HECKdigestion and absorption of carbs and proteins

Question 1

What are nondigestable polysaccharides

Answer 1

fiber like pectin and cellulose

Question 2

What are types of digestable polysaccharides

Answer 2

starch, glycogen, amylose and amylopectin

Question 3

Majority of consumed digestible peptides are what

Answer 3

starch primarily from plants

Question 4

What is the main source of glycogen that we consume

Answer 4

animals

Question 5

What is the difference between amylose and amyloopectin

Answer 5

amylose is a straight polymer and amylopectin is branched

Question 6

What are the two main dietary oligosaccharides and what are they digested into

Answer 6

sucrose: glucose and fructose
lactose: glucose and galactose

Question 7

What are the main dietary monosaccharides

Answer 7

glucose and fructose

Question 8

What type of carbohydrate can the intestine absorbe

Answer 8

monosaccharides

Question 9

What are the 2 steps in the digestive process

Answer 9

intraluminal hydrolysis

and membrane digestion

Question 10

What occurs in intraluminal hydrolysis

Answer 10

enzymatic digestion in the lime- alpha amylase

Question 11

What is the primary alpha maylase that we use? secondary?

Answer 11

salivary amylase

secondary: pancreatic amylase

Question 12

what activates alpha amylase and what inactivates the salivary amylase

Answer 12

secreted in active form to initiate starch digestion

inactivated by gastric acid

Question 13

What is the role of pancreatic amylase and what stimulate the release

Answer 13

completes stach digestion in lumen of SI

stimulated by CCK

Question 14

The pancreatic amylases cannot digest what

Answer 14

terminal linkages and branch points 1,6 on saccharides

Question 15

Describe where membrane digestion takes place and the key enzymes

Answer 15

brush border enzymes- integral membrane proteins mainly in the proximal jejunum and none in the colon
lactase, glucoamylase and sucrase-isomaltase

Question 16

What is the role of lactase

Answer 16

digests lactose into glucose and galactose

expression decreases after weaning in the infant

Question 17

what is the role of sucrase-isomaltase

Answer 17

sucrase splits sucrose

isomaltase splits the branch points

Question 18

What 3 monosaccharides are readily absorbed in SI

Answer 18

glucose, galactose and fructose

Question 19

What is the SGLT1

Answer 19

Na/glucose(galactose) transporter responsible for nutritional uptake
secondary active transcellular

Question 20

What drives the SGLT1

Answer 20

intracellular Na from activity of the NaKATPase

Question 21

What is the GLUT5 transporter and where is it

Answer 21

Only found in jejunum on apical membrane

responsible for fructose uptake and works based on fructose [ ] aka facilitated diffusion

Question 22

Where is the GLUT2 transporter and where is it

Answer 22

on basolateral membrane to transfer all monosccharides into interstitium based on [ ] so facilitated diffusion

Question 23

The best way to describe the lactase downregulation after weaning inheritance

Answer 23

epigenetic modification

Question 24

What are symptoms of a lactase deficiency or lactose intolerance and determined by?

Answer 24

cramps, diarrhea, flatulence

determined by rate of peristalsis and gastric emptying and colonic bacteria

Question 25

What does colonic bacteria have to do with lactase deficiencies

Answer 25

metabolize undigested lactose into: smaller chains to induce diarrhea CO2-->flatulence H2-->released in breath

Question 26

What is a good way to test for lactase deficiency

Answer 26

Hydrogen breath test

Question 27

What can cause a glucose-glactose malabsorption problem

Answer 27

single aa substitute missense in SGLT1 gene inhibiting its function

Question 28

What are the symptoms of glucose-glactose malabsorption and Tx

Answer 28

osmotic diarrhea | Tx: fructose based diet

Question 29

What muse proteins be digested into to be absorbed

Answer 29

oligopeptides and aa

Question 30

What are the different luminal protease pathways for protein digestion

Answer 30

when they are secreted by stomach and pancreas and hydrolyze into peptides and aa when they hydrolyze peptides to oligopeptides which are taken up in enterocyte and hydrolyzed intracell to aa when they hydrolyze peptides into oligopeptides and taken up by enterocyte then directly moved to interstitium

Question 31

What is the other bath of protein digestion that does not involve luminal proteases

Answer 31

brush border proteases that hydrolyze peptides to aa

Question 32

50% of protein entering SI comes from what

Answer 32

food | other 50 sloughed cells

Question 33

What is the difference with endopeptidases and exopeptidases

Answer 33

endopeptidase cleave internal sequences and result in oligopeptides exopeptidases cleave at terminal sequence (amino or carboxyl) and release single aa

Question 34

What state are proteases in when secreted from stomach and what are they

Answer 34

zymogens: pepsinogen

Question 35

What activates pepsinogen

Answer 35

pH dependent - very acidic | irreversible inactivated at pH7

Question 36

What type of peptidase is pepsinogen and what releases it

Answer 36

endopeptidase secreted from chief cell

Question 37

What state are pancreatic proteases secreted in and give examples

Answer 37

zymogens | Trypsinogen, chymotrypsinogen, proelastase and procarboxypeptidase A

Question 38

What activates tyrpsinogen

Answer 38

trypsin secreted by jejunal brush border

Question 39

What else does trypsin activate

Answer 39

chymotrypsinogen, proelastase and procarboxypeptidase A and B

Question 40

What pancreatic proteases are endopeptidases

Answer 40

trypsinogen, chymotrypsinogen, proelastase

Question 41

What pancreatic proteases are exopeptidases

Answer 41

Procarboxypeptidaase A and B

Question 42

Why is there such a large number of brush border peptidases in the SI

Answer 42

each peptidase recognizes only some peptide bonds on larger oligopeptides

Question 43

What do cytoplasmic peptidases cleave

Answer 43

smaller dipeptides and tripeptides

Question 44

What is the PepT1 transporter

Answer 44

transports oligopeptides across lumen

Question 45

When does whole prtein absorption take place

Answer 45

first 6 mo in neonate

Question 46

What is the reason for whole protein absorption in neonates

Answer 46

passive immunity from mother to chile (Ab)

Question 47

What causes closure of whol protein absorption

Answer 47

hormones | corticosteroid admin can induce this

Question 48

What cells are specifically available to allow full proteins to cross lumen barrier

Answer 48

M cells, bring to the peyers patches

Question 49

Where can full proteins cross in adults

Answer 49

still frhouth enterocytes but very rare | M cells in the peyers patches (lamina propria)

Question 50

How do M cells transport full proteins

Answer 50

package as Ag in clathrin coated vesicles and present to immunocompotent cells at basolateral side--> mucosal immunity

Question 51

What runs PepT1 transporter

Answer 51

H/oligopeptide co transporter from H/Na gradient

Question 52

What transporter allows for aa to enter blood the fastest way

Answer 52

PepT1 because active transport, higher kinetics

Question 53

What are the two main categories about single aa transporters on apical membrane

Answer 53

Na dependent transport neutral aa | Na independent transport basic aa and cysteine

Question 54

Describe the 5 types of basolateral aa single transporters

Answer 54

3 for exit that are Na independent | 2 for entrance Na dependent and good for enterocyte and nutrition

Question 55

What type of inheritance is hartnup disease and cystinuria

Answer 55

both are autosomal recessive

Question 56

What is hartnup disease

Answer 56

defect in apical transport of neutral aa (Na dependent) | pellagra, cerebellar ataxia, psychiatric abnormalities

Question 57

What is cystinuria

Answer 57

defect in apical transport of basic aa and cystein (Na independent) kidney stones

Question 58

What are the Tx for hartnup or cystinuria

Answer 58

no Tx except for dietary changes becuase each one can still transport the other type of aa