Question

Low pH, high CO\textsubscript{2, high temperature shifts the oxygen-haemoglobin dissociation curve towards}

• A. Left side
• B. Right side
• C. Remains same
• D. Upper side

Hint:

Remember the factors that shift the oxygen-haemoglobin dissociation curve to the \textbf{right} (decreased affinity, more O\textsubscript{2} released to tissues): R = \textbf{R}ight shift R = \textbf{R}eleased O\textsubscript{2} D = \textbf{D}ecreased affinity Conditions (mnemonic "CADET"): \textbf{C}O\textsubscript{2} (increased) \textbf{A}cid (increased H\textsuperscript{+} / decreased pH) \textbf{D}PG/BPG (increased 2,3-bisphosphoglycerate) \textbf{E}xercise (metabolism increases all these factors) \textbf{T}emperature (increased) A left shift implies increased affinity and less O\textsubscript{2} released.

Answer 1

The Correct Option is B

Step 1: Understand the Oxygen-Hemoglobin Dissociation Curve
The oxygen-hemoglobin dissociation curve illustrates the relationship between the partial pressure of oxygen (PO\textsubscript{2}) and the percentage of hemoglobin saturated with oxygen. It is typically S-shaped. Step 2: Analyze the given conditions and their effect on the curve (Bohr Effect)
The conditions mentioned – low pH, high CO\textsubscript{2}, and high temperature – are all factors that decrease the affinity of hemoglobin for oxygen. This phenomenon is known as the Bohr effect for pH and CO\textsubscript{2}, and also applies to temperature. Low pH (high H\textsuperscript{+} concentration): An increase in H\textsuperscript{+} ions (more acidic environment) binds to hemoglobin, reducing its affinity for oxygen. High CO\textsubscript{2:} High partial pressure of carbon dioxide (PCO\textsubscript{2}) also reduces hemoglobin's affinity for oxygen. CO\textsubscript{2} can directly bind to hemoglobin (forming carbaminohemoglobin) or lead to increased H\textsuperscript{+} concentration through the formation of carbonic acid.
High temperature: An increase in temperature weakens the bond between oxygen and hemoglobin.
These conditions are characteristic of metabolically active tissues (e.g., muscles during exercise), where more oxygen needs to be released from hemoglobin. Step 3: Determine the shift in the curve
When hemoglobin's affinity for oxygen decreases, it means that at a given partial pressure of oxygen, less oxygen will be bound to hemoglobin, or conversely, more oxygen will be released. Graphically, this is represented by a shift of the oxygen-haemoglobin dissociation curve to the right. A rightward shift signifies that hemoglobin is releasing oxygen more readily. Step 4: Conclude the correct option
Therefore, low pH, high CO\textsubscript{2}, and high temperature all cause the oxygen-haemoglobin dissociation curve to shift to the right.