VPB 121: Veterinary Physiology - II (2+1)

MECHANISM OF ABSORPTION

• The possible mechanisms of absorption are broadly classified into three groups:
  • Non-carrier mediated transport (passive diffusion)
    • It depends on the electro-chemical gradient, occurs through channel pathways of ions.
    • Non-carrier mediated process aids in the absorption of short chain fatty acids, inorganic salts and lipid soluble compounds.
  • Carrier mediated transport – includes
    • Facilitated transport from higher to lower concentration
    • Exchange diffusion Na+/H+ exchanger: transports H+ out and Na+ into the cell
    • Active transport against concentration  gradient with expenditure of energy
      • The carrier-mediated process may help water-soluble materials to pass the lipid layer of the cell membrane, whereas glucose and amino acids are absorbed by active transport.   

  • Pinocytosis  transport of intact luminal materials in the form of  vacuoles into the mucosal cells.  This is important for absorption of intact proteins and intact triglycerides.