Is fear natural response to our brain

Answer: Yes.

Explanation: Fear is a chain reaction in the brain that starts with a stressful stimulus and ends with the release of chemicals that cause a racing heart, fast breathing and energized muscles, among other things, also known as the fight-or-flight response.

Yes, your body can tense up, feeling 'unsecured' or nervous, it's a sign that lets the brain know that your either frighten, scared, happy, hurt, etc. It's all natural, it's how the human body works!