Digestion and absorption AAU

Question 1

Digestion of various food is by the process of

Answer 1

hydrolysis

Question 2

Digestion is?

Answer 2

different types of food are broken in the absorbable units “ principally in the small intestine.

Question 3

Absorption is ?

Answer 3

the products of digestion and vitamins, minerals and water crosses mucosa and enter the blood or lymph

Question 4

Carbohydrate Digestion the mouth ?

Answer 4

Salivary α amylase acts on polysaccharides
starches is hydrolyzed into maltose
not more than 5 %of all the starches will have become hydrolyzed

Question 5

Carbohydrate Digestion In the stomach ?

Answer 5

Salivary α amylase is essentially nonactive once the pH below 4.0.

Question 6

Carbohydrate Digestion In the intestine?

Answer 6

Pancreatic α amylase
the carbohydrates are almost totally converted into maltose and/or other very small glucose polymers before passing beyond the duodenum or upper jejunum.

Question 7

Products of starch digestion by α amylase ?(3)

Answer 7

1. Disaccharides: maltose.
2. Trisaccharides: maltotriose.
3. Short polymesr: α dextrins.

Question 8

enzymes found in the brush border ?(5)

Answer 8

1. α dextrinase
2. Maltase
3. Sucrase
4. Lactase
5. Trehalase

Question 9

α dextrinase:

Answer 9

Acts on alpha dextrins, maltose & maltotroise. α dixtrinase also known as isomaltase it hydrolyses 1:6α linkages. along with maltase and sucrase it also breaks down maltotriose and maltose.

Question 10

Maltase?

Answer 10

Acts on maltose to give glucose -glucose

Question 11

Sucrase ?

Answer 11

Acts on sucrose to give glucose =fructose

Question 12

Lactase?

Answer 12

Acts on lactose give glucose + galactose.

Question 13

Trehalase:

Answer 13

Acts on trehalose to give glucose+glucose

Question 14

The absorbed units of carbs enter

Answer 14

portal circulation portal vein.

Question 15

Glucose absorption On luminal membrane

Answer 15

Accomplished by carries for co-transport to inside the cell
Sodium –glucose transports 1 & 2 (SGLT1 & SGLT2).

Question 16

Glucose absorption On basolateral membrane?

Answer 16

(carriers for facilitated diffusion to the ISF). Glucose transporters 1 & 2 (GLUT1 & GLUT2).

Question 17

The Glucose transporter sensitive to insulin

Answer 17

GLUT-4

found in fat & muscle cells

Question 18

Galactose Absorption?

Answer 18

Similar to glucose (i.e.co transported with sodium “secondary active transport”).

Question 19

Fructose Absorption by

Answer 19

Facilitated diffusion that is Independent of Na

Question 20

Fructose Absorption To enterocytes by

Answer 20

GLUT5

Question 21

Fructose Absorption To interstitial by

Answer 21

GLUT2

Question 22

Pentose Absorption

Answer 22

Absorbed by simple diffusion

Produced from metabolism of nucleic acids.

Question 23

Protein Digestion In the mouth?

Answer 23

No enzyme for digestion.

Question 24

Protein Digestion In the Stomach?

Answer 24

Enzymes
gelatinase :  liquefies gelatin 
Pepsin :  It hydrolysis the bond between aromatic amino acids and a second amino acid
Product
polypeptides with very divers sizes.

Question 25

pepsin (activation , inhibition )

Answer 25

Pepsinogen in low pH activated to pepsin | Pepsin activity inhibited by alkaline secretion of the pancreas

Question 26

Protein Digestion In the intestine?

Answer 26

Enzymes Pancreatic endopeptidases (Trapsin, chymotrypsin, and elastase) Pancreatic exopeptidase (Caboxypeptidases A & B) Product They produce Di & Tri peptides but not aminoacids( endopeptidases ) Some free aminoacids liberated in the intestinal lumen ( exopeptidase )

Question 27

Endopeptidases act at

Answer 27

interior peptide bonds.

Question 28

carboxipeptidases hydrolyses aminoacids at

Answer 28

carboxyl and amino ends.

Question 29

proteolytic enzyme found in the brush border ?

Answer 29

Aminopeptidases Carboxipeptidases Endopeptidases Dipeptidases

Question 30

digestion of aminoacids occur in three locations

Answer 30

1. Intestinal lumen. 2. Brush boarder. 3. Cytoplasm of mucosal

Question 31

Products of Protein Digestion ?

Answer 31

* Free amino acids. * Dipeptides. * Tripeptides.

Question 32

The absorbed units of protein enter

Answer 32

portal circulation

Question 33

Absorption of free Amino Acids ?

Answer 33

Co transport with sodium (mainly)

Question 34

Absorption of Dipeptides & Tripeptides?

Answer 34

By a mechanism involving hydrogen ions

Question 35

absorption Complete Protein Undigested

Answer 35

Occurs in infants for IgA antibodies in milk | by endocytosis

Question 36

Abnormalities of Protein Digestion & Absorption?

Answer 36

Absorption of foreign proteins induces antibody formation; | Congenital defects in the mechanism of amino acid absorption

Question 37

Lipid Digestion In the mouth ?

Answer 37

Lingual lipase (acts on triglycerides). Lingual lipase digest as much as 30% of triglycerides

Question 38

Lipid Digestion In the stomach ?

Answer 38

Gastric lipase. Gastric lipase is of little importance.

Question 39

Lipid Digestion In the intestine (From the liver) ?

Answer 39

Bile salts, which cause emulsification and micelle formation

Question 40

Micelle contains ?

Answer 40

1. Fatty acids. 2. Monoglycerids . 3. Cholesterol .

Question 41

Lipid Digestion In the intestine ( From the pancreas ) ?

Answer 41

Pancreatic lipase & Co lipase .

Question 42

Pro-colipase activated by ....... to colipase

Answer 42

trypsin

Question 43

co-lipase act on

Answer 43

emulsified fat | tri-glycerides ( HYDROLYSIS 1& 3bonds easily but 2-bondes slowly )

Question 44

co-lipase product

Answer 44

1. Free fatty acids. | 2. 2-monoglycerids.

Question 45

Bile salt activated lipase act on ?

Answer 45

cholesterol esters, ester of fat soluble vitamins, phospholipids as well as Triglycerides .

Question 46

The absorbed units of fats enter ?

Answer 46

portal circulation or lymphatics

Question 47

Fats entering the portal blood have carbons

Answer 47

No answer here

Question 48

Fats entering the lymphaties have carbons >(10-12)e.g. long chain free fatty acids and cholesterol.

Answer 48

No answer here

Question 49

Chylomicrons

Answer 49

Before entering the lymphatic's, the long chain fatty acids and cholesterol are re-esterified within the cytoplasm of intestinal cells and become coated with protein & phospholipids to from it

Question 50

Chylomicrons are released to lymphatic's by ?

Answer 50

exocytosis.

Question 51

Steatorrhoea

Answer 51

Loss of more than 5 grams of fat in stool per day. Steatorhoea is caused by conditions that impairs of Fat Digestion & Absorption

Question 52

Nucleic acids digestion ?

Answer 52

1. Deoxiribonucleases act on DNA and release nucleotides 2. Ribonucleases act on RNA release nucleotides 3. Then different nucleases releases pyrimidines and purine bases.