Wat is the bloods ph......and how does our body maintains its ph?

The level of acidity: The level of acidity is the ph. Humans, and life in general, function inside a very narrow range of proper ph. Excess acidity has to be neutralized back to normal ph by chemicals that act as "buffers". If there is not enough acidity, the buffers can increase the acidity back to normal ph. Breathing out carbon dioxide gets rid of excess acidity. Some acidity goes out in the urine.

7.40: It seldom deviates far, and below 7.2 or above 7.6 it's seriously concerning and the person is usually obviously sick. The kidney handles it from hour to hour, the lungs from minute to minute by blowing off carbon dioxide (carbonic acid equivalent) as needed.