Biology - Nicotine and Carbon Monoxide


Nicotine and carbon monoxide:

­These two chemicals, found in cigarette smoke, enter the lungs and pass through the lung surface into the blood. In the blood they cause changes to the circulation. These changes lead to increased risk of cardiovascular diseases including:

·         atherosclerosis

·         coronary heart disease (CHD)

·         stroke



Nicotine is the chemical in cigarette smoke that causes addiction. It has a variety of effects on the body. The body becomes used to this effect and the smoker no longer feels well unless he or she has nicotine in their blood.

·         Nicotine mimics the action of transmitter substances at the synapses between nerves. This makes the nervous system more sensitive and the smoker feels more alert.

·         Nicotine causes the release of the hormone adrenaline. This hormone has a variety of effect that prepares the body for activity. These include increasing the heart rate and breathing rate, and causing constriction of the arterioles. This raises the blood pressure in the arterioles.

·         Nicotine also causes constriction of the arterioles leading to extremities of the body. This reduces blood flow and oxygen delivery to the extremities. In extreme cases it can lead to the need for amputation.

·         Nicotine also affects the platelets to make them sticky. This increases the risk that blood clot or thrombus may form.


Carbon Monoxide:

·         Carbon monoxide enters the red blood cells and combines with haemoglobin. It combines much more readily than oxygen, and form the stable compound carboxyhaemoglobin. This reduces the oxygen-carrying capacity of the blood. Smokers will feel this when they exercise. The body will detect the lower level of oxygen, and it may cause the heart rate to rise.

·         Carbon monoxide can also damage the lining of the arteries.


Problems caused by changes to the blood system:

The changes describes above are part of a chain of events that can lead to serious diseases such as CHD. CHD is a multifactorial disease – this means there is no single factor that causes it. A number of factors contribute to the risk of a person having CHD- these are called risk factors.


Carbon monoxide can damage the inner lining (endothelium) of the arteries.


No comments have yet been made