Lecture 22: The Small Intestine Flashcards
What are the three regions of the small intestine?
- duodenum
- jejunum
- ileum
What is the longest region of the small intestine?
ileum
In which region of the small intestine does most of the absorption take place?
in the jejunum
Is the duodenum retroperitoneum of intraperitoneum?
retroperitoneum
Why is the duodenum retroperitoneum?
Because it does not move, it is just a receiving chamber
The duodenum is fixed and bound to the _______ _______ _______ but it has the _______ _________ which is covering the anterior surface
posterior abdominal wall
visceral peritoneum
Which parts of the small intestine are retroperitoneum and which parts are intraperitoneum?
The duodenum is retroperitoneum and the ileum and jejunum are intraperitoneum
What are the two movements of the small intestine?
- peristalsis (propulsion of food along the small intestine)
- segmentation (mixing pattern)
The small intestine is held in place by
mesentary
What four things are in the messentery?
- arteries
- veins
- nerves
- lymphatics
What are the purposes of the mesenteric arteries and veins?
To deliver oxygenated blood to the mesentery and to remove deoxygenated, nutrient rich blood
We need to protect the mucosa in the small intestine from the chyme. What features are present in the small intestine that allow us to do this?
There are goblet cells secreting mucus and glands in the submucosa that transports mucus to the surface
Mucus secreting glands are only present in which part of the intestine?
the duodenum
What is present that can help neutralise the pH of the chyme?
bicarbonate from the pancreas
By the time the food reaches the small intestine, all the mechanical digestion has taken place but chemical digestion is still required. What do we need to do that?
enzymes
How is the small intestine modified for secretion and absorption?
increase surface area by
- being long
- fold the mucosa to make plicae circulares
- fold the mucosa is the villi
- microvilli
What are the plicae circulares?
permanent large folds of the small intestine
The plicae circulares have a core of ______ with overlying _________
submucosa
mucosa
What is the purpose of the plicae circulares?
to increase surface area and to spiral food as it is travelling through the lumen and slowing down its passage so we have more time for digestion and absorption
Are the plicae circulares permanent or not?
yes they are