The Small Intestine Flashcards
what is the small bowel
the small intestine
what are the three sections that make up the small intestine
duodenum
jejunum
ileum
what is the small intestine the primary site for in the body
digestion and absorption
where does the small intestine begin
the pylorus
where does the small intestine extend to
the ileocaceal junction
how long is the duodenum
twelve finger lengths, around 25-30cm
why is the jejunum typically empty at post mortem
the result of terminal peristalsis
what does the name jujunum come from
latin for empty and fasting
what is the peritoneum
a continuous membrane lining the abdominal cavity and covers the abdominal viscera
what does the name ileum come from
latin for twisting
what is the parietal peritoneum sensitive to
pressure, pain, temperature
what is the function of the peritoneum
support abdominal organs and provide a route for blood vessels
what does the visceral peritoneum cover
the majority of the abdominal visera.
where does pain from the visceral peritoneum transfer to
dermatomes
what is the serous membrane
two layers continous with each other that are made up of simple squamous epithelial cells called mesothelium
what are intraperitoneal organs enveloped by
visceral peritoneum
what are dermatomes
areas of skin supplied by a single spinal nerve
what does the visceral peritoneum envelope
the intraperitoneual organs
what are the retroperitoneal organs
duodenum, pancreas and rectum
what does the mesentry connect structure to
the posterior abdominal wall
what is the mesentry
a double layer of visceral peritoneum, connecting the structure to the posterior abdominal wall. the mesentry contains blood vessels, nerves and lymphatics.
what does the mesentry contain
blood vessels
nerves
lymphatics
what is the omentum
a sheet of visceral peritoneum extending from the stomach and proximal duodenum to other abdominal organs
where does chyme come from
the stomach
where are brunners glands
above where the pancreatic and biliary secretions enter to duodenum
what do brunners glands secrete
alkaline and mucous secretions
what is the function of brunners glands
to produce alkaline and mucous secretions to protect the duodenum from the acidity of chyme, and provide optimal condition for intestinal enzymes to be active and for lubrication
where is bile stored
the gall bladder
how does bile enter the duodenum of the small intestine
the sphincter of oddi
what does the sphincter of oddi do
controls the flow of bile and the pancreatic juice, or enzymes as they pass into the duodenum
where does the duodenum end
the duodenojejunal junction
what secretions enter the small intestine
bile and pancreatic juice
where is the duodenum found in relation to the vertebrae
sits between L1 and L3/4
what is the shape of the duodenum
C shaped
why is the duodenum C shaped
it comes from the pyloric sphincter through to the duodenojejunal flexure
what does the sphincter of oddi control
the pancreatic and biliary secretions
where is the sphincter of oddi found
the second of the four parts of the duodenum
what is the major duodenal papillae surrounded by
the sphincter of oddi
what is the major duodenal papilla
the rounded projection at the opening of the common bile duct and the pancreatic duct
what is the minor duodenal papilla
the opening of the accessory pancreatic duct - typically present in 10% of people
what does CCK stand for
cholecystokinin
what is CCK
a peptide hormone that helps to digest fat and protein. secreted by cells of the duodenum.
what is CCK secreted by
cells of the duodenum
when is CCK secretion at its highest
when there is fatty acids in the chyme entering the blood stream
what is the function of the CCK hormone
digestion of fat and protein. it also inhibits gastric emptying, but increases the release of pancreatic enzymes, as well as increasing the production of bile.
what does CCK inhibit
gastric emptying
how does CCK result in better fat digestion
increases the release of pancreatic enzymes, as well as increasing the production of bile by contraction of the gall bladder and relaxation of the sphincter of oddi
what are the four parts to the duodenum
- superior
- descending
- inferior
- ascending
what is the superior part to the duodenum
this is the cap and ascends upward from the pyrolus, it is the area that is most common to have a duodenal ulcer. sits at L1
what is the descending section of the duodenum
this passes downward around the head of the pancrea, lying behind the transverse colon, and in front of the right kidney. it is at this site where the major duodenal papilla lies. sits at the level of L1-L3
what is the inferior section of the duodenum
this portion passes to the left over the inferior vena cava and aorta. lies behind the superior mesentric artery, supplying the midgut
what is the ascending section of the duodenum
this crosse the aorta and curves up to join the jejunum at the duodenojejunal flexure