I think its the immune system <span>¯\_(ツ)_/¯</span>
Explanation:
Proteins
<h2>Learn at brainly </h2>
The answer is a the nervous system
The nervous system is connected to your brain and controls each and every action in your body.
Direct observation is an observation you make first hand. It is something you see with your own eyes and observe yourself.
Hope this helps!