The diaphragm is a large sheet of muscle that helps move air in and out of your lungs. Breathing is automatically controlled by the brain, but you can choose to hold your breath or breathe deeper. What kind of muscle do you suppose makes up the diaphragm? (Explain your answer.)

If a molecule of CO2 released into the blood in your left toe is exhaled from your nose, it must pass through all of the following excepta. the pulmonary vein.b. the trachea.c. the right atrium.d. the right ventricle.

In which of the following organisms does oxygen diffuse directly across a respiratory surface to cells, without being carried by the blood?a. a grasshopperb. a whalec. an earthwormd. a mous

What is the function of the cilia in the trachea and bronchi?a. to sweep air into and out of the lungsb. to increase the surface area for gas exchangec. to dislodge food that may have slipped past the epiglottisd. to sweep mucus with trapped particles up and out of the respiratory tract

What do the alveoli of mammalian lungs, the gill filaments of fish, and the tracheal tubes of insects have in common?a. use of a circulatory system to transport gasesb. respiratory surfaces that are infoldings of the body wallc. countercurrent exchanged. a large, moist surface area for gas exchange

Which of the following is not a true statement about open and closed circulatory systems? a. Both systems have some sort of a heart that pumps a circulatory fluid through the body. b. A frog has an open circulatory system; other vertebrates have closed circulatory systems. c. The blood and interstitial fluid are separate in a closed system but are indistinguishable in an open system. d. Some of the circulation of blood in both systems results from body movements.

Trace the path of blood starting in a pulmonary vein, through the heart, and around the body, returning to the pulmonary vein. Name, in order, the heart chambers and types of vessels through which the blood passes.

Predict how Antarctic icefish can transport enough oxygen in their blood to meet their needs even though they lack hemoglobin.

If blood were supplied to all of the body's capillaries at one time, a. blood pressure would fall dramatically. b. resistance to blood flow would increase. c. blood would move too rapidly through the capillaries. d. the amount of blood returning to the heart would increase.