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

ABSORPTION OF SALT AND WATER

• Sodium, K⁺ and Cl^- ions are almost completely absorbed. Na⁺ ions are involved in the transport of water, monosaccharides, amino acids, pyramidine and bile salts.
• Na⁺ is transported as
  • Na-co transport
  • Cl^- coupled transport  and
  • Diffusion by electro -chemical gradient.
• Chloride ions are transferred through Cl^- coupled Na⁺ transport
• Association with Na⁺ co-transport of glucose
• Diffusion by electro-chemical gradient.
• K⁺ is absorbed by passive diffusion due to concentration gradient.
• HCO₃ absorption is by active transport.
• Water is transported passively.
• Intestinal absorption of Ca⁺⁺ is by active transport. Vitamin D induces mucosal Ca⁺⁺ binding protein and increases Ca⁺⁺ absorption.
• Mg⁺⁺ is absorbed by active transport but its absorption is poor. Absorption of phosphorus is active process and related to active transport of Ca⁺⁺.
• Absorption of Fe⁺⁺ is related to its level in mucosal cell. Absorption is limited by binding capacity of apoprotein (carrier protein).
• Cu is absorbed in small amounts.
• Co and Mn are readily absorbed.
• Fat-soluble vitamins A, D, E and K pass through mucosa passively as also water-soluble vitamins. Vitamin B₁₂ requires an intrinsic factor secreted by stomach for its absorption by active transport.