Effects of cigarette smoking on breathing systems
Monacia Williams, Contributor

Well, here we are again! Welcome to another lesson! I hope you all had a very good week. For those of you who have started your external exams, I hope that you have been getting good and manageable papers and that you have been doing your best at answering them. The topics that we have been covering since September are topics that are done in year one of the CSEC biology course, so I hope you have been finding them useful for revision.

This week, we will complete respiration as we look at the effects of cigarette smoking on breathing systems.

Cigarette smoke contains:

• Nicotine
• Tar
• carbon monoxide

These substances have particular effects on the breathing systems and together they irritate the breathing passages causing them to produce more mucus and fluid which, along with dead bacteria, now begin to accumulate in the lungs. This accumulation causes the smoker to be always coughing to dislodge what has now become an irritant from the lungs. This results in what is known as smokers' cough.

The effects of nicotine

• Nicotine makes cigarette highly addictive; this means that smokers will always have a craving for the drug.
• It reduces air flow into and out of the lungs.
• It paralyses the cilia lining the respiratory tract; the cilia can no longer remove the dirt, mucus and the dead bacteria from the air passages.
• It raises blood pressure and increases the heart rate.
• It causes constriction of the bronchioles, reducing the volume of air going to the lungs.
• It increases the risk of osteoporosis.

The effects of tar

• Tar sticks to the cells in the lungs.
• It promotes cancer; it is carcinogenic. Lung cancer usually starts in the epithelium of the bronchioles, spreading throughout the lungs.
• It damages lung tissue
• It breaks down the alveoli; this reduces the surface that is available for the exchange of gases.
• It causes bronchitis, which can lead to emphysema. In this condition, the lung is less elastic due to the accumulation of scar tissue, preventing persons with emphysema from exhaling freely. Carbon dioxide accumulates in the blood and the individual's skin takes on a bluish appearance.

The effects of carbon monoxide

• It combines irreversibly with haemoglobin. This reduces the oxygen-carrying capacity of the blood. Please note: Oxygen is transported in the blood in combination with haemoglobin so carbon monoxide competes with oxygen for the binding sites on haemoglobin.
• The reduction in the uptake of oxygen causes breathlessness in the smoker.
• It reduces the birth weight of foetuses with less oxygen going to the developing foetus, hence less energy for growth and development. It can also cause premature birth.

Unfortunately, the effects of cigarette smoke are felt not only by the smoker, but also by anyone who is in the vicinity of the smoker. This type of smoke is known as passive smoke. Cigarette smoking can adversely affect a country's health-care system by increasing the incidence of these diseases. More money has to be spent in providing hospital beds and medication for these chronic illnesses.

As students approaching external exams, you need to pay particular attention to the experiments that are involved in respiration. Many of the questions that are set on this topic are based on these experiments. Read up on these in your class text. In many instances, there are questions included with them that you should attempt to answer. These answers will prove to be of tremendous help to you when similar questions appear on the exam paper.

Now let's look at some questions.

a. i. With the aid of a fully annotated diagram, explain how air reaches the lungs and oxygen is absorbed into the blood stream.

ii. The effect of smoke emission from factories on plant leaves is sometimes compared to the effect of cigarette smoke on the lungs. Suggest TWO

reasons why this comparison is appropriate.

iii. Many governments have passed legislation to reduce the amount of cigarette smoking in public. Explain why governments should consider it their responsibility to reduce smoking in public.

See you next week when we go through the answers!

It was not easy for tag rugby trainer, Victor Hyde (left), to get the ball from two of his student-coaches during a recent workshop at Petersfield in Westmoreland. - FILE

Monacia Williams teaches at Glenmuir High School.