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Obstructive Lung Disease
Obstructive lung disease is a category of respiratory disease characterized by airway obstruction. Many obstructive diseases of the lung result from narrowing (obstruction) of the smaller bronchi and larger bronchioles, often because of excessive contraction of the smooth muscle itself. It is generally characterized by inflamed and easily collapsible airways, obstruction to airflow, problems exhaling, and frequent medical clinic visits and hospitalizations. Types of obstructive lung disease include; asthma, bronchiectasis, bronchitis and chronic obstructive pulmonary disease (COPD). Although COPD shares similar characteristics with all other obstructive lung diseases, such as the signs of coughing and wheezing, they are distinct conditions in terms of disease onset, frequency of symptoms, and reversibility of airway obstruction. Cystic fibrosis is also sometimes included in obstructive pulmonary disease. Types Asthma Asthma is an obstructive lung disease where the bronchial t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bronchial Hyperresponsiveness
Bronchial hyperresponsiveness (or other combinations with airway or hyperreactivity, BH used as a general abbreviation) is a state characterised by easily triggered bronchospasm (contraction of the bronchioles or small airways). Bronchial hyperresponsiveness can be assessed with a bronchial challenge test. This most often uses products like methacholine or histamine. These chemicals trigger bronchospasm in normal individuals as well, but people with bronchial hyperresponsiveness have a lower threshold. Bronchial hyperresponsiveness is a hallmark of asthma but also occurs frequently in people with chronic obstructive pulmonary disease (COPD). In the Lung Health Study, bronchial hyperresponsiveness was present in approximately two-thirds of patients with non-severe COPD, and this predicted lung function decline independently of other factors. In asthma it tends to be reversible with bronchodilator A bronchodilator or broncholytic (although the latter occasionally includes secretory ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chronic Obstructive Pulmonary Disease
Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by long-term respiratory symptoms and airflow limitation. The main symptoms include shortness of breath and a cough, which may or may not produce mucus. COPD progressively worsens, with everyday activities such as walking or dressing becoming difficult. While COPD is incurable, it is preventable and treatable. The two most common conditions of COPD are emphysema and chronic bronchitis and they have been the two classic COPD phenotypes. Emphysema is defined as enlarged airspaces ( alveoli) whose walls have broken down resulting in permanent damage to the lung tissue. Chronic bronchitis is defined as a productive cough that is present for at least three months each year for two years. Both of these conditions can exist without airflow limitation when they are not classed as COPD. Emphysema is just one of the structural abnormalities that can limit airflow and can exist without ai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta2-adrenergic Agonist
Beta2-adrenergic agonists, also known as adrenergic β2 receptor agonists, are a class of drugs that act on the β2 adrenergic receptor. Like other β adrenergic agonists, they cause smooth muscle relaxation. β2 adrenergic agonists' effects on smooth muscle cause dilation of bronchial passages, vasodilation in muscle and liver, relaxation of uterine muscle, and release of insulin. They are primarily used to treat asthma and other pulmonary disorders, such as Chronic obstructive pulmonary disease (COPD). Mechanism of action Activation of β adrenergic receptors leads to relaxation of smooth muscle in the lung, and dilation and opening of the airways. β adrenergic receptors are coupled to a stimulatory G protein of adenylyl cyclase. This enzyme produces the second messenger cyclic adenosine monophosphate (cAMP). In the lung, cAMP decreases calcium concentrations within cells and activates protein kinase A. Both of these changes inactivate myosin light-chain kinase and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bronchodilator
A bronchodilator or broncholytic (although the latter occasionally includes secretory inhibition as well) is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lungs. Bronchodilators may be originating naturally within the body, or they may be medications administered for the treatment of breathing difficulties, usually in the form of inhalers. They are most useful in obstructive lung diseases, of which asthma and chronic obstructive pulmonary disease are the most common conditions. Although this remains somewhat controversial, they might be useful in bronchiolitis and bronchiectasis. They are often prescribed but of unproven significance in restrictive lung diseases. Bronchodilators are either short-acting or long-acting. Short-acting medications provide quick or "rescue" relief from acute bronchoconstriction. Long-acting bronchodilators help to control and prevent symptoms. The three types of pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pack Year
A pack-year is a clinical quantification of cigarette smoking used to measure a person's exposure to tobacco. This is used to assess their risk of developing lung cancer or other pathologies related to tobacco use. However, it is difficult to rely on the assessment based on the pack-year due to the different nature of the packaging by different companies. Definition The pack-year is a unit for measuring the amount a person has smoked over a long period of time. It is calculated by multiplying the number of packs of cigarettes smoked per day by the number of years the person has smoked. For example, 1 pack-year is equal to smoking 20 cigarettes (1 pack) per day for 1 year, or 40 cigarettes per day for half a year, and so on.http://www.cancer.gov/dictionary?CdrID=306510 National Cancer Institute definition of pack year One pack-year is the equivalent of 365.24 packs of cigarettes or 7,305 cigarettes, in a year as smoker. Calculation Number of pack-years = (packs smoked per day) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smoking
Smoking is a practice in which a substance is burned and the resulting smoke is typically breathed in to be tasted and absorbed into the bloodstream. Most commonly, the substance used is the dried leaves of the tobacco plant, which have been rolled into a small rectangle of rolling paper to create a small, round cylinder called a cigarette. Smoking is primarily practised as a route of administration for recreational drug use because the combustion of the dried plant leaves vaporizes and delivers active substances into the lungs where they are rapidly absorbed into the bloodstream and reach bodily tissue. In the case of cigarette smoking, these substances are contained in a mixture of aerosol particles and gases and include the pharmacologically active alkaloid nicotine; the vaporization creates heated aerosol and gas into a form that allows inhalation and deep penetration into the lungs where absorption into the bloodstream of the active substances occurs. In some cultures, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thoracic Diaphragm
The thoracic diaphragm, or simply the diaphragm ( grc, διάφραγμα, diáphragma, partition), is a sheet of internal Skeletal striated muscle, skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity. The diaphragm is the most important Muscles of respiration, muscle of respiration, and separates the thoracic cavity, containing the heart and lungs, from the abdominal cavity: as the diaphragm contracts, the volume of the thoracic cavity increases, creating a negative pressure there, which draws air into the lungs. Its high oxygen consumption is noted by the many mitochondria and capillaries present; more than in any other skeletal muscle. The term ''diaphragm'' in anatomy, created by Gerard of Cremona, can refer to other flat structures such as the urogenital diaphragm or Pelvic floor, pelvic diaphragm, but "the diaphragm" generally refers to the thoracic diaphragm. In humans, the diaphragm is slightly asymmetric—its right half is h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chest X-ray
A chest radiograph, called a chest X-ray (CXR), or chest film, is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most common film taken in medicine. Like all methods of radiography, chest radiography employs ionizing radiation in the form of X-rays to generate images of the chest. The mean radiation dose to an adult from a chest radiograph is around 0.02 mSv (2 mrem) for a front view (PA, or posteroanterior) and 0.08 mSv (8 mrem) for a side view (LL, or latero-lateral). Together, this corresponds to a background radiation equivalent time of about 10 days. Medical uses Conditions commonly identified by chest radiography * Pneumonia * Pneumothorax * Interstitial lung disease * Heart failure * Bone fracture * Hiatal hernia Chest radiographs are used to diagnose many conditions involving the chest wall, including its bones, and also structures contained within the thoracic c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barrel Chest
Barrel chest generally refers to a broad, deep chest found on a patient. A barrel chested person will usually have a naturally large ribcage, very round (i.e., vertically cylindrical) torso, large lung capacity, and can potentially have great upper body strength. It can sometimes be found alongside acromegaly (an enlargement of the acra resulting from excess levels of human growth hormone (HGH) in the body). Barrel chest, as a medical condition, is most commonly related to osteoarthritis as individuals age. Arthritis can stiffen the chest causing the ribs to become fixed in their most expanded position, giving the appearance of a barrel chest. Barrel chest refers to an increase in the anterior posterior diameter of the chest wall resembling the shape of a barrel, most often associated with emphysema. There are two main causes of the barrel chest phenomenon in emphysema: # Increased compliance of the lungs leads to the accumulation of air pockets inside the thoracic cavity. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airway Resistance
In respiratory physiology, airway resistance is the resistance of the respiratory tract to airflow during inhalation and exhalation. Airway resistance can be measured using plethysmography. Definition Analogously to Ohm's Law: :R_ = \frac Where: : = P_ - P_A So: :R_ = \frac Where: *R_ = Airway Resistance *P = Pressure Difference driving airflow *P_ = Atmospheric Pressure *P_A = Alveolar Pressure *\dot V = Volumetric Airflow (not minute ventilation which, confusingly, may be represented by the same symbol) N.B. PA and \dot V change constantly during the respiratory cycle. Determinants of airway resistance There are several important determinants of airway resistance including: *The diameter of the airways *Whether airflow is laminar or turbulent Hagen–Poiseuille equation In fluid dynamics, the Hagen–Poiseuille equation is a physical law that gives the pressure drop in a fluid flowing through a long cylindrical pipe. The assumptions of the equation are that the flow is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, coughing, chest tightness, and shortness of breath. These may occur a few times a day or a few times per week. Depending on the person, asthma symptoms may become worse at night or with exercise. Asthma is thought to be caused by a combination of genetic and environmental factors. Environmental factors include exposure to air pollution and allergens. Other potential triggers include medications such as aspirin and beta blockers. Diagnosis is usually based on the pattern of symptoms, response to therapy over time, and spirometry lung function testing. Asthma is classified according to the frequency of symptoms, forced expiratory volume in one second (FEV1), and peak expiratory flow rate. It may also be classified as atopic or non-atopic, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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