Digestion: Lipids (M2) Flashcards
digestion is a form of
catabolism
what is catabolism
hydrolytic process that breaks down large food molecules into smaller ones
large food molecules
carbohydrates
proteins
lipids
small food molecules
monosaccharides
amino acids
fatty acids
how do we obtain lipids
synthesized or obtained through diet
lipids are classified due to their
hydrophobicity
do lipids dissolve in water
no, they cluster together away from water
what is a TAG composed of
3 fatty acids + glycerol (sugar)
TAGs comprise __% of dietary lipids
90
what do lipids include
triacylglycerol (triglyceride, TAG)
cholesterol
phospholipids
what are phospholipids composed of
2 fatty acids + glycerol +phosphate + 1 of 4 polar groups
what is cholesterol composed of
steroid core of 4 fused rings + side chains
limited digestion occurs in
mouth and stomach
what hydrolyzes fatty acids with less than/equal to 12 carbons
lingual lipases and gastric lipases
fat globules leave the __ and enter the __
stomach; small intestine
what are bicarbonate and lipases secreted from
pancreas into small intestine
what is bicarbonate
buffer that neutralizes acidic stomach contents
what does pancreatic lipas hydrolyze
triglycerides into monoglyceride and (2) free fatty acides
what are bile salts secreted from
gallbladder into small intestine
what emulsifies fat globules
amphipathic molecules
emulsification
increases surface area of lipids and makes them more accessible to digestive enzymes
what enzymes are secreted by pancreas
trypsin
chemotrypsin
lipases
bile salts surround
fat droplets forming micelles
micelles
core of lipids (hydrophobic regions inside and hydrophilic regions outside) surrounded by bile salts
what do micelles transport
transport lipids through intestinal lumen to epithelial lining
once micelles reach __ of the __, they are _____
once micelles reach epithelial lining of the small intestine, they are absorbed into enterocytes
how do micelles enter enterocytes
simple diffusion
what are bile salts absorbed in
the more distal small intestine and transported back to the liver through the portal vein
what happens in the enterocyte
TAG is reformed and packaged into chylomicrons, along with other lipids
what are chylomicrons
water-soluble lipoproteins.
micelle with protein
what do chylomicrons transport
lipids through the bloodstream from the intestine, and remnants return to the liver for recycling
what is lacteal
lymphatic vessels of small intestine that store digestive fats
chylomicrons enter __ and bypass __
chylomicrons enter lymph capillaries and bypass blood capillaries
within blood capillaries chylomicrons are
digested
lipoprotein lipase (LPL)
hydrolyzes triglycerides into fatty aids and glycerol
chylomicron remnants are
transported to the liver
in the liver, chylomicron remnants are
recycled and TAG is reformed
TAG, along with other lipids (mainly cholesterol), is packaged into
VLDL (very low density lipoproteins) for transport through bloodstream to tissues
bad cholesterol
LDL and VLDL
within blood capillaries, VLDL is
digested
glycerol returns to the
liver to be reused
fatty acids enter cells to be
used as an energy source or stored as triglycerides
loss of triglycerides and some apoproteins converts
VLDL into LDL
LDL is an important carrier of
cholesterol to tissues
cholesterol can be
deposited in the cell membrane, used to make Vitamin D, bile acid, or steroid hormones
HDL carries
excess cholesterol away from tissues to the liver
what do high amount of HDL prevent against
cardiovascular disease
why are non-hdl bad
higher risk of cardiovascular disease
