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SOLUTE REABSORPTION - Coggle Diagram

- - - - The transcellular pathway (mediated transport)
        
        Substances transported through transcellular pathway cross the apical plasma membrane and discharge across the basolateral plasma into interstitial fluid on the blood side of the cell
      - The paracellular pathway (passive transport)
        
        Substances pass through the paracellular pathway from the tubule fluid across zona occludens at the junction of the apical and basolateral plasma membrane domains
    - - MAMMAL
        
        the peritubular capillary originates at the glomerular efferent arteriole, subdivides and wraps closely around basal aspect of the proximal tubule
        
        the plasma leaving the glomerulus has high oncotic pressure because water and salts are filtered but proteins are retained in the capillary
        
        the peritubular capillary has low resistance and thus the hydrostatic pressure in the capillary is low
        
        high peritubular plasma oncotic pressure and low peritubular capillary hydrostatic pressure
        
        favor fluid and solute uptake from interstitium into the bloodstream
      - BIRDS
        
        presence of a renal portal circulation
        
        renal portal veins anastomose with the efferent arteriole and supply peritubular blood to reptilian-type nephrons and proximal and distale tubules of mammalian-types nephrons
        
        the tubules are supplied with a mixture of portal venous and arterial blood
  - - - SODIUM REABSORPTION AND POTASSIUM SECRETION
        
        Aldosterone release is stimulated by systemic hypotension through the RAS.
        
        Aldosterone act on connceting segment cells and principal cells of collecting duct to enhance Na+ reabsorption
        
        Aldosterone increases permeability of the apical plasma membrane Na+ channels and stimulates Na+,K+-ATPase activity
      - SODIUM TRANSPORT
        
        enhanced sodium transport by stimulating aldosterone release and angiotensin II
- - - - actively extrudes intracellular Ca2+ into interstitial fluid
    - - exchange extracellular Na+ for intracellular Ca2+
    - - CALCITONIN
        
        reduces the serum Ca2+ concentration by stimulating Ca2+ deposition in bone
      - PARATHYROID HORMONE (PTH)
        
        Hypecalemia (low plasma Ca2+ leve) stimulates parathyroid hormone release
        
        Affects bone, intestines and kidney to raise plasma Ca2+ level
        
        Parathyroid hormone increase apical uptake of Ca2+ in distal convoluted tubule by increasing the activity of the apical Ca2+ channel
        
        PTH also increases Cl-conductance at the basolateral plasma membrane which hyperpolarize the cells
        
        Thus increases the driving force for Ca2+ entry