Body Systems: Digestion (Digestion) Flashcards
The small intestine is composed of 3 sections:
Duodenum, Jejunum, Ileum.
In what part of the small intestine does most digestion occur?
In the Duodenum.
Chyme (from stomach) moves through the small intestine by:
Peristalsis.
Small intestine (Physical digestion)=
Segmentation= chyme sloshing back and forth.
Ridged inner lining of the small intestine are covered in tiny projections called:
Villi, which are covered in micro villi.
What do villi and micro villi do?
Increase the surface area of the small intestine.
Each villus is supplied with:
Capillary networks and lymph vessels called lacteals.
What do capillary networks do?
Allow fluid and gas exchange to occur with blood stream.
What do lacteals do?
Transport products of fat digestion.
The pancreas:
Releases enzymes to the small intestine.
Enzymes chemically digest:
Proteins (trypsin), carbs (amylase), lipids (lipase).
Protein digestion in the small intestine (1):
Chyme enters the small intestine soaked in HCl and pepsin (from gastric secretions). The HCl triggers the conversion of the hormone prosecretin into secretin.
What is secretin?
Secretin: tells pancreas to release bicarbonate ions (HCO3-).
Protein digestion in the small intestine continued (2):
Bicarbonate ions (HCO3-) —> to increase the pH from 2.0 to 9.0 (becomes more basic).
-Secreted from pancreas.
-Basic pH inactivates (released in stomach).
Protein digestion in the small intestine continued (3):
Trypsinogen —> gets converted into trypsin by the enzyme enterokinase. (Secreted from small intestine).
-Secreted from pancreas.
-Chemical digestion of long chain proteins.