GIT System and Function

Question 1

What is the function of the GIT system?

Answer 1

Mechanical and chemical breakdown of food into absorbable units

Question 2

What are the two major components of the digestive system?

Answer 2

• The gastrointestinal tract
• Accessory glands and organs

Question 3

What is the gastrointestinal tract?

Answer 3

A 4.5m tube running through the body with opening at either end

Question 4

What are accessory glands and organs in the digestive system?

Answer 4

Organs and glands which are outside the GIT and secrete substances

Question 5

What are the four layers of the GIT?

Answer 5

• Mucosa
• Submucosa
• Muscularis externa
• Serosa

Question 6

What is the mucosa?

Answer 6

The inner lining of the GIT

Question 7

What is the submucosa?

Answer 7

The middle layer of the GIT with connective tissue with blood and lymph vessels

Question 8

What is the muscularis externa?

Answer 8

The outer wall of the GIT comprimised of 2 layers of smooth muscle

Question 9

What are the two muscles the muscularis externa is composed of?

Answer 9

• Circular
• Longitudinal

Question 10

What is the serosa?

Answer 10

The connective tissue covering the GIT

Question 11

What are the four main process of the GIT?

Answer 11

• Secretion
• Digestion
• Absorption
• Motility

Question 12

What is secretion in the GIT?

Answer 12

The movement of material from the cells into the lumen or ECF

Question 13

What is diegstion?

Answer 13

The chemical breakdown or food into absorbable units

Question 14

What is absorption in the GIT?

Answer 14

The movement of material from GI lumen to ECF

Question 15

What is motility in the GIT?

Answer 15

Movement of material through the GI tract as a result of muscle contraction

Question 16

What is mastication?

Answer 16

Mechanical digestion in the mouth

Question 17

What is in saliva?

Answer 17

• Water
• Ions
• Mucus
• Enzymes
• Proteins

Question 18

What are the three major salivary glands?

Answer 18

• Sublingual
• Parotid
• Submandibular

Question 19

Where is the sublingual gland located?

Answer 19

Under the tongue

Question 20

Where is the parotid gland located?

Answer 20

Near hinge of the jaw

Question 21

Where is the submandibular gland located?

Answer 21

Under jawbone

Question 22

What is deglutition?

Answer 22

Swallowing

Question 23

What is the lower oesophageal sphincter?

Answer 23

A band of muscle at the lower end of the oesophagus that prevents stomach acid and contents from flowing back up into the oesophagus

Question 24

What are the three process in the stomach?

Answer 24

• Chemical and mechanical breakdown of food into chyme
• Regulates passage of chyme to small intestine
• Very acidic environment to destroy bacteria and other pathogens

Question 25

What are the four main functions of gastric acid?

Answer 25

- Kills bacteria - inhibits salivary amylase - Denatures proteins - Promotes the release and activation of the enzyme pepsin

Question 26

What are the six steps for parietal cells to secrete gastric acid?

Answer 26

- Carbonic anhydrase dissociates into H⁺ and HCO₃⁻ - H+ secreted to lumen by ATPase pump - K⁺ enters the cell and is recycled back into the lumen - Cl⁻ enters the cell in exchange for HCO₃⁻ - Cl⁻ diffuses into the lumen through Cl⁻ channels - H⁺ and Cl⁻ combine in the lumen to form HCl

Question 27

What are the three phases of digestion?

Answer 27

- Cephalic - Gastric - Intestinal phases

Question 28

What is the cephalic phase of digestion?

Answer 28

Thinking, smelling, seeing and tasting food triggering acid production

Question 29

What is the gastric phase of digestion?

Answer 29

The acidification and homogenise of bolus into chyme

Question 30

How is the gastric phase stimulated?

Answer 30

- Distension - Chemoreceptors detecting peptides and pH

Question 31

What does the parietal cell secrete?

Answer 31

Gastric acid

Question 32

What stimulates the parietal cells to release gastric acid?

Answer 32

- Acetylcholine - Gastrine - Histamine

Question 33

What prevents the release of gastric acid by parietal cells?

Answer 33

Somatostatin

Question 34

What do ECL cells release?

Answer 34

Histamines

Question 35

What are the three functions of gastric acid?

Answer 35

- Activates pepsin - Denatures proteins - Kills bacteria

Question 36

What is the function of histamines?

Answer 36

Stimulates gastric acid secretion

Question 37

What stimulates ECL cells to produce histamines?

Answer 37

- Acetylcholine - Gastrin

Question 38

What do D cells release?

Answer 38

Somatostatin

Question 39

What is the function of somatostatin?

Answer 39

Inhibits gastric acid secretion

Question 40

What stimulates D cells to produce somatostatin?

Answer 40

Acid in the stomach

Question 41

What do G cells release?

Answer 41

Gastrin

Question 42

What is the function of gastrin?

Answer 42

Stimulates gastric acid secretion

Question 43

What stimulates G cells to produce gastrin?

Answer 43

- Acetylcholine - Peptides - Amino acids

Question 44

What do chief cells release?

Answer 44

- Pepsin - Gastric lipase

Question 45

What is the function of pepsin?

Answer 45

Digest proteins

Question 46

What is the function of lipase?

Answer 46

Digest fats

Question 47

What simulates chief cells to produce pepsin and lipase?

Answer 47

- Acetylcholine - Acid secretion

Question 48

What is pepsinogen?

Answer 48

A zymogen which is activated to pepsin by low pH

Question 49

What is a zymogen?

Answer 49

An inactive enzyme

Question 50

What are the two barriers to prevent auto digestion in the stomach?

Answer 50

- Mucus forms a physical barrier - Bicarbonate forms a chemical barrier by neutralising acid near the stomach wall