Lipid Digestion

Question 1

Where does lipid digestion take place

Answer 1

Mouth (lingual lipase)
Stomach (lingual lipase and gastric lipase)
Small intestine (pancreatic lipase and bile salts)

Question 2

Lipase activity: removal of fatty acid from locations ___ and ____ sequentially resulting in ___ and ___

Answer 2

1
3
two free fatty acids
one 2-monoacylglycerol (2-MAG)

Question 3

lingal lipase

Answer 3

secreted by cells at the back of the tongue
Acid pH optimum (remains active in the stomach)
Slow activity (only active on the surface of teh lipid droplet)

Question 4

Gastric Lipase

Answer 4

Secreted by gastric mucosa
Acid pH optimum
Activity limited to surface of lipid droplet

Question 5

Pancreatic Lipase

Answer 5

Mixed with bile to form micelles

Secreted by the pancreas with procoplipase

Question 6

_____ is required for lipase action

Answer 6

Procoplipase. Llipase alone is inhibited by bile salts

Procolipase is converted to colipase by trypsin

Question 7

Cholesterol esterase

Answer 7

hydrolyze cholesterol esters to cholesterol and FFA

Question 8

Phopsholipase A2 is activated by ____ and its activity requires ____

Answer 8

secreted as a zymogen and is activated by trypsin

activity requires bile salts

Question 9

Phsospholipase A2 removes ____ from ___ position of phospholipids resulting in _____ and ____

Answer 9

One FA
From 2 position of phospholipids
Results in 1 FFA and 1 lysophospholipid

Question 10

Bile contains

Answer 10

1. Bile Salts
2. Phospholipids
3. Cholesterol

Question 11

Bile malabsorption and also result in ____

Answer 11

malabsorption of fat soluble vitaments

Question 12

Major cholesterol (sterol) transporter

Answer 12

Niemann-Pick C1-like protein

SCARB1 and CD36 have also been identified

Question 13

ABC transporter

Answer 13

pump sterols that cannot be used back out of the cell (ABCG5 and 8)

Question 14

where are bile salts absorbed (what is this termed)

Answer 14

Ileum

Enterohepatic circulation - returned to the liver by portal circulation

Question 15

Transport of long chain fatty acids (>12C)

Answer 15

1. Long chain fatty acids bind intestinal fatty acid binding protein( FAB) and are transprted to the ER
2. Converted to triacylglycerols in the ER by acyl-CoA synthase
3. Transported to blood in chylomicron

Question 16

Transport of short and medium chain fatty acids

Answer 16

enter the hepatic portal vein as FFA and are transferred to the liver bound to albumin

Question 17

major apoprotein added to chylomicrons

Answer 17

B-48

apoproteins are synthesized in the RER, Newly formed apoprotiens are assembled in the goli to form chylomicrons

Question 18

chylomicrons are secreted to ____

Answer 18

lacteals (lymph) - travel up to the thoracic duct and then to the blood stream

Question 19

Steatorrhea

Answer 19

excess fat in the stool
symptom of anything that interrupts lipid digestion and/or absorption
stools may be greasy and foul smelling

Question 20

clay colored stools

Answer 20

result from lack of bile pigments

Question 21

Orlisat

Answer 21

inhibitor of gastric and pancreatic lipases
reduced fat absorption by preventing triacylglycerol digestion

Side effect: steatorrhea

Question 22

Olestra

Answer 22

resistant to action of lipases
Taste and consitency of fat but is nondigestible
Fat soluble vitamins may get passed through with olestra (** should be supplemented when taking)

Question 23

Exetimibe

Answer 23

inhibits NPC1L1- diminished absorption by inhibiting cholesterol transport