IN THE VIDEO I SAW THAT NEIL ARMSTRONG'S  PULSE RATE WAS 156/MINUTE ON MOON .WHY THE PULSE RATE IS MORE ON MOON?????????

Normally, the human heart beats 72 times per minute. The heart rate depends on factors such as age, gender, amount of physical activity, the surrounding atmosphere, etc. The moon has no atmosphere. Therefore, there is no oxygen. No or low oxygen level in the blood causes the blood vessels to become narrow. This causes the heart to pump harder. It strains to get blood through the lungs. This inturn causes an increase in the heart rate and breathing rate. Therefore, the heart will beat faster (around 156-160 times per minute) on the moon and may eventually stop because it cannot continue to beat when it does not get oxygen.