Explain what the core muscles do and why it's important to have a strong set of core muscles.

Explain how unhealthful weight loss or weight gain can lead to further weight loss or weight gain.

Check all that occur during ventricular systole. a. the av valves open to allow blood to enter the ventricles from the atria. b. the av valves open to allow blood to enter the ventricles from the atria. c. the semilunar valves remain closed throughout systole to prevent backflow of blood into the ventricles. d. the semilunar valves remain closed throughout systole to prevent backflow of blood into the ventricles. e. the semilunar valves open to allow blood to flow into the large arteries. f. the semilunar valves open to allow blood to flow into the large arteries. g. the av valves close to prevent backflow of blood into the atria.

Which of these is a fact about performance enhancing drugs? a. steroids lack addictive properties. b. steroids use can cause dangerous side effects. c. it is safe to use steroids when working out. d. a person can get in legal trouble for using steroids.