Hemoglobin Allosteric Effectors and Oxygen Dissociation

Vocabulary flashcards covering allosteric effectors of hemoglobin, the Bohr effect, oxygen dissociation curve shifts, and P50 parameters.

Hydrogen Ions ($H^+$)

An allosteric effector of hemoglobin where an increased concentration of $H^+$ lowers hemoglobin $O_2$ affinity, which helps hemoglobin unload $O_2$ in metabolically active tissues.

Carbon Dioxide ($CO_2$)

An allosteric effector where higher levels of $CO_2$ promote $O_2$ unloading and contribute to the Bohr effect through its effects on pH.

2,3-BPG

An allosteric effector that binds preferentially to deoxyhemoglobin, stabilizes the T state, and decreases $O_2$ affinity to help hemoglobin release $O_2$ to tissues.

Bohr Effect

A physiological phenomenon describing how increased $CO_2$ and $H^+$ decrease hemoglobin's $O_2$ affinity.

Active Tissue Conditions (Bohr Effect)

Conditions in active tissues where $CO_2$ increases, $H^+$ increases, and pH decreases, causing hemoglobin to release more $O_2$ and shifting the oxygen dissociation curve to the right.

Right Shift (Oxygen Dissociation Curve)

A shift in the oxygen dissociation curve that signifies lower $O_2$ affinity, meaning hemoglobin releases $O_2$ more easily.

Left Shift (Oxygen Dissociation Curve)

A shift in the oxygen dissociation curve that signifies higher $O_2$ affinity, meaning hemoglobin holds onto $O_2$ more strongly.

$$P_{50}$$

The oxygen partial pressure at which fractional saturation $Y = 0.50$, or 50% saturation.

Relationship Between $P_{50}$ and $O_2$ Affinity

An inverse relationship where $P_{50}$ and affinity go in opposite directions; a higher $P_{50}$ means lower $O_2$ affinity, while a lower $P_{50}$ means higher $O_2$ affinity.