Digestion & Absorption of Lipids, Absorption of Vitamins & Minerals Flashcards
What are triglycerides?
glycerol and fatty acids
Lipids must be solubilized in the _______ for digestion and absorption
small intestine
Stomach [quickly/slowly] empties chyme into small intestine
slowly
What things help with digestion of lipids?
lipase + colipase
cholesterol ester hydrolase
phospholipase A2
What do lipase + collapse do?
collapse binds to lipase and allows it to digest at a lipid-water interface
What cholesterol ester hydrolase do?
hydrolyzes cholesterol ester —> free cholesterol + FA + releases glycerol from triglycerides
What does phospholipase A2 do?
hydrolyzes phospholipids —> lysolecithin and fatty acids
What is phospholipase A2 activated by?
trypsin
Bile salts solubilize products within SI lumen as ______ EXCEPT
micelles
glycerol
After going into lumen as micelles, they diffuse to the _____ of _______. Products then diffuse into the cell.
brush-border membrane of enterocyte
Do bile salts diffuse into the enterocyte?
no
After products are released into the cell. products are _____ inside enterocyte to form original compounds
re-esterified
Re-esterified lipids are then packaged with _____ to form _______
apoproteins
chylomicrons
What do chylomicrons do?
move between endothelial cells of lymphatic capillaries enter blood at thoracic duct
In chylomicrons, cholesterol and triglycerides are in the [core/around outside], and apoproteins are in [core/around outside]
core
around outside
Chylomicrons are packaged in ________ and exocytosed across basolateral membrane into ________
secretory vesicles
lymphatic capillaries
What are some abnormalities of lipid digestion and absorption?
pancreatic insufficiency
acidity of duodenal contents
deficiency of bile salts
bacterial overgrowth
decreased intestinal cells for absorption
failure to synthesize apoproteins
What is the pH optimum for lipase?
6
A tumor means there is an over-production of ______ - aka too much ________
gastrin
too much HCl (parietal cells)
In bacterial overgrowth, bacterial remove ______ & ______ from bile salts
glycine
taurine
If there are decreased intestinal cells (enterocytes), there is less ______ for absorption of lipid products
surface area
Vitamin absorption is required as ______ or _____ for metabolic reactions
co-enzymes
co-factors
Fat-soluble vitamins are incorporated into _____ for transport
chylomicrons
Most water-soluble vitamins absorbed via which transport in small intestine? What is the exception?
Na+/dependent co-transport in SI
vitamin B12 (cobalamin), which requires intrinsic factor for absorption
Vitamin B12 requires _______ for absorption
intrinsic factor
Explain the steps for B12 absorption
Need active vitamin D to absorb ______
calcium
Calcium is absorbed by both _____ and _____ transport mechanisms
passive
active
In active transport, there is [high/low] calcium in the diet. What happens?
high
calbindin synthesis promoted by vitamin D
transport Ca2+ to basolateral membrane
In passive transport, there is [high/low] calcium in the diet. Which route?
low
paracellular
A lack of vitamin D or calcium causes
rickets (young)
osteomalacia (adult)
Iron can occur as ____ iron (Fe2+) OR as _____ iron
free
heme
Iron uses which transporter to transport into enterocyte
DMT-1 - LUMINAL membrane
The heme iron is digested into _____ by _______ inside enterocytes
free iron
lysosomal enzymes
Which transporter does free iron use to cross basolateral membrane into blood?
ferritin (from apoferritin)
Iron circulates bound to _____ and is STORED as _______.
transferrin
ferritin
