L03_4_The Alveoli and Disease

Gas Exchange and Effects of Smoking

Gas Exchange Sequence

The molecule of carbon dioxide moves through several structures in order during gas exchange: it starts at the alveoli, moves through the bronchiole, then the bronchus, and finally exits via the trachea.

Negative Pressure in Thorax

Creation of negative pressure in thorax is driven by the contraction of the diaphragm, which moves downward, and the contraction of intercostal muscles, causing the ribs to move up and out. This negative pressure effect leads to inhalation, as it expands the thoracic cavity, reduces pressure, and allows air to flow into the lungs.

Effects of Smoking

Smoking has numerous consequences affecting both the lungs and the circulatory system, and it is linked to coronary heart disease. Key vocabulary associated with smoking includes cigarettes, nicotine, tar, emphysema, bronchitis, carcinogen, cancer, and tumor. Smoking generally damages nearly every part of the body and is associated with various types of cancers, including cancers of the head or neck, lung, stomach, kidney, pancreas, colon, bladder, and cervix. Additionally, smoking contributes to chronic diseases, such as heart disease, chronic lung disease, stroke, pneumonia, blindness, gum infections, leukemia, and reduced fertility, alongside increasing the risk of hip fractures.

Specific Lung Diseases from Smoking

Some specific lung diseases connected to smoking include lung cancer, characterized by the formation of tumors in the lungs; chronic bronchitis, resulting from the inflammation of bronchiole linings; and emphysema, which is a disorder affecting the alveoli.

Carcinogens in Tobacco Smoke

In tobacco smoke, tar contains carcinogens that can induce cell mutations, leading to the formation of cancerous tumors.

Impact of Lung Tumours

Lung tumors significantly hinder an individual's ability to breathe. A diseased lung exhibits both large and small tumors, along with tar deposits.

Healthy Lung Structure

Healthy lungs possess cilia—tiny hairs on the bronchi and bronchioles—and goblet cells that secrete mucus to trap bacteria and dust. This mucus is subsequently moved to the throat by cilia, where it can be swallowed and destroyed in stomach acid.

Effects of Tar on Cilia

Tar damages and paralyzes cilia, resulting in bacterial buildup and increased mucus production, which leads smokers to develop chronic coughs and chronic bronchitis.

Emphysema and Gas Exchange

Emphysema affects gas exchange by damaging the walls of alveoli, thereby reducing the surface area available for gas exchange. This results in a lack of oxygen and an inability to perform basic activities, such as walking. Currently, there is no cure for emphysema.

Emphysema Visualization

Lung sections from individuals suffering from emphysema display large cavities and tar deposits where alveoli have burst.

Exam Question on Emphysema

One relevant exam question requires an explanation of how emphysema reduces oxygen diffusion into the blood, demonstrating a comprehensive understanding of lung functionality.

Lung Condition Comparison

It is important to observe and explain the differences between healthy and diseased lung images.

Smoking's Impact on Circulatory System

The primary harmful chemicals from smoking are carbon monoxide and nicotine, which damage the circulatory system.

Carbon Monoxide and Nicotine Effects

The impact of carbon monoxide on blood is significant; it binds to hemoglobin instead of oxygen, which increases the workload and pressure on the heart. Furthermore, nicotine causes blood cells to become sticky, leading to vasoconstriction and narrowed blood vessels.

Coronary Heart Disease (CHD)

Coronary Heart Disease occurs when fatty deposits in coronary arteries lead to blockages, potentially resulting in heart attacks.