Identify causes of non-infectious disease using an example from each of the following categories: -inherited disease, nutritional deficiencies, and environmental disease.
CALLAGHAN COLLEGE-JESMOND CAMPUS
HSC BIOLOGY
ASSESSMENT TASK ONE
THE SEARCH FOR BETTER HEALTH
"Non-Infectious Diseases and
Emphysema"
Hayley Watson
HBIO2
Mr. J. Leahy
Identify causes of non-infectious disease using an example from each of the following categories: -inherited disease, nutritional deficiencies, and environmental disease.
A non-infectious disease is defined, according to Alford and others (2002, p. 212), as a disease that cannot be spread from one organism to another. Alford continues to explain that non infectious diseases can be categorised into three distinct classes. These are inherited diseases, nutritional deficiencies and environmental diseases.
Inherited Disease
An inherited disease is "due to genetic defects passed on from previous generations." (Auburn and others, 2000, p. 384). An example of a genetic disease is glaucoma. "Glaucoma is an eye disease characterised by increased pressure of the fluid within the eye and is a leading cause of blindness worldwide." (Glaucoma, World Book Millennium Encyclopaedia, 2000) The aqueous humour--the fluid that nourishes the cornea and the lens--does not drain properly, and as pressure in the eye increases, the optic nerve is destroyed. This is described in World Book Millennium Encyclopaedia CD Rom Glaucoma article. The article further explains that Glaucoma is caused by an alteration within a gene that controls the eye's production of aqueous humour, and is passed on from one generation to the next.
Nutritional Disease
Alford and others, (2002, p. 78) describe a nutritional disease as resulting from malnutrition where there are either deficiencies in vitamin or protein intake, or an inadequate imbalanced diet. "Kwashiorkor is a specific protein deficiency caused by weaning a child on to a diet very low in protein and high in carbohydrate." (Auburn and others, 2000, p.385) Kwashiorkor mainly occurs in developing countries where rice and starchy foods are the basic diet and it affects children. The article Kwashiorkor on the World Book Millennium Encyclopaedia CD-Rom (2000) describes the cause of Kwashiorkor as severe malnutrition where the young body is not consuming enough protein needed to build and repair body tissue, something that is vital at a young age.
Environmental Disease
An environmental disease is "associated with factors in the environment that include high stress levels, noise, overcrowding, drugs and pollutants." (Alford and others, 2002, p. 78) An example of an environmental disease is Emphysema, "a disease of the lungs where tiny air sacs in the lungs, the alveoli, and the passage leading to the air sacs (the bronchioles) become permanently distended with air." (Emphysema, 1998, p. 475) The American Lung association ('Emphysema', Online, 2003) define the cause of emphysema as "an alteration in the chemical balance of the lungs, which occurs due to cigarette smoke (both passive and proactive), air pollution, industrial dust, and in rare cases a deficiency in Alpha- Antitrypsin1, a substance that fights destructive enzymes in the lungs." Emphysema is the disease that I will expand on for this report.
Identify data sources, father information from secondary sources to analyse and present information about the occurrence, symptoms, cause, treatment/management of a named non-infectious disease.
Overview
In literal terms, Emphysema is the disease characterised by "excess air in the lungs." The pathological definition of Emphysema is "a condition in which there is over-inflation of structures in the lungs known as alveoli or air sacs. This over-inflation results from a breakdown of the walls of the alveoli, which causes a decrease in respiratory function."("Encarta, Online, 2003) It is known from scientific research that the normal lung has a remarkable balance between two classes of chemicals that have opposing action. The elastic fibres in the lung allow the lungs to expand and contract. When the chemical balance is altered, the lungs lose their ability to protect themselves against the destruction of these elastic fibres. This is what occurs in emphysema.
Occurrence
In recent years, Emphysema has become a serious public health problem in terms of rapidly increasing numbers of disabilities and deaths. In a fact sheet produced by the 'American Lung Association,' Emphysema ranks 15th among chronic conditions that contribute to activity limitations. "The study concluded almost 44 percent of individuals with emphysema report that their daily activities have been limited by the disease." ('American Lung Association', Online, 2003) The occurrence of Emphysema can be assessed in terms of smoking status, age, gender, race, and occupation.
The highest degree of occurrence is among heavy cigarette smokers, especially those exposed to polluted air. In an Australian data study conducted by the Australian Bureau of Statistics in 1995('Austats', Online, 2003), the prevalence of respiratory conditions (including emphysema) overall was higher in smokers (37%) and in ex-smokers (41%) than in those who had never smoked (36%). As visible in the table below, Figure 1.1, Emphysema was present in 9.2% of smokers in the Australian community in 1995. However it is quite possible that this figure is significantly larger, as the table also indicates that the column "All respiratory conditions" is data collected where people had more than one respiratory condition. The American Lung Association ('American Lung Association, Online, 2003) supports this assertion as "emphysema is often coupled with other respiratory tract illness."
Figure 1.1
The occurrence of emphysema is almost limited to the aged population as "Emphysema rarely occurs before the age of 40." ('Emphysema,' 1998, p. 474) 'E-medicine' (Online, 2003) asserts that lung function naturally declines with age, and therefore it stands to reason that the older the person, the more likely they will have enough lung tissue destruction to produce emphysema.
In the analysis of the occurrence of emphysema in terms of gender, Men are more likely to develop emphysema than women. 'Emphysema' (1998, p.474) suggests the reason for this as "there may be a hormonal factor that protects women from the disease." However, research into this has so far been inconclusive.
Emphysema is also less likely to develop in Chinese and Afro-Caribbean races. This may be due to the population of smokers being comparatively less than other countries.
The occurrence of emphysema is also quite high in certain occupations. "The chance of developing emphysema is greater in people who have spent many years in contact with lung irritants such as air pollution, chemical fumes, vapours, and dusts." (National Heart, Lung, and Blood Institute Information Centre, Online, 2003)
The occurrence of emphysema is a prevalent concern in society, as it places stress on families of sufferers, health systems and economy of the country.
Symptoms
A person with emphysema will display many physical and psychological symptoms of the disease. "The most obvious physical symptom of emphysema is breathlessness." ('Emphysema, 1998, p.475) This breathlessness is followed by a chronic cough, with or without the production of mucus. E-medicine(online 2003, suggests even though coughing is quite normal, in a sufferer of emphysema even the slightest exertion, such as talking or laughing, can start a deep chronic cough. Other physical symptoms of emphysema are listed in the table below, however it must be stressed that the occurrence of these symptoms is dependant on the severity of condition:
Figure 1.2
An unusual increase in the amount of sputum.
An unusual increase in the consistency and stickiness of the sputum.
A change in the colour of the sputum to brown, yellow or green.
The presence of blood in the sputum.
An unusual increase in the severity of the breathlessness.
The development of a feeling of general ill-health.
The development of swelling of the ankles.
An unaccountable decrease in weight.
The necessity to increase the number of pillows in order to sleep in comfort.
Increasing fatigability and lack ...
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Figure 1.2
An unusual increase in the amount of sputum.
An unusual increase in the consistency and stickiness of the sputum.
A change in the colour of the sputum to brown, yellow or green.
The presence of blood in the sputum.
An unusual increase in the severity of the breathlessness.
The development of a feeling of general ill-health.
The development of swelling of the ankles.
An unaccountable decrease in weight.
The necessity to increase the number of pillows in order to sleep in comfort.
Increasing fatigability and lack of energy with a feeling that more rest is required.
The development of increasingly frequent morning headaches, dizzy spells, restlessness
The development, during an acute respiratory infection, of confusion, disorientation, slurring of the speech.
Figure 1.2-Courtesy of 'Lung Association' (Online, 2003)
Cyanosis is another symptom of severe emphysema. "Cyanosis is a bluish discoloration of the skin and mucous membranes." ('Cyanosis,' World Book, 2000) Cyanosis occurs when the level of haemoglobin in the blood is reduced. "Haemoglobin is the compound in red blood cells that carries oxygen. When combined with oxygen, haemoglobin makes blood bright red." ('Cyanosis,' World Book, 2000) E-medicine affirms when this occurs in a person with emphysema, it is an indication that the condition is deteriorating.
Psychological symptoms of emphysema, according to 'E-medicine' (Online, 2003) can involve a decrease for tolerance of exercise. Also, anxiousness and anxiety are common in sufferers of severe emphysema due to their fear of going into respiratory failure. The lung association also asserts a loss of libido and insomnia can be found in sufferers of emphysema
However, some of the symptoms are not confined to Emphysema and they can be indicative of another respiratory disease. This is why correct diagnosis by a qualified physician is necessary. The University of Maryland Medicine (Online, 2003) gives this advice about the diagnosis of emphysema.
"A physical examination may show decreased breath sounds, wheezing, and/or prolonged exhalation (exhalation takes more than twice as long as inspiration). There may be an increased front-to-back diameter of the chest (barrel shaped chest). There may be signs of chronically insufficient oxygen levels in the blood.
These tests help confirm the diagnosis:
* pulmonary function tests
* chest X-ray
This disease may also alter the results of the following tests:
* arterial blood gases showing reduced oxygen
* pulmonary ventilation/perfusion scan
* Chest CT scan
The symptoms of emphysema are preventable this is because the most common cause of emphysema is a lifestyle choice.
Causes
The cause of emphysema is primarily due to environmental factors, including one preventable lifestyle choice.
Cigarette smoking is by far the most common origin, and most preventable cause of emphysema. The 'American Lung Association' (Online, 2003) suggests that cigarette smoking is responsible for 90% of cases of Emphysema in the USA. Cigarette smoke contributes to the disease process in three ways - firstly by destroying lung tissue. According to E-medicine (Online, 2003), "Cigarette smoke directly affects the cells in the airways responsible for clearing mucus and other secretions. Due to cigarette smoke, mucus secretions cannot be cleared from the lower respiratory tract." Therefore, resulting in a mucus build up and infection in the lungs, as bacteria have a rich source of food. Guyton (1996, p. 539) affirms this and also asserts that the nicotine in cigarettes inflames the lining of the bronchioles. "The infection, excess mucus, and inflammation, causes the chronic obstruction of the airways."(Guyton, 1996, p.539) E-medicine (Online, 2003) reports cigarette smoke also is responsible for deactivating a type of proteins, elastases, present in the lungs which hold a balance with the alpha-antitrypsin1 of the lungs. The imbalance that cigarette smoke causes is responsible for the destruction of alveolar walls, and the oxygen diffusion in the lungs.
Another environmental cause of emphysema is air pollution. "Air pollution acts in a similar manner to cigarette smoke. The pollutants cause inflammation in the airways, leading to lung tissue destruction." ('E-medicine', Online, 2003)Continuous exposure to dust, including asbestos, is another cause of pulmonary emphysema. "The Encyclopaedia of Family Health" ('Emphysema',1998, p. 474) asserts that the dust causes irritation and inflammation within the bronchioles, which in turn creates obstruction in the airways.
However, information has recently been gathered that suggest that previous infection can result in emphysema. Chronic Bronchitis and bacterial infection could also be contributory factors. The Encyclopaedia of Family Health ('Emphysema,' 1998, p.474) states that "To breathe in when suffering an infection or Bronchitis, a person must make a great deal of effort to overcome the resistance of the mucus, and the inspiration of air may result in the distension of the alveoli." This distension or inflation is what causes the overstretching, and subsequent demise of the structure of the lungs.
Another possible cause of emphysema is a genetic deficiency of the previously mentioned molecule present in the lungs, Alpha-Antitrypsin1. This is an inherited autosomal recessive disorder which is fairly rare in the general gene pool. The estimated prevalence, according to 'Priory Lodge' (Online, 2003) is about 2-3% of the western population, and it accounts for less than 5% of all emphysema cases.
Though it is now apparent environmental factors are not the only causes of Emphysema, these cases only account for up to 10% of the total people who have emphysema. This is quite an insignificant figure in comparison to the rates of emphysema that cigarette smoking causes. Also, all of the causes produce the same symptoms and are treated and managed in the same way.
Treatment and Management
Although the deterioration in the lungs brought about by emphysema is permanent and irreversible, treatment can give relief and increase functioning capacity. The National Heart, Lung, and Blood Institute Information Centre (Online, 2003) asserts the "goal of treatment is to provide relief of symptoms and prevent progression of the disease with a minimum of side effects. The "American Lung Association" (Online, 2003) affirms this, and reports other goals of treatment are to improve exercise tolerance, prevent and treat complications and sudden onset of problems, and to improve overall health.
The 'American Lung Association' (Online, 2003) asserts that doctor's advice and treatment may include:
*quitting smoking: the single most important factor for maintaining healthy lungs. 'Encyclopaedia of Family Health' (1998, p. 475) also reports as there is no way of repairing lung damage, it is important not to begin smoking at all.
*Bronchodilator drugs: prescription drugs that relax and open air passages in the lungs) may be prescribed to treat emphysema if there is a tendency toward airway constriction or tightening. These drugs may be inhaled as aerosol sprays or taken orally. Bronchodilators can be either short-acting or long-acting. Short-acting bronchodilators last about 4 to 6 hours and are used only when needed. Long-acting bronchodilators last about 12 hours or more and are used every day.
* Antibiotics: if there is a bacterial infection, such as pneumococcal pneumonia.
* Inhaled Glucocorticosteroids (Steroids): Inhaled steroids are used for some people with moderate or severe COPD. Inhaled steroids work to reduce airway inflammation.
* Exercise: including breathing exercises to strengthen the muscles used in breathing as part of a pulmonary* rehabilitation program to condition the rest of the body.
* Treatment: with Alpha 1-Proteinase Inhibitor (A1PI) only if a person has AAT deficiency-related emphysema. A1PI is not recommended for those who develop emphysema as a result of cigarette smoking or other environmental factors.
* Lung transplantation: This is a major procedure, which can be effective.
* Lung volume reduction surgery (LVRS) is a surgical procedure in which the most severely diseases portions of the lung are removed to allow the remaining lung and breathing muscles to work better. The short term results are promising but those with severe forms are at higher risk of death.
* Beta-Agonists: Beta-agonists work by relaxing the muscles surrounding the airways.
* Anticholinergics: Anticholinergic drugs block the chemical produced by our bodies that normally causes the airways to contract. They also decrease mucous secretions. A commonly prescribed anticholinergic is ipratropium bromide.
* Oxygen: a medicine that is commonly delivered as a gas from an oxygen cylinder and humidifier through a face mask or nasal cannula.
E-medicine (Online, 2003) suggests once diagnosis has occurred and treatment is administered, it is essential that follow up appointments occur with a doctor. "As the disease gradually develops, periodically it is important to return to a physician, as a greater dosage of medication or different medication may be necessary." (E-medicine, Online, 2003)
Assess the impact of particular advances in biology on the development of technologies
The most important advance for the medical and scientific community in terms of research into the alleviation of environmental disease, and also technological development has been the discovery of appropriate animal models. Animals have been used in medicine and scientific research for hundreds of years. However, the species used, has been controversial for the past century, and now, according to "The Poytner Centre" (Online, 2003) there are many "ethical issues surrounding the use of animals in research." 'Respiratory Research'(Online, 2003) assert that after many years of using a variety of species as models for emphysema, researchers now use only laboratory bred white mice and rats for their investigation. The use of the white mice and rats has allowed researchers to do definitive controlled studies of the bronchioles and alveoli of the lungs. This increased understanding, because of the advance of appropriate animal models, led to the technological development of effective 'bronchodilators.'
Bronchodilators are used in the treatment of Emphysema. "Bronchodilators are medicines that help open the bronchial tubes (airways) of the lungs, allowing more air to flow through them." (Biology Index, Online, 2003) People suffering Emphysema have trouble breathing, because their airways are inflamed and become narrowed. "Bronchodilators work by relaxing the smooth muscles that line the airways." (E-medicine, Online, 2003) Biology Index (Online, 2003) affirms that this makes the airways open wider and allows air to leave the lungs. "Bronchodilators can be categorised into beta-agonists, anticholinergics, methyl-xanthines." (E-medicine, Online, 2003) Beta Agonists are more commonly known as puffers, and examples include Ventolin.
The impact of animal models on the continual development of bronchodilators is quite significant. On a grand scale, the introduction of animal models has allowed the scientific community at large to test hypotheses, find cures, develop preventative treatments, and investigate the pathophysiology and etiology of various diseases. In relation to emphysema and bronchodilators, initially animal models were able to determine the effects of cigarette smoke and air pollution on live models, without the scientists having the fear of committing cruelty against humanity. The physiology of the internal structures of the lungs were investigated, especially the alveolar walls and the bronchioles. The increased understanding of the mechanisms that cause the blockage and narrowing of the airways prompted by the animal models, then allowed a hypothesis to be written which investigated a management of the constriction.
During the process of developing an initial bronchodilator, Respiratory Research (online, 2003) assert that animal models were used during the stages of testing chemicals, dosage recommendations and in testing the most effective form of the treatment.
I believe that it is evident that the development of appropriate animal models impacted greatly on the development of bronchodilators in emphysema, not to mention animal models having a predominant role in all of science. They allowed for investigation that if performed on humans would be classed as cruelty, and control animals to also be used. Animal Models have had, and will continue to hold a significant role in the development of bronchodilator drugs.
Assess the impact of applications of biology on society and their environment
The conclusive studies of emphysema completed over the past 35 years have been prominent in increasing society's awareness of the debilitating disease. The increased biological knowledge gained from the research has influenced society's understanding the cause, symptoms and occurrence of the disease. This interpretation of this information has prompted health promotion campaigns, support for those suffering from emphysema, and research groups.
The epidemiological studies that have occurred during the past 35 years have been able to pinpoint the predominant cause of emphysema as the lifestyle choice of cigarette smoking. This fact has been agreed on by many sources, including 'Encarta' (Online, 2003) and Tortora (1989, p. 757). The information regarding the adverse effects of cigarettes on the lungs, and the link between the cause and the symptoms has instigated many health promotion campaigns against smoking. In Australia, one program aimed at warning of the effects of smoking is the 'Quit campaign' run by the 'NSW Department of Health.' Television advertisements and brochures have been used by The NSW Department of Health to show the mucus build-up, and alveoli destruction of the lungs after every puff of a cigarette which results in emphysema. Smoking kills, is the basic interpretation that society has from the advertising campaigns. Society is quite aware of the risk of emphysema however, many people still continue to smoke.
Furthermore, the statistics regarding the occurrence of emphysema produced by foundations such as the "World Health Organisation" and the "Australian Bureau of Statistics," have prompted support groups for those suffering from emphysema. Refer to Figure 1.1, for statistics of emphysema in Australia. Society has interpreted this data regarding the prevalence of emphysema as a concern, and is therefore willing to help support those suffering from the debilitating disease.
Also, the information gathered concerning the epidemiology has prompted society to take a role in clinical studies. Many who are suffering from the disease, as well as those with normal lung functions have participated in recent studies done by the National Institute of Health. These trials will be discussed further in the next section of the report.
In conclusion, the impact of the biological studies completed by many researchers has had a valuable impact on society in terms of increasing awareness of the severity of the disease. However, I believe for further awareness and cohesion in the fight against the disease in society, further more comprehensive research will have to be completed.
Identify possible future directions of biological research:
A cure for emphysema has not yet been identified, nor has much research been completed to isolate a particular path of research to follow. For the past 50 years, the research undertaken into Emphysema has been focused on epidemiology. Epidemiologists have experienced great success in determining that people who develop emphysema are much more likely to be smokers, or have an alpha-antitrypsin1 deficiency. All this has established is the cause and effect principle, leaving the research of emphysema to be classified as open ended. Robert Foronjy and Jeanine D'Armiento (Respiratory, Online, 2003) believe the lack of research is due to the basic pathophysiology of emphysema still being debated. "While it is clearly established that cigarette smoke is the principal cause of emphysema, the mechanism by which cigarette smoke exposure leads to the destruction of lung architecture seen in emphysema is controversial." (Respiratory, Online, 2003) There is also dissimilarity between what society expects from the research (more emphasis on treatment for the macroscopic symptoms), and what the scientific community is aiming for (treating this disease at a microscopic level). However, it is essential that ample research soon takes place as Emphysema is already the 4th most prominent disease in the USA ('Emphysema,' Online, 2003), as well as affecting upwards of 37% of smokers in Australia as found in a study completed by the Australian Bureau of Statistics.('Austats,' Online, 2003)
Drug Development, Molecular Characterization of Diseased Tissues and Cells, Imaging Technologies, Inflammation, Genetics, Biomarkers, Alveolar Regeneration, Role of Blood Vessels, Apoptosis, Mucous Hypersecretion, Viral Infection, and Oxidant Injury are just some of the areas in which research into emphysema is taking place. But according to the National Institute of Health (Online, 2003), currently, there are three aspects of emphysema where research trends are developing.
The first is Clinical Studies, to research into the therapeutic treatment of sufferers of Emphysema. One current study is the 'Lung Volume Reduction Surgery,' due to start in January. The research is being completed by Harold S. Nelson, MD for the National Institute for Heart, Lungs and Blood, in the USA. "The main objective of this study is to see if a type of lung surgery, known as lung reduction surgery, in addition to standard medical treatment improves the quality of life, lung function, and reduces the high mortality associated with severe emphysema when compared to standard medical treatment alone. To accomplish these objectives, patients who meet clinical criteria and complete a pulmonary rehabilitation-program will be randomized into 2 groups: 1) Continuing optimal medical care or 2) bilateral LVRS via median sternotomy in addition to medical therapy. " (National Institute for Heart, Lungs and Blood, Online 2003)
From this research Clinical Study may possibly become an area for future research. The possible future of Clinical Studies of Emphysema include: methods of indications for long-term oxygen therapy, management of sleep disturbance in Emphysema, alleviation of nocturnal hypoxemia, prevention and treatment of exacerbations, and better tools for disease monitoring. All of these will be essential in treating and managing the symptoms of emphysema.
Another current trend in research of Emphysema is the use of animal models for the disease. The development of using a mouse as a model of emphysema is important for hypothesis testing regarding the pathogenetic mechanisms and the etiology of the disease. The use of mice is allowing researchers at Lovelace Respiratory Research Institute (Lovelace, Online, 2003) to research into how cigarettes cause emphysema in mice, and relate this to human beings. Just recently, research was conducted into cigarette smoke-induced pulmonary inflammation and increased proteinases/elastases in mice prior to development of emphysema, and elastase-induced emphysema in rats. At Respiratory Research (Online, 2003) efforts are being made to determine pulmonary physiological abnormalities, radiographic images, proteomic profiles, and small airway pathology in Emphysema, simply by using the mice as models.
There seems to be quite a future in using mice as models when investigating the basic etiology of emphysema. However, the anatomical structure of the lungs and body of a mouse are far from identical to that of a human being. For more pressing and pertinent research to occur a new animal model will have to be found. This, according to Lovelace (Lovelace, Online, 2003) will allow Topics of special interest to be researched. These include "the biochemical basis of lung growth, damage, and repair; the necessity and sufficiency of specific inflammatory and mucous pathways for the development of small airways disease; and the reversibility of lung damage."
The third area in which trends are apparent in current research of emphysema is non-invasive research. Conclusive evidence has been made to suggest that the characterisation of emphysema may no longer need to involve invasive diagnosis. Respiratory Research (online, 2003) reports there has been encouraging progress in the identification of chemical markers of emphysema. Subjects (animal models) with stable emphysema were shown to have elevated markers of oxidant stress in exhaled air, of inflammation in serum and sputum, and of elastin degradation in urine. Researchers are now using this information as a way to diagnose and look for improvement in their subjects.
In conclusion, the future of research into emphysema lies in developing tools and processes now for use in the future. From the information gathered, it is evident that research into emphysema will become ongoing and possibilities are apparent in the areas of:
* The treatment/management of the macroscopic symptoms- One notable possibility stated by Lovelace (Online, 2003) is Lung development and alveolar regeneration. Stimulation of alveolar regeneration is an exciting possibility for disease-modifying therapy of emphysema as fundamental advances in this area are likely to determine the capacity of mature lungs for alveolar regrowth and the conditions under which alveolar regeneration can occur. Lung reconstruction will inevitably reduce the macroscopic symptoms of emphysema. Furthermore, Aggravations of emphysema are a major concern of both patients with emphysema and their physicians. Future research will be concerned with understanding the origins and development of these exacerbations. There is a need for research directed toward identifying the bases of emphysema exacerbations and clarifying the pathophysiological processes that contribute to worsening of symptoms.
* The pathogenesis of emphysema- 'Respiratory Research' (Online, 2003) accepts that knowledge of genetic determinants of emphysema could lead to recognition of biochemical pathways that contribute to the disease and allow targeting of public health interventions to individuals at greatest risk.
Explain why the biochemical processes in cells are related to macroscopic changes in the organism
Emphysema is an environmental disease caused by the inhalation of smoke, polluted air or industrial dust, substances that irritate the bronchi and bronchioles in the lungs. The consequences are major pathophysiological events taking place in the lungs which cause adverse micro and macroscopic symptoms.
Firstly, chronic infection occurs because "the irritant in cigarette seriously deranges the normal protective mechanisms of the airways." (Guyton and others, 1996, p.539) Partial paralysis of the cilia (hairs) of the respiratory epithelium occurs because of the effect of nicotine. "Long term exposure to cigarette smoke causes the cilia to disappear from the cells lining the air passages."(E-medicine, Online, 2003)
Guyton (1996, p.539) explains that due to the paralysis, mucus cannot be moved easily out of the passageways of the lungs. The resulting mucus build up then provides bacteria with a rich source of food, leading to further infection.
The infection, along with the inflammation of the bronchiolar epithelium causes the chronic obstruction of many of the smaller airways. Guyton (1996, p.539) also asserts "that this obstruction of the airways make it especially difficult to expire, which causes the microscopic symptom of the entrapment of air in the alveoli and the bronchioles being overstretched." The trapped air combined with the infection due to nicotine, causes a "marked destruction of as much as 50-80% of the alveolar walls."
In terms of the macroscopic symptoms, the obstruction in the bronchioles increases airway resistance. To move air through the bronchioles during expiration this means more voluntary effort from the individual, which is the cause of chest tightness and shortness of breath. An increase in the amount of sputum is the natural immune response to the infection that is present in the lungs.
The loss of alveolar walls decreases the diffusing capacity of the lung. This reduces the lungs ability to oxygenate the blood and remove carbon dioxide, which causes the symptoms of fatigue, unaccountable increase or decrease in weight, and the rare condition of cyanosis. Loss of large portions of the alveolar walls also decrease the number of pulmonary capillaries through which blood can pass. As a result, the pulmonary vascular resistance increases remarkably which can cause pulmonary hypertension. This in turn overloads the right side of the heart and frequently causes right-sided heart failure.
* Alford, Hill (2002) Excel HSC Biology, Pascal Press, Glebe.
* American Lung Association http://www.lungusa.org/diseases/lungemphysem.html (Retrieved via Internet 22/11/03)
* Auburn, Kennedy (2000) Biology in Context The Spectrum Of Life, Oxford University Press, Melbourne
* Austats Data base - www.abs.gov.au (Retrieved via Internet 1/12/03)
* Biology Index -http://emphysema.allbio.org/ (Retrieved via Internet 28/11/03)
* E-medicine http://www.emedicinehealth.com/articles/16255-2.asp?pd=11/29/2003%208:47:44%20PM (Retrieved via Internet 22/11/03)
* 'Emphysema', Encyclopaedia of Family Health, (1998) Vol. 4 Marshall Cavendish Corporation, Sydney
* "Emphysema," Microsoft(r) Encarta(r) Online Encyclopaedia (2003)
http://encarta.msn.com (Retrieved via Internet 28/11/03)
* Guyton, Hall (1996) Textbook of Medical Physiology, W.B Saunders Company, USA
* "Lung association" http://www.lung.ca/copd/anatomy/emphysema.html (Retrieved via Internet 1/12/03)
* Medicine, University of Maryland http://www.umm.edu/ency/article/000136sym.htm (Retrieved via Internet 9/12/03)
* National Institute of Health. http://dci.nhlbi.nih.gov/Diseases/Copd/Copd_OtherNames.html (Retrieved via Internet 22/11/03)
* National Institute for Heart, Lungs and Blood, USA http://dci.nhlbi.nih.gov/Diseases/Copd/Copd_WhatIs.html (Retrieved via Internet 22/11/03)
* National Jewish Medical and Research Centre http://www.njc.org/diseases/dt17.html (Retrieved via Internet 9/12/03)
* Priory Lodge http://www.priory.com/cmol/causesof.htm (Retrieved via Internet 6/12/03)
* "Respiratory System" Microsoft(r) Encarta(r) Online Encyclopaedia (2003)
http://encarta.msn.com (Retrieved via Internet 28/11/03)
* Reynolds, Totora (1989) Principles of Anatomy and Physiology, Textbook Incorporated, USA
* World Book Millennium Encyclopaedia (2000) (CD Rom) IBM Corp, New York
Assess the validity of conclusions from gathered data and information
The term validity is described by the Department of Medical Oncology at the University of Newcastle upon Tyne, (Validity, Online, 2003) as, "the extent to which a measurement, test or study measures what it purports to measure." To try and find the most valid information in order to successfully answer the criteria set for this task I gathered the information for this report from visiting thirty internet sites, two encyclopaedic CD-Rom, two biology textbooks, and four medical guides. In the analysis of this information I was able to identify trends, patterns and relationships between the sources and composition of the sources gathered that proved that my information was valid and also reliable.
An apparent trend was that most of the internet sites I found were those of Universities (Medicine, University of Maryland, Online, 2003) and Professional Health Advisory Boards such as the "National Jewish Medical and Research Centre." (Online, 2003) Also, the information was more abundant and more substantial from these websites than from other sources such as the Encyclopaedic CD-Roms ('Emphysema', CD Rom, 2000). The information on the university websites was always reaffirmed by the Health Advisory Boards, which is an indication of its validity.
An advantage of the internet sites I accessed was they displayed the most up to date information available. This was a demise of one library book in particular, The "New Illustrated Medical Aid Encyclopaedia." It was written in 1992, and provided information about treatment using Bronchodilators, which was now outdated. The internet site, 'Virtual Hospital' (Online, 2003) was able to list in detail the new method of administering Bronchodilators, which was pivotal to my understanding of the treatments of emphysema.
When analysing the information provided to me on websites, I ensured that I used websites with end text referencing, or acknowledgement pages. I found a relationship between the sites who had acknowledgement pages, such as "Microsoft(r) Encarta(r) Online Encyclopaedia" (Online, 2003), and the 'American Lung Association' (Online, 2003) having similar and more correct information. The "Biology Index" (Online, 2003) provided a comprehensive list with the author's details. From gathering the details of the authors, I was able to firstly ensure that the information was reliable. I did so, by looking at the variety of authors, as many authors from different institutes who are delivering the same information, gives a general consensus that the information is reliable.
One trend proved to be an adversity in my research was some websites, focussing on Emphysema as a holistic concept being a Chronic Obstructive Pulmonary Disease. When I accessed information from The "National Institute of Health" (Online, 2003) and "Practical Pathology of Chest Disease" (Online, 2003) I was aware I had to cross reference, especially when discussing the symptoms of emphysema, to ensure that the information was correct.
In conclusion, I believe that the resources I have used have been successful in answering the criteria for this task. The websites and books that I found my information in, involved a variety of authors and the information I found was able to be verified and authenticated by other sources. This information was therefore valid and reliable.
