters, apolipoproteins, fat soluble vitamins, TAG
Term
what happens to chylomicron reamins
Definition
interacti with liver cells and are endocytosed
Term
what happens to nitrogenous bases and phospholipids associated with FA transport to tissues
Definition
they are recycled
Term
how can you tell there is lipid malabsorption
Definition
fat soluble vitamins and essential fatty acids in excretion
Term
what diseases involve lipid malabsorption
Definition
cystic fibrosis and shortened bowl
Term
what type of inheritence is cystic fibrosis
Definition
autosomal recessive
Term
what is mutated in cystic fibrosis, what does this cause
Definition
CL ion channels CFTR that hydrate mucous in secretory ducts of pancreas mutations lead to viscous mucous tha blocks pancreatic enzymes needed for lipid digestion in si
Term
what are the symptoms, other than lipid malabsorption of cystic fibrosis related to lipids
Definition
delayed growth, energy deficient
Term
how is cystic fibrosis treated
Definition
with enzyme replacement and fat soluble vitamin supplements
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