Breakdown Of Food

Question 1

What are proteins broken down into?

Answer 1

Amino acids

Question 2

What are carbohydrates broken down into?

Answer 2

Sugars

Question 3

What are lipids broken down into?

Answer 3

Glycerol and fatty acids

Question 4

How s glucose converted to pyruvic acid?

Answer 4

Glycolysis forming glyceraldehyde 3 phosphate which is converted to pyruvic acid
Converted to acetyl coA which enters the krebs cycle

Question 5

How is starch/glycogen broken down?

Answer 5

Amylase breaks it down into maltose/sucrose/lactose

Question 6

How is maltose broken down?

Answer 6

By maltose to form glucose

Question 7

How is sucrose broken down?

Answer 7

By sucrase to form glucose+fructose

Question 8

How is lactose broken down?

Answer 8

By lactase to for glucose and galactose

Question 9

How are carbohydrates absorbed?

Answer 9

Na+/glucose transport
Glucose/galactose moves into cell with one Na+
Na+ leaves cell and is exchanged for K+
However, fructose moves in via GLUT5 and leaves via GLUT2

Question 10

How is fructose absorbed?

Answer 10

Moves in via GLUT5 and out via GLUT2

Question 11

How are proteins broken down?

Answer 11

Broken down by pepsin and pancreatic proteases
Exogenous proteins -> di and tri peptides
Endogenous proteins -> amino acids

Question 12

How are di and tri peptides absorbed?

Answer 12

Through PEPT1 then move out of cell not capillary through Na+ independent channels

Question 13

How are amino acids transported?

Answer 13

Through Na+ dependent or independent channels then into capillary through Na+ independent channels

Question 14

What produced trypsinogen?

Answer 14

Pancreatic zymogens

Question 15

What activates trypsinogen to form trypsin?

Answer 15

Enterokinase (brush border)

Question 16

How are lipids digested?

Answer 16

Large lipid droplet is mixed and bile salts are added forming micelles.
Pancreatic lipase digests them to form fatty acids and monoglycerides

Question 17

What happens in the endoplasmic reticulum of mucosal cells to fatty acids and monoglycerides?

Answer 17

Triglycerides are synthesised
Chylomicrons are formed
Exocytosis of chylomicrons into lymphatic vessels

Question 18

What vitamins are fat soluble?

Answer 18

D E A K

Question 19

How are vitamins absorbed into the small intestine?

Answer 19

Passively

Facilitated by bile and incorporated into chylomicrons

Question 20

How is vitamin D absorbed?

Answer 20

Absorbed not chylomicrons and vitamin D binding protein

Question 21

What does the liver convert vitamin D3 into?

Answer 21

25(OH)D which is active

Question 22

Where does 25(OH)D travel to?

Answer 22

Kidneys where it is converted to 1alpha-25(OH)D

Question 23

What is the function of vitamin A (retinol)?

Answer 23

Epithelial tissue maintenance, vision

Question 24

What is the role of vitamin D (cholecalciferol)?

Answer 24

Bone calcification

Parathyroid hormone

Question 25

What is the role of vitamin E (tocopherol)?

Answer 25

Biological antioxidant

Question 26

What is the role of vitamin K?

Answer 26

Blood clotting

Question 27

What happens to B12 in mouth?

Answer 27

Unbound B12 may be absorbed under the tongue

Question 28

How is B12 absorbed in the stomach?

Answer 28

Enzymes and acid cause protein bound B12 to detach from protein R protein picks up B12 IF secreted

Question 29

What happens to B12 in upper small intestine?

Answer 29

R protein releases B12 | IF picks up B12

Question 30

What happens to B12 in lower small intestine?

Answer 30

IF-B12 attaches to IF-B12 receptor on intestinal cell | Some unbound B12 absorbed into intestinal cell through passive diffusion

Question 31

What happens to B12 in intestinal cell?

Answer 31

B12 attaches to transcobalamin II

Question 32

What happens to B12 n the blood?

Answer 32

Transcobalamin II carries B12 to the body’s cells where it is used, and to the liver where it is stored on transcobalamin III Transcobalamin III also circulates in the blood

Question 33

What happens to B12 in the liver?

Answer 33

B12 is stored and released into the small intestine via the bile

Question 34

What s the role of vitamin B1 thiamine?

Answer 34

Carbohydrate metabolism

Question 35

What is the role of vitamin B2 riboflavin?

Answer 35

Hydrogen transfer

Question 36

What is the role of pyridoxine B6?

Answer 36

Protein metabolism

Question 37

What is the role of vitamin B3 niacin?

Answer 37

Hydrogen transfer

Question 38

What is the role of folic acid?

Answer 38

Single carbon metabolism

Question 39

What is the role of B12 cyanocobalamin?

Answer 39

Red blood cell formation

Question 40

How is iron absorbed as Heme?

Answer 40

Travels from lumen of intestine through HCP1 | Processed by an endosome to form Fe2+

Question 41

How is dietary iron absorbed?

Answer 41

Converted from Fe3+ to Fe2+ in the lumen of intestine, then travels in via DMT1

Question 42

How is iron absorbed as ferritin?

Answer 42

Ferritin absorbed and encapsulated in a lysosome then converted to Fe2+