What happens to the sodium and potassium ions when the neurons are stimulated. How does the concentration inside and outside the cell change

If you relate the doppler effect on sound to the color of light waves, a police car would be the color as it approaches and the color as it recedes away from the observer.

Wich is not standing in the way of astronomers getting a good view of different star

Which of these would most likely be a stimulus that would cause the body to initiate feedback mechanisms a.) normal body temperature in an arctic environment b.) normal boy temperature in a tropical environment c.)light physical activity d.)low blood sugar