increasing blood pressure

[fluff]

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aldosterone functions to cause an influx of sodium into the blood, thereby increasing blood pressure. the hormone also causes an increase in water reabsorption.

i have two questions:

1) is the increase in water reabsorption due to the movement of sodium into the blood (osmotic gradient)?

2) is the increase in blood pressure solely a function of the movement of ions such as sodium? in other words, if there is movement of water into the blood without the movement of any ions, the blood pressure remains the same...is this correct?

 

[VanBrown]

the increase in blood pressure due to aldosterone action is secondary. Water follows the sodium.

you should also remember that aldosterone increases Cl- reabsorption both in the distal tubule and in the sweat glands.

the overall effect is to limit water loss.

also a useful way to remember the difference between the actions of ADH and aldosterone is to remember that aldosterone is a mineralcorticoid which means that it regulates ions.

 

[Charles_Carmichael]

1. Aldosterone increases salt reabsorption. Water follows. So, the water reabsorption is secondary to salt reabsorption.

2. Blood volume is a major determinant of blood pressure. High blood volume would mean a higher blood pressure. Water wouldn't be reabsorbed without the movement of ions; there needs to be an osmotic gradient for water to move.

Edit: VanBrown beat me.