Presentation on theme: "Today we are covering from the specification:"— Presentation transcript:
1 Today we are covering from the specification: Pages 82 to 85 of your textbook
2 Pulmonary Tuberculosis VideoCourse of infectionSymptomsTransmission
3 What is the cause of pulmonary TB? Tuberculosis is caused by one of two rod-shaped bacteria.Either Mycobacterium tuberculosis (pictured) or Mycobacterium bovis.
4 What is the cause of pulmonary TB? It is estimated that around 30% of the world’s population have one or other form of the bacterium within their bodies.
5 What are the symptoms of pulmonary TB? Persistent coughTirednessLoss of appetite (leading to weight loss)As the disease develops:FeverCoughing up blood
6 Tuberculosis infection Boardworks AS BiologyInfectious DiseasesTuberculosis infectionWhen a person becomes infected with TB, an immune response is produced.In healthy people, white blood cells called macrophages engulf the bacteria by phagocytosis, controlling the infection.A tissue mass called a tubercle forms around the infected site, and after 3–8 weeks the infected region heals.Photo credit: CDCAn anteroposterior X-ray of a patient diagnosed with advanced bilateral pulmonary tuberculosis. This AP X-ray of the chest reveals the presence of bilateral pulmonary infiltrate, and “caving formation” present in the right apical region. The diagnosis is far-advanced tuberculosis.However, the bacteria can survive inside macrophages for years until the immune system becomes weak.
7 Symptoms of tuberculosis Boardworks AS BiologyInfectious DiseasesSymptoms of tuberculosisIf the patient’s immune system is unable to contain the infection, active tuberculosis may occur. The bacteria will multiply rapidly, destroying the lung tissue, which can be fatal.A patient with active tuberculosis may experience symptoms such as coughing, shortness of breath, loss of appetite, weight loss, fever, night sweats and extreme fatigue.Fever and night sweats occur due to neutrophils and macrophages releasing fever-causing substances, as part of the inflammatory response. These chemicals affect the hypothalamus and increase core body temperature.Teacher notesSee ‘Immunology’ presentation for more information about the inflammatory response.Why might an increase in temperature be harmful?
8 Course of InfectionPrimary infection – enlargement of lymph nodes that drain the area of the lungs, due to accumulation of white blood cells at the site of infection.Post-primary infection – the dormant bacteria re-emerge many years later to cause an infection in the upper regions of the lungs.The bacteria destroy the lung tissue.
11 Recap from last lesson.... What is pulmonary tuberculosis? What is it caused by?How is it transmitted?How does it affect the lungs?How could it be prevented?Discuss – 10min into lesson
12 Lung disease – fibrosis, asthma and emphysema Pulmonary tuberculosis is only one disease which affects the lungs.Fibrosis, asthma and emphysema can all also impair lung function in a number of different ways...
13 Pulmonary Fibrosis Description Happens when scars form on the pulmonary epithelium, causing them to become irreversibly thickened. This means that in patients with fibrosis, O2 cannot diffuse properly into the blood. Fibrosis also reduces the elasticity of the lungs and therefore makes ventilating the lungs difficult.CauseThe exact cause is unclear, but evidence suggests it is a reaction to microscopic lung injury, to which some individuals are more susceptible.Cigarette smoking can increase the risk or worsen the disease.
14 Pulmonary Fibrosis Symptoms Shortness of breath, especially when exercising due to a decrease in volume of lungs as there is an increase in scar (fibrous connective) tissue. Thickened epithelium means that diffusion pathway is greater. Loss of elasticity makes ventilation difficult. All of these factors combine to decrease the rate of diffusion.Chronic, dry cough due to the fibrous tissue causing an obstruction. This is the body’s reflex to remove an obstruction.Pain and discomfort in the chest occurs due to the pressure in the lungs and hence damage from the mass of fibrous tissue.Weakness and fatigue results from reduced intake of O2.
16 AsthmaDescriptionAsthma is an example of a localised allergic reaction. It affects up to 10% of the world population and accounts of 2000 deaths each year in the UK. Some of the most common allergens include pollen, animal dander, faces of house dust mites.It can be triggered or worsened by pollutants (e.g sulphur dioxide, ozone, nitrogen oxides), exercise, cold air, anxiety or stress. These allergens cause white blood cells to release histamines in the bronchi and bronchioles, causing the following effects....
17 Asthma The lining of these airways becomes inflamed. The cells of the epithelial lining secrete larger quantities of mucus than normal.Fluid leaves the capillaries and enters the airways.The muscle surrounding the bronchioles contracts and so constricts the airways.
18 AsthmaCausesGenetics appears to play a role, as asthma tends to run in families. The number of asthmatics continues to rise and many explanations have been put forward for this;Increase in air pollution.Increase in stress levels.Increase in chemicals used in food and other manufactured products.Our now ‘cleaner’ lifestyles means we are exposed to fewer allergens and therefore don’t build up a tolerance to them.
19 AsthmaSymptomsDifficulty in breathing due to the constriction of the bronchi and bronchioles, their inflamed linings and the additional fluid and mucus within them.A wheezing sound when breathing caused by the air passing through very constricted bronchi and bronchioles.A tight feeling in the chest is a consequence of not being able to ventilate the lungs adequately because of constricted bronchi and bronchioles.Coughing is the body’s response to the obstructed bronchi and bronchioles in an attempt to clear them.
21 Emphysema Description One in every five smokers will develop emphysema. It develops over a period of around 20 years or so, and it is virtually impossible to diagnose until the lungs have been irreversibly damaged.Healthy lungs contain large amounts of elastic tissue, mostly made up of the protein elastin. This tissue stretches when we breathe in and springs back when we breathe out.In emphysematous lungs the elastin has become permanently stretched and the lungs are no longer able to force out all of the air from the alveoli. The surface area of the alveoli are reduced and sometimes they burst. As a result, little if any exchange of gases can take places across the surface of the stretched and damaged sacs.
22 EmphysemaCausesEmphysema is almost always caused by smoking tobacco. A few cases have been found to have other causes, and these will be known as secondary emphysema.The only way at all to minimise the changes of developing emphysema is to not smoke at all.
23 EmphysemaSymptomsShortness in breath results from difficulty exhaling air due to loss of elasticity in the lungs. If the lungs cannot be emptied, then it is even more difficult to inhale fresh air containing oxygen and so the patient feels breathless.Shallow, rapid breathing due to the smaller alveolar surface area resulting in a reduced intake of O2. The patient tries to increase intake of O2 by breathing more rapidly.Chronic cough is the consequence of lung damage and the body’s effort to remove damaged tissue and mucus that cannot be removed naturally because the cilia have been destroyed.Bluish skin colouration due to low levels of O2 in the blood.
29 Boardworks AS Biology Lifestyle and Disease Respiratory diseasesRespiratory diseases are one of the biggest causes of death worldwide.Respiratory diseases affect the lungs, bronchi, trachea and throat. They can be mild (e.g. cold) or life-threatening (e.g. pneumonia, lung cancer).Chronic obstructive pulmonary disorder (COPD) is a term for a group of diseases that cause a reduction in the airflow in the lungs and which are not fully reversible.Teacher notesObstructive respiratory diseases reduce the airflow in the lungs, whereas restrictive respiratory diseases (such as pulmonary fibrosis) reduce the functional volume of the lungs.Particulates such as asbestos and coal dust can also cause emphysema.Two of the more serious types of COPD are chronic bronchitis and emphysema, and are both usually caused by smoking.
30 COPD: chronic bronchitis Boardworks AS BiologyLifestyle and DiseaseCOPD: chronic bronchitisChronic bronchitis is a narrowing of the bronchi. It is characterized by:bronchinormal airwaymucusinflammed airwaya persistent cough that produces phlegm - due to an increased number and size of goblet cellsTeacher notesAcute bronchitis lasts for a few days and is usually due to viral or bacterial infection.See the ‘Gas Exchange’ presentation for more information about the structure of lungs.shortness of breath and wheezing - irritants in cigarette smoke cause inflammation in the lining of the bronchioles. Over time this leads to scarring and narrowing of the bronchioles, reducing airflow.
31 Boardworks AS Biology Lifestyle and Disease COPD: emphysemaEmphysema is a gradual breakdown of alveolar walls and damage to terminal bronchioles and alveolar capillaries.This reduces the efficiency of gas exchange, causing chronic breathlessness and hyperventilation.Using this photo of healthy lung tissue (left) and emphysema lung tissue (right), can you explain why gas exchange is less efficient in emphysema?Photo credit: BioPhoto Associates / Science Photo LibraryEmphysema and normal lung tissue, light micrograph. In normal lung tissue (left), there are lots of small air spaces (alveoli). In the lung of a patient with emphysema, the walls of the alveoli have broken down, making the spaces much larger. The capillaries that transport blood through the lungs are also damaged, and small airways can collapse. This means that the lungs are less efficient at gaseous exchange, leading to shortness of breath and hyperventilation to compensate. The disease is mainly found in long-term smokers, almost always in combination with chronic bronchitis. This is termed a chronic obstructive pulmonary disease (COPD). There is no cure and the condition is irreversible. Treatment is aimed at preventing further damage.
33 Determining lung function Boardworks AS BiologyLifestyle and DiseaseDetermining lung functionTeacher notesFEV1 enables COPD to be classified in one of three categories:mild COPD: FEV1 = 50–80% of predicted FEV1moderate COPD: FEV1 = 30–49% of predicted FEV1severe COPD: FEV1 < 30% of predicted FEV1
34 Boardworks AS Biology Lifestyle and Disease Treating COPDStopping smoking is the single most important step in slowing the decline in lung function in people with COPD.Medicines commonly prescribed to treat COPD include bronchodilators, which widen the airways by relaxing smooth muscles, and corticosteroids, which act as anti-inflammatories.Oxygen therapy, especially for people with emphysema, may be required for most of each day.Photo credit: Boehringer Ingelheim LtdTeacher notesSome research has showed that, despite their widespread use, corticosteroids, have little effect on COPD, whether inhaled or taken orally.
35 Boardworks AS Biology Lifestyle and Disease What is asthma?Asthma is a chronic condition in which the airways occasionally narrow and become inflamed, limiting airflow.Asthma causes difficulty breathing, wheezing and chest tightness, and can be mild or life-threatening.Asthma is triggered by a range of stimuli, such as allergens, dust, exercise, stress and infections.Photo credit: Annie Cavanagh, Wellcome ImagesA grain of marigold pollen.Teacher notesUnlike COPD, asthma is common in people under the age of 35, and this is often used to help make a diagnosis.Treatment is with bronchodilators, corticosteroids, or a combination of the two.
36 Boardworks AS Biology Lifestyle and Disease Lung cancerLung cancer is the biggest cause of cancer-related deaths in men and second-biggest cause in women. About 90% of cases are caused by smoking.Most incidences of lung cancer are due to uncontrolled growth of epithelial cells lining the airways. Cancers arising from these cells are called carcinomas.Photo credit: Medimage / Science Photo LibraryLung cancer, gross specimen. Large whitish tumour mass with several other smaller tumours. The whitish tumour is a primary tumour and is located near the hilar region. The hilar region is where the bronchi split into the many bronchioles that spread out throughout the lung. It is a very common site for cancers caused by smoking.Symptoms include shortness of breath, coughing (including coughing up blood) and loss of weight.
37 Boardworks AS Biology Lifestyle and Disease Lung cancerLung cancer generally develops quite slowly. By the time it has been diagnosed, the cancer may have spread to other areas of the body. This is called metastasis, and makes it difficult to treat successfully.Lung cancer can be seen on an X-ray or a CT scan, and diagnosis is usually confirmed after a small sample of tissue is taken (a biopsy) and analysed.Photo credit: Cancer Research UKPatient in a CT scanner. More information about cancer is available atTeacher notesMetastasis occurs when cancerous cells break away from the primary tumour, enter the circulatory or lymphatic system and are transported to other tissues/organs where they form secondary tumours.Computed tomography (CT) is a medical imaging technique where a large number of 2D X-ray images are taken through an object (a human, other organism or non-living material such as fossils, building and engineering materials) and which can be assembled to form a 3D image of the inside of the object.The two main types of lung cancer are small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC, which accounts for over three-quarters of all lung cancers). They are differentiated by the size, appearance and location of the cancerous cells. SCLC may become quite large and grows quickly, and is often treated by surgery. NSCLC grows more slowly and responds better to chemotherapy and radiotherapy.Like many other cancers, lung cancer is treated by surgery, chemotherapy and/or radiotherapy.
38 Boardworks AS Biology Lifestyle and Disease Cancer statisticsTeacher notesData from Office for National Statistics (Incidence/mortality rates are calculated as three-year averages that have been age-standardised to a standard European population.Five-year survival rates are for year olds, diagnosed during 1999–2003 and followed up in 2004, age-standardised to a standard European population. It was not possible to produce an age-standardised five-year survival rate for brain cancer in men and lung cancer in women, therefore, these figures refer to the un-standardised survival estimate.An age-standardised rate is one that has been adjusted to take into account the fact that different geographical areas will have a different composition of young and old people. As cancer mainly affects older people, a lack of age-standardisation can make meaningful comparisons between different populations very difficult.
39 Smoking and lung cancer Boardworks AS BiologyLifestyle and DiseaseSmoking and lung cancerTeacher notesData from NIH.In the first half of the 20th century, smoking was widely considered a harmless activity, although there was some circumstantial evidence that it did have an impact on health. Some tobacco companies even advertised smoking as offering various health benefits.
40 Smoking and lung cancer: epidemiology Boardworks AS BiologyLifestyle and DiseaseSmoking and lung cancer: epidemiologyThe first solid epidemiological evidence that smoking increased the risk of lung cancer came from a 1950 study by Richard Doll, a British doctor and epidemiologist, and Austin Bradford Hill, a British epidemiologist and statistician.Before their study, it was unclear whether the rapid rise in lung cancer was due to smoking or other atmospheric pollution, such as exhaust fumes, industrial plants or tarmac.Their study of over 1,700 men and women in London concluded that: “The risk of developing the disease increases in proportion to the amount smoked. It may be 50 times as great among those who smoke 25 or more cigarettes a day as among non-smokers.”Teacher notesDoll, R. and A. Hill, Smoking and carcinoma of the lung; preliminary report. BMJ. 1950; 2:739-48Students could be asked to read the paper and comment on the methods, results and conclusions.It is important when looking at whether an activity has an effect on health to examine whether it is biologically plausible that an effect could occur. The fact that there are at least 60 known carcinogens in tobacco smoke is very strong evidence that there is a biological mechanism by which smoking can cause cancer.
41 Smoking and health: epidemiology Boardworks AS BiologyLifestyle and DiseaseSmoking and health: epidemiologyFollowing Doll and Hill’s research, a large-scale study into the health and smoking habits of British male doctors began in 1950, continuing with periodic updates until 2001.Two of the main findings of this British Doctors Study were:life-long smokers died, on average, 10 years earlier than non-smokersthe earlier smokers stop smoking, the more chance they have of avoiding reduced life expectancy.Teacher notesThe British Doctors Study ran from 1951 to Researchers wrote to all male British doctors - almost 35,000 (two-thirds) responded, providing details of their age, general health and illnesses, and smoking habits. Further responses were provided in 1957, 1966, 1971, 1978, 1991 and The study’s objectives were: “To compare the hazards of cigarette smoking in men who formed their habits at different periods, and the extent of the reduction in risk when cigarette smoking is stopped at different ages.”Doll R, Peto R, Boreham J and Sutherland I. Mortality in relation to smoking: 50 years' observations on male British doctors. BMJ June 26; 328(7455): 1519.Students could be asked to read the paper and comment on the methods, results and conclusions.
45 You are now.... Gregory House, M.D You are going to diagnose a number of patients who are suffering with various lung diseases.You can work in groups (as House would!) but you must write up your own case notes (i.e why you have diagnosed with one disease and not another).The group to get the most number correct may win a prize!
46 You are now.... Gregory House, M.D Read the patient’s case notes.Consider past medical history and current symptoms.Come up with a diagnosis (write this down).Reason your decision (write this down).80 min30 minutes (5 minutes per patient)
47 You are now.... Gregory House, M.D PatientGroup 1Group 2Group 3Group 4Group 5ABCDEX
48 You are now.... Gregory House, M.D Patient A Is suffering from.... Tuberculosis
49 You are now.... Gregory House, M.D Patient B Is suffering from.... Emphysema
50 You are now.... Gregory House, M.D Patient C Is suffering from.... Pulmonary fibrosis
51 You are now.... Gregory House, M.D Patient D Is suffering from.... Asthma
52 You are now.... Gregory House, M.D Patient E Is suffering from.... Tuberculosis
53 You are now.... Gregory House, M.D Patient X Is suffering from.... Take your pick (except asthma!) but requires clear justification for a single or multiple disease diagnosis.90min