|A) when the pH of the urine decreases||B) when the specific gravity of urine rises above 1.10|
|C) when the peritubular capillaries are dilated||D) by a decrease in the blood pressure|
The kidneys are stimulated to produce renin by a decrease in the blood pressure.
The renin-angiotensin system or RAS regulates blood pressure and fluid balance in the body. When blood volume or sodium levels in the body are low, or blood potassium is high, cells in the kidney release the enzyme, renin. Renin's primary function is therefore to eventually cause an increase in blood pressure, leading to restoration of perfusion pressure in the kidneys.