Mechanisms of absorption Flashcards
What absorbs the products of digestion?
The intestinal lining.
What mechanism absorbs monosaccharides and amino acids?
Co -transport
What is digestion?
The breaking down of food into smaller, soluble molecules.
Where are carrier molecules found?
Within the cell-surface membrane of the epithelial cells in the ileum.
When do carrier molecules transport amino acids?
Only when sodium ions are present
What is facilitated diffusion?
The spontaneous transport of material across the cell membrane via membrane proteins embedded in it. ‒ The transport is dependent on the interaction of material and the channel or carrier protein.
How and where amino acids diffuse?
Diffuse across the epithelial cell and then pass into the capillaries via facilitated diffusion.
How is the concentration gradient of sodium ions from the lumen of the ileum into the epithelial cell maintained
By the active transport of sodium ions out of the cell and into the blood via a sodium-potassium pump at the other end of the cell.
How are sodium ions and glucose molecules transported?
Are co-transported into the epithelial cells via facilitated diffusion.
How is the concentration gradient of sodium ions maintained?
By actively transporting sodium ions out of the epithelial cells into the blood.
How do the glucose molecules diffuse?
Across the epithelial cell and enter the capillary at the other end of the cell by facilitated diffusion.
What are the products of lipid digestion?
fatty acids, monoglycerides and glycerol.
What are micelles?
The association of monoglycerides, fatty acids and phospholipids and bile salts to form very small droplets
Why are micelles non polar molecules?
So they can diffuse through the phospholipid bilayer of the cell membrane.
What do micelles do?
Break down and add to a pool of fatty acids and monoglycerides that are dissolved in the small intestine solution surrounding the epithelial cells.
These freely dissolved molecules enter the epithelial cell by diffusion.
