Nutrient Digestion (Fats, Vitamins and Minerals) Flashcards
Almost all ingested fat is a form of
Triacylglycerol
All fat digestion takes place in ___ by ___ enzyme
The small intestine
Pancreatic lipase
Triacylglycerols
Large droplets of lipid
Insoluble in water
Lipase
Water soluble enzyme
Lipase mechanism
Turns triacylglycerol into a monoglyceride and 2 fatty acids
Where on the droplet can digestion take place
Surface (very slow for a large droplet)
Emulsification
Divide large lipid droplets into smaller droplets which gives an increased surface area and accessibility to lipase action
Emulsification requires
Mechanical disruption of droplets (by smooth muscle contraction which grinds and mixes lumenal contents) Emulsifying agent (prevents the smaller droplets reforming into larger droplets
Function of amphiphatic molecules
Coat droplets to keep them separate
Micelles
Similar to emulsion droplets but much smaller
Bile salt + monoglyceride + fatty acids + phospholipids
Micelle breakdown
Release of small amounts of free fatty acids and monoglycerides into solution which then diffuse across the plasma membrane of absorbing cells
Dynamic equilibrium of ____ and ____ in solution and in micelles
Fatty acids and monoglycerides
After entering epithelial cells, ____ and ____ enter ____ where they are reformed into ____ (by enzymes located within the sER)
Fatty acids
Monoglycerides
Smooth endoplasmic reticulum (sER)
Triacylglycerols
Chylomicrons
Extracellular fat droplets
Fat soluble vitamins
A, D, E, K
Follow same absorptive path as fat
Water soluble vitamins
B group, C and folic acid
Either absorbed by passive diffusion or carrier mediated transport
Vitamin B12
Large charged molecule
Binds to intrinsic factor in stomach to form complex which is absorbed via specific transport mechanism in distal ileum
Vitamin B12 deficiency
Pernicious anaemia (failure of red blood cell maturation)
Iron transported across brush border membrane into ____
Duodenal enterocytes via DMT1
Iron ions incorporated into
Ferritin
Unbound iron transported across ____ membrane to ____
Serosal
Blood
Iron in blood binds to ____
Transferrin
Ferritin expression regulated depending on body’s iron status
Hyperaemia increased ferritin levels more iron bound in enterocytes
Anaemia decreased ferritin levels more iron released to blood
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