The Digestive System

Question 1

Why do we need organ systems?

Answer 1

The human body consists of eight integrated organ systems. These organ systems work together and depend on one another to make sure we survive.

Question 2

What are the eight different organ systems?

Answer 2

The musculoskeletal system
The endocrine system
The respiratory system
The nervous system
The excretory system
The reproductive system
The circulatory system
The digestive system

Question 3

What is nutrition?

Answer 3

Nutrition refers to nutrients and how organisms get their nutrients.

Question 4

What is autotrophic nutrition?

Answer 4

All plants have autotrophic nutrition. These organisms are all able to make their own food by photosynthesis.

Question 5

What is heterotrophic nutrition?

Answer 5

Animals have heterotrophic nutrition. Animals must eat other organisms such as plants and/or animals to get their nutrients.

Question 6

Why do humans eat food?

Answer 6

Humans eat food to supply their bodies with nutrients. Nutrients supply the body with building materials (molecules and ions) for the growth, repair and replacement of cells. Nutrients also supply the body with energy (glucose sugar for respiration).

Question 7

What are three different food types?

Answer 7

Proteins (meat, fish, dairy, nuts)
Carbohydrates (vegetables, bread, sugars, sweets)
Fats and oils (fats and oils in meat, fish, nuts, etc.)

Question 8

What does a balanced diet consist of?

Answer 8

One part protein, one part fats and four parts carbohydrates.

Question 9

What is the digestive system?

Answer 9

The digestive system breaks down large insoluble food molecules into smaller soluble food molecules that can be absorbed into the blood and transported to the cells where they are needed.

Question 10

What are the main processes in the digestive system?

Answer 10

Ingestion, Digestion, Absorption, Transportation, Assimilation and Egestion.

Question 11

What is ingestion?

Answer 11

Ingestion is the intake of food into the alimentary canal through the mouth.

Question 12

What is digestion?

Answer 12

Food undergoes mechanical and chemical digestion which converts large insoluble food molecules into smaller soluble food molecules. Only soluble food molecules can be absorbed.

Question 13

What is absorption?

Answer 13

Digested food molecules move by osmosis through the cells lining the alimentary canal (particularly the stomach and small intestine) into the blood capillaries surrounding the alimentary canal.

Question 14

What is transportation?

Answer 14

The soluble digested food molecules are transported to all the body cells by the blood.

Question 15

What is assimilation?

Answer 15

Assimilation occurs when the digested food molecules move by osmosis from the blood into the cells of the body where they are used for energy (respiration) or building materials.

Question 16

What is egestion?

Answer 16

Undigested food is passed out of the body as faeces.

Question 17

What are the salivary glands?

Answer 17

There are three pairs of salivary glands that open into the mouth cavity. Saliva consists mainly of water and contains mineral salts and mucus and salivary amylase.

Question 18

What is salivary amylase?

Answer 18

Salivary amylase is an enzyme that converts cooked starch into maltose in the mouth.

Question 19

What does the pancreas do?

Answer 19

The pancreas secretes pancreatic juice containing enzymes to aid digestion. Cells of Islets of Langerhans produce hormones glucagon and insulin that control blood glucose concentration.

Question 20

What does the liver do?

Answer 20

The liver synthesizes and secretes bile which is stored in the gall bladder. Bile emulsifies fats in the small intestine (breaks fats into small droplets). In the liver, there is the formation of glycogen from excess glucose and there is the storage of glycogen. In the liver, there is the breakdown of alcohol, drugs and hormones (detoxification function). In the liver, there is also the removal of blood toxins.

Question 21

What does the gallbladder do?

Answer 21

Bile, produced in the liver, is stored in the gallbladder until needed. Bile emulsifies fats (breaks fats into small droplets).

Question 22

What are enzymes?

Answer 22

Enzymes are special molecules that speed up certain cell chemical reaction but are not used up in the process.

Question 23

What are hormones?

Answer 23

Hormones are chemical messenger molecules that control certain body functions such as blood glucose concentration.

Question 24

What are the two types of digestion?

Answer 24

Mechanical digestion - mainly through chewing (large chunks of food are broken down into smaller chunks).
Chemical digestion - enzymes are required for this process (large molecules in the food are broken down into simpler molecules by enzymes).

Question 25

After digestion, what are the names of the small soluble food molecules for proteins, carbohydrates and fats?

Answer 25

Proteins - Amino Acids Carbohydrates - Monosaccharide sugars e.g. glucose Fats - Glycerol and fatty acids

Question 26

What are the different types of teeth?

Answer 26

Incisors, canines, pre-molars and molars.

Question 27

What is the dental formula?

Answer 27

2.1.2.3 _____ 2.1.2.3

Question 28

What type of digestion are the teeth used for?

Answer 28

The teeth are used for mechanical digestion (chewing or mastication).

Question 29

What are the incisors used for?

Answer 29

They are used for cutting food.

Question 30

What are the canines used for?

Answer 30

They are used for piercing food.

Question 31

What are the pre-molars used for?

Answer 31

They are used for grinding food.

Question 32

What are the molars used for?

Answer 32

They are used for grinding food.

Question 33

What is the structure of a villus?

Answer 33

The inside of the small intestine is covered in tiny villi. Each villus contains blood capillaries and a single lacteal.

Question 34

What is the function of a villus?

Answer 34

Digested food molecules move from the cavity of the small intestine into the villus by osmosis. Amino acid, monosaccharide sugar and glycerol are absorbed into the blood capillaries of each villus. Fatty acids are absorbed into the lacteal of each villus. Absorbed food molecules are first transported to the liver before the blood transports them to the rest of the body.

Question 35

What is absorbed in the stomach during digestion?

Answer 35

The thickness of the stomach wall prevents effective absorption however, water, glucose, alcohol and mineral nutrients are absorbed here.

Question 36

What is absorbed in the small intestine during digestion?

Answer 36

Monosaccharide sugars (e.g. glucose) are absorbed by osmosis into the blood capillaries of villi. Amino acids are absorbed by osmosis into the blood capillaries of villi. Glycerol is absorbed by osmosis into the blood capillaries of villi. Fatty acids are absorbed by osmosis into the lacteal of villi.

Question 37

What is absorbed into the large intestine during digestion?

Answer 37

Mainly water and mineral salts are absorbed by osmosis into the surrounding blood capillaries in the large intestine.

Question 38

How does the surface area of the small intestine affect digestion?

Answer 38

The small intestine's inner lining is folded and covered in villi - this increases the surface area for the absorption of digested food molecules into the blood. The small intestine is long thus increasing the surface area for absorption of digested food molecules.

Question 39

How does the stomach play a role in both mechanical and chemical digestion?

Answer 39

The stomach has a thick muscular wall that contracts and plays a role in mechanical digestion. The stomach secretes digestive enzymes used for chemical digestion.