Carb, Protein and Fat digestion Flashcards
what are the two types of enzymes and give some examples
Caviteal enzymes from the pancreas stomach and saliva such as amylase, carboxypeptidase, trypsin
enzymes released from the small intestine such as enterokinase or the disaccharidases
what are the layers of the mucosal barrier in the small intestine from lumen to capillary
unstirred layer where enzymes are secreted from. glycocalyx layer on the micro villi apical surface basolateral surface basement membrane
how much of our diet is made up of carbs an what are those carbs made up of
50% of our diet 50% starch 30% sucrose 6% lactose 1-2% maltose
what kind of enzymes digestion occurs in the mouth from saliva for carbs
amylase and pancreatic alpha amylase released from the parotid and submandibular glands cause breakdown of starch to tri and di saccs
what kind of breakdown occurs for carbs in the duodenum
breakdown of complex carbs
where does breakdown of di/tri saccs occur
on the intestinal mucosal brush border where enzymes such as maltase sucrase and lactase are found
what is the difference in digestion for amylose and amylopectin
amylose contains an a1-4 which can be broken down by pancreatic and salivary enzymes
amylopectin contains an a1-6 bind which cannot be broken down by these enzymes
what do you get when amylase breaks down amylose
maltose, maltotriose and a limit dextrins
which are all broken down to only glucose
what breaks down a1-4 dextrins
60% glucoamylase
20% isomaltase
20% sucrase
what breaks down a1-6 dextrins
95% isomaltase
5% glucoamylase
what breaks down maltose and multariose
25% glucoamylase
25% sucrase
50% isomaltase
what breaks down lactose and sucrose
lactase and sucrase
what breaks down trehalose
trehalase
describe the process of carb absorption
Na/k on the bsaolateral membrane using ATP transfers Na out the basolateral and K in to keep intracellular Na low
Na with glucose and galactose travel down Na gradient via SLGT1 into the cells
fructose enters passively via GLUT5
monosaccharides freely pass through the basolateral membrane via GLUT2
describe the relationship between parietal cells and chief cells in protein digestion in the stomach
chief cells secrete pepsinogen which is activated by the low ph in the stomach from parietal cells releasing HCL
where does protein digestion begin
in the stomach
what happens to pepsin in the duodenum
becomes inactivated
what is the differences between endo/exo peptidases in the duodenum
endo split internal bonds of polypeptides making shorter chain peptide
exo cleave individual amino acids from the ends of peptides
what are the three endopeptidases
trypsin
chymotrypsin
elastase
what are the two exopeptidase s
a/b carboxypeptidase
what causes activation of peptidases in the duodenum
trypsinogen from the pancreas is transformed to trypsin via enterokinase in the duodenum to activate the other peptidases
describe how proteins are absorbed in duodenum
3 Na out for 2K into the cell via ATP on basolateral membrane
Na in and H+ out on apical membrane
H+ in and di/tri peptides into cell via PEPT1 down conc gradient
peptides moves passively across basolateral membrane
why is it difficult to absorb aa
inside cell is already high conc of aa
what are fats made up of
phospholipids, triglycerides and cholesterol
how are fats broken down
fats are solubilised by bile salts which allows lipase to binds to the globules and break down the fats to ffa which are passively absorbed into enterocytes
how is the ffa conc gradient maintained in enterocytes
ffa are concerted back to triglycerides but the smooth ER
how do ffa leave the basolateral membrane
they are converted to triglycerides by the smooth er and transporter to the golgi and packaged into chylomicrons. these then exit via exocytosis into the lymphatic system (lacteal)
where do lipase get secreted from
sublingual, gastric and pancreatic
what is hartnups disease symptoms and treatment
hereditary autosomal recessive disease causing lack of aa uptake in intestine
causes mental retardation, ataxia and dermatitis
produces increased urinary output of indolaecetic acid and indolpyruvic acid
causes low plasma tryptophan
what is congenital glucose galactose malabsorption
autosomal recessive disorder causing mutation in the SLGT1 transporter on the apical membrane
severe to babies causing dehydration and neonatal diarrhoea
fructose therapy
what is lactose intolerance
lactose causing bacterial fermentation in the intestines causing build of acid and gas producing flatulance and abdominal pain
