Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GIT > Digestion and Absorption > Flashcards

Digestion and Absorption Flashcards

1
Q

Define digestion

A

The chemical breakdown of food by enzymes secreted by glandular cells in the mouth, chief cells in the stomach and the exocrine cells of the pancreas, or enzymes bound to the apical membranes of enterocytes.
Although some digestion of carbohydrates, proteins and fats occurs in the stomach, most occurs in the small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are cavital enzymes?

A

Enzymes secreted from the salivary glands, stomach and pancreas, have signifiant chemical degradation of food.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are hydrolytic enzymes?

A

Enzymes associated with the small intestinal brush border. Hydrolysis by these enzymes is termed contact or membrane digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where in the GIT does most digestion occur?

A

Small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define absorption

A

The movement of material from the intestinal lumen to the blood. Secretion implies movement in the opposite direction. The brush border is the barrier of movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the glycocalyx layer?

A

Layer of glycoproteins on the outside of the microvilli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the unstirred layer?

A

Layer of intestinal secretions that sit on top of the microvilli, the first barrier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is an enterocyte?

A

Cell of the intestinal lining

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What percentage of calories digested are carbohydrates?

A

50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Composition of carbohydrates

A 
50% starch 
30% sucrose
6% lactose 
1-2% maltose
trehalose, glucose, fructose, cellulose, sorbitol, hemicellulose and pectins make up the remainder
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does the starch compound consist of?

A

Two polysaccharides, amylose and amylopectin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is amylose?

A

Straight chain polymer of glucose linked by a-1,4-glycolytic bonds. The repeating disaccharide unit is maltose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is amylopectin?

A

Plant starch, major form of carbohydrate in the diet and is similar to amylose; however, in addition to the 1,4-glycosidic bonds, there is a 1,6-linkage for every 20-30 glucose units

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is glycogen?

A

High-molecular weight polysaccharide similar to amylopectin in molecular structure but with considerably more 1,6-linkages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How many glucose residues does the average alpha-limit dextrin contain?

A

5-10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Percentages of membrane enzymes that break down alpha-1,6 bonds in alpha-dextrin

A

95% isomaltase

5% glucoamylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Percentages of membrane enzymes that break down alpha-1,4 bonds in alpha-dextrin

A

60% glucoamylase
20% sucrase
20% isomaltase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Percentages of membrane enzymes that break down maltotriose

A

50% isomaltase
25% sucrase
25% glucoamylase

19
Q

Percentages of membrane enzymes that break down maltose

A

50% isomaltase
25% sucrase
25% glucoamylase

20
Q

What is the enzyme that breaks down lactose into glucose and galactose?

A

Lactase

21
Q

What is the enzyme that breaks down sucrose into glucose and fructose?

A

Sucrase

22
Q

What is the enzyme that breaks down trehalose into glucose?

A

Trehalase

23
Q

Is digestion or absorption the rate limiting step of carbohydrate digestion?

A

Absorption

24
Q

What are the transporters involved in carbohydrate absorption?

A

GLUT2, GLUT5 and SGLT1

25
Q

What does GLUT5 allow to enter the cell?

A

Fructose

26
Q

What does GLUT2 allow to leave the cell?

A

Fructose, glucose and galactose

27
Q

What does SGLT1 allow to enter the cell?

A

Glucose and galactose, is Na+ dependent, Na+ has to move out of the basolateral membrane via a Na+/K+ ATPase to maintain concentration gradient

28
Q

Where is pepsinogen secreted from?

A

Chief cells of the crypt pits of the stomach

29
Q

How is pepsinogen converted to pepsin?

A

Converted in the presence of H+, HCl secreted from the parietal cells in the stomach

30
Q

What percentage of protein digestion occurs in the stomach?

A

Around 15%

31
Q

What is the function of pepsin?

A

Breaks down proteins into smaller peptide fragments - optimum pH 1-3

32
Q

At what pH does pepsin stop working?

A

pH 5

33
Q

Where is the main site of protein digestion?

A

Duodenum

34
Q

What does an endopeptidase do?

A

Splits proteins into smaller fragments by breaking bonds

35
Q

What does an exopeptidase do?

A

Cleaves single amino acids off the end of proteins

36
Q

What size peptides can be absorbed in the small intestine?

A

Small peptides - di and tripeptides

Single amino acids

37
Q

What transporters are involved in the absorption of proteins?

A

PepT1, 3Na+/2K+ ATPase and NaH exchanger

38
Q

What are most fats in the diet in the form of?

A

Triglycerides - 3FAs linked with glycerol

39
Q

What is TAG hydrolysed by in the digestive tract?

A

Pancreatic lipase

40
Q

What do bile acids to do to fats?

A

Solubilises larger fat molecule, increasing surface area for the action of lipase enzyme

41
Q

What are micelles?

A

Monoglycerides and fatty acids associate with bile salts and phopholipids to form micelles. Cannot be absorbed

42
Q

What types of fat can be absorbed?

A

Free fatty acids or monoglycerides pass through the cell membrane via diffusion

43
Q

What happened to free fatty acids when they are in the cell?

A

Meet the smooth endoplasmic reticulum, which turns them back into triglycerides in order to maintain a concentration

GIT (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions