Exam 27: A: Physiology of the Respiratory System

A well profused but poorly ventilated part of the lung wastes blood.

The Bohr effect explains what happens to oxygen,whereas the Haldane effect explains what happens to carbon dioxide.

Internal respiration and cellular respiration refer to the same thing.

To produce the highest possible oxygen concentration in the blood,gas exchange occurs in only one direction at the respiratory membrane-from the lung to the blood.

Normal tidal volume is about 500 ml.

The transport of carbon dioxide will tend to lower blood pH.

The tendency of the lungs and thorax to return to their preinspiration volume is a physical phenomenon called elastic recoil.

About 10% of the carbon dioxide carried in the blood is simply dissolved in the plasma.

Increased cellular activity would decrease the carbon dioxide gradient between the cells and the arterial blood.

Charles law deals with the relationship between pressure and volume.

The partial pressure of oxygen in an artery is always lower than the partial pressure of oxygen in a vein.

Anatomical dead space contains air that does not ventilate the alveoli.

Although interstitial fluid and intracellular fluid oxygen partial pressure are not definitely established,they are known to stay within a very narrow range.

Because of tissue layers between alveolar air and the blood supply,arterial blood PO₂ is always less than alveolar PO₂.

The pneumotaxic center normally inhibits the apneustic center and the inspiratory center to permit a normal rhythm of breathing.

On a percentage basis,there is more carbon dioxide dissolved in the plasma than there is oxygen dissolved in the plasma.

The Hering-Breuer reflexes are activated by stretch receptors in the lungs that send messages to the inspiratory center.

For air to remain in the lungs,the pressure in the lungs must be equal to or less than atmospheric pressure.

In the lung,oxygen moves down its pressure gradient,whereas carbon dioxide moves up its pressure gradient.

The inspiratory capacity is equal to the sum of the tidal volume and the inspiratory reserve volume.