The Digestive System

Question 1

What is the primary function of the digestive system?

Answer 1

To chemically and mechanically break down food and absorb products.

Question 2

Which eight structures make up the alimentary canal?

Answer 2

1. Mouth
2. Pharynx
3. Oesophagus
4. Stomach
5. Small intestine
6. Large intestine
7. Rectum
8. Anus

Question 3

What are the four structures which are accessory organs for the alimentary canal?

Answer 3

1. Salivary glands
2. Liver
3. Gallbladder
4. Pancreas

Question 4

What four layers make up the wall of the alimentary canal?

Answer 4

1. Mucous membrane
2. Submucosa
3. Muscular layer
4. Serosa

Question 5

What are the two main movements of the tube?

Answer 5

Mixing movements (to combine food and digestive juices) and propelling movements (to push food down the alimentary canal).

Question 6

What is the mouth made up of?

Answer 6

Cheeks, lips, palate, tongue and teeth.

Question 7

What are the two primary features of the mouth?

Answer 7

To receive food and break down food particles using the teeth

Question 8

What are the primary functions of the salivary glands?

Answer 8

To secrete saliva (which begins the chemical digestion of carbohydrates). Saliva also helps to moisten and bind food particles together.

Question 9

Salivary glands have two types of secretory glands- what are these called and what are their functions?

Answer 9

1. Serous cells - produce salivary fluid containing amylase to digest carbohydrate
2. Mucous cells - produce mucous to bind food and act as a lubricant

Question 10

What are the names of the three major salivary glands?

Answer 10

Parotid glands, submandibular glands, sublingual glands

Question 11

What is the primary role of the pharynx and oesophagus?

Answer 11

The pharynx and oesophagus are not actively involved in the digestion process but are important passageways within the alimentary canal.

Question 12

What are the three structural elements of the pharynx?

Answer 12

Nasopharynx, oropharynx, larangopharynx.

Question 13

Describe the three stages of swallowing mechanism.

Answer 13

1. Food is chewed and mixed with saliva. This combination is called a bolus. Here it is forced into the oropharynx.
2. Involuntary swallowing reflexes move food from the oropharynx into the oesophagus.
3. Peristalsis (the propelling movement) moves food into the stomach to begin digestion

Question 14

What is the role of the lower oesophageal sphincter?

Answer 14

To close the entrance of the stomach preventing stomach contents from reentering the oesophagus.

Question 15

What are the four primary roles of the stomach?

Answer 15

1. Receives food from the oesophagus
2. Mixes food with gastric stomach juices
3. Absorbs some elements of food
4. Moves food forward into the small intestine

Question 16

What is the most important digestive enzyme contained within gastric juice? How is it formed?

Answer 16

Pepsin. Formed when the inactive enzyme pepsinogen combines with hydrochloric acid.

Question 17

What is the role of pepsin?

Answer 17

To begin the process of protein digestion.

Question 18

What four parts is the stomach made up of?

Answer 18

The cardia, fundus, stomach body and pylorus.

Question 19

What is the role of the pyloric sphincter?

Answer 19

The pyloric sphincter is a valve between the stomach and the small intestine. It opens to allow food to pass into the small intestine from the stomach and closes to prevent food in the small intestine from coming back up into the stomach.

Question 20

What regulates gastric juice secretion in the stomach?

Answer 20

Parasympathetic impulses within the nervous system and the active hormone gastric effect the rate of gastric juice secretion. When food reaches the small intestine gastric juice secretion is inhibited.

Question 21

What is chyme and where is it produced?

Answer 21

Chyme is produced in the stomach. It is a mixture of food particles, gastric juice and saliva. Some particles and water are absorbed in the stomach.

Question 22

What is the primary role of the pancreas?

Answer 22

The pancreas secretes a digestive fluid called pancreatic juice. Pancreatic juice contains enzymes which digest carbohydrates, fats, proteins and nucleic acids.

Question 23

Pancreatic juice effects the pH of intestinal contents. How does it do this?

Answer 23

Pancreatic juice contains a high bicarbonate ion concentration which helps to neutralise acidic chyme and therefore causes intestinal contents to be alkaline.

Question 24

Which two hormones stimulate the realise of pancreatic juice?

Answer 24

1. Secretin stimulates the realise of pancreatic juice with a high bicarbonate ion concentration.
2. Cholecystokinin stimulates the realise of pancreatic juice with a high concentration of digestive enzymes.

Question 25

Name the enzymes that digest: 1. Fats 2. Carbohydrates 3. Proteins

Answer 25

1. Pancreatic lipase 2. Pancreatic amylase 3. Trypsin and chemotrypsin

Question 26

What is the name of the livers functional units?

Answer 26

Hepatic lobules.

Question 27

Give 5 functions of the liver.

Answer 27

1. Metabolises carbohydrates, fats and proteins 2. Stores substances 3. Filters blood 4. Destroys toxins 5. Produces bile

Question 28

By which process does the liver removes damaged cells and other foreign particles?

Answer 28

Phagocytosis.

Question 29

What 5 substances make up the composition of bile?

Answer 29

Water, bile salts, cholesterol, bilirubin, biliverdin and electrolytes.

Question 30

Where in the digestive system is bile stored?

Answer 30

In the gallbladder

Question 31

Which hormone regulates the realise of bile into the small intestine?

Answer 31

Cholecystokinin.

Question 32

What is the primary function of bile salts?

Answer 32

To emulsify fats and aid in the digestion of fatty acids, cholesterol and vitamins.

Question 33

What does the small intestine receive?

Answer 33

Chyme from the stomach, pancreatic fluid from the pancreas and bile from the liver/gallbladder.

Question 34

What are the four main functions of the small intestine?

Answer 34

1. Receives products from stomach, pancreas and liver 2. Complete nutrient digestion 3. Absorb the products of digestion 4. Transport residues to the large intestine

Question 35

What three parts make up the small intestine?

Answer 35

The duodenum, jejunum and ileum.

Question 36

Why is the wall of the small intestine lined with villi and microvilli?

Answer 36

Villi and microvilli greatly increase the surface area of the small intestine. They also aid in mixing and the absorption of nutrients.

Question 37

What does the small intestine secrete? Why?

Answer 37

Digestive enzymes- to split molecules of sugars, fats, and proteins into simpler forms Mucous- brings digestive products towards the villi to absorb

Question 38

What is the function of a lacteal within the small intestine?

Answer 38

Lacteals carry away absorbed nutrients.

Question 39

Which muscle control movements of substances from the small to the large intestine?

Answer 39

The ileocecal sphincter

Question 40

Which four structures make up the large intestine?

Answer 40

The colon, cecum, rectum and anal canal.

Question 41

What four sections can we separate the colon into?

Answer 41

Ascending, descending, transverse and sigmoid.

Question 42

What are the three functions of the large intestine?

Answer 42

1. Secretes mucous for lubrication 2. Absorbs water and electrolytes 3. Forms and stores faeces

Question 43

What six things make up faeces?

Answer 43

1. Water 2. Electrolytes 3. Undigested materials 4. Mucous 5. Shed intestinal cells 6. Bacteria

Question 44

Which muscle realises faeces from the large intestine?

Answer 44

The anal sphincter.