Final answer:
Dehydration leads to an increase in hemoglobin and hematocrit due to a lower blood volume while maintaining the number of RBCs. Increased carbon dioxide levels and temperature decrease the affinity of hemoglobin for oxygen, affecting oxygen delivery to tissues. Conditions like sickle cell anemia and thalassemia reduce blood's oxygen-carrying capacity and can lead to complications such as hypovolemia.
Step-by-step explanation:
The changes occurring in the levels of hemoglobin and hematocrit (H&H) during dehydration and the resulting effects on the body can be effectively understood through oxygen-hemoglobin saturation/dissociation curve. In a dehydration state, the blood volume decreases leading to a higher concentration of red blood cells (RBCs) and thus, an increase in H&H. This is due to the fact that while the fluid volume decreases, the number of RBCs remains constant.
As the carbon dioxide levels increase in the blood, it reacts with water to form bicarbonate (HCO3) and hydrogen ions (H+), resulting in a decrease in pH. This process shifts the oxygen dissociation curve to the right, indicating a lower affinity of hemoglobin for oxygen. Consequently, more oxygen is required for the same level of hemoglobin saturation. Similarly, an increase in the body temperature reduces hemoglobin's affinity for oxygen. Conditions like sickle cell anemia and thalassemia affect the blood's oxygen-carrying capacity differently. Sickle cell anemia changes the shape of RBCs, causing obstruction in capillaries and thus impeding oxygen delivery. Thalassemia results in a high count of RBCs with abnormally low hemoglobin, impairing the oxygen-carrying capacity despite a high number of RBCs.
It is also crucial to note that with decreased blood volume (hypovolemia), the body's compensatory mechanisms work to maintain blood pressure to such an extent that individuals might not exhibit symptoms until a significant amount of blood volume has been lost. This condition requires prompt treatment through intravenous fluid replacement. Lastly, it's important to understand the Bohr effect where decreased blood pH, caused by increased carbon dioxide, promotes oxygen dissociation from hemoglobin, thus affecting tissue oxygenation.