The Digestive System

Question 1

Gastrointestinal tract consists of

Answer 1

Upper - mouth, oesophagus, stomach, small intestine
Lower -caecum( start of large intestine) colon, rectum(end of l I), anus

Question 2

4 layers of gastrointestinal tract

Answer 2

Mucosa
Submucosa
Muscularis externa
Adventitia/serosa

Question 3

Mucosa

Answer 3

Innermost layer of GI tract
Surrounds lumen or open space within tube and comes into contact with food

Question 4

Submucosa

Answer 4

Consists of a dense, irregular layer of connective tissue with large, blood vessels, lymphatics, and nerves branching

Question 5

Muscularis externa

Answer 5

In a circular, muscular layer and longitudinal outer muscular layer
The coordinated contractions of these layers is called peristalsis, which propels food through GI tract

Question 6

Adventitia/serosa

Answer 6

Outermost layer of GI tract
Consists of several layers of connective tissue that surrounds sections of the GI tract
Serosa = smooth tissue, all of GI tract apart from oesophagus
Adventitia = fibrous collective, oesophagus

Question 7

Stages of digestion

Answer 7

Ingestion
Mechanical digestion
Chemical, digestion
Absorption
Elimination

Question 8

Functions of the stomach

Answer 8

Storage of food until small, intestines, ready to receive
Disinfection = acidic environment helps kill any microbes
Digestion = stomach contains protease called pepsin
Disruption = acidic environment, breaks down some chemical bonds in food
Mechanical breakdown = churning nature of stomachs, muscular contractions, macerate food

Question 9

The three distinct areas of the small intestine

Answer 9

Duodenum
Jejunum
Ileum

Question 10

Liver and gall bladder

Answer 10

Liver and gallbladder exert their role in digestion in the duodenum
Liver produces bile
Bile stored in the gallbladder
File squeezed into duodenum via common bile duct

Question 11

Function of bile

Answer 11

Bile emulsifies fat, breaking them down, smaller droplets, which increases surface area available for enzymes to act upon

Question 12

The pancreas

Answer 12

Main sites of enzyme synthesis
Has both endocrine and exocrine functions


Question 13

Function of amylase

Answer 13

Breaks down starch into smaller sugars

Question 14

Function of trypsin

Answer 14

Hydrolysis of peptide bonds (breaks down proteins)

Question 15

Function of lipase

Answer 15

Hydrolyses triglycerides (breaks down fat)

Question 16

Why is trypsin an important protease in the duodenum

Answer 16

It’s secreted into the duodenum as inactive trypsinogen
an enzyme produced by intestinal epithelial cells called enteropeptidase activates trypsin
Trypsin is then free to activate further zymogens
Trypsin activation within the duodenum and then initiate the activation of multiple zymogens with important roles in digestion

Question 17

Microvilli

Answer 17

Increase surface area of epithelial cells, line, small intestine – required for nutrient absorption 

Question 18

Functions of the colon

Answer 18

Reabsorption of water and electrolytes from intestinal fluid
Compaction of intestinal contents into faeces
Storage of faecal material, prior to defecation
Absorption of important vitamins produced by bacteria