The Digestive System Flashcards
What is the most distal part of the digestive tract to the mouth: the anus or the rectum?
The anus
List 4 accessory organs.
Liver
Pancreas
Gall bladder
Salivary glands
What is the passageway of food called spanning from the mouth to the anus?
The alimentary canal
List the 4 layers of the guy wall.
Mucosa
Submucosa
Muscular is externae (external muscular layers)
Serosa
What 3 layers compose the mucosa of the gut wall? List these starting with the structure proximal to the gut lumen.
The epithelium
Lamina propia
Muscularis mucosae
What is the submucosa? What kind of structures are located within the submucosa?
The submucosa is a layer of connective tissue surrounding the mucosa. It contains structures such as blood vessels, nerve cells, and glands
What specific antibody does saliva contain? S the solution generally alkaline or acidic?
IgA - the solution is generally acidic
Why does the saliva contain fairly high levels of Ca2+?
This protects teeth, which aid in the breakdown of food for digestion
Name 2 enzymes commonly associated with saliva.
Amylase and lipase
How many layers of muscle does the muscularis externae consist of? Describe them.
The muscularis externae consists of 2 layers - the innermost layer of smooth muscle runs circularly around the lumen, while the outermost layer runs longitudinally parallel to the lumen
How does the stomach protect its epithelium from highly acidic conditions?
Secretion of mucus by goblet cells
What is the most distal portion of the small intestine?
The illeum
To which portion of the alimentary canal is bile secreted? What are the components of bile, and what are their purposes?
Bile is secreted into the duodenum - it’s contains:
- water - helps turn the chyme into a isotonic solution
- HCO3- - helps neutralise the acidic chyme solution
- bile salts - helps emulsify fats belonging to the chyme
What are the folds of the stomach called? What process are they thought to aid?
Rugae - the physical breakdown of a bolus by churning
Through which vessel are all nutrients absorbed from the all intestine? What organ does this ensure all nutrients pass through?
The hepatic portal vein, which ensures all nutrients pass through the liver before being distributed throughout the body
What is the outermost layer of the mucosa of the oesophagus?
The adventitia, composed entirely of connective tissue, which replaces the serosa
What controls emptying of the stomach into the duodenum of the small intestine?
The pyloric sphincter (named after the pylorus portion of the stomach)
What are Brunner’s glands? Where are they located?
Brunner’s glands secrete bicarbonate in an effort to alliance the acidic chyme produced by the stomach - they are located in the duodenum of the small intestine
Where is the lamina propria located? What role does it play?
The lamina propria is located underneath the epithelium in the mucosa - it contains many immunoregulatory cells (plasma cells, mast cells, macrophages), provides nutrition to the epithelium, and provides support where they can anchor
What is the serosa?
An outermost covering of simple squamous epithelium and a thin layer of adjacent connective tissue
What is heartburn?
Heartburn occurs when stomach acid regurgitates into the oesophagus
Does the oesophagus consist of a serosa?
No
What 2 nerves innervate the oesophagus? What common saying does their action lead to?
Myenteric plexus and submucosal plexus - their action nears the term ‘to choke with emotion’
How many layers of muscle are there in the stomach?
3
