Final answer:
The aspect being referred to likely involves the body's oxygen consumption and carbon dioxide production, especially how these processes are adjusted during exercise versus at rest, and how the respiratory system, encompassing processes like external and internal respiration, supports these metabolic demands. The correct option is A.
Step-by-step explanation:
Considering the context of exercising tissue, tissues at rest, and lungs, the aspect being referred to relates to internal processes regarding oxygen and carbon dioxide in the body. During exercise, the metabolic rate increases, necessitating a higher oxygen consumption and increased carbon dioxide production. The respiratory system adjusts to these demands through hyperpnea, enhancing the supply of oxygen and the elimination of carbon dioxide.
The basal metabolic rate (BMR) reflects the energy used at rest, and it is closely tied to oxygen consumption since energy production in the body is dependent on the oxidation of food. When we discuss the lungs and their function, we refer to external respiration, which involves gas exchange (oxygen in, carbon dioxide out) between the lungs and the blood, and also internal respiration, the exchange of gases between the blood and the tissues.
Different fuels such as glucose, protein, and fat can alter the respiratory quotient (RQ), which is the ratio of carbon dioxide produced to oxygen consumed, indicating which type of substrate is being used for metabolism.