Question

Carbon monoxide is harmful to human beings as it (a) is carcinogenic (b) is antagonistic to \(\mathrm{CO}_{2}\) (c) has higher affinity for haemoglobin as compared to oxygen (d) is destructive to \(\mathrm{CO}_{2}\).

Short answer

The harmful effect of CO is due to its higher affinity for haemoglobin as compared to oxygen, which disrupts oxygen transport within the body.

Step-by-step solution

Identifying the Harmful Effect of CO on Human Health

To understand why carbon monoxide (CO) is harmful, we need to know about its interaction with hemoglobin, a protein in red blood cells that carries oxygen. CO competes with oxygen by binding to the same spot on the hemoglobin molecule.

Understanding Affinity of CO to Hemoglobin

The affinity of CO for hemoglobin is much higher, about 200-250 times more, than that of oxygen. This high affinity means CO can bind to hemoglobin more easily, thus preventing oxygen from binding and being transported to different parts of the body.

Analyzing the Given Options

Analyze each given option to determine which correctly explains why CO is harmful. (a) Carcinogenic properties pertain to cancer, not directly related to how CO affects oxygen transportation. (b) Antagonistic to \(\mathrm{CO}_{2}\) doesn't accurately describe CO's effect on oxygen transport. (c) CO's higher affinity for haemoglobin compared to oxygen directly explains how it interferes with oxygen transport. (d) Destructive to \(\mathrm{CO}_{2}\) is incorrect as CO does not destroy carbon dioxide.

Identifying the Correct Option

Based on our analysis, we conclude that option (c) is correct because CO's higher affinity for hemoglobin prevents oxygen from binding to hemoglobin, disrupting the transport of oxygen in the body.

Key concepts

Hemoglobin and Gas Exchange

Hemoglobin is a critical protein found in red blood cells imperative for gas exchange. It transports oxygen from the lungs to various tissues throughout the body and carries carbon dioxide back to the lungs for exhalation.
In this intricate exchange, oxygen molecules bind to hemoglobin at sites called heme groups. When you inhale, oxygen from the air enters your lungs and attaches to hemoglobin. As the blood circulates, oxygen detaches and is delivered to cells that use it for vital processes.

Affinity Matters

However, this process entails a delicate balance. The efficiency of oxygen transport relies on hemoglobin's affinity for oxygen. High affinity means oxygen binds tightly but may not release readily where needed, while low affinity allows for easy release but can also hinder pick up from the lungs.
This balance ensures that our bodies function correctly, emphasizing the importance of hemoglobin's role in healthy respiration and why any interference can have detrimental effects.

Affinity of CO to Hemoglobin

Carbon monoxide's danger lies in its misleading similarity to oxygen, at least in the eyes of hemoglobin. The affinity of CO for hemoglobin is alarmingly high—about 200 to 250 times greater than that of oxygen.
When CO is inhaled, it binds to the heme groups on hemoglobin with voracity, forming a stable complex called carboxyhemoglobin. This process usurps the spots typically reserved for oxygen.

A Dangerous Displacement

Due to this high affinity, even low concentrations of CO can be harmful. It prevents adequate oxygen from binding to hemoglobin, essentially suffocating cells on a molecular level. This illustrates the critical fact that not all gas interactions with hemoglobin are beneficial and that certain molecules can significantly impair its function.

Oxygen Transport in Blood

Oxygen transport is a life-sustaining process, where oxygen molecules travel through the circulatory system bound to hemoglobin. Each red blood cell packs millions of hemoglobin molecules, optimized to make the most of each breath we take.
The movement of oxygen from the lungs to the tissues, and of carbon dioxide from the tissues to the lungs, is a cycle essential for our survival. Hemoglobin releases oxygen into the tissues because of a decrease in oxygen concentration and increase in carbon dioxide concentration, as well as a lower pH in actively metabolizing tissues.

Tight Bonds and Tissue Needs

Respiring tissue has a high demand for oxygen which hemoglobin fulfills by releasing its bound oxygen. This release is regulated by factors such as pH, temperature, and the concentration of certain molecules, ensuring that oxygen is delivered efficiently to cells in need.

Biological Impact of Pollutants

Pollutants like carbon monoxide have far-reaching impacts on biological systems. Being an invisible, odorless, and non-irritating gas makes CO particularly treacherous as it can cause harm without warning signs.
Once in the bloodstream, pollutants can affect multiple organs. In the case of CO, it not only blocks oxygen transport by binding to hemoglobin but can also lead to hypoxic stress. This can result in symptoms ranging from headaches and dizziness to more severe effects like impaired cognition and cardiac arrest.

Long-Term Consequences

Chronic exposure to pollutants can lead to long-term health issues, including cardiovascular and neurological diseases. It is crucial to understand the biological impact of pollutants to advocate for better air quality and to take precautionary measures, especially in environments at risk of CO exposure, to protect human health.