Grand Tour of the Alimentary Canal Flashcards
(28 cards)
List the salivary glands and their functions.
Parotid
Sublingual
Submandibular
They secrete and coat the mouth in saliva which acts as a lubricant
Also begins 5digesting starch through salivary amylase
What are the functions of the stomach?
- Digests Proteins
- Reduces food to a liquid
- Stores food during digestion
- Sterilizes food
What is the digestive function of the pancreas?
Releases digestive enzymes that digests carbs, fats and proteins
Function of the liver in digestion?
Produced bile salts for digestion/absorption of fats in small intestine
Also stores fat/sugar delivered from the small intestine via the portal vein
Function of gallbladder?
Stores and concentrates bile up to 50ml
Whats the function of the small intestine?
Performs the last bit of chemical digestion and the vast bulk of nutrient absorption
Whats the function of the large intestine?
- Absorbs water
- Forms faeces
- Bacterial fermentation
What are the layers of the GI tract?
- Mucosa (Epithelium - Lamina Propria - Muscularis Mucosae)
- Submucosa
- Muscularis Externa
- Serosa/Adventitia
What epithelium does the mouth, oesophagus and anal canal have? (The two ends) Why this type?
Stratified squamous to protect against solids
What epithelium does the stomach and the large and small intestines have? Why this type?
Simple columnar to aid in absorption/secretions
Do glands exist in the submucosa?
Only in two places:
- The esophagus where they make mucous to aid motility
- The duodenum where they make bicarbonate to neutralize stomach acid
What are the layers and functions of these layers in the muscularis externa?
Inner circular layer - contracts the tube
Outer longitudinal layer - shortens the tube
Together they produce GI motility by peristalsis & segmentation
What are the serosa/adventitia? What is the difference between the two?
The connective tissue sheath surrounding the GI tract
Inside the peritoneal cavity its called serosa
Outside its called Adventitia (Oesophagus & Rectum)
What is the enteric nervous system and what is it made up of?
It is one of the main divisions of the ANS and governs the function of the gastrointestinal tract. Made up of 2 parts
(1) Submucosal/Meissner’s plexus on the submucosa
(2) Myenteric/Auerbach’s plexus between layers of the muscularis externa
Whats the function of the epithelium in the mucosa?
- Absorbing digestive products
- Secreting digestive enzymes, hormones and mucous
What makes up the lamina propria?
Loose CT
What else is found in the lamina propria?
Glands
Lymph vessels/Nodes
Bloods vessels
What is the muscularis mucosae?
A thin layer of smooth muscle on the mucosa which does very little.
What is the submucosa?
A thick band of irregular connective tissue which supports the mucosa
Also has neurons (submucosal plexus), blood vessels and lymphatic vessels
What kind of nervous control is the gut under?
ANS
What nerves supply the gut with parasympathetic stimulation and what effect do they have?
Vagus nerve supplies all PS activity besides in the salivary glands - facial & glossopharyngeal nerves
When stimulated they increase gut secretion and motility
What supplies the GI tract with sympathetic activity and what is its effect?
Splanchnic nerve
Is inhibitory - so decreases secretion and motility -EXCEPT to salivary glands
What 3 branches come off the abdo aorta to supply the GI tract?
Celiac trunk - foregut
Superior mesenteric - midgut
Inferior mesenteric - hindgut
How is sympathetic stimulation of the salivary glands different to parasympathetic?
They produce different types of saliva
