Amy, a high-strung teenager, was suddenly startled by a loud bang that sounded like a gunshot. Her heartbeat accelerated rapidly. When she realized that the noise was only a car backfiring, she felt greatly relieved but her heart kept beating heavily for several minutes more. What hormone was released into her bloodstream that is causing this response

Catecholamines, endothelins, glucocorticosteroids and thyroid hormones.

Explanation:

Catecholamines, endothelins, glucocorticosteroids and thyroid hormones are the type of hormones that is released into the bloodstream that causes increase of heart rate. Stress and anxiety is responsible for the raising of your heart rate. It may also increases when you're very happy or upset. People who have severe obesity can have a slightly faster pulse as compared to normal people.

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.

not too sure but maybe in the hot springs.