Transcript The Digestive Process

Digestive Process and
Enzymes
Review
• What is the difference between physical
digestion and chemical digestion?
• What is an enzyme?
• Why are enzymes specific to one
substrate?
• Chemical digestion involves the
hydrolysis of macromolecules in food
• Enzymes are required - why?
• Water is also required - why?
• Each digestive enzyme has a specific
substrate (examples?)
• Each area of the digestive tract has a
specific pH range; this is the optimal pH
for enzymes that work there
• pH in the mouth is 7; in the stomach is
2; in the small intestine is 7 to 8
• HCl in gastric juice causes the low pH of
the stomach
• required for the conversion of
pepsinogen into pepsin
What other functions does the acidity of
the stomach have?
• Digestive enzymes are produced by
glands - where are these located?
– mouth - salivary glands
– stomach - gastric glands
– pancreas – most cells of the pancreas
– small intestine (intestinal glands in walls)
Name the enzymes produced by:
• Mouth
– Salivary amylase
• Stomach
– pepsin
• Pancreas
– Pancreatic amylase, lipase, trypsin, nuclease
• Small intestine
– Maltase, peptidase
Products
• What are the final products of
digestion?
• glucose and other monosacharides,
amino acids, fatty acids, glycerol,
nucleic acids
Absorption
• How do nutrients get into the blood from
the small intestine?
– Absorbed through the cell membranes, by
facilitated transport
• Where does the blood go first, as it
leaves the digestive tract?
– Liver, via hepatic portal vein
• How do nutrients get into cells where
they are needed?
– Facilitated transport through cell
membranes
Which structure releases an enzyme that
would catalyze the production of the above
molecules?
a)Liver
b)Salivary glands
c)Pancreas
d)Stomach