Nutrient Digestion and Absorption I and II

Question 1

What form of carbohydrates are small enough to be absorbed by the small intestine ?

Answer 1

Monosaccharides

Question 2

Where is the primary area of disaccharide breakdown within the alimentary system ?

Answer 2

The enzymes on the brush border of the small intestine

Question 3

How is starch broken down in the Alimentary system ?

Answer 3

Hydrolysed by amylase (pancreatic and saliva)

Question 4

How is cellulose broken down in the alimentary system ?

Answer 4

It cant be broken down, no enzymatic digestion in vertebrates

Question 5

What is the stored form of glucose within the liver ?

Answer 5

Glycogen

Question 6

What kind of cells are found within the small intestine ?

Answer 6

Cuboidal cells

Question 7

What are the 2 layers of the cell within the small intestine ?

Answer 7

Basolateral membrane and the apical membrane

Question 8

What is found on the upper membrane of the cells within the small intestine ?

Answer 8

The brush border

Question 9

Which transporter on the apical membrane of the cell transports glucose ?

Answer 9

SGLT1

Question 10

Which transporter on the basolateral membrane of the cell transports glucose into the bloodstream ?

Answer 10

GLUT-2

Question 11

What kind of bonds are found in carbohydrates ?

Answer 11

Glycosidic bonds

Question 12

What kind of bonds are found in proteins ?

Answer 12

Peptide bonds

Question 13

What do proteases and peptidases do ?

Answer 13

Digest proteins

Question 14

What do endopeptidases do ?

Answer 14

Digest protein by breaking down the middle of the protein structure

Question 15

What do exopeptidases do ?

Answer 15

Digest protein by cutting the ends of the protein so it can be broken down

Question 16

What is the name of the transporter that allows amino acids across the cell barrier ?

Answer 16

SAAT1

Question 17

Which transporter on the apical border requires a proton coupled process ?

Answer 17

PepT1

Question 18

Which transporter on the apical border recycles protons and brings in Na ?

Answer 18

NHE3

Question 19

What is the name of the transporter on RBC that allows Glucose into their cell ?

Answer 19

GLUT-1

Question 20

What is the name of the transporter that allows Fructose to be absorbed into the small intestine ?

Answer 20

GLUT-5

Question 21

Where in the Alimentary system are fats broken down ?

Answer 21

The small intestine

Question 22

What enzyme breaks down fat and what organ secretes this enzyme ?

Answer 22

Lipase and the pancrease

Question 23

Define emulsification

Answer 23

The breakdown of large lipid droplets into smaller lipid droplets which allows Lipase to act on a larger surface area.

Question 24

What allows for easier digestion of lipid droplets ?

Answer 24

The decreased size of the droplets creates a larger surface area for lipase to act

Question 25

Emulsification requires what ?

Answer 25

1: Mechanical disruption of large lipid droplets to small droplets (muscle contractions within the gut) 2: An emulsifying agent

Question 26

What does an emulsifying agent do ? and give an example of the agent in lipid breakdown

Answer 26

Prevents the small lipid droplets from re-aggregating and becoming large again. In lipid breakdown the agent is bile salts and phospholipids

Question 27

Absorption of fat across the cell is enhanced by what ?

Answer 27

Micelles

Question 28

What are micelles made of ?

Answer 28

bile salts and phospholipids and FA's and monoglycerides

Question 29

what components of the original lipid are allowed to cross the cell barrier ?

Answer 29

Fatty acids and monoglycerides

Question 30

What is the fate of the fat molecules that are absorbed across the cell ?

Answer 30

The FA's and monoglycerides enter the smooth ER where they are reformed into Triglycerides by enzymes within the smooth ER. The triglycerides are then coated by an emulsifying agent creating vesicles. The vesicles are then transported through the cell through the golgi apparatus and exocytosed into the ECF.

Question 31

What are chylomicrons ?

Answer 31

Extracellular fat droplets

Question 32

Where do chylomicrons go during the fat absorption process ?

Answer 32

Pass between the endothelial cells into lacteals as they cannot pass through the capillary basal membrane.

Question 33

Name 4 fat soluble vitamins

Answer 33

A,D,K and E

Question 34

Name 3 water soluble vitamins

Answer 34

B Group C Group Folic Acid

Question 35

What is vitamin B12 ?

Answer 35

A large charged molecule

Question 36

How is vitamin B12 absorbed in the Alimentary system ?

Answer 36

Binds to intrinsic factor within the stomach to form a complex which is then absorbed via a specific transport process in the distal ileum

Question 37

What is the medical term for B12 deficiency ?

Answer 37

Pernicious anaemia

Question 38

How is iron transported across the brush border ?

Answer 38

Via a transporter known as DMT1 as an H coupled reaction in duodenal enterocytes

Question 39

What is Ferritin ?

Answer 39

An iron-protein complex and is how iron is stored within cells

Question 40

How does unbound iron travel in the bloodstream ?

Answer 40

Binds to transferrin