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?

Most of the nutrients in the food we eat make the transition out of the digestive system in:

a. the stomach.

b. the liver.

c. the small intestine.

d. the large intestine.

e. the pancreas.

Which of the following are energy-yielding nutrients?

a. proteins

b. minerals

c. lipids

d. carbohydrates

e. vitamins

In nutrition, calories are (select all that apply):

a. units of weight.

b. a units of energy.

c. most densely packed in carbohydrates.

d. most densely packed in lipids.

e. optional components of human nutrition.

Unprocessed carbohydrates generally have the advantage of providing a relatively (select all that apply):

a. low glycemic load.

b. high amount of fiber.

c. high glycemic load.

d. low amount of fiber.

e. large array of vitamins and minerals.

Saturated fats (select all that apply):

a. lower circulating LDL levels.

b. raise circulating LDL levels.

c. are supplied mostly by animal sources.

d. are supplied mostly by plant sources.

e. lower the risk of coronary heart disease.

In addition to filtering waste from the body, what are two other critical functions of the kidneys?

a. storage of blood, distribution of nutrients

b. production of urea, production of hemoglobin

c. regulation of blood volume, conservation of useful materials

d. production of hemoglobin, channeling of lymphatic fluid

e. storage of nutrients, regulation of digestive system

The two central functions of respiration are capturing and distributing _______ and disposing of _______.

The air-exchange chambers of the lungs are tiny sacs called _______, which are surrounded by _______.