Digestion & Absorption of Carbohydrates & Proteins

Question 1

What is absorption?

Answer 1

movement of macronutrients, water, and electrolytes from intestinal lumen into blood

Question 2

What are the two pathways of absorption?

Answer 2

transcellular
paracellular

Question 3

Define transcellular

Answer 3

cross luminal membrane into cell by either passive diffusion or transporter process
- type of absorption

Question 4

Define paracellular

Answer 4

moving across tight junctions between cells

Question 5

What is the structure of intestinal mucosa?

Answer 5

arrange in transverse folds of kerckring with finger-like villi

Question 6

The folds of the intestinal mucosa are _____ and _______, in order to [increase/decrease] surface area and [quicken/slow] digesta

Answer 6

large
circular
increase
slow

Question 7

What are the villi of the small intestine lined with?

Answer 7

epithelial cells
goblet cells

Question 8

Horses, cattle, and sheep have a diet naturally high in ______, but they don’t have an enzyme for it

Answer 8

cellulose

Question 9

Chickens and pigs who eat commercial animal diets have a diet high in _______, with the enzyme ______

Answer 9

starch
amylase

Question 10

Dogs do well on diets with _____ & ________

Answer 10

starch
soluble fiber

Question 11

Cats get _____ in food diets and can digest it but also get ______ in prey

Answer 11

starch
glycogen

Question 12

What is the primary source of energy for most cells?

Answer 12

glucose

Question 13

What are simple sugars?

Answer 13

monosaccharides

Question 14

What are disaccharides? Name one

Answer 14

2 monosaccharides
sucrose

Question 15

What are polysaccharides? Name one

Answer 15

complex chain of sugars
amylose - starch

Question 16

What are oligosaccharides?

Answer 16

short chains of sugars
(dextrins)

Question 17

Digestion of carbohydrates begins how?

Answer 17

enzymatic cleavage and ultimate release of oligosaccharides, disaccharides, and some monosaccharides

Question 18

Where can you find alpha-amylase? What does it do?

Answer 18

salivary glands & pancreas
cleaves internal linkages of amylose (1,4 glycosidic bonds)

Question 19

What is glucoamylase, or amyloglucosidase?

Answer 19

cleaves linear or branched portions of amylase or glycogen

Question 20

What are the brush border enzymes?

Answer 20

alpha-dextrinase for oligosaccharides (also alpha-glucosidase)
maltase
sucrase
lactase

Question 21

What does maltase do?

Answer 21

cleave maltose (2 glucoses)

Question 22

What are monosaccharides for absorption?

Answer 22

glucose
galactose
fructose

Question 23

What enzymes are not made by mammals? (there’s a lot, but asking for 2 from lecture)

Answer 23

cellulose
hemicellulose

Question 24

What transporter transports BOTH glucose and galactose from intestinal lumen into enterocyte?

Answer 24

SGLT 1 - Na+/glucose co-transporter

Question 25

_______ is used for transporting fructose from intestinal lumen into enterocyte

Answer 25

facilitated diffusion (GLUT 5)

Question 26

Name the type of transporter and type used to transport glucose, galactose, and fructose from ENTEROCYTE to BLOOD

Answer 26

GLUT 2
facilitated diffusion!

Question 27

Name 2 disorders of carbohydrate digestion and absorption

Answer 27

hold onto water — isosmotic diarrhea
lactose intolerance (lactase deficiency) and also isosmotic diarrhea

Question 28

Amino acids are usually provided in form of ______

Answer 28

protein

Question 29

Digestion of protein ultimately completed by ______ & ______

Answer 29

endopeptidases
exopeptidases

Question 30

Protein digestion begins in the _______

Answer 30

stomach

Question 31

Pepsinogen is activated to ______

Answer 31

pepsin (endopeptidase)

Question 32

Chief cells produce _____ in young ruminants.

Answer 32

rennin

Question 33

What is rennin?

Answer 33

an enzyme that coagulates milk

Question 34

As digesta enters the small intestine, _____ is released which causes a release of ________

Answer 34

CCK
zymogens

Question 35

Which is the first enzyme to be activated following the release of CCK? It is activated by what?

Answer 35

trypsinogen
enterokinase (found on brush border)

Question 36

List the endopeptidases

Answer 36

trypsin
chymotrypsin
elastase

Question 37

List the exopeptidases

Answer 37

carboxypeptidases A and B (acts on carboy ends of proteins)

Question 38

What is the final digestion step? (peptidase)

Answer 38

amino peptidases at the brush border
- release either single aa or dipeptides

Question 39

Enterocytes can absorb ________

Answer 39

amino
dipeptides
tripeptides

Question 40

What are the 4 co-transporters in luminal membrane for amino acids using the Na+ gradient

Answer 40

neutral amino acids
acidic aa
basic aa
imino (proline) aa

Question 41

What transporters do dipeptides and tripeptides use on the luminal membrane?

Answer 41

H+-dependent co-transporters for di- and tri- peptides

Question 42

Peptides are cleaved to amino acids inside cell by _________

Answer 42

aminopeptidase

Question 43

In absorption of amino acids and peptides, amino acids move across the basolateral membrane via _________

Answer 43

facilitated diffusion

Question 44

What are some general disorders of protein digestion and absorption

Answer 44

pancreatitis (short-term or long-term)
exocrine pancreatic insufficiency
cystinuria

Question 45

In pancreatitis, what portion of the kidney is damaged

Answer 45

exocrine pancreas

Question 46

What can be caused by long-term pancreatitis? What is this disorder?

Answer 46

exocrine pancreatic insufficiency
insufficient production and secretion of digestive enzymes

Question 47

What is cystinuria?

Answer 47

defect or absence of a Na+/amino acid co-transporter (transporter from dibasic aa)