Carb, Protein and Fat digestion

Question 1

what are the two types of enzymes and give some examples

Answer 1

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

Question 2

what are the layers of the mucosal barrier in the small intestine from lumen to capillary

Answer 2

unstirred layer where enzymes are secreted from. 
glycocalyx layer on the micro villi 
apical surface 
basolateral surface 
basement membrane

Question 3

how much of our diet is made up of carbs an what are those carbs made up of

Answer 3

50% of our diet 
50% starch 
30% sucrose 
6% lactose 
1-2% maltose

Question 4

what kind of enzymes digestion occurs in the mouth from saliva for carbs

Answer 4

amylase and pancreatic alpha amylase released from the parotid and submandibular glands cause breakdown of starch to tri and di saccs

Question 5

what kind of breakdown occurs for carbs in the duodenum

Answer 5

breakdown of complex carbs

Question 6

where does breakdown of di/tri saccs occur

Answer 6

on the intestinal mucosal brush border where enzymes such as maltase sucrase and lactase are found

Question 7

what is the difference in digestion for amylose and amylopectin

Answer 7

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

Question 8

what do you get when amylase breaks down amylose

Answer 8

maltose, maltotriose and a limit dextrins

which are all broken down to only glucose

Question 9

what breaks down a1-4 dextrins

Answer 9

60% glucoamylase
20% isomaltase
20% sucrase

Question 10

what breaks down a1-6 dextrins

Answer 10

95% isomaltase

5% glucoamylase

Question 11

what breaks down maltose and multariose

Answer 11

25% glucoamylase
25% sucrase
50% isomaltase

Question 12

what breaks down lactose and sucrose

Answer 12

lactase and sucrase

Question 13

what breaks down trehalose

Answer 13

trehalase

Question 14

describe the process of carb absorption

Answer 14

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

Question 15

describe the relationship between parietal cells and chief cells in protein digestion in the stomach

Answer 15

chief cells secrete pepsinogen which is activated by the low ph in the stomach from parietal cells releasing HCL

Question 16

where does protein digestion begin

Answer 16

in the stomach

Question 17

what happens to pepsin in the duodenum

Answer 17

becomes inactivated

Question 18

what is the differences between endo/exo peptidases in the duodenum

Answer 18

endo split internal bonds of polypeptides making shorter chain peptide
exo cleave individual amino acids from the ends of peptides

Question 19

what are the three endopeptidases

Answer 19

trypsin
chymotrypsin
elastase

Question 20

what are the two exopeptidase s

Answer 20

a/b carboxypeptidase

Question 21

what causes activation of peptidases in the duodenum

Answer 21

trypsinogen from the pancreas is transformed to trypsin via enterokinase in the duodenum to activate the other peptidases

Question 22

describe how proteins are absorbed in duodenum

Answer 22

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

Question 23

why is it difficult to absorb aa

Answer 23

inside cell is already high conc of aa

Question 24

what are fats made up of

Answer 24

phospholipids, triglycerides and cholesterol

Question 25

how are fats broken down

Answer 25

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

Question 26

how is the ffa conc gradient maintained in enterocytes

Answer 26

ffa are concerted back to triglycerides but the smooth ER

Question 27

how do ffa leave the basolateral membrane

Answer 27

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)

Question 28

where do lipase get secreted from

Answer 28

sublingual, gastric and pancreatic

Question 29

what is hartnups disease symptoms and treatment

Answer 29

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

Question 30

what is congenital glucose galactose malabsorption

Answer 30

autosomal recessive disorder causing mutation in the SLGT1 transporter on the apical membrane
severe to babies causing dehydration and neonatal diarrhoea
fructose therapy

Question 31

what is lactose intolerance

Answer 31

lactose causing bacterial fermentation in the intestines causing build of acid and gas producing flatulance and abdominal pain