Describe the effects of NE and Ach on contractile force that you observed today. Given your knowledge of sympathetic and parasympathetic nervous system anatomy, which neurotransmitter should have resulted in a more dramatic change in contractile force and why?

The answer is Norepinephrine.

Explanation:

Acetylcholine (Ach) and Norepinephrine (NE) are both chemical substances (neurotransmitters) released primarily by nerve cells and they affect different parts and systems of the body. Acetylcholine mostly targets the muscles and the brain and it is a part of the parasymphatetic nervous system whereas norepinephrine targets the whole body and has an effect that leads to the contraction of muscles and the increase of the heart rate. Norepinephrine is a part of the symphatetic nervous system.

Since the symphatetic nervous system is responsible for the crucial "fight-or-flight" response of our body, it has a more dramatic effect on the muscle contraction. Norepinephrine, being a part of the symphatetic nervous system, should result in a more drastic change in contractile force.

I hope this answer helps.