Nutrient Digestion Flashcards
what are the monosaccharides?
glucose, galactose and fructose
what is lactose constituted of?
glucose and galactose
what is sucrose constituted of?
glucose and fructose
what is maltose constituted of?
2 glucoses
what are the 3 disacccharide enzymes?
lactase, sucrase and maltase
what form of sugar does our liver store?
glycogen
what bonds link glucose monomers in glycogen?
alpha-1,4 glycosidic
how do plants store glucose?
as in starch and cellulose (in cell walls)
what bonds exist in cellulose
beta-1,4 glycosidic
what enzyme breaks down polysaccharides?
amylases
two membranes of columnar epithelium
apical and basolateral
two routes for molecules to cross epithelium
transcellular (through) or paracellular (side)
what connects epithelial cells at the top?
tight junctions
glucose transport
image (into cell by SGLT1 with Na, out by GLUT-2, Na out by Na-K pump, water moves through to blood)
fructose transport
image (in cell by GLUT-5, out by GLUT-2)
where does an endopeptidase cut a peptide?
in the middle
what are the two types of exopeptidases and where do they cut?
aminopeptidases and carboxypeptidases at the ends
does cutting a peptide use water or create water?
uses water i.e. hydrolysis
how are amino acids transported across epithelium
image (in by SAAT1 with Na, dunno how out cell, Na and water into blood)
di/tripeptide transport
image (in by PepT1 with an H, dont know how out, H out to lumen by NHE3 with an Na moving into cell)
what happens with pH around the epithelial surface on the lumen side?
pH is acid closer to/ in the villi
What amount of protein in diet in absorbed as di/tripeptides
70%
enzyme which breaks down TAG
lipase
where does lipase breakdown TAG
small intestine
is lipase water soluble or insoluble?
water soluble
why do large lipid droplets need to be broken down into smaller ones?
too speed up TAG digstion. Lipase can only act on the surface of droplets, therefore
more small droplets –> more surface area –> faster digestion
what does TAG break down into?
monoglyceride and 2 fatty acids
glucose transporter into cell
SGLT1
transporter out of cell for glucose and fructose
GLUT-2
transport of nutrients which also move Na across the cell
glucose, galactose, amino acids and di/tripeptides
how does Na moving from lumen –> blood affect H2O
increase osmolarity on blood side, causing water to move across
molecules with a polar end and non-polar end
amphiphatic molecules
what amphiphatic molecules are used to emulsify lipid droplets
bile salts and phospholipids
whats bigger, a micelle or emulsion droplet
a micelle
which molecules are on the inside of a micelle
monoglycerides and fatty acids
what causes micelles to breakdown
low acidic pH
where do micelles breakdown
at the acid microclimate at the cell membrane surface of the villi
how do the fatty acids and monoglycerides move into the cell
by diffusion
where do they reform once inside the villi cells
on the smooth endoplasmic reticulum
what protein re-emulsifies TAG into chylomicrons
amphiphatic protein
exit of TAG droplets
exocytosed into extracellular fluid at serosal membrane
content of chylomicrons
TAG, phospholipids, cholesterol and fat-soluble vitamins
what final structure picks up the chylomicron away to store
lacteal
what are the fat-soluble vitamins
A, D, E and K
which vitamins follow the same absorptive path as fat
A, D, E and K
what are the water soluble vitamins
B, C and folic acid
how are vitamins B, C and folic acid absorbed
by diffusion or carried-mediated transport
what condition can arise from a B12 deficiency
pernicious anaemia
how long does it take for the B12 store to fully replace itself
3 years
what is pernicious about pernicious anaemia
it takes 3 years from the onset of the problem till the onset of symptoms
what aspect of RBC is B12 neccessary for
RBC maturation
what substance binds with B12
intrinsic factor
where is the B12 intrinsic factor complex absorbed
distal part of the ileum
how is iron stored intracellularly
bound to ferritin
how is iron bound in blood
to transferrin
what effect will consuming more iron have on ferritin production
it will increase it
what organ does transferrin bound iron go to
liver
what transporter moves iron into cells
DMT1
why does iron need to be bound to ferritin and transferrin
because it is highly reactive
in what state does iron cross the serosal membrane of the cell
unbound
