Gi 1

Front 1

List the four functions of the GI system

Back 1

1) ingestion 2) digestion 3) absorption 4) elimination

Front 2

Digestive enzymes are...

Back 2

hydroxylases

Front 3

What kind of cells line the intestine?

Back 3

Enterocytes

Front 4

What kinds of digestive enzymes do enterocytes produce?

Back 4

1) carboxylases 2) proteases 3) lipases 3) ribonucleases

Front 5

Describe absorption

Back 5

1) occurs in the small intestine 2) products must pass through enterocytes to lymph/blood

Front 6

Describe the physiology of the small intestine that makes it ideal for absorption

Back 6

1) villae and microvillae provide very large surface area 2) enzymes on surface of and within cytoplasm of enterocytes specialized to digest food

Front 7

Describe glycogen linkages

Back 7

long 1:4a chains, with 1:6a branches

Front 8

Describe the difference b/t amylopectin and amylose

Back 8

amylopectin is like glycogen w/ fewer branches; amylose consist of strait chains of 1:4a linkages

Front 9

Describe lactose

Back 9

1:4 a glycosidic linkage of galactose and glucose

Front 10

Describe sucrose

Back 10

1:4a glycosidic linkage of glucose and fructose

Front 11

Describe trehalose

Back 11

Dimer of glucose, 1:1a glycosidic linkage

Front 12

Describe a-amylase (origin, what it does, activator)

Back 12

1) from salivary glands and pancreas 2) hydrolyzes non-terminal 1:4a bonds 3) activated by Cl-

Front 13

Describe maltase (origin, what it does)

Back 13

1) secreted by intestinal mucosa (enterocytes) 2) hydrolyzes glycosidic bonds of maltose, maltotriose, and a-dextrins

Front 14

Describe lactase (origin, what it does)

Back 14

1) secreted in intestinal mucosa 2) hydrolyzes lactose [=glucose and galactose]

Front 15

Describe sucrase (origin, what it does)

Back 15

1) secreted by enterocytes 2) hydrolyzes glycosidic bonds of sucrose, maltotriose, and maltose [=glucose + fructose]

Front 16

Describe trehalase (origin, what it does)

Back 16

1) origin: enterocytes 2) fx: hydrolyzes 1:1a-bonds [=2 glucose]

Front 17

Describe a-dextrinase (origin, what it does)

Back 17

1) secreted by enterocytes 2) hydrolyzes 1:6a linkages

Front 18

What happens w/ a lack of oligosaccaridases in the small intestine?

Back 18

1) diarrhea [increased osmotically active particles in SI, broken down by bacteria into even more!] 2) bloating, flatulence [CO2, H2, d/t bacterial breakdown in lower SI, colon]

Front 19

How is glucose absorbed into the enterocyte?

Back 19

SGLT molecules couple NA w/ glucose transport into the cell

Front 20

Where is the Na+/K+ pump in the enterocyte?

Back 20

The basolateral wall

Front 21

How is glucose transported out of the cell?

Back 21

via GLUT2 [facilitated diffusion] in the interstitial membrane [glucose then diffuses to portal vein]

Front 22

What happens in glucose/galactose malabsoption?

Back 22

severe diarrhea

Front 23

How is fructose absorbed?

Back 23

Via GLUT5 [facilitated diffusion] on the brush-border, and into the interstitum via GLUT2 [facilitated diffusion]. Some fructose is converted to glucose by enterocytes

Front 24

How are pentose sugars absorbed?

Back 24

Via simple diffusion

Front 25

What is the maximum rate of glucose absorption?

Back 25

120g/hr

Front 26

Describe pepsin (origin, precursor, activated by, action)

Back 26

1) secreted by stomach [pepsinogen I from acid-secreting region, II from pyloric region] 2) pepsinogen I & II 3) Acid [optimum pH 1.6-3.2; stops working in SI] 4) hydrolyzes peptide bonds next to aromatic R groups

Front 27

Describe gelatinase (origin, action)

Back 27

1) stomach 2) liquefies gelatin

Front 28

Describe Chymosin (origin, action)

Back 28

1) stomach of young animal (not humans) 2) milk-clotting enzyme

Front 29

Describe trypsin (origin, precursor, activated by, action)

Back 29

1) pancreas 2) tripsinogen 3) activated by enteropeptidase in intestinal mucosa 4) hydrolyzes peptide bonds of proteins on the carboxyl side of basic AAs [arginine or lysine] - endopeptidase

Front 30

Describe chymotrypsin (origin, precursor, activated by, action)

Back 30

1) pancreas 2) chymotripsinogen 3) trypsin 4) hydrolyzes peptide bonds on the carboxyl side of aromatic AAs

Front 31

Describe elastase (origin, precursor, activated by, action)

Back 31

1) pancreas 2) proelastase 3) trypsin 4) hydrolyzes peptide bonds of elastin and other proteins on the carboxyl ide of aliphatic amino acids

Front 32

Describe Carboxypeptidase A (origin, precursor, activated by, action)

Back 32

1) pancreas 2) procarboxypeptidase A 3) trypsin 4) hydrolyzes peptide bonds of carboxy-terminal AAs that have aromatic or branched aliphatic side chains

Front 33

Describe Carboxypeptidase B (origin, precursor, activated by, action)

Back 33

1) pancreas 2) procarboxypeptidase B 3) trypsin 4) hydrolyzes peptide bonds of carboxy-terminal AAs that have basic side chains