Case 3 - nutrient absorption Flashcards
what are proteins broken down into and where
broken down into amino acids, di peptides and tri peptides, by the stomach, pancreas and brush border
what can all of these be absorbed by
the gut
what are polysaccharides broken down into
broken down into monosaccharides by saliva, pancreas and the brush border
what breaks down disaccharides
brush border
what are examples of polysaccharides
glycogen and starch
what are triglycerides broken down into and where
broken down into free fatty acids, and monoglycerides, but the stomach, pancreas and bile salts
what is incomplete absorption
malabsorption
what Is the potential absorption method for lipids
simple diffusion
what is the absorption method for amino acids and sugars
carrier mediated;
- secondary active
- facilitated diffusion
what is the absorption method for vitamin B12, intrinsic factor and cholesterol
receptor mediated endocyotisis
where are the major sites of absorption
duodenum and jejunum
where is there limited diffusion
mouth, oesophagus, stomach
what is absorbed in the ileum
Vit.B12, bile salts and K+
what is absorbed in the colon
Na+, some H20 and short chain fatty acids
why are the mouth and rectum not used really
they go straight into the blood stream to the heart
what is the total area of the small intestine
200m squared
why is the surface area of the small intestine so big
foldings in the wall
villi
microvilli - brush border
why else is the small intestine so important
polarised expression of transport proteins
what are the carbohydrates absorbed
glucose, galactose, and fructose
what is SGLT1 and where is it found. what carb does it absorb
secondary active transport
found on apical lumen side
it is for glucose
what is GLUT5 and where is it found. what carb does it absorb
facilitated diffusion - found on apical (lumen) side
for fructose
what is GLUT2 and where is it found. what carb is it for
for facilitated diffusion
found on other side of the membrane
for fructose
describe secondary active transport
against concentration gradient. energy derived from Na+ gradient created by Na+ pump
what is the Na+ pump
primary active transport
what is glucose-galactose malabsorption syndrome
genetic disease
mutated version of SGLT1 - no absorption
severe and potentially fatal diarrhoea in infants
what is the treatment for Glucose-galactose malabsorption syndrome
avoid glucose and galactose
what are 50% of amino acids absorbed by
PEPT1 as di and tri peptides
where is it hydrolysed and what to
to amino acid in enterocyte
what is the other 50% absorbed by
Xag- : anionic (aspartate, glutamate)
B0 : neutral a.a
B0+ : cationic and cystine
PAT1 : proline
what are all the transporters all part of
the SLC superfamily
amino acids use what kind of active transport
secondary active transport
what does PepT1 use
uses proton gradient to carry peptides and co-transports H+
what does B0 use
uses sodium cotransport, sodium and alanine moving across the cell membrane
what does Xag- use
uses 3 ions; sodium and glutamate going in and potassium going out
what rare genetic diseases cause appearance of amino acids in urine
Hartnup disease (B0)
bystinuria
Bo+ - kidney stones
