Grand Tour of the Alimentary Canal 13092019 Flashcards
What are the four functions of the digestive system?
1) Digestion
2) Secretion
3) Absorption
4) Motility
Describe the organs / path included in the digestive system
Mouth Oesophagus Stomach Pancreas Gall Bladder Duodenum Small Intestine Large Intestine Sigmoid Colon Rectum Anal Canal
What does the pancreas digest?
Fats, carbohydrates and protein
In relation to the processes of digestion, secretion, absorption and motility, what process occurs in the mouth. Describe how the structure / anatomy of the mouth aids the relevant process.
The mouth is involved in the mechanical disruption of food. As well as this, the introduction of saliva acts as a lubricant. The introduction of amylase from 2 pairs of salivary glands also aids in the breakdown of complex carbohydrates.
In relation to the processes of digestion, secretion, absorption and motility, what processes occur in the stomach. Describe how the structure / anatomy of the mouth aids the relevant process.
The bulk of digestion occurs in the stomach via the secretion of concentrated HCL
The stomach also acts as a storage organ for food - if we digested everything at once then osmolarity would increase rapidly - causing water to be drawn out of our tissues
the process of sterilisation also occurs in the stomach.
What does the pancreas do?
Secretes enzymes that aid the digestion of fats, carbohydrates and protein
What does the (liver) do?
Produces bile salts for the emulsification of fats in the small intestine
In relation to the processes of digestion, secretion, absorption and motility, what processes occur in the stomach. Describe how the structure / anatomy of the mouth aids the relevant process.
Final stages of digestion and nutrient absorption - carbohydrates and protein
What happens in the large intestine?
Water is absorbed. Bacterial fermentation occurs and faeces are formed.
What does the gall bladder do?
Stores and concentrates bile
What does the small intestine do?
Final stages of digestion occur here and nutrients are absorbed
What does the stomach do?
Stores, digests and sterilises
What are the histological layers of the gut tube?
Mucosa
Submucosa
Muscularis Externa
Serosa / Adventitia
What are the layers of the mucousa of the gut tube?
Epithelium
Lamina propria
Muscularis mucousae
What layer of the gut tube produces gut motility?
Muscualris externa
What two kinds of muscularis externa are present?
Round and longitudinal
What surrounds the muscularis externa?
A dense myenteric neuronal network
What kind of epithelium is found in the mouth, oesophagus and anal canal?
stratified squamous epithelium
What kind of epithelium is found in the stomach, small and large intestines?
Simple columnar epithelium
What is found in the submucosa?
A dense neuronal network form the parasympathetic nervous system called the Meisinners Plexus
Glands that in the oesophagus secret mucus and in the duodenum secrete bicarbonate
What tissue is found in the submucosa?
dense irregular connective tissue
Serosa is found inside or outside the peritoneal cavity
inside
What does the serosa do?
Surrounds the stomach and small intestine
What does the adventitia do?
attached oesophagus and rectum to surrounding structures
Adventitia is found inside or outside the peritoneal cavity
Outside
What plexus controls the sub-mucosa?
Heisselbach’s plexus (para)
What plexus controls the muscularis externa?
Auerbach’s plexus (ENS)
What parasympathetic nerve controls the digestive system?
The vagus X
What nerve controls salvation?
Facial VII and Glossopharangeal IX
What does the celiac artery feed?
Foregut - stomach, liver, pancreas, small intestine
what does the superior mesenteric artery feed?
Midgut - small intestine, ascending colon, transverse colon and cecum
what does the inferior mesenteric artery feed?
Hindgut - descending colon, sigmoid colon & rectum
Describe the venous drainage of the small intestine, ascending colon & transverse colon
drainage into the superior mesenteric vein - into the hepatic portal vein - into the portal vein - into the inferior vena cava
Describe the venous drainage of the descending colon, sigmoid colon & rectum
drainage into the inferior mesenteric vein - into the hepatic portal vein - into the portal vein - into the inferior vena cava
What vein drains the stomach?
Gastric vein
What vein drains the pancreas?
Splenic vein
Are the intestines and liver in series or parallel?
Series
