Questions

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.

Neza-Chalco-Itza is one of Mexico City's barrios(slums). Most of its approximately four million inhabitants live there illegally. Mexico City's slums have been growing for more than 100 years, after the railways allowed new industry to beign in the city. 

Force of impact is the force when the objects meet. The speed of the object plays an important role in the generation of force of impact. The laws of physics determine that the force of impact increases with the square of the increase in speed.