Term
| Where is most of ingested fluid absorbed? |
|
Definition
|
|
Term
| What are the two routes of water and electrolyte absorption across epithelia in the GI? |
|
Definition
| Transcellular and Paracellular routes |
|
|
Term
| Where are leaky epithelia mainly found? |
|
Definition
| Small Intestines with a high permeability to water and small ions |
|
|
Term
| What is the function of transcellular routes? |
|
Definition
| Transfers solutes across membranes into interecllular and subepithelial spaces, bringing water along with it |
|
|
Term
| What is the function of paracellular routes? |
|
Definition
| Contributes to solute movement in the small intestine by solvent drag of small ions across highly permeable leaky junctions |
|
|
Term
| Where are semi-tight epithelia mainly found? |
|
Definition
|
|
Term
| What is the function of semi-tight epithelia? |
|
Definition
| Less permeable than leaky epithelia, results in exclusive transcellular water absorption |
|
|
Term
| Paracellular diffusion employs what electrolyte gradient? |
|
Definition
| Na+/K+ATPase pump favors inward Cl- movement |
|
|
Term
|
Definition
| Cl-/HCO3- counter transport exclusively in the colon |
|
|
Term
| Where does K+ absorption occur? |
|
Definition
| Small Intestine via paracellular diffusion |
|
|
Term
| Where does K+ secretion occur in the GI? |
|
Definition
|
|
Term
| How is calcium absorbed in the GI? |
|
Definition
| Paracellular absorption along entire small intestine as well as transcellular |
|
|
Term
| What ion has the greatest absorption rate? |
|
Definition
|
|
Term
| What releases Fe from heme in enterocytes? |
|
Definition
|
|
Term
| What does free Fe bind to in enterocytes? |
|
Definition
| Apoferritin (stored as ferritin) |
|
|
Term
| What transports Fe basolaterally into plasma via receptors? |
|
Definition
|
|
Term
| What form is the absorption of nonheme iron almost exclusively in? |
|
Definition
|
|
Term
| How does nonheme iron (Fe2+) become absorbed? |
|
Definition
|
|
Term
| What reduces free dietary Fe3+ to Fe2+ |
|
Definition
|
|
Term
| What does cytoplasmic Fe2+ bind to for transit across the cell to the basolateral membrane? |
|
Definition
|
|
Term
| What does Fe2+ use to exit enterocytes across the basolateral membrane? |
|
Definition
|
|
