3.3.3 Digestion and absorption Flashcards
What is the function of amylase in digestion and where is it secreted?
Amylase hydrolyzes starch (a polysaccharide) into maltose (a disaccharide). It is secreted by the salivary glands and pancreas.
What enzymes are used in protein digestion and where does this occur?
Epithelial cells on small intestine
Endopeptidases: Break peptide bonds within the protein.
Exopeptidases: Remove terminal amino acids.
Dipeptidases: Hydrolyze dipeptides into individual amino acids.
How do endopeptidase and exopeptidase work together for efficient gas exchange ?
Exopeptidase hydrolyses internal peptide bonds so therefore more ends for exopeptidase to work as increased surface area
How does bile aid in the digestion of Lipids ?
Emulsifies the fatty acid molecules
Meaning many small droplets of lipids providing a larger surface area to enable faster hydrolysis action by lipase
What process are both monosaccharides and amino acids absorbed by in the ileum
Co- Transport with sodium ions
What does a chylomicron contain ?
Triglyceride and protein molecule
What is the role of the pancreas in digestion?
The pancreas secretes digestive enzymes (amylase, lipase, and proteases) into the small intestine and produces alkaline secretions to neutralize stomach acid.
Why can the contents in the micelle move into cell by simple diffusion ?
Fatty acids and monoglycrides = non polar and lipid soluble can dissolve through phospholipid bilayer
Describe the steps involved in the absorption and transport of digested lipid molecules from the ileum into the lymph system
- Micelles contain bile salts, monoglycerdies and fatty acids
- Micelles make the fatty acids soluble in water and transport them to the ileum epithelial cells
- Difusses into these epithelial cells through simple diffusion
- Reforms triglyceride at Golgi body and packaged into a vesicle
- Vesicle containing the triglyceride travels to cell membrane where it fuses with it and exocustios occurs
- Triglyceride is released and enters the lymph system
What is the name of the fluid In between the epithelial cell in the small intestine and a lacteal ?
Tissue Fluid
How do chylomicrons leave epithelial cell and why do they leave this way ?
Exocytosis as large molecule
The absorption of galactose from the small intestine is reduced if the absorbing cells are treated with a respiratory inhibitor, such as cyanide. Suggest an explanation for this.
No ATP formed so no energy released by respiration
No active transport of galactose into cells
What type of transport mechanism is co - transport
Facilitated diffusion
Describe the process involved in the absorption of the glucose in the small intestine
Glucose moves into epithelial cell with sodium ions
Via carrier protein
Sodium removed from epithelial cell by active transport through sodium potassium pump into blood
Maintaining a low concentration of sodium in the lumen and epithelial cell
Glucose is then moved into blood
By facilitated diffusion
Suggest an advantage of producing trypsin (protease) in an inactive form inside the cells in the pancreas
Does not digest proteins inside the cell
So pancreatic cells not destroyed
