The Grand Tour of the Alimentary Canal Flashcards
GI tract
series of hollow organs joined in a long, twisting tube from the mouth to the anus
what makes up the GI tract
mouth, oesophagus, stomach, small intestine, large intestine, and anus
accessory organs
salivary glands, liver, pancreas, gallbladder
main functions of digestive system
digestion, secretion, absorption, motility
digestion
breaking down of the food we eat into simple substances that our bodies can absorb
Digestive absorption
passage of the end products of digestion from the gastrointestinal tract into the blood, and lymphatic vessels.
secretion
process by which substances are produced and discharged from a cell, gland, or organ for a particular function in the organism or for excretion.
motility
ability of an organism to move independently, using metabolic energy.
What is the function of the mouth?
Break down foodstuff by chewing, saliva acting as a lubricant
What is the function of the oesophagus?
Conduit between the mouth and stomach
What is the function of the stomach?
Digestion of proteins
Foodstuff reduced to liquid form
Storage
Sterilisation
What is the function of the pancreas?
Digestive enzymes for digestion of fats, carbohydrates and proteins
What is the function of the liver?
Produce bile salts for digestion/absorption of fats in the small intestine
What is the function of the gallbladder?
Stores and concentrates bile
What is the function of the small intestine?
Final stages of chemical digestion and nutrient absorption
What is the function of the large intestine?
Water absorption
Bacterial fermentation and formation of faeces
In basic terms what is the alimentary canal?
Continuous hollow tube from the oesophagus to the rectum
How long is the alimentary canal?
About 8m long
What can be said about the structural formation of the alimentary canal throughout its length?
it is the same throughout its length with 4 distinct layers
What are the 4 distinct layers of the alimentary canal?
Mucosa
Submucosa
Muscularis external
Serosa/adventitia
Where is stratified squamous epithelium found?
Mouth
Oesophagus
Anal canal
Where is simple columnar epithelium?
Stomach
Small intestine
Large intestine
What is the functions of epithelium?
Separate lumen of alimentary canal from the body
Synthesis and secretion of digestive enzymes, hormones and mucus
Absorbs products of digestion
What are the layers of the mucosa?
mucous epithelium
Lamina propria
Muscularis mucosae
What is lamina propria?
Loose connective tissue (glands, blood and lymph vessels)
What is muscularis mucosae?
Thin smooth muscle layer
What is submucosa?
Thick, irregular connective tissue to support mucosa
What does the submucosa contain?
neurons
Blood vessels
Lymphatic vessels
What do neurons form in the submucosa?
Submucosal plexus (parasympathetic)
Is the submucosal plexus sympathetic or parasympathetic?
parasympathetic
Where are submucosal glands found?
Oesophagus
Duodenum
What makes up the muscularis externa?
Two concentric thick layers of smooth muscles (inner layer and outer layer)
What is the inner layer of the muscularis externa?
Circular muscle
What is the outer layer of the muscularis externa?
Longitudinal muscle