During exercise, the cardiovascular system must supply muscles with large amounts of oxygen and fuel and get rid of a lot of waste.
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. Understand the oxygen–hemoglobin dissociation curve: This curve represents the relationship between the partial pressure of oxygen and the saturation of hemoglobin with oxygen. It is crucial for understanding how oxygen is delivered to tissues.
2. Consider the effects of exercise on the body: During prolonged exercise, muscles require more oxygen to sustain activity, and the body needs to efficiently deliver this oxygen to the tissues.
3. Analyze the shift in the curve: A rightward shift in the oxygen–hemoglobin dissociation curve indicates that hemoglobin releases oxygen more readily to the tissues. This is beneficial during exercise as it allows more oxygen to be available for muscle use.
4. Evaluate the options: Given the need for increased oxygen delivery during exercise, the correct response would involve a shift that facilitates more oxygen unloading to tissues.
5. Select the correct answer: Based on the analysis, the cardiovascular system of athletes during prolonged exercise would likely cause the oxygen–hemoglobin dissociation curve to shift to the right, unloading more oxygen to tissues.

Key Concepts

Cardiovascular System Adaptations

During prolonged exercise, the cardiovascular system adapts by increasing cardiac output, which is the volume of blood the heart pumps per minute. This is achieved through a higher heart rate and stroke volume, allowing more oxygen and nutrients to reach the muscles. Over time, athletes develop a more efficient cardiovascular system, with increased capillary density and improved blood flow to active tissues.

Oxygen-Hemoglobin Dissociation Curve

The oxygen-hemoglobin dissociation curve illustrates how readily hemoglobin in the blood releases oxygen to tissues. A rightward shift in the curve indicates that hemoglobin releases more oxygen at a given partial pressure, which is beneficial during exercise as it enhances oxygen delivery to active muscles. Factors like increased temperature, CO2, and acidity during exercise promote this shift, facilitating better oxygen unloading.

Bohr Effect

The Bohr effect describes the physiological phenomenon where an increase in carbon dioxide concentration and a decrease in pH result in hemoglobin proteins releasing their load of oxygen. This effect is crucial during exercise, as active muscles produce more CO2 and lactic acid, lowering blood pH and causing the oxygen-hemoglobin dissociation curve to shift to the right, thus enhancing oxygen delivery to tissues.