Digestion

Question 1

What is digestion?

Answer 1

The process of breaking down the nutrients in your food in order for them to be absorbed

Question 2

What are the 2 ways of digestion?

Answer 2

Physical digestion and chemical digestion

Question 3

Why is food broken down by our mouth first?

Answer 3

Before chewing on the substance, it is a large insoluble molecule.

It is needed to become small soluble molecules so that it can be absorbed by your blood plasma or lymph.

Question 4

What are the 2 types of fluids which carry the products of fat digestion (food broken down)?

Answer 4

Blood plasma and lymph

Question 5

What is physical digestion?

Answer 5

Breaking down the big lumps of food into smaller pieces by-

• chewing (using your mouth)
• Breaking them using the stomach

Question 6

Why is it important for physical digestion to happen before chemical digestion?

Answer 6

• Food can pass easily through the digestive system

- Larger surface area provided for chemical digestion

Question 7

What is chemical digestion?

Answer 7

It involves enzymes which are biological catalysts that speed up the reaction.

Digestive enzymes break down molecules that are too big to pass through cell membranes.

Question 8

What are the 3 main types of digestive enzymes?

Answer 8

• Carbohydrases
• Proteases
• Lipases

Question 9

What are carbohydrases and what do they do?

Answer 9

Enzyme that break down big carbohydrates into simple sugars. e.g breaking down starch

Process: Breaking down Starch

• Starch with carbohydrase enzyme break into MALTOSE (smaller pieces of starch)
• Maltose with carbohydrase enzyme break into GLUCOSE (a simple sugar)

Question 10

In what parts of the body are Carbohrydase enzymes active in?

Answer 10

Mouth & Small intestine

Question 11

What are Proteases and what do they do?

Answer 11

Proteases are enzymes that break down proteins into amino acids.

Process:

• Proteas enzyme with proteins will turn into amino acids

Question 12

In what parts of the body are Protease enzymes active in?

Answer 12

Stomach & Small intestine

Question 13

What are Lipases and what do they do?

Answer 13

Lipases are enzymes that break down FATS into FATTY ACIDS and GLYCEROL.

Process:

-Lipase enzymes with Fats will turn into fatty acids and glycerol

Question 14

In what part of the body are Lipase enzymes active in?

Answer 14

The small intestine

Question 15

What pH does the stomach have and for which enzyme is it most suitable to?

Answer 15

Have a pH between 1-2

It is most suitable for protease enzymes (it is the optimum pH for them)

Question 16

What kind of pH does the mouth or small intestine have?

Answer 16

Either an alkali or neutral (pH 7)

Always higher than an acid

Question 17

Where is Bile found and what does it do?

Answer 17

It is found in the liver, stored in the gall bladder.

It helps fat digestion in the small intestine (breaks the fat down into tiny droplets)

Question 18

What is emulsification?

Answer 18

When fat in the small intestine is broken down to tiny droplets by bile (in order for the fat to have a bigger surface area for the lipase enzyme to work on them)

Question 19

What pH is bile and why?

Answer 19

Bile is an alkaline so it has a high pH

It helps to have a high pH as it can neutralise the acid from the stomach, which helps enzymes in the small intestine to work better (as they can’t work in a low pH)

Get the idea- The journey of fat

From stomach (acid) - to Liver/gall bladder (neutralises acid to a higher pH level) - to the intestine (where enzymes work better at a higher pH e.g neutral or alkaline)

Question 20

How to the food molecules reach the blood plasma?

Answer 20

Food molecules in the intestine gets absorbed into the blood by diffusion

Question 21

Which 2 substances (food molecules) are small enough to diffuse into the blood plasma?

Answer 21

Amino acids and Glucose

Question 22

Which food molecule cannot diffuse into the blood?

Answer 22

Fat

Question 23

Fat does not diffuse into the blood plasma like glucose or amino acids, how does it reach the blood?

Answer 23

1. Fat gets diffused out of the intestines
2. Go into a fluid called lymph (in the lymphatic system)
3. Then from the lymph to the blood

Question 24

Using the idea of diffusion, how do cells get their nutrients?

Answer 24

1. Food molecules get diffused into the blood
2. Then travel inside the blood, to where it needs to go
3. Diffuses back out of the blood and goes into the body cell
   e. g Glucose will travel inside to blood, to a muscle, during exercise (for respiration)

Question 25

Why is the small intestine very long?

Answer 25

There is time to break down and absorb the food before it reaches the end

Question 26

What are villi? (villus for singular)

Answer 26

Millions of little projections that cover up the inside of the intestine in order for food to get absorbed by them.

(They look like little tentacles)

Question 27

What are microvilli?

Answer 27

Lots of microvilli on top of each villus (projections inside the small intestine that look like tentacles)

Question 28

Why does the small intestine have microvilli and villi?

Answer 28

To have a really big surface area for food absorption (as food passes through the small instestine, villi and micro villi absorb the nutrients needed which goes into the blood through diffusion)

Question 29

What are the properties of a villi?

Answer 29

• They are found in the small intestine
• Have microvilli surrounding each villus
• Each villus have one permeable layer (a thin lining that makes happen really quick which is great as a blood supply)

Question 30

What do villi have inside of them?

Answer 30

A network of capillaries to allow diffusion (Villi absorb food, goes into capillaries, capillaries diffuse food molecule into the blood)