Hemoglobin Derivatives: Oxy-, Deoxy-, Carboxyhemoglobin
Start with the big picture
Oxyhemoglobin carries bound oxygen and is associated with the relaxed, higher-affinity R-state; deoxyhemoglobin has no ligand bound and favors the tense, lower-affinity T-state. Their differing light-absorption patterns help explain pulse-oximetry principles and the visible appearance of blood. Carboxyhemoglobin forms when carbon monoxide binds heme. Its strong binding both occupies oxygen-binding sites and stabilizes the R-state, reducing oxygen availability to tissues. Because pulse oximetry does not distinguish oxyhemoglobin from carboxyhemoglobin, its reading can be misleading in carbon monoxide poisoning. The full lesson develops these structural, spectral, and clinical connections, including key considerations in poisoning management.
What you'll learn
- Distinguish oxyhemoglobin, deoxyhemoglobin, and carboxyhemoglobin by their bound ligands.
- Relate hemoglobin’s R-state and T-state to ligand binding and oxygen affinity.
- Describe how hemoglobin derivatives differ in color and light absorption.
- Explain why carbon monoxide can cause tissue hypoxia despite normal PaO₂.
- Recognize why pulse oximetry may appear normal in carbon monoxide poisoning.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
