Transcript Beyond the Stomach - Blue Valley Schools

Beyond the Stomach
Small Intestine
Small Intestine
Functions
• Most of the bodies digestion occurs in the
small intestine
• All of the absorption of foodstuffs occurs in
the small intestine
Small Intestine Parts
• Duodenum- shortest section, begins at the
pyloric sphincter and runs 25 cm (10 in).
“Duodenum” means 12, and is 12 fingers
breadth in length.
• Jejunum- is about 1 meter in length, (3ft)
Jejunum means “empty”, since at death it
is found empty
SI parts continued
• Ileum- final portion of the small intestine.
Ileum refers to twisted. The Ileum is about
2 meters in length (6 ft). It joins the large
intestine at the ileo-cecal valve, which also
marks the end of the small intestine.
Microvilli
• Microvilli line the entire small intestine.
These folds drastically increase surface
area, so absorptive rates are much higher
Note
• Blood vessels
• Simple columnar epithelium
Peristalsis
• Peristalsis is the wave like contractions of
the alimentary canal propelling foodstuffs
forward through the canal.
• Peristalsis is weaker in the small intestine
that the stomach or esophagus. Chyme
remains in your small intestine for 3-5
hours.
Absorption
• Most of the bodies absorption happens in
the small intestine. Aided by villi
• Stomach wall is impermeable to the
passage of most materials in to the blood,
however, the stomach does absorb some
water ions, certain drugs(especially
asprin), and alcohol.
Other structures adding to SI
• Liver- bodies largest gland. Divided into 2
principal lobes (cat has 5 lobes). Liver is
composed of hepatocytes. These hepatocytes
secrete bile. 800-1000 ml per day
• Bile emulsifies lipids, which means is breaks
down large lipid molecules. The principal bile
pigment bilirubin, when bilirubin breaks down, it
turns into a chemical called stercobilin, which
give feces their normal brown color.
Liver continued
• Bile leaves the liver through the common
bile duct. Bile is temporarily stored in the
gall bladder.
• Bile has a dark green color, and the gall
bladder is basically a bag, so it will have
that dark green color as well.
Pancreas
• Pancreas secretes pancreatic amylase,
which aides in carbohydrate digestion
• Pancreas also secretes pancreatic lipasewhich also aides in the digestion of lipids
• Pancreas also secretes trypsin which
aides in the digestion of proteins
More pancreatic secretions
• Chymotrypsin- aides in the digestion of
proteins
• Carboxypeptidase- aides in the digestion
of proteins.