The central structure of the digestive system is a muscular tube called the ______ that passes through the body from the _______ to the _______•

Eighty percent of our nutrients make the transition out of the digestive system along the length of the _______.

A central function of the digestive system is to get food into a form that can move into the _______.

Bile is a substance secreted by the _______ and stored and concentrated by the _______. The pancreas secretes _______ and _______ into the small intestine.

Food is moved along the length of the digestive tract through the action of sets of _______ in a process called _______.

Arrange the following parts of the digestive system in the order in which food passes through them: stomach, large intestine, esophagus, small intestine.

Some weightlifters take protein supplements in the belief that these supplements will provide them with additional energy. Based on what you learned about the dietary role of proteins, are these supplements likely to be doing weightlifters any good?

The essential functions of the digestive system are to (select all that apply):

a. add nutrients to food.

b. put food into a form that can be transferred into circulation.

c. filter waste products from the blood.

d. transfer digested food into circulation.

e. retain undigested food and eliminate it from the body.

Contrary to popular belief, urine normally has no bacteria in it at all. Indeed, the movement of urine down the urinary tract is one reason the kidneys and the bladder tend to stay free from infection—the flow of urine washes away any encroaching bacteria. Keeping this and the difference between male and female urethras in mind, why is it that women are more prone to bladder infections than men?

Which of the following is not part of the digestive system?

a. gallbladder

b. kidneys

c. liver

d. small intestine

e. pancreas

Suppose that instead of returning nearly all nutrients and 98 percent of fluids back into circulation, the kidneys could return only half these proportions. Could human beings function? How would it change the way they live?