Final answer:
Decreased blood pH near active muscles during exercise causes vasodilation, enhancing blood flow to satisfy the increased metabolic demand. Vasodilation reduces resistance in blood vessels and is a part of the body’s adaptive cardiovascular response to physical activity.
Step-by-step explanation:
The correct option : a
Decreased blood pH near working muscles during exercise causes local vasodilation. This response increases blood flow to the active muscles, delivering more oxygen and nutrients, and removing waste products such as carbon dioxide. During vigorous exercise, the muscles produce lactic acid and carbon dioxide which decreases the pH of the blood. The body's autoregulatory mechanisms detect this decrease in pH and induce vasodilation to enhance blood flow and support the increased metabolic demand of the muscles.
Essentially, vasodilation acts to decrease the resistance in the blood vessels, which results in an increased blood supply to the working muscles. Endothelins, which normally help to constrict blood vessels, are overridden by other factors during exercise, leading to vasodilation instead. This adaptive response is crucial for the body to maintain optimal function during periods of increased physical stress.
The described process is an example of how the body's cardiovascular system adjusts to ensure that tissues such as skeletal muscles receive adequate oxygen and nutrients during periods of increased activity. It also demonstrates the body's capability to selectively dilate or constrict blood vessels in different organs, depending on the current physiological needs, such as directing more blood flow to the muscles and less to the digestive and reproductive organs during exercise.