When you “pull your tummy in” and compress your abdomen, you…

When you “pull your tummy in” and compress your abdomen, you use the rectus abdominis, external abdominal oblique, internal abdominal oblique, and transversus abdominis muscles. This is an example of muscles working as A. prime movers B. fixators C. synergists D. antagonists E. cooperatives   

A researcher discovered a new hormone that raises blood calc…

A researcher discovered a new hormone that raises blood calcium levels. According to the principles of negative feedback, this hormone would be secreted when A. blood calcium levels increase. B. blood calcium levels decrease. C. blood calcium levels are stable. D. blood calcium levels are elevated. E. None of these choices are correct.