Gas exchange in humans：練習題

Which statement correctly describes a characteristic of the gas exchange surface in the human lungs that helps maintain a steep concentration gradient?

Why does the rate and depth of breathing increase during physical activity?

Which feature is not characteristic of the gas exchange surfaces in the human lungs (alveoli)?

The graph shows the volume of air in a person's lungs over a period of 20 seconds. Based on the data, what is the ventilation rate (the total volume of air breathed in one minute) for this individual?

Which row correctly describes the actions of the diaphragm and the external intercostal muscles during inspiration (breathing in)?

Identify two structural features of the alveoli that adapt them for the efficient exchange of gases in the human lungs.

The diagram shows a cross-section of the lining of the trachea. Identify the two types of specialized cells labeled and explain how their structures protect the gas exchange surfaces from pathogens.

A student at rest has a breathing rate of \(12\) breaths per minute. During a short race, the rate increases to \(30\) breaths per minute. Calculate the percentage increase in the breathing rate and suggest why the depth of breathing also increases during exercise.

A student investigated the effect of exercise on their breathing rate. The data collected was used to produce a graph showing the breathing rate before, during, and after a 5-minute period of intense running.

(a) Using the information in the graph, describe the changes in breathing rate from time \(t = 5\) minutes to \(t = 15\) minutes.

(b) Explain why the breathing rate increases during exercise in terms of energy requirements and cell respiration.

Gas exchange in the lungs occurs across the surface of the alveoli. For efficient diffusion, a steep concentration gradient must be maintained between the air in the alveoli and the blood in the capillaries.

(a) Identify the gas that has a higher concentration in the blood than in the alveolar air as blood enters the lung capillaries.

(b) Explain how ventilation and blood flow work together to maintain a steep concentration gradient for oxygen at the gas exchange surface.