Connections: Diuresis

• what are the four kinds of mediated transport?

  - facilitated diffusion

  - primary active transport

  - secondary active transport

  - ion channels
• explain the importance of solute concentration concerning water movement; what is the starling force associated with this relationship?

  high osmolarity -> low osmolarity

  • water will move to area of high concentration
• what are two endogenous substances that regulate Na+ and water reabsorption?

  ADH & aldosterone
• what are the stimuli for the release of ADH and aldosterone?

  dehydration, sweating, overhydration, blood loss

  
• loop diuretics act within the loop of Henle to decrease Na+ reabsorption from the tubule; where specifically do they act in the loop of Henle, and what transporter is being affected?

  ascending limb; NKCC transporter
• what ions are associated with the NKCC transporter? what are the specific changes to the movement of these ions from inhibition of this transporter?

  less reabsorption of Na+, Cl-, and K+
• potassium-sparing diuretics spare potassium while increasing water excretion through manipulation of Na+ transport and thus water movement

  • what type of actions can you guess this type of diuretic has?

  decrease Na+ reabsorption and inhibit aldosterone
• osmotic diuretics are the final type of diuretics; they are freely filtered at the glomerulus but not reabsorbed or secreted afterward; how might this diuretic control water?

  increase GFR and decrease Na+ reabsorption
• congestive heart failure is a failure of the heart to adequately eject blood into circulation; this will lead to a backup of blood into the venous side of the capillaries

  • what are the implications of the decreased CO as well as this backup of blood flow?
  • why would diuretics be useful here?

  1.) decreased MAP; ^ symp; ^ vasoconstriction; decreased Na+ secretion; ^ fluid retention; need diuretic to excrete fluid

  2.) ^ aldosterone released; ^ Na+ reabsorption, ^ H2O reabsorption; causes swelling
• uncontrolled hypertension, or chronically elevated blood pressure, is another disease in which diuretics can be useful; how might the use of diuretics be useful for this disease?

  starling forces:

  ^ MAP causes edema in ECF; diuretics allow more water to be filtered