Week 3 : Digestion and absorption of nutrients

Question 1

____ [1] is the basic chemical process in digestion. Specific ____ [2] in our body helps ___ [1] to occur.

Answer 1

[1] Hydrolysis
[2] Enzymes

Question 2

What physical process occurs in the mouth when we are eating?

Answer 2

Mechanical crushing, where food is mixed with saliva

Question 3

What is digested and absorbed in the mouth? Also state the enzymes products involved in digestion if any.

Answer 3

DIGESTION
- Starch –> broken down by amylase
- Fats –> NEGLIGIBLE amounts broken down by lipase
- proteins DO NOT GET DIGESTED

ABSORPTION
- None

Question 4

In the stomach, the pH is ~2. What are the 3 functions the low pH environment serves?

Answer 4

1. Activate pepsin , enzyme which digests proteins
2. Denatures food protein – unfolding of proteins which allow for easier digestion by enzymes
3. Destroys bacteria in food

Question 5

What is digested and absorbed in the stomach? Also state the enzymes products involved in digestion if any.

Answer 5

DIGESTION

• carbs and fats –> NEGLIGIBLE amounts digested
• Protein –> broken down by pepsin

ABSORPTION
- None

Question 6

What is digested and absorbed in the small intestine? tomach Also state the enzymes products involved in digestion if any.

Answer 6

DIGESTION
1. Polysaccharides broken down by pancreatic amylase ;; Disaccharides broken down into monosaccharides by intestinal enzymes (sucrase, maltase, lactase)

2. Digestion by pancreatic and intestinal lipase into fatty acids and glycerol
3. Proteins broken down into AA or small peptides by trypsin

ABSORPTION
- simple sugars. fatty acids and glycerol, amino acids(all products of digestion)

Question 7

Since digestion and absorbtion mainly occurs in small intestines, what happens to remaining carbs, fat and protein in the large intestine?

Answer 7

Carbs : undigested carbs partly broken down by intestinal bacteria (gut microbiome)

Fat : carried out as waste

Protein : carried out of large intestine as waste

Question 8

Most micro-nutrients do not require hydrolysis and are directly absorbed. True or False?

Answer 8

True

Question 9

What 2 factors determine the optimal absorption of micro-nutrients?

Answer 9

1. Chemical form (active/inactive) –> some absorbed better in active form, some better absorbed in inactive form and converted into active form in body
2. Size of molecules : smaller molecules directly absorbed