Acute bronchitis
Acute bronchitis is most often caused by viruses that infect the epithelium of the bronchi, resulting in inflammation and increased secretion of mucus. Cough, a common symptom of acute bronchitis, develops in an attempt to expel the excess mucus from the lungs. Other common symptoms include sore throat, runny nose, nasal congestion (coryza), low-grade fever, malaise, and the production of sputum.
Acute bronchitis often develops during the course of an upper respiratory infection (URI) such as the common cold or influenza]. About 90% of cases of acute bronchitis are caused by viruses, including rhinoviruses, adenoviruses, and influenza. Bacteria, including Mycoplasma pneumoniae, Chlamydia pneumoniae, and Bordetella pertussis, account for about 10% of cases.
Treatment for acute bronchitis is primarily symptomatic. Non-steroidal anti-inflammatory drugs (NSAIDs) may be used to treat fever and sore throat. Decongestants can be useful in patients with nasal congestion, and expectorants may be used to loosen mucus and increase expulsion of sputum. Cough suppressants may be used if the cough interferes with sleep or is bothersome, although coughing may be useful in expelling sputum from the airways. Even with no treatment, most cases of acute bronchitis resolve quickly.
Only about 5-10% of bronchitis cases are caused by a bacterial infection. Most cases of bronchitis are caused by a viral infection and are "self-limited" and resolve themselves in a few weeks. As most cases of acute bronchitis are caused by viruses, antibiotics should not be used since they are only effective against bacteria. Using antibiotics in patients who do not have bacterial infections promotes the development of antibiotic-resistant bacteria, which may lead to greater morbidity and mortality. Antibiotics should only be prescribed if microscopic examination of Gram stained sputum shows large numbers of bacteria present.
Chronic bronchitis
Chronic bronchitis, a type of chronic obstructive pulmonary disease, is defined by a productive cough that lasts for 3 months or more per year for at least 2 years[3]. Other symptoms may include wheezing and shortness of breath, especially upon exertion. The cough is often worse soon after awakening, and the sputum produced may have a yellow or green color and may be streaked with blood.
Chronic bronchitis is caused by recurring injury or irritation to the respiratory epithelium of the bronchi, resulting in chronic inflammation, edema (swelling), and increased production of mucus by goblet cells. Airflow into and out of the lungs is partly blocked because of the swelling and extra mucus in the bronchi or due to reversible bronchospasm.
Most cases of chronic bronchitis are caused by smoking cigarettes or other forms of tobacco. Chronic inhalation of irritating fumes or dust from occupational exposure or air pollution may also be causative. About 5% of the population has chronic bronchitis, and it is two times more common in males than females.
Chronic bronchitis is treated symptomatically. Inflammation and edema of the respiratory epithelium may be reduced with inhaled corticosteroids. Wheezing and shortness of breath can be treated by reducing bronchospasm (reversible narrowing of smaller bronchi due to constriction of the smooth muscle) with bronchodilators such as inhaled β-Adrenergic agonists (e.g., albuterol) and inhaled anticholinergics (e.g., ipratropium bromide). Hypoxemia, too little oxygen in the blood, can be treated with supplemental oxygen. However, oxygen supplementation can result in decreased respiratory drive leading to increased blood levels of carbon dioxide and subsequent respiratory acidosis.
The most effective method of preventing chronic bronchitis and other forms of COPD is to avoid smoking cigarettes and other forms of tobacco.
On pulmonary tests, a bronchitic (bronchitis) may present a decreased FEV1 and FEV1/FVC. However, unlike the other common obstructive disorders, asthma and emphysema, bronchitis rarely causes a high residual volume. This is because the air flow obstruction found in bronchitis is due to increased resistance, which does not generally cause the airways to collapse prematurely and trap air in the lungs.
понедельник, 30 ноября 2009 г.
Bronchitis
Bronchitis is an infection of the bronchial tubes that carry air from your throat to your lungs. When infected, bronchial tubes become inflamed, making it difficult to breath, and produce mucus which causes coughing. Other symptoms may include a slight fever, sore throat, muscle pain when breathing, and wheezing. It is even possible, during acute bronchitis, to cough so hard that the explosive vacuum you create in your lungs can crack or otherwise hurt your ribs, which makes further coughing even more painful.
Bronchitis can be either chronic or acute. Acute bronchitis is often the result of a cold or flu, in which case it is said the cold 'turned into bronchitis'. Acute bronchitis is most often caused by a virus, rather than bacteria, so taking antibiotics will probably not help, although doctors often prescribe them because their patients insist.
Acute bronchitis will usually go away on its own. The best treatment is bed rest and fluids. Because bronchitis causes the buildup of mucus, an expectorant cough syrup can help thin down the mucus and make it easier to cough up. Drinking fluids will also help with this, as well as replace the fluids you lose to the infection. See your doctor if you are still having symptoms after two weeks - you may have another respiratory problem.
The best way to avoid acute bronchitis is the same way you would try to avoid a cold. Wash your hands often, disinfect as necessary during cold season, and avoid crowded or confined spaces if there's 'something going around'.
Chronic bronchitis is a condition most often seen in smokers. This is a more permanent inflammation of the bronchial tubes caused by the irritation of cigarette smoke. Chronic bronchitis is like an on-going, less severe case of acute bronchitis. The bronchial tubes are always slightly inflamed, mucus is always being produced, and the result is the 'smoker's hack'. The best cure for chronic bronchitis is to stop smoking, but if that is unworkable for you, cutting down can reduce the stress on your bronchial tubes and allow them to recover somewhat.
Bronchitis can be either chronic or acute. Acute bronchitis is often the result of a cold or flu, in which case it is said the cold 'turned into bronchitis'. Acute bronchitis is most often caused by a virus, rather than bacteria, so taking antibiotics will probably not help, although doctors often prescribe them because their patients insist.
Acute bronchitis will usually go away on its own. The best treatment is bed rest and fluids. Because bronchitis causes the buildup of mucus, an expectorant cough syrup can help thin down the mucus and make it easier to cough up. Drinking fluids will also help with this, as well as replace the fluids you lose to the infection. See your doctor if you are still having symptoms after two weeks - you may have another respiratory problem.
The best way to avoid acute bronchitis is the same way you would try to avoid a cold. Wash your hands often, disinfect as necessary during cold season, and avoid crowded or confined spaces if there's 'something going around'.
Chronic bronchitis is a condition most often seen in smokers. This is a more permanent inflammation of the bronchial tubes caused by the irritation of cigarette smoke. Chronic bronchitis is like an on-going, less severe case of acute bronchitis. The bronchial tubes are always slightly inflamed, mucus is always being produced, and the result is the 'smoker's hack'. The best cure for chronic bronchitis is to stop smoking, but if that is unworkable for you, cutting down can reduce the stress on your bronchial tubes and allow them to recover somewhat.
суббота, 28 ноября 2009 г.
Skin
The skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system made up of multiple layers of mesodermal tissue, and guards the underlying muscles, bones, ligaments and internal organs. Skin of a different nature exists in amphibians, reptiles, birds. Human skin is not unlike that of most other mammals except that it is not protected by a pelt and appears hairless though in fact nearly all human skin is covered with hair follicles. The adjective cutaneous literally means "of the skin" (from Latin cutis, skin).
Because it interfaces with the environment, skin plays a key role in protecting (the body) against pathogens and excessive water loss. Its other functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and the protection of vitamin B folates. Severely damaged skin will try to heal by forming scar tissue. This is often discolored and depigmented.
In humans, skin pigmentation varies among populations, and skin type can range from dry to oily. Such skin variety provides a rich and diverse habit for bacteria which number roughly a 1000 species from 19 phyla.
Skin has mesodermal cells, pigmentation, or melanin, provided by melanocytes, which absorb some of the potentially dangerous ultraviolet radiation (UV) in sunlight. It also contains DNA-repair enzymes that help reverse UV damage, and people who lack the genes for these enzymes suffer high rates of skin cancer. One form predominantly produced by UV light, malignant melanoma, is particularly invasive, causing it to spread quickly, and can often be deadly. Human skin pigmentation varies among populations in a striking manner. This has led to the classification of people(s) on the basis of skin color.
Mammalian skin often contains hairs, which in sufficient density is called fur. The hair mainly serves to augment the insulation the skin provides, but can also serve as a secondary sexual characteristic or as camouflage. On some animals, the skin is very hard and thick, and can be processed to create leather. Reptiles and fish have hard protective scales on their skin for protection, and birds have hard feathers, all made of tough β-keratins. Amphibian skin is not a strong barrier to passage of chemicals and is often subject to osmosis. A frog sitting in an anesthetic solution could quickly go to sleep.
The skin is the largest organ in the human body. For the average adult human, the skin has a surface area of between 1.5-2.0 square meters (16.1-21.5 sq ft.), most of it is between 2–3 mm (0.10 inch) thick. The average square inch (6.5 cm²) of skin holds 650 sweat glands, 20 blood vessels, 60,000 melanocytes, and more than a thousand nerve endings.
Skin performs the following functions:
1. Protection: an anatomical barrier from pathogens and damage between the internal and external environment in bodily defense; Langerhans cells in the skin are part of the adaptive immune system.
2. Sensation: contains a variety of nerve endings that react to heat and cold, touch, pressure, vibration, and tissue injury; see somatosensory system and haptics.
3. Heat regulation: the skin contains a blood supply far greater than its requirements which allows precise control of energy loss by radiation, convection and conduction. Dilated blood vessels increase perfusion and heatloss, while constricted vessels greatly reduce cutaneous blood flow and conserve heat. Erector pili muscles are significant in animals.
4. Control of evaporation: the skin provides a relatively dry and semi-impermeable barrier to fluid loss. Loss of this function contributes to the massive fluid loss in burns.
5. Aesthetics and communication: others see our skin and can assess our mood, physical state and attractiveness.
6. Storage and synthesis: acts as a storage center for lipids and water, as well as a means of synthesis of vitamin D by action of UV on certain parts of the skin.
7. Excretion: sweat contains urea, however its concentration is 1/130th that of urine, hence excretion by sweating is at most a secondary function to temperature regulation.
8. Absorption: Oxygen, nitrogen and carbon dioxide can diffuse into the epidermis in small amounts, some animals using their skin for their sole respiration organ (contrary to popular belief, however, humans do not absorb oxygen through the skin). In addition, medicine can be administered through the skin, by ointments or by means of adhesive patch, such as the nicotine patch or iontophoresis. The skin is an important site of transport in many other organisms.
9. Water resistance: The skin acts as a water resistant barrier so essential nutrients aren't washed out of the body.
Because it interfaces with the environment, skin plays a key role in protecting (the body) against pathogens and excessive water loss. Its other functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and the protection of vitamin B folates. Severely damaged skin will try to heal by forming scar tissue. This is often discolored and depigmented.
In humans, skin pigmentation varies among populations, and skin type can range from dry to oily. Such skin variety provides a rich and diverse habit for bacteria which number roughly a 1000 species from 19 phyla.
Skin has mesodermal cells, pigmentation, or melanin, provided by melanocytes, which absorb some of the potentially dangerous ultraviolet radiation (UV) in sunlight. It also contains DNA-repair enzymes that help reverse UV damage, and people who lack the genes for these enzymes suffer high rates of skin cancer. One form predominantly produced by UV light, malignant melanoma, is particularly invasive, causing it to spread quickly, and can often be deadly. Human skin pigmentation varies among populations in a striking manner. This has led to the classification of people(s) on the basis of skin color.
Mammalian skin often contains hairs, which in sufficient density is called fur. The hair mainly serves to augment the insulation the skin provides, but can also serve as a secondary sexual characteristic or as camouflage. On some animals, the skin is very hard and thick, and can be processed to create leather. Reptiles and fish have hard protective scales on their skin for protection, and birds have hard feathers, all made of tough β-keratins. Amphibian skin is not a strong barrier to passage of chemicals and is often subject to osmosis. A frog sitting in an anesthetic solution could quickly go to sleep.
The skin is the largest organ in the human body. For the average adult human, the skin has a surface area of between 1.5-2.0 square meters (16.1-21.5 sq ft.), most of it is between 2–3 mm (0.10 inch) thick. The average square inch (6.5 cm²) of skin holds 650 sweat glands, 20 blood vessels, 60,000 melanocytes, and more than a thousand nerve endings.
Skin performs the following functions:
1. Protection: an anatomical barrier from pathogens and damage between the internal and external environment in bodily defense; Langerhans cells in the skin are part of the adaptive immune system.
2. Sensation: contains a variety of nerve endings that react to heat and cold, touch, pressure, vibration, and tissue injury; see somatosensory system and haptics.
3. Heat regulation: the skin contains a blood supply far greater than its requirements which allows precise control of energy loss by radiation, convection and conduction. Dilated blood vessels increase perfusion and heatloss, while constricted vessels greatly reduce cutaneous blood flow and conserve heat. Erector pili muscles are significant in animals.
4. Control of evaporation: the skin provides a relatively dry and semi-impermeable barrier to fluid loss. Loss of this function contributes to the massive fluid loss in burns.
5. Aesthetics and communication: others see our skin and can assess our mood, physical state and attractiveness.
6. Storage and synthesis: acts as a storage center for lipids and water, as well as a means of synthesis of vitamin D by action of UV on certain parts of the skin.
7. Excretion: sweat contains urea, however its concentration is 1/130th that of urine, hence excretion by sweating is at most a secondary function to temperature regulation.
8. Absorption: Oxygen, nitrogen and carbon dioxide can diffuse into the epidermis in small amounts, some animals using their skin for their sole respiration organ (contrary to popular belief, however, humans do not absorb oxygen through the skin). In addition, medicine can be administered through the skin, by ointments or by means of adhesive patch, such as the nicotine patch or iontophoresis. The skin is an important site of transport in many other organisms.
9. Water resistance: The skin acts as a water resistant barrier so essential nutrients aren't washed out of the body.
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