Describe the effects of smoking on the mammalian gas exchange system, with reference to the symptoms of chronic bronchitis, emphysema (chronic obstructive pulmonary disease)

By Fin Roberts and Jake Riggs

What is the Maximilian gas exchange system?

The gas exchange surface of a mammal is the Alveolus. There are numerous alveoli - air sacs, supplied with gases via a system of tubes (trachea, splitting into two bronchi - one for each lung - and numerous bronchioles) connected to the outside by the mouth and nose. This understanding is important in seeing the affects of smoking on the different parts of the Maximilian gas exchange system.

What's so bad about cigarettes?

Cigarette smoke is composed of over 4000 different chemicals, many of which are toxic. Both smoke that the smoker inhales (through the filter) and the smoke from the burning end is incredibly toxic. There are three main components that are hazardous to health.

  • Tar - settles in the lungs and stimulates a series of changes that lead to obstructive lung disease and lung cancer
  • Nicotine - is the addictive element of cigarettes, stimulates the nervous system to reduce arteriole diameter and release adrenaline - increasing heart rate and blood pressure. Causes increased stickiness of blood platelets, which increases the risk of blood clotting.
  • Carbon monoxide - combines irreversibly with haemoglobin meaning that oxygen cannot bind effectively. This causes a strain on the heart muscle because it must pump more to provide the same amount of oxygen

What damage and smoking related diseases does this cause to the lungs?

Smoking damages the airways and small air sacs in the lungs. This can cause chronic coughing, wheezing, trouble breathing, and long-term (chronic) lung disease. More than 90% of deaths due to chronic bronchitis and emphysema – together these are known as chronic obstructive pulmonary disease (COPD) – are caused by smoking. Today, more women than men die from COPD, and evidence suggests that women are more likely to get severe COPD at younger ages than men.

(Chronic obstructive pulmonary disease (COPD) is a name for long-term lung disease which includes both chronic bronchitis and emphysema for which there's no cure.)

The risk of COPD goes up with the number of cigarettes smoked each day and with the length of time a woman has been smoking. Female smokers aged 35 or older are almost 13 times more likely to die from emphysema or bronchitis than those who have never smoked.

The lungs grow more slowly in teenage girls who smoke. And adult women who smoke start losing lung function in early adulthood.

Chronic bronchitis

Chronic bronchitis is a type of COPD, a disease where the airways make too much mucus, forcing the person to cough it out. It’s a common problem for smokers. The airways become inflamed (swollen) and the cough becomes chronic (long-lasting). The symptoms can get better at times, but the cough keeps coming back. Airways get blocked by scar tissue and mucus, which can lead to bad lung infections (pneumonia).

Emphysema

Smoking is also the major cause of emphysema, the other type of COPD, which slowly destroys a person’s ability to breathe. Oxygen gets into the blood by moving across a large surface area in the lungs. Normally, thousands of tiny sacs make up this surface. In emphysema, the walls between the sacs break down and create larger but fewer sacs. This decreases the lung surface area, which lowers the amount of oxygen reaching the blood. Over time, the lung surface area can become so small that a person with emphysema must work very hard to get enough air, even when at rest.

Here's an interesting  picture regarding different smoking induced diseases and their location of symptoms :

(Optional)Watch this video on the effect of smoking on lungs if you prefer to learn through video:

Comment Stream

2 years ago
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Have a go at these exam questions if you want to extend your knowledge....

2 years ago
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Thank you chaps. I am pleased that you have included the exam Qs. Lots for folks to do..Markscheme can be found if you look for June 2011 F212 Q4

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The QR above will take you to the other disease presentations. Make sure that you study them all!