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Flashcards in Digestion Lecture Deck (28):
1

Cell types in the small intestine

enterocytes

respon. for digestion, absorption, secretion

turnover rate 3-6 days

susceptible to irradiation and chemotherapy

2

Cell types in the small intestine

goblet cells

mucous secreting

produce physical, chemical and immunological barrier

3

Cell types in the small intestine

patneth cells

part of defense, secrete agents that destroy bacteria

4

forms of enterocyte membrane control

pinocytosis (at base of microvilli)
passive diffusion
active diffusion
facilitated diffusion

5

transporters on the apical membrane of the enterocyte designed for taking in monosaccharides via _____transport

SGLT 1 is a Glucose-Na cotransporter, Galactose-Na cotransporter; uses secondary transport (duh)

GLUT2 is a fructose transporter

6

transporters on the basolateral membrane of the enterocyte designed for taking in monosaccharides via _____transport

Glut2, it takes in everything (glucose, galactose, fructose)

7

where is lactase located

on the brush boarder. deficiency causes osmotic diarrhea
undigested lactose is fermented into methane and hydrogen gas, causing excess flatulence

8

Stomach: protein digesting enzymes

"endopeptidases"



pepsin, typsin, chymotrypsin, elastase

"endopeptidases"

degrade peptides from interior peptide bonds

9

Stomach: protein digesting enzymes

"exopeptidases"

carboxypeptidase A
carboxypeptidase B

degrade peptides beginning at C terminus

10

Trypsinogen

converted to trypsin by ENTEROpeptidase

trypsin converts the ENDOpeptidases into their active form

11

what are the inactive/active form of the endopeptidases?

trypsinogen---> trypsin
chymotrypsinogen --> chymotrypsin
Proelastase ---> elastase
Pro-carboxypeptidase A and B --> A and B carboxypeptidase

12

where are proteases actives?

in the stomach AND the SI

13

autocatalysis

trypsin's conversion of trypsinogen into trypsin

pancreatic enzymes digest one another

14

Protein in the stomach is digested to ___ by ____

amino acids and oligopeptides by pepsin

15

protein in the small intestines is digested to ______ by ______

amino acids, dipeptides, tripeptides, oligopeptides

oligopeptides are further degraded by peptidase on the brush border to amino acids, dipeptides and tripeptides

16

Amino acid transporters in the small intestine in the apical membrane

secondary a.a.-Na cotransporter

there are four: one for acidic a.a., neutral a.a., imino a.a.s, basic a.a's

dipeptides/tripeptides have an H-Di/Tri cotransporter as well

17

Amino acid transporters in the small intestine in the basolateral surface

four transporters for each group of amino acids using facilitated diffusion

internally there's a peptidase to degrade dipeptides and tripeptides to a.a.s

dipeptides and tripeptides can diffuse out of the cell

18

pancreatic preteases

trypsin, chymotrypsin, elastase, caeboxypeptidase A and carboxypeptidase B

19

after degrading proteins, what happens to pancreatic enzymes?

they degrade one another and are reabsorbed

20

cystinuria

defect or absence of Na-amino acid cotransporters

transporter for di-basic amino acids (cystine, lysine, arginine, and ornithine) are absent from small intestine and kidney

genetic disorder

amino acids are secreted into feces

21

Hartnup Disease

Cannot absorb neutral amino acids e.g. tryptophan

recessive genetic disorder

symptoms resemble those cause by pellagra
deficiency of niacin)


symptoms: diarrhea, mood changes, neurologic problems,
res scaly skin
photosensitivity
short stature
uncoordinated movements

urine has high concentration of neutral amino acids

22

Cystic fibrosis transporter mutations

associated with deficiency of amino acid transporters
CFTR transporter in the apical region of duct cells in pancreas

CFTR secretes chlorine, which moves back into the cell down a gradient, and pushing HCO3 into the duct lumen

CFTR mutations decrease bicarbonate secretion

pH elevation prevents activated trypsin from catalyzing the trypsinogen to trypsin conversion

ability to flush active enzymes from the duct may be lost

result-- acute or recurrent peancreatits

23

Where are lipids digested?

in the stomach and small intestine

24

Triglycerides are digested via 3 enzymes

lingual lipase, gastric and prancreatic lipase

25

cholesterol esters are degrade by one important enzyme

cholesterol esterase hydrolase

26

phospholipids are degraded by

phospholipase A2

phospholipid ---> lysolecithin-FA

27

what must occur initially for lipid digestion

solubilized, formed into micelles by bile and transported to the apical region of the enterocytes

28

pancreatic lipase

cholesterol ester hydrolase, phospholipase A2, and pancreatic lipase