Blood as a Buffer: Carbonic Acid-Bicarbonate Buffer System in Blood (A-level Chemistry)

Summary

The video script explains the buffer system in human blood, which maintains pH levels. It involves carbonic acid (H2CO3) and hydrogen carbonate ions (HCO3-). When H+ ion concentration increases, the equilibrium shifts left, removing excess H+ ions to prevent pH decrease. Conversely, a decrease in H+ ion concentration shifts the equilibrium right, increasing H+ ions and preventing pH increase. This system helps keep blood pH nearly constant.

Takeaways

• 🩸 The blood in humans has a buffer system involving carbonic acid (H2CO3) and hydrogen carbonate ions (HCO3-).
• 🔄 Hydrogen carbonate ions act as the conjugate base of carbonic acid in the buffer system.
• ↔️ If the concentration of H+ ions in the blood increases, the equilibrium between carbonic acid and hydrogen carbonate ions shifts to the left.
• 🛑 This shift helps remove the extra H+ ions, maintaining the pH balance in the blood.
• 📉 This process prevents a significant decrease in blood pH by keeping H+ ion levels stable.
• ➡️ Conversely, if the H+ ion concentration decreases, the equilibrium shifts to the right.
• ⬆️ This shift increases the H+ ion concentration, balancing the pH levels.
• ⚖️ The system ensures that both increases and decreases in H+ concentration are regulated, maintaining near-constant pH levels.
• 🧪 This dynamic equilibrium plays a crucial role in minimizing changes in blood pH.
• 🔬 The buffer system ensures homeostasis in blood pH, protecting the body from harmful pH fluctuations.

Q & A

What is the buffer system in human blood composed of?

The buffer system in human blood is composed of carbonic acid (H2CO3) and hydrogen carbonate ions (HCO3-).

What role do hydrogen carbonate ions play in the blood buffer system?

Hydrogen carbonate ions (HCO3-) act as the conjugate base of carbonic acid in the blood buffer system, helping to regulate pH by neutralizing excess hydrogen ions (H+).

What happens when the concentration of H+ ions increases in the blood?

When the concentration of H+ ions increases in the blood, the equilibrium between carbonic acid and hydrogen carbonate ions shifts to the left, causing the extra H+ ions to be removed, which helps maintain a nearly constant pH.

How does the buffer system respond to a decrease in H+ ion concentration in the blood?

If the H+ ion concentration decreases, the equilibrium shifts to the right, which increases the concentration of H+ ions, thereby minimizing any rise in pH.

What is the main purpose of the blood buffer system?

The main purpose of the blood buffer system is to maintain a stable pH by neutralizing changes in hydrogen ion concentration, ensuring that pH levels remain nearly constant.

What is the chemical formula for carbonic acid?

The chemical formula for carbonic acid is H2CO3.

Why is the equilibrium shift important in the blood buffer system?

The equilibrium shift is important because it allows the blood to either absorb or release H+ ions as needed, maintaining a stable pH and preventing dangerous fluctuations.

What could happen if the buffer system in the blood fails?

If the buffer system in the blood fails, pH levels could fluctuate significantly, potentially leading to conditions such as acidosis (low pH) or alkalosis (high pH), which can be harmful to the body.

How does the buffer system minimize decreases in pH?

The buffer system minimizes decreases in pH by removing excess H+ ions from the blood when their concentration increases, keeping the pH stable.

How does the body naturally regulate pH through the blood buffer system?

The body naturally regulates pH through the blood buffer system by shifting the equilibrium between carbonic acid and hydrogen carbonate ions in response to changes in H+ ion concentration, either removing excess H+ ions or generating more to maintain pH balance.