Question

At which concentration of carbon monoxide causes headache and dizziness?

Answer 1

Respiration provides oxygen to the tissue and removes carbon dioxide. Most tissues in the body survive on the oxygen for the production of energy. Oxygen is continuously supplied in and carbon dioxide is supplied out. The lungs are the organs for respiration and are two, right and left lungs.

Complete answer:
Aerobic respiration is complete cellular oxidation of organic molecules, utilizing molecular oxygen and releasing carbon dioxide. So, during it, oxygen is taken from the environment and delivered to the cells. In turn, carbon dioxide is released to the environment.

Respiratory exchange of gases takes place at two sites, namely first in the respiratory surface or respiratory organ and then in cells or tissues. The former takes place between ${O_2}$ of the surrounding medium and $C{O_2}$ of the blood or body fluid, and the latter between ${O_2}$ of the extracellular fluid and the $C{O_2}$ produced within the cell.

Haemoglobin is an iron containing and oxygen carrying red pigment. It is found in the erythrocytes of the erythrocytes of all vertebrates and in the blood plasma of some invertebrates. Respiratory gases like ${O_2},C{O_2},CO$ etc. carried by this haemoglobin. Haemoglobin has more affinity towards the carbon monoxide than oxygen.

Oxygen binds with haemoglobin to form oxyhaemoglobin.

$Hb + {O_2} \rightleftarrows Hb{O_2}$

Then, the oxyhaemoglobin is dissociated in the tissue to release ${O_2}$.
Carbon monoxide is bound with haemoglobin to form carboxyhemoglobin. This carboxyhemoglobin is more stable than oxyhaemoglobin.

$Hb + CO \rightleftarrows HbCO$
If carbon monoxide binds with haemoglobin, then there will be less haemoglobin to bind with oxygen. It will create respiratory problems. If the concentration of $CO$ is about $100$ ppm, then there will be headache and dizziness.

Note: Respiratory gas exchange is purely a physical process, without energy expenditure. It takes place by simple diffusion across the respiratory surface. For a high rate of diffusion and maximum intake of ${O_2}$ , most organisms continuously move air or water over their respiratory surface. This is known as ventilation. Flow of water over the gills in aquatic animals and the breathing in and out of air in terrestrial animals are examples of ventilation.