Answer:
Parasympathetic nervous system
Explanation:
Parasympathetic nervous system (PNS) along with sympathetic nervous system (SNS) makes autonomic nervous system (ANS). ANS controls the functioning of internal processes like digestion rate, heart rate, respiratory rate etc. During a threat or stressful situation SNS is activated. It increases heart rate, respiratory rate and directs blood flow towards peripheral muscles as a part of "fight or flight response". When the situation becomes normal, PNS is activated which restores all the vitals as a part of "rest and digest" mechanism.
Since here Byron almost got into an accident, he was scared a lot due to which his SNS was activated. Eventually when he realized that he is out of danger, his PNS got activated which returned his heart rate and blood pressure to normal levels.
Answer: More than 99 percent of all organisms that have ever lived on Earth are extinct. As new species evolve to fit ever changing ecological niches, older species fade away. But the rate of extinction is far from constant. At least a handful of times in the last 500 million years, 75 to more than 90 percent of all species on Earth have disappeared in a geological blink of an eye in catastrophes we call mass extinctions.
Though mass extinctions are deadly events, they open up the planet for new forms of life to emerge. The most studied mass extinction, which marked the boundary between the Cretaceous and Paleogene periods about 66 million years ago, killed off the nonavian dinosaurs and made room for mammals and birds to rapidly diversify
