Grand Tour Of The Alimentary Canal

Question 1

What is the digestive system made up of?

Answer 1

GI tract & Accessory Organs
Salivary Gland
Liver
Pancreas
Gallbladder

Question 2

What are the solid organs of the digestive system?

Answer 2

Accessory organs
Salivary gland
Liver
Pancreas
Gallbladder

Question 3

What are the main functions of the digestive system?

Answer 3

Digestion
Absorption
Secretion
Motility

Question 4

What is the flow of food through the GI system

Answer 4

Esophagus > Stomach > Small intestine > Colon > Rectum > Anus

Question 5

Where does absorption and secretions take place?

Answer 5

Mostly small intestine and a little bit in the colon

Question 6

What happens at the mouth?

Answer 6

Foodstuff broken down by chewing; saliva added as lubricant

Question 7

What is the oesophagus

Answer 7

Conduit between mouth and stomach

Question 8

What happens in the stomach

Answer 8

Digestion of proteins, foodstuffs reduced to semi liquid form, storage and sterilisation

Question 9

What happens at the pancreas

Answer 9

Digestive enzymes for digestion of fats, carbs and proteins

Question 10

What happens at the liver?

Answer 10

Bile salts for digestion/absorption of fats in small intestine

Question 11

What is the purpose of the gallbladder

Answer 11

Stores and concentrates bile

Question 12

What happens at the small intestine

Answer 12

Final stages of chemical digestion and nutrient absorption

Question 13

What happens large intestine

Answer 13

Water absorption, bacterial fermentation and formation of faeces

Question 14

What is the general structure of the alimentary canal

Answer 14

Continuous hollow tube that runs from oseophagus to rectum made up of 4 distinct layers (tunics)

Question 15

What are the 4 distinct layers

Answer 15

Mucosa
Submucosa
Muscularis externa
Serosa/adventitia

Question 16

What is serosa/adventitia?

Answer 16

Connective tissue sheet

Known as serosa in peritoneal cavity and adventitia if outside the peritoneal cavity

Question 17

What is mucosa composed of?

Answer 17

3 distinct layers

Epithelium
Lamina proprietor
Muscularis mucosae

Question 18

What is the purpose of epithelium in GI tract

Answer 18

Barrier separating lumen of alimentary canal from body

Synthesis and secretion of digestive enzymes, hormones, mucus

Absorbs products of digestion

Epithelium differs along length of gut tube - it adapts depending on function

Question 19

What is the lamina proprietor

Answer 19

Lose CT found in glands, blood/lymph vessels

Question 20

What is the Muscularis muscosae

Answer 20

Thin smooth muscle layer

Question 21

What is submucosa composed of?

Answer 21

Thick, irregular CT

Contains neurones, blood vessels

These neurones form extensive network called submucosal meissners plexus (parasympathetic)

Submucosal glands in oesophageal and duodenum

Question 22

How does adventitia occur outside the peritoneal cavity

Answer 22

Adventitia attaches oesophagus and rectum to surrounding structures

Question 23

How does serosa occur outside the peritoneal cavity

Answer 23

Surrounds stomach, small intestine and large intestine

Question 24

What is the Muscularis externa composed of?

Answer 24

Two concentric thick layers of smooth muscle

Inner layer - circular muscle which constricts lumen
Outer layer - longitudinal muscle which shortens tube

Motility produced by peristalsis and segmentation

Myenteric plexus between circular and longitudinal muscle

Submucosal + myenteric plexuses = enteric nervous system - independent control of gut function

Question 25

How is the alimentary system autonomically controlled

Answer 25

By long - parasympathetic and;

Short - ENS - reflexes

Question 26

What is the parasympathetic innervation of alimentary function?

Answer 26

Vagal Nerve CX

Except salivation - facial VII and glossopharyngeal (IX)

Stimulatory

• secretion
• motility

Question 27

What is the sympathetic innervation of alimentary function

Answer 27

Splanchnic nerve

Inhibitory (except salivation)

• secretion
• motility