Gut Secretion and Absorption
- Fluid + electrolyte transport are important functions of the GIT
- Gut epithelial cells may:
o secrete water and electrolytes e.g. transport from blood to gut lumen
o absorb water and electrolytes e.g. transport from gut lumen to blood
Movement of water and solutes
- Water moves down osmotic gradients
- Electrolytes move down electrochemical gradients
- To move solutes against their concentration
gradients requires energy
- Energy is supplied by:
o Sodium gradients (generated by the sodium
pump)
o Proton gradients
Structure of the SI
- Plicae Circularis (circular folds) in SI increase S.A.
Absorption in the villus: Secretion in the crypt
- Cells in villus involved in fluid absorption
- Cells in crypt involved in fluid secretion
- Fluid + electrolyte transport are important functions of the GIT
- Gut epithelial cells may:
o secrete water and electrolytes e.g. transport from blood to gut lumen
o absorb water and electrolytes e.g. transport from gut lumen to blood
Movement of water and solutes
- Water moves down osmotic gradients
- Electrolytes move down electrochemical gradients
- To move solutes against their concentration
gradients requires energy
- Energy is supplied by:
o Sodium gradients (generated by the sodium
pump)
o Proton gradients
Structure of the SI
- Plicae Circularis (circular folds) in SI increase S.A.
Absorption in the villus: Secretion in the crypt
- Cells in villus involved in fluid absorption
- Cells in crypt involved in fluid secretion
