Tour of The Alimentary Canal

Question 1

What are the four functions of the digestive system?

Answer 1

Digestion
Secretion
Absorption
Motility

Question 2

What are the three salivary glands called?

Answer 2

Sublingual (superior), Submandibular (inferior), Parotid (posterior)

Question 3

Where foodstuffs are broken down by chewing; saliva added as lubricant

Answer 3

Mouth

Question 4

Conduit between mouth + stomach

Answer 4

Oesophagus

Question 5

The conduit between the mouth and stomach

Answer 5

Oesophagus

Question 6

Location where proteins are digested; foodstuffs reduced to liquid form; storage and sterilisation occurs

Answer 6

Stomach

Question 7

Produces and secretes digestive enzymes for fat, carbohydrates and proteins

Answer 7

Pancreas

Question 8

Forms bile salts and amphipathic molecules which emulsifies and absorbs fat in the small intestine

Answer 8

Liver

Question 9

Stores and concentrates bile

Answer 9

Gallbladder

Question 10

Where the final stages of chemical digestion and nutrient absorption occurs

Answer 10

Small intestine

Question 11

Site of water absorption, bacterial fermentation and faecal formation

Answer 11

Large intestine

Question 12

What are the four functions of the stomach?

Answer 12

Protein digestion
Liquifying foodstuffs
Storage
Sterilisation

Question 13

For every 8-9L which enters the body how much of it leaves it?

Answer 13

200ml

Question 14

What is the approximate length of the GI tract (Oesophagus to rectum)?

Answer 14

Approx 8m

Question 15

What are the four distinct layers (tunics) of the GI tract called?

Answer 15

Mucosa
Submucosa
Muscularis Externa
Adventitia/Serosa

Question 16

What are the three layers of the mucosa?

Answer 16

Epithelium
Lamina Propria
Muscularis Mucosae

Question 17

When is it adventitia and when is it Serosa?

Answer 17

Adventitia is located outside the peritoneal cavity whereas the Serosa is located within
(Adventitia is the upper/proximal 2/3rds of the Oesophagus whilst lower/distal 1/3rd is Serosa)

Question 18

Where are the two intramural plexuses?

Answer 18

Myenteric Plexus/Auerbach’s (between circular and longitudinal muscles in Muscularis externa)
Submucosal Plexus/Meissner’s plexus (between Muscularis externa + submucosa)

Question 19

What is the epithelial lining in the Mouth, Oesophagus, anal canal

Answer 19

Stratified Squamous NON-KERATINISED epithelium

Question 20

What is the epithelial lining of the stomach, small and large intestine

Answer 20

Simple columnar epithelium

Question 21

What are the three functions of the mucosa

Answer 21

1. A barrier dividing the intestinal lumen from the body
2. Synthesis and secretion of digestive enzymes, hormones + mucus
3. Absorbs products of digestion

Question 22

What are the two layers of the Muscularis externa?

Answer 22

Circular muscle (constricts the lumen)
Longitudinal muscle (shortens tube)

Question 23

What forms the enteric nervous system (ENS)?

Answer 23

Submucosal + myenteric plexuses

Question 24

What are the two ways autonomic control affects the alimentary canal?

Answer 24

Long Parasympathetic (afferent to CNS)
Short ENS reflexes (both afferent + efferent, reflex in Submucosal + myenteric plexus)

Question 25

What is the main nerve controlling the parasympathetic response of the alimentary system

Answer 25

Vagus nerve (X)

Question 26

What two nerves control salivation?

Answer 26

Facial (VII) and glossopharyngeal (IX) (both are sympathetic)

Question 27

What action does the vagus have on the alimentary system?

Answer 27

Stimulatory: 1) increases secretion 2) increases motility

Question 28

How is the alimentary system sympathetically innervated?

Answer 28

Via the splanchnic nerve

Question 29

What action does the sympathetic nervous system have on the alimentary system?

Answer 29

Inhibition: 1) inhibits secretion 2) inhibits motility

Question 30

What branch of the abdominal aorta supplies the stomach, pancreas, liver and proximal small intestine?

Answer 30

Coeliac trunk

Question 31

What organs does the coeliac trunk supply?

Answer 31

stomach pancreas liver proximal small intestine

Question 32

What branch of the abdominal aorta does supplies the caecum, ascending colon, transverse colon and distal small intestine?

Answer 32

Superior mesenteric artery

Question 33

What organs does the superior mesenteric artery supply?

Answer 33

Caecum, ascending colon, transverse colon, distal small intestine

Question 34

What branch of the abdominal aorta supplies the descending colon, sigmoid colon and rectum?

Answer 34

Inferior mesenteric artery

Question 35

What organs does the inferior mesenteric artery supply?

Answer 35

descending colon sigmoid colon rectum

Question 36

What veins drain the stomach?

Answer 36

Gastric vein

Question 37

What vein drains the pancreas?

Answer 37

Splenic vein

Question 38

What vein drains the caecum, small intestine, ascending colon, transverse colon

Answer 38

Superior mesenteric vein

Question 39

Vein which drains the descending colon, sigmoid colon and rectum

Answer 39

Inferior mesenteric vein

Question 40

Vein which drains the gastric veins, splenic vein, superior and inferior mesenteric veins

Answer 40

Hepatic portal vein

Question 41

Hepatic portal vein ==> ______ ====> ______

Answer 41

Hepatic portal vein ===> Hepatic vein ====> inferior vena cava

Question 42

What is the nutrient content and oxygenation of the blood in the hepatic portal vein, hepatic vein and inferior vena cava?

Answer 42

hepatic portal vein: low O2, high nutrient Hepatic vein: High O2, low nutrient Inferior vena cava: High O2, High nutrient