Regulation of gas content in blood: Practice Questions

Carbon dioxide is transported from the tissues to the lungs in three main forms. In which location (blood component) is the vast majority (around 70%) of the carbon dioxide carried?

During vigorous exercise, the contraction of skeletal muscles significantly increases the volume of blood returning to the heart (venous return). Which of the following best explains how this increase in venous return contributes to the regulation of cardiac output during this period?

During intense aerobic exercise, the rate of cellular respiration greatly increases, producing large amounts of \(CO_2\). This metabolic activity leads to increased ventilation (breathing rate and depth). Which statement best explains why the regulation of breathing is primarily sensitive to blood \(CO_2\) concentration, even though \(O_2\) is also being depleted?

Which part of the autonomic nervous system is primarily responsible for increasing the heart rate and strength of contraction (stroke volume) in response to rising blood \(CO_2\) levels or stress?

In the context of the cardiac cycle, what does cardiac output represent, and how is it calculated?

Name the two main arterial locations where peripheral chemoreceptors are found that monitor blood gas content, particularly the partial pressure of oxygen.

When a person transitions from a state of vigorous exercise to rest, describe how the vagus nerve contributes to the regulation of gas content in the blood by acting on the pacemaker.

Describe the mechanism by which carbon dioxide (\(CO_2\)) from the blood leads to the stimulation of central chemoreceptors, specifically addressing the role of the blood-brain barrier and the chemical conversion within the cerebrospinal fluid. (5 marks)

Maintaining a stable gas content in the blood is essential for human physiological function.

(a) Explain the importance of maintaining a stable oxygen concentration in the blood. (2 marks)

(b) Briefly describe how the body detects changes in blood gas content and initiates a rapid response to regulate breathing. (2 marks)

The regulation of gas content in the blood is a vital homeostatic process. Suppose a person is resting in a room where the carbon dioxide levels are gradually increasing.

(a) Describe how the increase in blood carbon dioxide concentration is detected by the body. (2 marks)

(b) Explain how the respiratory centre responds to this stimulus to maintain the stability of the internal environment. (3 marks)