Final answer:
Abnormally low paO2, known as hypoxemia, is when the partial pressure of oxygen falls below the normal level of 80 mmHg, leading to inadequate oxygenation of tissues and potential damage, especially to neurons. It can result from diminished oxygen transfer due to lower partial pressure differences across the respiratory membrane.
Step-by-step explanation:
Abnormally low paO2, or arterial partial pressure of oxygen, is referred to as hypoxemia. Hypoxemia occurs when the paO2 falls below the normal range, which is typically higher than 80 mmHg. As mentioned in Figure 20.10, this value is approximately 93.33 mmHg. When the paO2 value falls below normal, it can lead to ischemia, an insufficient blood flow, often accompanied by hypoxia, which is inadequate oxygenation of tissues. This is particularly dangerous for neurons, which may die or become damaged without quick restoration of blood flow and oxygen supplies.
Moreover, hypoxemia can compromise oxygen transport to the tissues as the amount of oxygen that crosses the respiratory membrane into the blood decreases when partial pressure of oxygen is low. This situation affects hemoglobin's oxygen binding capacity. Conditions like hypercapnia and hypocapnia refer to abnormally high and low blood levels of CO2 respectively, which are related to respiratory function impairments and hypoventilation or hyperventilation issues. Percent saturation, often monitored using a pulse oximeter, can indicate cases of hypoxemia when readings are lower than the normal 95-100 percent range.