|A) adrenaline||B) acetylcholine|
|C) thyroxine||D) pituitrin|
Answer: A) adrenaline
The hormone adrenaline also called epinephrine is known as a stress harmone. In emotional upset (like fear, anger etc.) this harmone is poured into the blood and it accelerates heart beat. The hormone acetylcholine decelerates heartbeat rate.