Physiology- Grand Tour of the Alimentary Canal Flashcards
What 4 functions can the physiology of the digestive system be broken down into?
Digestion
Secretion
Absorption
Motility
How many salivary glands are found in the mouth and what are they called?
3 Salivary glands:
Parotid salivary gland on the roof.
Sublinguinal salivary gland under the tongue.
Submandibular salivary gland at the back of the jaw.
What are the two sphincters of the oesophagus?
Upper oesophageal sphincter (controls entry of food)
Lower oesophageal sphincter (prevents food leaving the stomach back into oesophagus)
What basic role does the mouth play in digestion?
Breaks foodstuffs down by chewing.
Saliva is added as lubricant
What basic role does the oesophagus play in digestion?
The oesophagus acts as a conduit between mouth and stomach
What basic role does the stomach play in digestion?
Stomach is the main start of digestion.
Specialises in the breakdown of proteins
Foodstuffs are reduced to liquid form.
Avid in the stomach helps to sterilise food.
Acts as a storage vessel.
How does the stomach act as a storage vessel?
Without the stomach to hold a large meal and slowly release the products into the GI tract there would be a massive influx of food.
Macromolecules would be broken down increasing the osmolarity of the intestines and large amounts of fluid would rush in. This causes a massive decrease in body fluid which causes shock and abdominal swelling.
This shock can be fatal and is called dumping syndrome.
What basic role does the pancreas play in digestion?
Produces digestive enzymes for digestion of fats, carbohydrates and proteins.
What basic role does the liver play in digestion?
Produces bile salts for digestion/ absorption of fats in small intestine
What basic role does the Gallbladder play in digestion?
Bile salts are produced all the time and stored in the gall bladder.
What role does the small intestine play in digestion?
The final stages of chemical digestion and nutrient absorption.
What role does the large intestine play in nutrient absorption?
Location of water absorption, bacterial fermentation and the formation of faeces.
What is the general structure of the Alimentary canal?
It is a continuous hollow tube of varying diameter.
From the oesophagus to the rectum its 8 meters long.
The tube wall has the same structural organisation throughout its length.
What are the 4 distinct histological layers of the alimentary canal?
- Mucosa (inside of the tube = basically outside the body)
- Submucosa (contains glands in oesophagus for mucous and glands in duodenum to cancel out stomach acid)
- Muscularis externa (the important muscular layer)
- Serosa/ adventitia (series below diaphragm, adventitia above the diaphragm)
What are the three layers of the alimentary mucosa?
- Epithelium
- Lamina Propria (next layer) = small layer of loose connective tissue (blood/ lymph vessels, glands)
- Muscularis mucosae (doesn’t really do much)