Gastrointestinal System - Small Intestine Flashcards
How long does it take for food to reach the small intestine?
Either minutes or hours depending on what youve eaten
What is the first part of the small intestine called?
The dudodenum
How does food enter the small intestine?
It is squirted into the duodenum as chyme
What is the smallest part of the intestine called?
The duodenum
How long is the duodenum?
Only a couple of cm long
What is the duodenum often called?
The ‘mixing bowl’
Other than chyme what enters the duodenum?
2
secretions from other accessory organs such as;
Bile
Pancreatic juice
What is the main role of the duodenum?
To neutralise chyme/gastric acid
Where does bile come from?
Liver
Other than from the liver and pancreas, from where does the duodenum accept secretions?
Brunner’s glands
What do the Brunner’s glands secrete?
Alkaline mucous secretions
What is the middle part of the small intestine called?
The jejunum
What is the role of the jejunum?
2
Chemical digestion
Nutrient absorption
How long is the jejunum?
2.5m long
What is special about the tissue in the jejunum?
They form small villi
What is the final part of the small intestine called?
The ileum
How long is the ileum?
3.5meters long
What are the main functions of the ileum?
2
To absorb vitamin B12
To absorb bile salts
What is the final part of the ileum called?
The ileocecal valve
What is the function of the ileocecal valve?
It acts as a sphincter that controls the flow of material from the ileum into the large intestine
What is the largest part of the small intestine called?
The ileum
List the layers to the tissue of the small intestine?
4
Mucosa
Submucosa
Muscularis Externa
Serosa
How is the mucosa of the small intestine specialised?
2
The mucosa has a ‘brush-border’
The epithelia are simple columnar epithelia with microvilli
What type of epithelia are present in the small intestine?
Simple columnar epithelia with microvilli
Describe the submucosa in the small intestine.
2
Brunner’s glands are present
Crypts are present
Describe the Brunner’s glands.
3
They are deep glands
They open into crypts
The crypts reach all the way down to the muscularis externa
What is secreted by the Brunner’s glands?
Alkaline fluid and enterogasterones
Why do the Brunner’s glands need to secrete an alkaline fluid?
(2)
To lower the pH of chyme
This ensures that enzymes can work
