Topic 4 Digestive System Flashcards
The digestive system is an organ system where
several organs work together to digest and absorb food.
Physical digestion:
mouth (chewing) and stomach (churning) - breaks food into smaller pieces to increase the surface area for chemical digestion
Chemical digestion by enzymes which:
Are biological catalysts that speed up chemical reactions in living organisms
Are large proteins
Catalyse a specific reaction due to the shape of the active site being complementary to the shape of one specific substrate
Are denatured by high temperature and extremes of pH due to changes in the shape of the active site
Have an optimum temperature
Have an optimum pH.
The ‘lock and key theory’ is a simplified model of:
In reality:
enzyme action.
the active site changes shape a bit as the substrate binds to it. This enables a tighter fit, and is called the induced fit model
Digestive enzymes convert large food molecules into
small soluble molecules that can be absorbed into the bloodstream.
Carbohydrases break down carbohydrates to
simple sugars.
Amylase is a carbohydrase which
breaks down starch into glucose
Proteases break down
proteins to amino acids.
Lipases break down
lipids (fats) to glycerol and fatty acids.
carbohydrase sites of production
pancreas, salivary glands and small intestine
carbohydrase site of action
mouth and small intestine
protease sites of production
stomach pancreas and small intestine
protease action sites
stomach and small intestine
amylase site of production
salivary glands and pancreas
amylase site of action
mouth and small intestine
