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

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 gases

b. Respiratory surfaces that are infoldings of the body wall

c. Countercurrent exchange

d. A large, moist surface area for gas exchange

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.)

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.

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.

Why did separate systemic and pulmonary circulations evolve in species that have the high-pressure circulatory system required for rapid movement of blood?

Trace the path of an oxygen molecule in its journey from the air to a muscle cell in your arm, naming all the structures involved along the way.