Carbon monoxide is a toxic  gas that binds haemoglobin and form a stable compound known by name carboxy haemoglobin. The affinity of haemoglobin to carbon monoxide is 240 times greater than oxygen .so that  the amount of heamoglobin available for oxygen transport is reduced . the effect of this is deficiency of oxygen causes the symptoms like headache , dizziness, nausea etc. in severe cases it can cause death. This is known as carbon monoxide poisoning . the treatment of carbon monoxide poisoning is the administration of oxygen with 6.5% of carbon dioxide, the carbon dioxide will stimulate the respiratory centre of brain.

Anoxia

The deficiency of oxygen at the tissue level is known as anoxia or hypoxia. It may be classified ito the following types.

Anaemic hypoxia – it is due to the low level of hemoglobin in the blood.

Arterial hypoxia – this is due to the low level oxygen in the blood. The reason is that the deficiency of oxygen in the atmosphere .

Histoxic hypoxia- in this situation tisses cannot use of oxygen delivered to them because of toxic components .ie cynide poisoning., carbon monoxide poisoning etc.

Stagnant hypoxia – in this the blood flow is inadequate to deliver oxygen to the tissues.