Changes

The total body content of sodium is regulated rather than the actual plasma concentration.  It would be impossible to regulate actual plasma concentration for 3 reasons:

The total body content of sodium is regulated rather than the actual plasma concentration.  It would be impossible to regulate actual plasma concentration for 3 reasons:

* When sodium is reabsorbed water follows it so the volume of the plasma is altered rather than the concentration of sodium changing

* When sodium is reabsorbed water follows it so the volume of the plasma is altered rather than the concentration of sodium changing

* [[Renin-Angiotensin-Aldosterone System (RAAS) - Anatomy & Physiology| Angiotensin 2]] and [[Aldosterone]] affect sodium but they also affect ECF volume so only quantity affected not concentration

* [[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#Effects of Angiotensin 2 On Sodium|Angiotensin 2]] and [[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#Aldosterone|Aldosterone]] affect sodium but they also affect ECF volume so only quantity affected not concentration

* ADH and thirst response also work together to dilute the ECF if concentrations of sodium is high so although there is more NaCl the actual concentration is not really changed.

* [[Pituitary Gland - Anatomy & Physiology #Posterior Pituitary Gland | ADH]] and thirst response also work together to dilute the ECF if concentrations of sodium is high so although there is more NaCl the actual concentration is not really changed.