During exercise, the cardiovascular system must supply muscles with large amounts of oxygen and fuel and get rid of a lot of wastes. How do the cardiovascular systems of athletes respond to prolonged exercise? During athletic training, the oxygen–hemoglobin dissociation curve a. shifts to the right, unloading more oxygen to tissues. b. shifts to the right, unloading less oxygen to tissues. c. shifts to the left, unloading more oxygen to tissues. d. shifts to the left, unloading less oxygen to tissues.

Verified step by step guidance

1. During exercise, muscles require more oxygen for aerobic respiration and produce more carbon dioxide as a waste product. The cardiovascular system adapts to efficiently meet these demands.
2. The oxygen-hemoglobin dissociation curve is a graph that shows the relationship between the partial pressure of oxygen and the percentage of hemoglobin saturated with oxygen. It helps in understanding how readily hemoglobin acquires and releases oxygen molecules into the blood.
3. During prolonged exercise, the body produces more carbon dioxide, which increases the acidity (lowers the pH) of the blood. This condition is known as the Bohr effect, which causes the oxygen-hemoglobin dissociation curve to shift to the right.
4. A rightward shift in the dissociation curve indicates that at a given partial pressure of oxygen, hemoglobin releases more oxygen to the tissues. This is crucial during exercise as active muscles consume more oxygen.
5. Therefore, the correct answer is: a. shifts to the right, unloading more oxygen to tissues.

Key Concepts

Oxygen-Hemoglobin Dissociation Curve

The oxygen-hemoglobin dissociation curve illustrates how readily hemoglobin binds to oxygen and releases it to tissues. A rightward shift indicates that hemoglobin releases oxygen more easily, which is beneficial during exercise when tissues require more oxygen. Conversely, a leftward shift means hemoglobin holds onto oxygen more tightly, reducing oxygen delivery to tissues.

Cardiovascular Response to Exercise

During prolonged exercise, the cardiovascular system adapts by increasing heart rate, stroke volume, and blood flow to active muscles. These changes enhance oxygen delivery and nutrient supply while facilitating the removal of metabolic wastes like carbon dioxide and lactic acid, ensuring that muscles can sustain activity over time.

Physiological Adaptations in Athletes

Athletes undergo physiological adaptations that improve their cardiovascular efficiency, such as increased capillary density and enhanced mitochondrial function in muscle cells. These adaptations allow for better oxygen utilization and energy production, enabling athletes to perform at higher intensities for longer durations during training and competition.