Nicotine, cigarette problem - carbon monoxide problem?

Nicotine, one of the components of cigarettes, slows cilia lining the respiratory tract, causes blood vessels to constrict, and increase heart rate. Another component of cigarette smoke is carbon monoxide. Explain why carbon monoxide is dangerous to you respiratory tract.

Following inhalation, carbon monoxide diffuses rapidly across the alveolar and capillary membranes of the lungs. Once absorbed, it diffuses through the plasma, passes the red blood cell membrane and enters the red blood cells, where approximately 80 - 90 % binds with haemoglobin in the same way as does oxygen, to form carboxyhaemoglobin.

This binding decreases the oxygen carrying capacity of the blood and interferes with oxygen exchange at tissues. The affinity of haemoglobin for carbon monoxide is 234-fold !!! higher than that for oxygen hence the amount of oxygen in the blood becomes greatly reduced.

Furthermore, once carbon monoxide is bound it alters the dissociation curve of oxyhaemoglobin, reducing the rate at which oxygen is delivered to the cells. This impaired delivery of oxygen can interfere with cellular respiration and causes tissue hypoxia.

This inhibits the transference of oxygen to the organs. Particularly affected are the heart, central nervous system and brain. The heart responds to hypoxia from CO poisoning by beating rapidly, irregularly, and with a decrease in blood pressure. Cardiac arrhythmia's (irregularities) frequently occur in the face of CO, causing heart blocks and ventricular ectopic beats (P.V.C.- Premature Ventricular Contraction). This cardiac irregularity may lead to heart attack and even death.

Cerebral edema (swelling of the brain) is also a common result of severe carbon monoxide poisoning. This life threatening condition entails the destruction of brain cells by compressing them into themselves within the cranial compartment. Drugs that are normally used for the treatment of cerebral edema, like Dexamethasone and Mannitol, do not seem to be of assistance in the treatment of CO induced cerebral edema. Studies have shown that cerebral edema caused by CO poisoning can cause delayed neurological problems that involve the "higher" or cognitive functions, and may cause a Parkinsonian-like brain syndrome.

Hope that helps a bit.