L16 Flashcards
LDL delivers cholesterol via ____
_______ delivers endogenous fatty acids
Apo-B100
VLDL
True or False: LDL delivers endogenously made fatty acids to tissues through the same mechanisms as chylomicrons
VLDL
True
Where is LPL most highly expressed?
Capillaries of adipose, skeletal/cardiac muscle
How are chylomicrons degraded?
Liver enzymes
Binding of ___ to its receptor leads to internalization of chylomicron remnant
Apo-E
When do chylomicron remnants form?
After delivery of fatty acids
What do chylomicrons have on their surface?
Apo-CII
Interactions between what two molecules leads to cleavage of triacylglycerol in chylomicron, releasing fatty acids?
Apo-CII and LPL
Chylomicrons containing ___ are taken up into the lymphatic system
Apo-B48
What do mature chylomicrons contain?
Fat soluble vitamins and Dietary fat
Re-synthesis of what three molecules is REQUIRED for formation of chylomicron re-synthesis?
Triacylglycerol; CE; phospholipids
____ deliver dietary fatty acids and have Apo-CII on their surface
Chylomicrons
Do chylomicrons delivery exogenous or endogenous dietary fatty acids?
Exogenous
What enzyme transfers
resynthesized lipids to Apo-B48?
Microsomal triglyceride transfer
protein (MTP)
What is found in inner core of lipoprotein?
CE and TAG (triacylglycerol)
The outer core of the lipoprotein contains a single layer of ___ and ___
Phospholipids and Cholesterol
___ and __ are the
transport/storage forms of
fatty acids and cholesterol
TAG; CE
Lipids are packaged and transported in the
body within vesicles known as ____
lipoproteins
Decreasing lipid digestion
and absorption can lead to ____
steatorrhea (oily stool)
Which drug inhibits cholesterol absorption in small intestines? How?
- Ezetimibe: blocks NPC1L1 cholesterol transporter on absorptive intestinal cells
- Less cholesterol
absorbed from diet
due to inhibition of
uptake in the intestine
Orlistat blocks the actions of ___ and ___
gastric lipase
(stomach) and pancreatic lipase (intestine)
How can CF cause EPI?
Buildup of mucus blocks
secretion of enzymes
____ facilitate absorption of degraded lipids because its formation allows for penetration of the intestinal water layer
Mixed micelles
Absorption occurs at ___ surface of absorptive small intestine cells by ___ proteins
apical ; transport
_____ cells are the absorptive
cells of the small intestine
“Brush border”
Degraded lipids form mixed micelles in the ___
intestine
___ and ____ also
incorporated into mixed micelles
Bile ; fat-soluble vitamins
True or False: Formation of mixed micelles in the small intestine occurs naturally due to hydrophobic regions facing away from the aqueous environment
True
___and ____ help coordinate digestion
of lipids by signaling to gall bladder and pancreas
Cholecystokinin (CCK) ; Secretin
Intestinal cells recognize lipid
entering the small intestine and
secrete ___ and
___ in response
cholecystokinin; secretin
CCK causes gall bladder to
release ___
CCK signals to pancreas
to secrete ___
bile
degradative
enzymes
LDL has a higher concentration of
cholesterol esters and its role is to
deliver ______ to ____
cholesterol to cells
In LDL receptor mediated endocytosis,
cholesterol is either used by cell or
esterified by ___and stored
ACAT
Mutations in ___ or ___
disrupt the ability of LDL to be
internalized and broken down
ApoB-100; LDLR
Errors in LDL metabolism can lead to ____of cholesterol in ____
deposition of cholesterol in arteries
____returns cholesterol to liver
HDL
HDL is predominately made in what two locations?
1) Liver
2) Small intestine
True or False: HDL circulates in body and
collects excess cholesterol from
peripheral (non-hepatic) tissues
True
True or False: HDL returns cholesterol
to liver for storage,
metabolism or excretion
True
Newly synthesized
HDL is low in
___
cholesterol
ApoA1 interacts
with ___
ABCA1 transports
phosphatidylcholine and
free cholesterol to ___
LCAT is activated by __ and uses a
fatty acid from phosphatidylcholine to
create cholesterol esters
ABCA1
HDL
ApoA1
___ receptor on liver cells binds HDL and selectively takes up cholesterol esters
SRB1
Binding of HDL to
___ allows uptake
of cholesterol esters and completes reverse cholesterol transport
SRB1
Statins compete with _____.
How do they lower cholesterol synthesis?
HMG-CoA
- Lead to less HMG-CoA being converted to
mevalonate (thereby reducing cholesterol
synthesis in the body)
Statins upregulate ___ on cell surface, which stimulates more cholesterol internalization from blood
LDL-R
____
cholesterol synthesis
inhibited by statin
Endogenous
_____ bind to
bile acids/salts and prevent its
reabsorption in small intestine
Bile acid sequestrants
Bile acid sequestrants force liver to synthesize more
___ from cholesterol, reducing
overall levels of cholesterol
bile
Which drugs disrupt enterohepatic
circulation leading to less
“recycling” of bile salts?
Bile acid sequestrants
