Alimentary Canal

Question 1

What is the function of the mouth?

Answer 1

Foodstuffs broke down by chewing (mastication): saliva is added as a lubricant

Question 2

What is the function of the oesophagus?

Answer 2

Conduit between the mouth and the stomach

Question 3

What is the function of the stomach?

Answer 3

Digestion of proteins; foodstuffs reduced to liquid from. Also plays a role in storage and sterilisation

Question 4

What is the function of the pancreas?

Answer 4

Digestive enzymes for digestion (duh), helps with the absorption of fats, carbohydrates and proteins

Question 5

What is the function of the liver?

Answer 5

Secretes bile salts to aid the absorption of fats in the ileum

Question 6

What is the function of the gallbladder?

Answer 6

Stores and concentrates bile

Question 7

What is the function of the small intestine?

Answer 7

Final stage of chemical digestion and nutrient absorption

Question 8

What is the function of the large intestine?

Answer 8

Water absorption, bacterial fermentation and formation of faeces

Question 9

Describe the length, diameter and organisation of the GI tract

Answer 9

Approx. 8m long, varying diameter and organisation of cells vary depending on function

Question 10

Describe the difference in the microscopic composition of the GI tract?

Answer 10

Mouth, anal canal and oesophagus - stratified squamous epithelium

Stomach and intestines - simple columnar epithelium

Question 11

What are the four layers common to the GI tracts length?

Answer 11

• Mucosa
• Submucosa
• Muscularis externa
• Serosa/Aventitia

Question 12

What structures comprise the mucosa?

Answer 12

Epithelium, lamina propria and muscularis mucosae

Question 13

What is the function of the mucosa?

Answer 13

• Synthesis and secretion of enzymes

- bAbsorbs products of digestion

Question 14

What is the lamina propria?

Answer 14

Loose connective tissue containing glands and blood/lymph vessels

Question 15

What is the muscularis externa?

Answer 15

A thin layer of muscle

Question 16

What is the structure of the submucosa?

Answer 16

Thick irregular connective tissue

Question 17

What is the function of the submucosa?

Answer 17

Supports the mucosa

Question 18

What structures permeate the submucosa?

Answer 18

Neurones, blood vessels (to the mucosa, adventitia and muscularis external)

Question 19

What is the network of neurones in the submucosa known as?

Answer 19

Meissner’s Plexus (parasympathetic)

Question 20

Where are submucosal glands located?

Answer 20

Oesophagus and duodenum

Question 21

What is the muscularis externa?

Answer 21

Two layered ring of muscle

Question 22

What are the functions of the two layers of muscle in the muscularis externa? What two processes do these functions accommodate?

Answer 22

Inner - circular muscle - contraction of GI tract lumen
Outer - longitudinal - constriction of tube length

Allows peristalsis and segmentation

Question 23

What neural system lies between the layers of the muscularis externa?

Answer 23

Auerbach’s Myenteric Plexus

Question 24

What is the enteric nervous system comprised of?

Answer 24

Submucosal (Meissner’s) and Myenteric (Auerbach’s) plexi

Question 25

What is the function of the enteric nervous system?

Answer 25

Independent control of the GI tract

Question 26

What is the difference between the serosa and the adventitia?

Answer 26

Both outer layer of connective tissue for the alimentary canal Location is the difference Serosa = inside the peritoneal cavity Adventitia = outside the peritoneal cavity

Question 27

What division of the autonomic nervous system governs long reflexes in the alimentary canal?

Answer 27

Parasympathetic

Question 28

What division of the autonomic nervous system governs short reflexes in the alimentary canal?

Answer 28

Sympathetic

Question 29

What nerve delivers parasympathetic innervation?

Answer 29

Vagus nerve (X) except salivation (facial VII and glossopharyngeal IX)

Question 30

What is the effect of the parasympathetic system in the GI tract?

Answer 30

Increases gut motility and secretion

Question 31

What nerve delivers sympathetic innervation to the GI tract?

Answer 31

Splanchnic

Question 32

What is the effect of the sympathetic nervous system in the GI tract?

Answer 32

Inhibitory (except salivation) - decreases secretion and motility

Question 33

What three branches of the descending aorta supply the GI tract?

Answer 33

Celiac trunk, superior and inferior mesenteric artery

Question 34

What organs does the celiac trunk supply?

Answer 34

Stomach, small intestine, pancreas and liver

Question 35

What organs does the superior mesenteric artery supply?

Answer 35

Small intestine, caecum, ascending colon and transverse colon

Question 36

What organs do the inferior mesenteric artery supply?

Answer 36

Descending colon, sigmoid colon and rectum

Question 37

What vein(s) drain from the stomach?

Answer 37

Gastric veins

Question 38

What vein(s) drain from the pancreas?

Answer 38

Splenic vein

Question 39

When organs drain into the superior mesenteric vein?

Answer 39

Small intestine, caecum, ascending and transverse colon

Question 40

What organs drain into the inferior mesenteric vein?

Answer 40

Descending colon, sigmoid colon and rectum

Question 41

Where do the gastric, splenic and mesenteric veins drain into?

Answer 41

Hepatic portal vein

Question 42

Outline the route to the inferior vena cava from the hepatic portal vein

Answer 42

Hepatic portal vein (through the liver) to the hepatic vein to the inferior vena cava

Question 43

What is the purpose of the hepatic portal system?

Answer 43

Clean blood in liver before reoxygenation in the cardio-pulmonary system