In response to low blood pressure, the kidneys release renin, which activates the renin-angiotensin-aldosterone system to help increase blood pressure.

Aldosterone increases sodium reabsorption in the kidneys, which also leads to increased water retention and higher blood pressure.

The loop of Henle is primarily responsible for concentrating urine by creating a concentration gradient in the renal medulla.

The kidneys regulate acid-base balance primarily through the excretion of hydrogen ions and reabsorption of bicarbonate.

Fluid retention is a common consequence of renal failure due to the kidneys' inability to excrete excess fluid and waste.

The proximal convoluted tubule is primarily responsible for the reabsorption of glucose, along with other nutrients and ions.