Human Digestive System

Question 1

Parts?

Answer 1

1. Mouth
2. Oesophagus
3. Stomach
4. Small Intestine
5. Large Intestine
6. Rectum
7. Anus

Question 2

Define Digestion

Answer 2

A SERIES of chemical reactions that breaks down LARGE and INSOLUBLE food into SMALL and SOLUBLE molecules for absorption

Question 3

When, Why and How does absorption happen?

Answer 3

When - substances CROSS THE CELL MEMBRANE
Why - substances are SMALL and SOLUBLE
How - happens through diffusion and osmosis

Question 4

Example of diffusion in digestion?

Answer 4

• Glucose, amino acids, fatty acids and glycerol are SMALL and SOLUBLE enough to cross the PARTIALLY PERMEABLE cell membrane
• In the small intestine, after digestion, the concentrations of these substances are HIGHER than the concentrations in the blood
• Thus, these substances DIFFUSE across the membrane to enter the

Question 5

3 major food groups to be digested?

Answer 5

1. Carbohydrates
2. Proteins
3. Fats / Lipids

Question 6

What do enzymes do?

Answer 6

They help to SPEED UP digestion

Question 7

Two properties of enzymes?

Answer 7

1. Enzymes are SPECIFIC WITH RESPECT TO THE SHAPE of the molecule it can react with
2. Enzymes SPEED UP chemical reactions such as digestion, so that chemical reactions will occur faster

Question 8

Enzymes for each food group?
Carbohydrates?
Proteins?
Fats / Lipids?

Answer 8

Carbohydrase
Protease
Lipase

Question 9

End products of each food group?

Answer 9

1. Carbohydrates - Glucose
2. Proteins - Amino acids
3. Fats / Lipids - Fatty acids & Glycerol

Question 10

Where are carbohydrates digested at?
Organ(s)?
Enzyme(s) involved?
Digestion of ___?

Answer 10

Mouth & Small intestine
Carbohydrase
Carbohydrates into glucose

Question 11

Where are proteins digested at?
Organ(s)?
Enzyme(s) involved?
Digestion of ___?

Answer 11

Stomach & Small intestine
Protease
Proteins into amino acids

Question 12

Where are fats / lipids digested at?
Organ(s)?
Enzyme(s) involved?
Digestion of ___?

Answer 12

Small intestine only
Lipase
Fats into fatty acids & glycerol

Question 13

What is glucose used for after digestion?

Answer 13

1. Undergoes CELLULAR RESPIRATION to release ENERGY for cells

Question 14

What is proteins used for after digestion?

Answer 14

1. Re-assembles to form proteins that form ENZYMES, HORMONES & MUSCLES
2. Forms NEW CELLS for growth and tissue repair

Question 15

What is fats used for after digestion?

Answer 15

1. Re-assembles to form FATS that form
   - as a storage of EXCESS ENERGY
   - surround organs as CUSHION
   - underneath the skin as INSULATION
2. Forms part of CELL MEMBRANE