How do pairs of skeletal muscles work together?
a. both muscles contract at the same time.
b. both muscles extend at the same time.
c. while one muscle in the pair contracts, the other returns to its original length.
d. one muscle in the pair pulls on a bone, while the second muscle pulls on the
first muscle.

Sally is a 43-year-old mother of two who has gained 50 pounds over the past 5 years. she is 64 inches tall and weighs 180 pounds with a bmi of 30.8. her waist circumference is 37 inches. she acknowledges that she is not as physically active as she would like to be. she also notes how recent stresses in her life have affected her sleep and seem to have triggered her appetite for sweets and comfort foods. sally's father recently died from complications of type 2 diabetes, and her mother and sisters are overweight. sally says she is very motivated to "not get diabetes" and is disturbed that her recent physical exam revealed mildly elevated blood pressure, glucose, and cholesterol levels. 1. sally stated that recent stresses in her life are affecting her sleep and seemed to have triggered her appetite for sweets and comfort foods. which of the following statements would be best to explain why her lack of sleep has increased her appetite? a. lack of sleep decreases ghrelin levels. b. levels of neuropeptide y, a brain chemical that causes carbohydrate cravings, are high and may contribute to her sleep problems. c. the satiety hormone leptin increases with lack of sleep. d. lack of sleep increases uncoupling protein. e. lack of sleep increases levels of ghrelin which stimulates appetite and decreases levels of leptin which decreases appetite.