B6.2 The Alimentary Canal

Question 1

What is ingestion?

Answer 1

Taking food and drink into the body (through the mouth)

Question 2

What is digestion?

Answer 2

The breaking down of large food molecules into smaller water-soluble molecules using mechanical and chemical processes

Question 3

What is absorption?

Answer 3

Movement of small food molecules through the wall of the intestine into the blood

Question 4

What is assimilation?

Answer 4

The movement of digested food molecules into the cells of the body where they are used to produce other molecules or in respiration

Question 5

What is egestion?

Answer 5

The passing out of food that has not been digested, as faces, through the anus

Question 6

What is mechanical digestion?

Answer 6

The breakdown of food into smaller pieces without chemical change to the food molecules

Question 7

What is chemical digestion?

Answer 7

The breakdown of large, insoluble molecules into small, soluble molecules

Question 8

Identify the 8 main regions of the alimentary canal

Answer 8

Mouth
Salivary glands
Oesophagus
Stomach
Small intestine
Large intestine
Rectum
Anus

Question 9

Functions of the gall bladder

Answer 9

• Stores bile from the liver

- Bile is passed along the bile duct into the small intestine, where it neutralizes the stomach acid in the chyme

Question 10

Functions of the pancreas

Answer 10

• Produces amylase protease and lipase (pepsin and trypsin)

- Secretes digestive enzymes in an alkaline fluid into the small intestine

Question 11

Functions of the small intestine

Answer 11

• First section: Duodenum
• Second section: ileum
• Secretions from the gall bladder and pancreas enter the duodenum to complete the process of digestion
• Digested food molecules are absorbed in the ileum

Question 12

Functions of the large intestine

Answer 12

• Water is absorbed from the remaining material

- Faces is stored in the rectum and removed through the anus

Question 13

Function of the anus

Answer 13

• Faeces are egested through the sphincter

Question 14

Define peristalsis

Answer 14

Contractions of the muscles in the walls of the alimentary canal.
- Fibre in the food keeps the bolus bulky

Question 15

Function of the mouth

Answer 15

• Teeth and tongue break down food into smaller pieces

Question 16

Functions of the salivary glands (List 3)

Answer 16

• Produce liquid saliva
• Moistens food –> easily swallowed
• Contains amylase –> breakdown of starch

Question 17

Functions of the oesophagus

Answer 17

• Bolus (each lump of swallowed and chewed food) is moved from the mouth to the stomach –> by waves of muscle contraction called peristalsis

Question 18

Functions of the stomach (List 5)

Answer 18

• Food is mechanically digested by churning
• Acid and protease enzymes are secreted to start protein digestion
• Provides optimum pH for protease to work
• Secretion of pepsin
• Kills bacteria in the food

Question 19

Functions of the liver

Answer 19

• Cells in the liver make bile (emulsifies fats)
• Amino acids that are not used for making proteins are broken down to form urea –> passes to the kidneys for excretion
• Converts glucose to glycogen

Question 20

In which organ does the digestion of proteins take place?

Answer 20

• Stomach

- Small intestine

Question 21

Which structures secrete enzymes that digest proteins?

Answer 21

• Stomach

- Pancreas

Question 22

Where does the digestion of carbohydrates take place?

Answer 22

• Mouth

- Small intestine