Digestion and Absorption - Sheet1

Question 1

2 forms of digestion

Answer 1

luminal, membrane/brush border

Question 2

small intestine surface modifications

Answer 2

plicae circulares x3, villi x10, microvilli x20

Question 3

what inactivates salivary amylase?

Answer 3

gastric secretion, since non active na at pH

Question 4

starch digestion %%

Answer 4

20-40% sa mouth (starch -> oligosacch), 60-80% pancreas (disacch –> monosacch)

Question 5

intestinal epithelial enzymes (4)

Answer 5

lactose, sucrose, maltose, a-dextrinase

Question 6

absorption of carbs in what form

Answer 6

monosacch

Question 7

20% of absorbed monosacch is made of

Answer 7

fructose and galactose

Question 8

glucose and galactose transport

Answer 8

2ndary active; cotransport with Na through SGLT1 (2 Na : 1 GLU/GAL) (apical)

Question 9

fructose transport

Answer 9

facilitated diff; GLUT 5 (apical)

Question 10

all 3 monosaccharides absorption

Answer 10

facilitated diff; GLUT 2 (basolateral)

Question 11

monosaccharides in increasing order of absorbability

Answer 11

arabinose xylose mannose fructose glucose galactose

Question 12

proteins can be absorbed as proteins

Answer 12

in neonates up to 6 months; in adults in small amounts, can trigger allergies

Question 13

oh no walang pepsin di na ko makakadigest ng protein???

Answer 13

nope! kaya mag process ng protein ang intestinal secretions yey

Question 14

pepsin inactivation

Answer 14

mixed with alkaline pancreatic juices in duodenum

Question 15

trypsinogen is activated by what, secreted by?

Answer 15

enterokinase; epithalium of duo and jejunum

Question 16

individual amino acids can be absorbed in the presence of? vs oligopeptides

Answer 16

sodium (secondary active cotransport), oligo - hydrogen; PepT1;;; endocytosis (active) - minor pathway for longer proteins

Question 17

which is easier to absorb? di/tripeptide or amino acid?

Answer 17

di/tripeptide! :o

Question 18

what do you need to form emulsified fat?

Answer 18

bile and agitation

Question 19

emulsified fat + pancreatic lipase =

Answer 19

FA, 2-MG

Question 20

why do we seldom have fat malabsorption

Answer 20

we have excessive amounts of pancreatic lipase :-)

Question 21

TG + _ & _ = FA, MG (-> micelles)

Answer 21

lipase and colipase

Question 22

PL + _ = FA, lysolecithin

Answer 22

phospholipase A2

Question 23

CE + cholesterol esterase = _, _

Answer 23

FA, cholesterol

Question 24

FA & MG diffuse into enterocyte, reform in?

Answer 24

sER

Question 25

absorbed fats combine with cholesterol and proteins and are processed by what to form what

Answer 25

golgi, chylomicrons (exocytosed –> lacteals)

Question 26

fat absorption mainly occurs in

Answer 26

duodenum, but completed in jejunum

Question 27

what condition may one have if there is a lack of bile acids

Answer 27

steatorrhea

Question 28

what secretes large amounts of bicarbonate

Answer 28

pancreas and liver

Question 29

how are bicarbonate ions indirectly absorbed? (“active absorption of bicarbonate ions”)

Answer 29

NHE absorb sodium, secrete H into lumen; H + HCO3 –> H2CO3 (carbonic acid) –> CO2 + H2O

Question 30

calcium actively absorbed, passing through which 2 structures?

Answer 30

ion channels (TRPV6), ca pump (PMCA1)

Question 31

what activates vit D3

Answer 31

parathyroid hormone

Question 32

interfere with Ca absorption

Answer 32

oxalate (spinach, nuts, rhubarb), phytate (soybeans, wheat, bran)

Question 33

chloride absorption: upper vs ileum and colon

Answer 33

simple diffusion (follow sodium); chloride-bicarbonate exchanger

Question 34

iron mainly absorbed in? how is it excreted?

Answer 34

duodenum, upper jej; blood loss

Question 35

facilitates iron transfer across intestinal epithelium

Answer 35

DMT1

Question 36

absorption of fat-soluble vs water-soluble vitamins

Answer 36

fat -> micelles; water - facilitated diff or Na-dependent cotransport

Question 37

vit b12 absorption needs what, where?

Answer 37

IF from parietal; absorbed in ILEUM