Physical barriers
immune system
body temp
Answer:
True
Explanation:
I am pretty sure thats true...sorry if its wrong
Answer: Endorphins
Explanation: Endorphins are chemicals secreted by the brain also known as neurotransmitters that send electrical signals inside the nervous systems.
The factors that initiate the secretion of endorphins are stress and pain.
When endorphins are secreted they reduce feelings of pains, and in runners that cause a phenomenon called " Runners high" which allows runners to keep running without feeling pain or stress.
B is the answer to this question