Nutrient digestion and absorption

Question 1

What are the 3 monosaccharides ?

Answer 1

Glucose
Galactose
Fructose

Question 2

Where are monosaccharides absorbed ?

Answer 2

Small intestine

Question 3

What are disaccharides ?

Answer 3

2 monosaccharides linked by glycosidic bond

Question 4

What breaks down disaccharides into monomers in small intestine ?

Answer 4

Brush border enzymes

Question 5

What does lactase do ?

Answer 5

Breaks down lactose into glucose and galactose

Question 6

What does sucrase do ?

Answer 6

Breaks down sucrose into glucose and fructose

Question 7

What does maltase do ?

Answer 7

Breaks down maltose into 2 glucose

Question 8

What are 3 polysaccharides ?

Answer 8

Starch- plants
Cellulose- plant cell wall
Glycogen- animal storage form of glucose

Question 9

In glycogen what are glucose monomers linked by ?

Answer 9

Alpha-1,4 glycosidic bonds

Question 10

What are proteins ?

Answer 10

Polymers of amino acids linked by peptide bonds

Question 11

What do proteins undergo ?

Answer 11

Post-translational modification

Question 12

What are small proteins called ?

Answer 12

Peptides

Question 13

What enzymes breakdown proteins and peptides ?

Answer 13

Proteases and peptidases

Question 14

What is the breakdown products of proteins and peptides ?

Answer 14

Amino acids

Question 15

In what form is fat digested ?

Answer 15

Triacylglycerol

Question 16

What enzymes digest fats ?

Answer 16

Pancreatic lipases

Question 17

Are lipases water soluble ?

Answer 17

Yes

Question 18

What is triacylglycerol broken down into ?

Answer 18

Monoglyceride + 2FAs

Question 19

What is emulsification ?

Answer 19

Dividing large liquid droplets into small droplets

Question 20

What does emulsification require ?

Answer 20

Mechanical disruption- smooth muscle contraction grinds and mixes lumenal contents
Emulsifying agents- bile salts + phospholipid secretion in bile

Question 21

How is absorption enhanced ?

Answer 21

Formation of micelles

Question 22

What are micelles ?

Answer 22

Bile salt + monoglyceride + FA + phospholipid

Question 23

What is the product of micelle breakdown ?

Answer 23

Release of small amounts of free fatty acids and monoglycerides into solution that diffuse across plasma membrane of absorbing cells

Question 24

Where do FAs and monoglycerides enter after entering epithelial cells ?

Answer 24

sER- where they are reformed into triacylglycerols

Question 25

How are triacyclglycerols transported ?

Answer 25

In vesicles formed from sER and processed through golgi apparatus and exocytosed into extracellular fluid at serosal membrane

Question 26

What are chylomicrons ?

Answer 26

Extracellular fat droplets

Question 27

Where do chylomicrons pass into ?

Answer 27

Lacteals between endothelial cells - cannot pass through capillary membrane

Question 28

What are the fat soluble vitamins ?

Answer 28

A
D
E
K
Absorbed same as fat

Question 29

What are the water soluble vitamins ?

Answer 29

B group
C
Folic acid

Question 30

How are water soluble vitamins absorbed ?

Answer 30

Bind to intrinsic factor in stomach to form complex which is absorbed via specific transport mechanism in distal ileum

Question 31

How is iron absorbed ?

Answer 31

Iron transport across brush border membrane (via DMT1) into duodenal enterocytes
Iron ions incorporated into ferritin (protein-iron complex-> intracellular iron store)
Unbound iron transported across serosal membrane-> blood

Question 32

What does iron in the blood bind to ?

Answer 32

Transferrin

Question 33

What is hyperaemia ?

Answer 33

Increased ferratin levels-> more iron to enterocytes

Question 34

What is aneamia ?

Answer 34

Decreased ferratin levels-> more iron released to blood