The 'Bohr Effect' describes the relationship between:

RML Lucknow - 2021

Applied Physiology

Easy

Appeared in: RML Lucknow - 2021

Explanation

The Bohr effect is a physiological phenomenon where hemoglobin's affinity for oxygen is inversely related to the concentration of carbon dioxide and the acidity (H+ ion concentration) of the blood.
In tissues with high metabolic activity, increased CO₂ and lower pH cause hemoglobin to release oxygen more easily. This is represented by a rightward shift in the oxyhemoglobin dissociation curve.
Conversely, in the lungs, lower CO₂ levels and higher pH increase hemoglobin's affinity for oxygen, facilitating efficient oxygen uptake from the alveoli.

Option B: The relationship between blood pressure and heart rate is primarily regulated by the baroreceptor reflex, a fast-acting neural pathway for cardiovascular homeostasis.
Option C: This describes the endocrine feedback mechanism for blood glucose control, where the pancreas releases insulin in response to high glucose levels.
Option D: The relationship between lung volume and respiratory rate is governed by the neural control of breathing, involving respiratory centers in the brainstem and reflexes like the Hering-Breuer reflex.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiology of Gas Exchange: Bohr Effect as background academic context rather than a clinical decision trigger.
Understanding the Bohr effect is crucial for nurses interpreting arterial blood gas (ABG) results. Conditions like metabolic or respiratory acidosis lower blood pH, enhancing the Bohr effect to improve oxygen delivery to tissues, but can also impair oxygen uptake in the lungs if severe.
In clinical practice, this principle explains why patients with fever (increased temperature) or sepsis (lactic acidosis) have an increased demand for oxygen and why their hemoglobin unloads oxygen more readily at the tissue level.
What if? A patient is hyperventilating due to an anxiety attack. They will 'blow off' excess CO₂, leading to respiratory alkalosis (increased pH). This shifts the oxyhemoglobin curve to the left, increasing hemoglobin's affinity for oxygen and making it harder to release to the tissues. This can cause symptoms like dizziness and peripheral tingling (paresthesia).

How to Approach the Question

Identify the key term in the question stem, which is 'Bohr Effect'.
Recognize this as a factual recall question from physiology, specifically related to gas transport in the blood.
Systematically evaluate each option against the definition of the Bohr effect.
Option A directly links hemoglobin's oxygen affinity to CO₂ concentration, which is the core of the Bohr effect.
Eliminate the other options by identifying the distinct physiological mechanisms they describe: baroreceptor reflex (Option B), endocrine regulation (Option C), and respiratory control (Option D).

Concept Tested & Keywords

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