Chapter 9 - The Digestive System

Question 1

How are carbohydrates (starch) digested?

Answer 1

1. Mouth - salivary glands secrete amylase
2. Duodenum - pancreatic amylase, breaks polysaccharide into dissacharides
3. Small intestine - maltase enzyme breaks dissacharides into monosaccharides

Question 2

What molecular shape are carbohydrates?

Answer 2

Hexagons

Question 3

What enzymes do the pancreas secrete (6)?

Answer 3

lipase, maltase, p. amylase, erepsin, trysinogen, enterokinase

Question 4

What does the -ogen suffix indicate?

Answer 4

That it is the inactive form of the enzyme.

Question 5

Which enzyme stops working in acidic conditions?

Answer 5

Amylase

Question 6

What enzyme changes trypsinogen into trypsin?

Answer 6

Enterokinase

Question 7

What is erepsin?

Answer 7

Enzymes that break down polypeptides into amino acids

Question 8

How many different amino acids are used to build proteins? How many of these can the human body make and how many must be obtained from food?

Answer 8

• 20 different amino acids
• 12 of which the human body makes
• 8 is obtained from food

Question 9

What happens when you swallow?

Answer 9

• soft palate raises to stop food from entering nasal passages
• larynx moves up, covering glottis with epiglottis to prevent food from entering airway

Question 10

What is peristalsis?

Answer 10

Wave like contractions to move food through the gastrointestinal tract

Question 11

What are the sphincters in the stomach called?

Answer 11

Opening: gastroesophageal sphincter
Exit: pyloric sphincter

Question 12

What are the 4 layers of the stomach?

Answer 12

1. Mucosa
2. Submucosa
3. Muscularis (longitudinal, circular, oblique)
4. Serosa

Question 13

Purpose of the cecum and rectum

Answer 13

Cecum: “blind pouch” where material from sm. intestine is received
Rectum: holds waste until elimination

Question 14

Main function of the large intestine

Answer 14

Water absorption, and vitamins and minerals

Question 15

How are proteins chemically digested in the stomach?

Answer 15

HCl in gastric juice converts pepsinogen into pepsin, beginning the breakdown of protein into amino acids

Question 16

What substance protects the stomach from acid damage?

Answer 16

Mucus

Question 17

How are fats absorbed into the lymph system?

Answer 17

Through lacteals in the villi

Question 18

Which enzyme ONLY works in acidic conditions? Which enzyme STOPS working in acidic conditions?

Answer 18

Pepsin required an acidic environment to be activated

Amylase stops working in acidic environments

Question 19

What is trypsin?

Answer 19

A protein digesting enzyme produced from trypsinogen (with enterokinase)

Question 20

What is bile?

Answer 20

A substance that emulsifies fats for faster breakdown by lipase

Question 21

What is egestion?

Answer 21

The removal of waste from the body

Question 22

Explain how carbohydrates are digested.

Answer 22

1. Mouth - Salivary amylase
2. Duodenum - pancreatic amylase, maltase from pancreas
   Result: monosaccharides/simple sugars (e.g. fructose, glucose)

Question 23

Explain how lipids are digested.

Answer 23

1. Duodenum - bile emulsifies fats (but still same structure)
2. Jejunum - lipase from pancreas
   Result: glycerol + 3 fatty acids (absorbed into lymph system through lacteals)

Question 24

Explain how protein is digested.

Answer 24

1. Stomach - pepsin
2. Duodenum - trypsin
3. Ileum - erepsin (from pancreas)
   Result: amino acids (look for N)