Question

Assertion: 70 per cent of \(\mathrm{CO}_{2}\) is carried as bicarbonate ion in plasma. Reason: If it is transported directly then \(\mathrm{pH}\) of blood becomes acidic.

Short answer

Yes, 70 per cent of CO2 is carried as bicarbonate ion in plasma to prevent the blood from becoming acidic. If CO2 is transported directly it will dissolve in water to form a weak acid, causing the blood to become acidic.

Step-by-step solution

Understand the Role of Bicarbonate ions

When carbon dioxide dissolves in water, it forms carbonic acid (\( H_2CO_3 \)), which can quickly react to form bicarbonate ions (\( HCO_3^- \)) and hydrogen ions (\( H^+ \)). These ions help regulate the pH level in blood.

Recognize the transportation phenomenon

A majority, about 70 per cent, of the CO2 is converted to bicarbonate ions and carried in the plasma. The rest of the CO2 either binds to hemoglobin and amino acids (making up approximately 23%) or dissolves directly into the plasma (making up approximately 7%). The transportation occurs in these ways to avoid an increase in the acidity of the blood.

Analyze the effect of direct transportation

If CO2 would be transported directly in the blood, the reaction with water to form an acid (H2CO3) would result in an increased concentration of H+ ions, turning the blood more acidic, thereby lowering the pH. This could lead to a condition called acidosis. Therefore, the body uses a majority of bicarbonate ions to transport CO2 to avoid this situation.

Key concepts

Bicarbonate Ions

Bicarbonate ions play a crucial role in the transport of carbon dioxide (CO2) in our blood. When CO2 enters the blood, it reacts with water to form carbonic acid (\( H_2CO_3 \)). This carbonic acid then swiftly dissociates to produce bicarbonate ions (\( HCO_3^- \)) and hydrogen ions (\( H^+ \)).

This transformation is essential because bicarbonate ions can move easily in the blood. They act as a buffer, helping to maintain the blood's pH at a stable level. This buffering capacity is crucial as it prevents the pH from becoming too acidic or too basic.

Approximately 70% of carbon dioxide is transported in the blood as bicarbonate ions, which makes them the primary carriers of CO2. This process efficiently prevents significant fluctuations in blood acidity as CO2 levels change. It's like a natural balance system, managing CO2 transport with finesse.

Blood pH Regulation

Keeping blood pH within a narrow range is vital for body function. The body's pH is slightly basic, typically ranging from 7.35 to 7.45. Any fluctuation outside this range can harm bodily functions. Bicarbonate ions are central to maintaining this delicate balance.

As they carry CO2, bicarbonate ions maintain equilibrium through a reversible reaction:

• When pH decreases (more acidic), bicarbonate can absorb excess hydrogen ions, reducing acidity.
• When pH increases (more basic), bicarbonate can release hydrogen ions, increasing acidity.

This buffering action stabilizes the pH by neutralizing any excess acids or bases introduced into the bloodstream.

The conversion of CO2 into bicarbonate is facilitated by an enzyme called carbonic anhydrase. This enzyme enhances the reaction speed, ensuring quick adjustment to any pH change, effectively keeping blood pH levels in their optimal range.

Acidosis Prevention

Acidosis occurs when blood becomes too acidic, with a pH level dropping below the normal range. It can lead to symptoms like fatigue, confusion, and even severe organ dysfunction. Preventing acidosis is vital, and the transformation of CO2 to bicarbonate ions plays a pivotal role here.

If CO2 were carried directly in the blood without conversion to bicarbonate, it would increase hydrogen ion concentration significantly. This increase would decrease the pH, leading to acidosis.

However, the body's conversion process prevents this. By converting CO2 into bicarbonate, the acidic potential of CO2 is neutralized. This reaction keeps the hydrogen ion levels in check, safeguarding against drastic drops in pH.

Therefore, efficient conversion to bicarbonate is crucial for keeping the body's pH in harmony and preventing the development of acidosis. This natural system of checks and balances is one of the body's many ways to maintain homeostasis, ensuring optimal health and function.