Lecture 26 Flashcards
What are the main nutrients that undergo chemical digestion?
Protein
Carbohydrates
Fat
Composition of ingested carbohydrate?
Large chains of glucose monosaccharide) joined by glycosidic bonds.
Disaccharides; sucrose, maltose, lactose
Why are proteins important?
Required for Amino acids:
12 can be synthesised and the rest cannot therefore are called essential amino acids.
Sources of protein. in the body>
50% diet and 50% endogenous proteins, secreted into intestine, things such as enzymes and immunoglobulins.
How do fatty acids vary in length??
Short chain fatty acids < 6 carbons
Medium chain fatty acids – 6 to 12 carbons
Long chain fatty acids – 12 – 24 carbons
Purpose of chemical digestion?
reduces the size of nutrients to allow them to be
absorbed
How does mechanical digestion assist chemical digestion?
Mechanical digestion breaks up food to increase the surface area available for chemical digestion
Where does chemical digestion occur?
On the surface of food particles
What is chemical digestion important?
Nutrients can only be absorbed s small molecules
Features of digestive enzymes?
Extracellular
organic catalysts
Very specific
have optimum pH
What is the optimum pH for different enzymes?
Salivary enzymes – alkaline
} Gastric enzymes – acidic
} Small intestinal - alkaline
What is stage one of chemical digestion?
Lumina; digestion:
Initial digestion involving enzymes secreted into lumen
} Salivary glands – salivary amylase
} Stomach – pepsin
} Small intestine – Pancreatic enzymes
¨ Pancreatic amylase, trypsin, chymotrypsin, carboxypeptidase, lipase
What is stage 2 of chemical digestion?
Contact digestion: In small intestine } Completes digestion before absorption } Involves enzymes produced by enterocytes and attached to brushborder of enterocytes
