Digestion and Absorption: Carbs, Proteins, Nucleotides, and Lipids

Question 1

What is the length of the duodenum and jejuum combined?

Answer 1

3 meters

Question 2

Cause a 5x increase in surface area of small intestine

Answer 2

Valvulae conniventes

Question 3

Cause a 10x increase in surface area of small intestine

Answer 3

Villi

Question 4

Cause a 20x increase in surface area of small intestine

Answer 4

Microvilli

Question 5

The entire small intestine absorbs carbohydrates, proteins, and lipids, but absorption is greatest in the

Answer 5

Duodenum (then jejunum and then ileum)

Question 6

What is a mineral absorbed in the duodenum

Answer 6

Iron (as Fe2+)

Question 7

Folate is a vitamin absorbed in the

Answer 7

Small intestine

Question 8

Absorbed in the terminal ileum along with bile salts

-requires intrinsic factor

Answer 8

B12

Question 9

Total sugars on a food label is referring to

Answer 9

Sucrose, lactose, glucose, and fructose

Question 10

Total carbohydrates minus total sugars and dietary fiber gives you

Answer 10

Complex carbohydrates like starch or sugar alcohol

Question 11

Of the digestible carbohydrates

1. ) 50% =
2. ) 40% =
3. ) 10% =

Answer 11

1. ) Polysaccharides (starch and glycogen)
2. ) Disaccharides (Sucrose and lactose)
3. ) Monosaccharides (Glucose and fructose)

Question 12

The small intestine can only absorb

Answer 12

Monosaccharides

Question 13

Can not absorb monosaccharides

Answer 13

Colon

Question 14

Can not be digested

Answer 14

Dietary fiber

Question 15

Important sources of starch include

Answer 15

Corn, potato, and rice

Question 16

Exists in the form of granules, each of which consist of several million amylopectin molecules together with an even larger number of amylose molecules

Answer 16

Starch

Question 17

Glycogen from animals is a more highly branched form of

Answer 17

Amylopectin

Question 18

In the mouth, starch is attacked by salivary

Answer 18

α-amylase

Question 19

The optimal pH for salivary α-amylase is

Answer 19

7 (i.e. it is inactivated in the stomach)

Question 20

In the duodenum, the acted polysaccharides are then acted on by

Answer 20

Pancreatic α-amylase

Question 21

The main enzyme that breaks the α-1,4 linkage

Answer 21

Glucoamylase

Question 22

Also have activity in breaking the α-1,4 linkage, even though their names suggest otherwise

Answer 22

Sucrase and isomaltase

Question 23

Glucoamylase removes one glucose from the α-limit dextrin formed by

Answer 23

Amylase

Question 24

Then isomaltase acts as the only enzyme that can break the

Answer 24

α-1,6 linkage

Question 25

A More Alkaline Environment in the Duodenum is Required for function of

Answer 25

Pancreatic enzymes

Question 26

Brush border digestion of sucrose and lactose results in glucose and galactose. The uptake of glucose and galactose is then dependent on

Answer 26

SGLT-1

Question 27

Uptake of glucose and galactose is then dependent on sodiumglucose cotransporter-1 (SGLT-1) and driven secondarily by the low intracellular sodium concentration established by the

Answer 27

Basolateral Na+/K+ ATPase

Question 28

Specifically inhibit glucose reabsorption in the kidney tubule

Answer 28

SGLT2 inhibitors

Question 29

The only diabetes-specific drug class that has been show to reduce CV morbidity and death

Answer 29

Gliflozins

Question 30

At about age 5, normal lactase expression in the small intestine is suppressed by the

Answer 30

MCM6 gene

Question 31

This results in about a 70% world-wide prevalence of

Answer 31

Lactose intolerance

Question 32

Has allowed for the continued consumption of milk and milk products in the other 30% of the worlds population

Answer 32

MCM6 mutation

Question 33

To prevent autodigestion, gastric and pancreatic proteases are secreted as

Answer 33

Proenzymes

Question 34

Secrete pepsinogen, which is activated to pepsin after exposure to HCL

Answer 34

Gastric Chief Cells

Question 35

Peptides in the stomach stimulate gastrin secretion --> gastric acid secretion increases --> increased

Answer 35

Protein digestion

Question 36

Because pepsin has a pH optimum around 2.0, it is inactivated in the

Answer 36

Duodenum (pH = 6)

Question 37

In infants IgA antibodies in maternal colostrum enter the circulation of the infant from the intestine, providing

Answer 37

Passive immunity against infection

Question 38

Tri- and dipeptides and amino acids can be absorbed from the

Answer 38

GI tract

Question 39

Causes secretion of pancreatic proenzymes -Stimulated by peptides in the duodenum

Answer 39

CCK

Question 40

Trypsinogen is cleaved to trypsin by the enzyme

Answer 40

Enterokinase

Question 41

Amplifies its own activation leading to activation of the remaining proteolytic enzymes from the exocrine pancreas

Answer 41

Trypsin

Question 42

Peptides are absorbed together with a proton supplied by an apical

Answer 42

Sodium/Hydrogen exchanger (NHE)

Question 43

Peptides are absorbed together with a proton supplied by an apical sodium/hydrogen exchanger (NHE) using

Answer 43

Peptide transporter 1 (PepT1)

Question 44

Absorbed peptides are digested by cytosolic proteases, and amino acids are transported into the bloodstream at the

Answer 44

Basolateral membrane

Question 45

Some amino acids are absorbed directly from the lumen via specific

Answer 45

Transporters

Question 46

Made in the exocrine pancreas and secreted into the duodenum via the pancreatic juice

Answer 46

RNAse and DNAse

Question 47

At the brush border, phosphatase and nucleosidase convert nucleotides to

Answer 47

Pentose sugar, nitrogenous base, and phosphate

Question 48

Pentose, nitrogenous base and phosphate are absorbed in the

Answer 48

Duodenum and Jejunum

Question 49

These products enter the blood capillaries of the intestinal villi and travel to the -For further metabolism

Answer 49

Liver

Question 50

A gastric acid lipase is responsible for about -activated in the duodenum

Answer 50

15% of fat digestion

Question 51

Fatty acids enter the duodenum, triggering the release of

Answer 51

CCK

Question 52

Contracts the gallbladder and relaxes the sphincter of Oddi resulting in secretion of bile and stimulation of pancreatic enzyme secretion

Answer 52

CCK

Question 53

Emulsify fat and increase micelle formation

Answer 53

Bile Acids

Question 54

Further digest TAG (90% of fat in the diet)

Answer 54

Pancreatic lipase and Colipase

Question 55

Need the higher pH in the duodenum (pH = 6) to act

Answer 55

Pancreatic lipase and colipase

Question 56

Packaged into chylomicrons and travel in thoracic duct to the venous circulation

Answer 56

TAG and Cholesterol

Question 57

Produced in the colon and absorbed from it

Answer 57

Short-chain fatty acids (acetate, propionate, butyrate)

Question 58

Formed by the action of colonic bacteria on complex carbohydrates, and resistant starches

Answer 58

Short-chain fatty acids (acetate, propionate, butyrate)

Question 59

Synthesized in the intestine, travels in thoracic duct to the L subclavian vein, then to the liver

Answer 59

Chylomicron

Question 60

The apolipoprotein of the chylomicrons

Answer 60

ApoB-48

Question 61

Carry TAG, phospholipid, CE, and fat soluble vitamins (ADEK)

Answer 61

Chylomicrons

Question 62

Transfers an acyl CoA residue to cholesterol forming a cholesterol ester (CE)

Answer 62

ACAT

Question 63

Most of the lipid in the diet is in the form of

Answer 63

TAGs