Hemoglobin bind with oxygen is termed as?

Appeared in: SGPGI Nursing Officer-2022

Explanation

Oxyhemoglobin (HbO₂) is the correct term for hemoglobin that has reversibly bound to oxygen.
This binding process, known as oxygenation, occurs at the iron atom within the heme group of the hemoglobin molecule.
The formation of oxyhemoglobin happens primarily in the capillaries of the lungs, where the partial pressure of oxygen is high.
It is responsible for the characteristic bright red color of arterial blood and is essential for transporting oxygen to the body's tissues.

Option B: Carbaminohemoglobin is formed when carbon dioxide (CO₂) binds to hemoglobin, not oxygen.
Option C: Carboxyhemoglobin is formed when carbon monoxide (CO) binds to hemoglobin, not oxygen.
Option D: This option is incorrect because there is a correct term among the choices for hemoglobin bound with oxygen.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Gas Transport by Hemoglobin as background academic context rather than a clinical decision trigger.
A nurse uses a pulse oximeter to measure a patient's oxygen saturation (SpO₂), which represents the percentage of hemoglobin that is in the form of oxyhemoglobin. A normal SpO₂ is typically 95% or higher.
Recognizing the signs of carbon monoxide poisoning (which forms carboxyhemoglobin) is a critical nursing skill. Symptoms can include headache, dizziness, nausea, and confusion, progressing to collapse and death. A key sign can be cherry-red skin, although this is often a late finding. The priority nursing intervention is to administer 100% high-flow oxygen.
What if? If a patient is rescued from a house fire, a standard pulse oximeter might show a falsely high reading (e.g., 99%). This is because most pulse oximeters cannot distinguish between oxyhemoglobin and carboxyhemoglobin. The nurse must suspect CO poisoning and advocate for a co-oximetry blood test to measure the actual carboxyhemoglobin level.

How to Approach the Question

First, identify the core concepts in the question: 'hemoglobin' and 'oxygen'.
The question asks for the specific term for the compound formed when these two substances bind.
This is a direct factual recall question based on respiratory physiology.
Analyze the prefixes of the options: 'Oxy-' relates to oxygen, 'Carbamino-' relates to carbon dioxide and an amino group, and 'Carboxy-' relates to carbon monoxide.
Based on the prefix 'Oxy-', select Oxyhemoglobin as the logical answer for the binding of oxygen.

Concept Tested & Keywords

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E6 Physiology Essentials Sembulingam 10e Part 1 pp. 95-97, 94-96

E6 Biochemistry U Satyanarayana— Part 1 (pp 26-420 of 840) p. 191-193

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