Topics:
Animal Physiology, Animal Refresher
Oxidation Product of Hemoglobin
The product of oxidation of hemoglobin is known as:
- Oxyhemoglobin
- Methemoglobin — Correct Answer
- Carboxyhemoglobin
- None
Explanation:
Correct Answer: Methemoglobin
Methemoglobin is the product of oxidation of hemoglobin, where the iron (Fe²⁺) in the heme group is oxidized to Fe³⁺ (ferric state).
Key Distinction — Oxidation vs Oxygenation
- Oxidation of Hb → Methemoglobin (Fe³⁺): Involves actual electron loss from iron (Fe²⁺ → Fe³⁺). Methemoglobin CANNOT bind or carry oxygen → reduces oxygen carrying capacity of blood. Leads to tissue hypoxia.
- Oxygenation of Hb → Oxyhemoglobin: Iron remains as Fe²⁺ but binds reversibly to O₂. This is a normal physiological process in the lungs. Iron does NOT change oxidation state during oxygenation.
Methemoglobinemia in Animals
- Caused by: Nitrate/nitrite poisoning (from nitrate-rich forages, water), oxidizing drugs (sulfonamides, chlorates).
- Signs: Chocolate-brown coloured blood, mucous membranes appear brown/cyanotic, dyspnea, weakness.
- Example: Cattle grazing on high-nitrate pastures (e.g., Sudan grass, oat stubble) can develop methemoglobinemia.
- Treatment: Methylene blue (1–4 mg/kg IV) — converts Fe³⁺ back to Fe²⁺.
📚 About this Topic — Animal Physiology
This multiple choice question is from Animal Physiology, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Physiology to strengthen your preparation.
