Final answer:
The gas content in blood changes with breathing, as O2 and CO2 are exchanged during gas exchange, and N's concentration remains relatively constant. The release of O2 from hemoglobin is influenced by the presence of CO2 and lactic acid, and NO can bind to hemoglobin to aid in vascular dilation.
Step-by-step explanation:
The composition of gases in the blood does not remain constant when breathing; it changes as a result of gas exchange. During respiration, oxygen (O2) is inhaled and transported to the body's cells, while carbon dioxide (CO2) is an output of cellular respiration and is exhaled. When we inhale, the partial pressure of oxygen is highest in the lungs, so it diffuses into the blood where its concentration is lower. Conversely, carbon dioxide has a higher concentration in the exhausted blood coming from cells and thus diffuses out into the lungs. Nitrogen (N) is not directly involved in this process; its concentration remains relatively constant as it is not easily absorbed by blood due to its inert nature.
Furthermore, the production of lactic acid and CO2 during muscle exertion leads to the Bohr effect, which causes a decrease in the affinity of hemoglobin for oxygen, thus stimulating the release of O2 from oxyhemoglobin. This helps to supply active muscles with more oxygen. Hemoglobin also binds nitric oxide (NO), which acts as a vasodilator and aids in improving blood flow and gas exchange.