Carbon dioxide

Definition

Carbon dioxide is a colorless, odorless gas produced by the metabolic process of respiration and the combustion of organic materials. It plays a crucial role in various physiological processes, particularly in the respiratory system where it is exchanged during breathing and transported throughout the body to maintain acid-base balance.

5 Must Know Facts For Your Next Test

1. Carbon dioxide is generated during cellular respiration, when glucose is broken down to produce energy.
2. In the lungs, carbon dioxide is expelled from the bloodstream and replaced with oxygen through gas exchange.
3. Carbon dioxide is transported in the blood in three forms: dissolved in plasma, as bicarbonate ions, and bound to hemoglobin.
4. The concentration of carbon dioxide in the blood helps regulate breathing rate; higher levels signal the body to increase respiration.
5. Maintaining proper levels of carbon dioxide is vital for acid-base balance; imbalances can lead to respiratory acidosis or alkalosis.

Review Questions

• How does carbon dioxide play a role in the respiratory process, particularly during gas exchange?
  • During gas exchange in the lungs, carbon dioxide diffuses from the blood into the alveoli, where it is expelled when we exhale. This process occurs because carbon dioxide levels are higher in the blood than in the alveoli, allowing it to move along its concentration gradient. Conversely, oxygen from inhaled air diffuses into the blood due to its higher concentration in the alveoli, highlighting the vital exchange of gases that occurs during respiration.
• Discuss the methods by which carbon dioxide is transported in the bloodstream and their significance to overall physiology.
  • Carbon dioxide is transported in the bloodstream primarily through three methods: dissolved in plasma (about 7%), as bicarbonate ions (around 70%), and bound to hemoglobin (approximately 23%). The conversion of carbon dioxide to bicarbonate ions is crucial for maintaining pH balance in the body. The ability of hemoglobin to carry both oxygen and carbon dioxide allows for efficient transport between tissues and lungs, facilitating effective gas exchange and ensuring proper cellular function.
• Evaluate the impact of elevated carbon dioxide levels on acid-base balance and overall health.
  • Elevated levels of carbon dioxide can lead to respiratory acidosis, a condition where excess CO2 causes a decrease in blood pH. This imbalance can result from hypoventilation or lung diseases that impair gas exchange. Prolonged respiratory acidosis can disrupt cellular functions and lead to severe health issues such as confusion, lethargy, and even coma if not corrected. The body may attempt to compensate by increasing respiratory rate or renal adjustments, but persistent high levels require medical attention to restore balance.

Related terms

Respiration:

The biochemical process in which cells convert glucose and oxygen into energy, producing carbon dioxide as a waste product.

Hemoglobin:

A protein in red blood cells that binds to oxygen for transport and also carries carbon dioxide from the tissues back to the lungs.

Acidosis:

A condition characterized by an excessive amount of acid in the body, often resulting from elevated levels of carbon dioxide.