drugs acting on respiratory system

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this ppt contains a general overview of respiratory system;its pathophysiology and drugs affecting respiratory system

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VICKY ANTHONY & SHUBHAM VERMA DRUGS ACTING ON RESPIRATORY SYSTEM & PATHOPHYSIOLOGY OF RESPIRATORY SYSTEM

RESPIRATORY SYSTEM:

RESPIRATORY SYSTEM The respiratory system (also called respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for the process of respiration in an organism. The respiratory system is involved in the intake and exchange of oxygen and carbon dioxide between an organism and the environment.

various organs of respiratory system are:

various organs of respiratory system are STRUCTURE FUNCTION nose / nasal cavity   warms, moistens, & filters air as it is inhaled pharynx (throat)   passageway for air, which leads to trachea larynx   the voice box, where vocal chords are located trachea (windpipe)   keeps the windpipe "open"   trachea is lined with fine hairs called cilia which filter air before it reaches the lungs bronchi   two branches at the end of the trachea, each lead to a lung bronchioles   a network of smaller branches leading from the bronchi into the lung tissue & ultimately to air sacs alveoli   the functional respiratory units in the lung where gases are exchanged

ANATOMY OF HUMAN RESPIRATORY SYSTEM:

ANATOMY OF HUMAN RESPIRATORY SYSTEM

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nose Two nostrils or nares allow air to pass from the outside and into the nasal cavities. Ciliated cells found in the upper parts of the nasal cavities are odor receptors and are responsible for the sense of smell. Pharynx or Throat The pharynx is a common passage way for both the respiratory and digestive systems. it consists of three parts-nasopharynx,oropharynx & laryngopharynx. Larynx or Voice Box The larynx is a structure located below the epiglottis that acts as a passage way for air between the pharynx and trachea. The larynx contains the vocal cords. Trachea or Windpipe The trachea lies in front of the esophagus and directs air between the larynx and the bronchi. The trachea is constructed from a number of cartilaginous rings stacked on top of each other. These rings prevent the trachea from collapsing as the pressure in the thoracic cavity decreases during inhalation.

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Bronchi (one is a bronchus) Bronchi branch off the trachea to supply air to both lungs. Each main bronchus branches into many secondary bronchi that have smaller diameters, thinner walls, and less cartilage for support. Secondary bronchi lead to the smaller tubes called bronchioles. Bronchioles Bronchioles are the smallest tubes within the lungs and carry air to the alveoli. Each bronchiole will supply air to a lobule within the lung that contains many alveoli. Thoracic Cavity The thoracic cavity is the enclosed space formed on the top and sides by the ribs and the diaphragm on the bottom. This cavity functions in breathing and protects vital organs like the heart and large blood vessels.

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Alveoli (one is an alveolus) Alveoli are the air sacs of the lungs. They have thin walls made of simple squamous epithelial cells and are surrounded by blood capillaries (another layer of simple squamous epithelium). Gas exchange occurs in the alveoli. Oxygen gas is in higher concentration in the alveoli than in the blood and so it diffuses into the blood through this thin layer of cells. Carbon dioxide is in higher concentration in the blood than the alveoli and so it diffuses into the alveoli through this thin layer of cells.

physiolology of respiratory system :

physiolology of respiratory system The respiratory system has a complex physiology and is responsible for multiple functions. There are multiple roles performed by the respiratory system: pulmonary ventilation, external respiration, internal respiration, transportation of gases and homeostatic control of respiration.Here is a brief description of each of those functions.

PULMONARY VENTILATION:

PULMONARY VENTILATION Pulmonary ventilation is the main process by which air flows in and out of the lungs. This is done through the contraction of muscles, as well as through a negative pressure system that is accomplished by the pleural membrane covering the lungs. When the lungs are completely sealed in this membrane, they remain at a pressure that is slightly lower than the pressure of the lungs at rest. As a result of this, the air passively fills the lungs until there is no more pressure difference. At this point, if necessary, additional air can be inhaled by contracting the diaphragm as well as the surrounding intercostal muscles. During exhalation, the muscles relax and this reverses the pressure dynamic, increasing the pressure on the outside of the lungs and forcing air to escape them until both pressures equalize again. As the lungs have elastic nature,they revert back to their state at rest and the entire process repeats itself.

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EXTERNAL RESPIRATION External respiration is a process that allows an exchange of gases to take place between the air located in the alveoli and the blood that is traveling through the capillaries. This is possible through a difference in pressure between the oxygen and carbon dioxide located in the air, and the oxygen and carbon dioxide in the blood. As a result of this, oxygen from the air is transferred to the blood while carbon dioxide from the blood goes into the air. The useful oxygen is then carried out throughout the body while the carbon dioxide is dispelled through exhalation. INTERNAL RESPIRATION Internal respiration is a similar process except it involves gas exchange between the blood in the capillaries and body tissue. Again, a difference in pressure allows oxygen to leave the blood and enter the tissue while carbon dioxide does the opposite.

gas exchange between blood and alveoli:

gas exchange between blood and alveoli alveoli

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This function of the respiratory system enables oxygen and carbon dioxide to travel throughout the body to wherever they are needed. Most of the gases are carried through blood attached to transport molecules such as hemoglobin, although blood plasma will also have a minimal content of gas. Almost 99% of the entire oxygen found in the human body is transported by hemoglobin. Most of the carbon dioxide is transported from all areas of the body back to the lungs by plasma in the form of bicarbonate ions. This is created from a catalytic reaction (caused by a carbonic anhydrase enzyme) between water and carbon dioxide, which combine to form carbonic acid. The carbonic acid then splits into hydrogen and bicarbonate ions, with the latter eventually being transformed into carbon dioxide again, taken to the lungs and exhaled. TRANSPORTATION OF GASES

pathophysiology of respiratory system:

pathophysiology of respiratory system some common diseases associated with respiratory system are asthma common cold pneumonia bronchitis tuberculosis

ASTHMA:

Asthma is a serious condition in which the small airways of the affected person's lungs suddenly constrict when they are exposed to certain triggers, such as dust mites,pollen,or even dry air and during exercise . During an asthma 'attack', the person's airway lining rapidly becomes inflamed and swollen, the muscles around the airways tighten, and excess muc o us is produced as the body reacts to the trigger. This reaction causes reduced airflow into and out of the lungs, and the person has to gasp for breath. ASTHMA

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signs and symptoms: Asthma is characterized by recurrent episodes of wheezing, shortness of breath chest tightness and coughing Sputum may be produced from the lung by coughing but is often hard to bring up. Symptoms are usually worse at night and in the early morning or in response to exercise or cold air

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treatment: Treatment of acute symptoms is usually with an inhaled short-acting beta-2 agonist (such as salbutamol) and oral corticosteroids. In very severe cases, intravenous corticosteroids, magnesium sulfate, and hospitalization may be required

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cause: Most ly caused by viral infection (rhinovirus or influenza virus—the “flu”) Virus invades tissues (mucosa) of upper respiratory tract, causing upper respiratory infection (URI). Excessive mucus production results from the inflammatory response to this invasion. signs and symptoms: Fluid drips down the pharynx into the esophagus and lower respiratory tract, causing cold symptoms: sore throat, coughing, upset stomach. COMMON COLD

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contd..... Irritation of nasal mucosa often triggers the sneeze reflex. Mucosal irritation also causes release of several inflammatory and vasoactive substances, dilating small blood vessels in the nasal sinuses and causing nasal congestion. treatment: Involves combined use of antihistamines, nasal decongestants, antitussives, and expectorants.

PNEUMONIA:

Pneumonia is an inflammatory condition of the lung affecting primarily the microscopic air sacs known as alveoli. cause: It is usually caused by infection with viruses or bacteria and less commonly other microorganisms, certain drugs and other conditions such as autoimmune diseases PNEUMONIA

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signs & symptoms:--- People with infectious pneumonia often have a productive cough fever accompanied by shaking chills shortness of breath sharp or stabbing chest pain during deep breaths an increased respiratory rate.

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Pneumonia fills the lung's alveoli with fluid, hindering oxygenation. The alveolus on the left is normal, whereas the one on the right is full of fluid from pneumonia.

BRONCHITIS:

Bronchitis means swelling in your air passages (bronchi). Bronchi are the air passages that connect your windpipe (trachea) with tiny air sacs (alveoli) in your lungs. The air sacs are where your body absorbs the oxygen you breathe in. Bronchitis is an inflammation of the bronchi. This inflammation means the walls of your bronchi are swollen and filled with extra sticky mucus. Airflow into and out of your lungs is partly blocked because of the swelling and extra mucus in your bronchi. This makes you cough. There are two kinds of bronchitis: Acute bronchitis: bronchitis that makes you sick for a while, and it gets better after 2 to 3 weeks. Chronic bronchitis: bronchitis that doesn't go away, chronic bronchitis is when you have a cough with mucus most days for 3 months of the year. BRONCHITIS

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cause Acute bronchitis is usually caused by viruses, typically the same viruses that cause colds and flu (influenza). The most common cause of chronic bronchitis is smoking cigarettes. Air pollution and dust or toxic gases in the environment or workplace also can contribute to the condition. symptoms For either acute bronchitis or chronic bronchitis, signs and symptoms may include: Cough Production of mucus (sputum), which can be clear, white, yellowish-gray or green in color — rarely, it may be streaked with blood Fatigue Shortness of breath Slight fever and chills Chest discomfort

treatment:

treatment Conventional treatment for acute bronchitis may consist of simple measures such as getting plenty of rest, drinking lots of fluids, avoiding smoke and fumes, and possibly getting a prescription for an inhaled bronchodilator and/or cough syrup. In some cases of chronic bronchitis, oral steroids to reduce inflammation and/or supplemental oxygen may be necessary.

TUBERCULOSIS:

TUBERCULOSIS cause Tuberculosis (TB) is a disease caused by bacteria called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but they can also damage other parts of the body. mode of spread: TB spreads through the air when a person with TB of the lungs or throat coughs, sneezes, or talks. You are more likely to get TB if you have a weak immune system.

Symptoms of TB in the lungs may include :

Symptoms of TB in the lungs may include A bad cough that lasts 3 weeks or longer Weight loss Loss of appetite Coughing up blood or mucus Weakness or fatigue Fever Night sweats

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treatment: The most common medications used to treat tuberculosis include: Isoniazid Rifampi ci n (Rifadin, Rimactane) Ethambutol (Myambutol) Pyrazinamide

Drugs that act on the respiratory system include :

Drugs that act on the respiratory system include antiasthmatic bronchodilators Corticosteroids mast cell stabilizers Leukotriene receptor antagonists Antihistamines Cough preparations Nasal decongestants expectorants antitussives

expectorants (mucokinetics):

these are drugs which increase bronchial secretion or reduce its viscosity,facilitating its removal by coughing. they are believed to "loosen"cough which becomes less tiring and more productive. used for productive cough conditions. expectorants (mucokinetics)

expectorants:

expectorants a)directly acting sodium and potassium citrate potassium iodide guaiacol balsum of tolu b)reflexly acting ammonium chloride or carbonate potassium iodide c)mucolytics bromhexine ambroxol acetyl cysteine and carbocisteine

antitussives:

these are drugs that act in the CNS to raise the threshold of cough centre or act peripherally in the respiratory tract to reduce tussal impulses,or both these actions. Because they aim to control rather than eliminate cough,antitussives should be used only for dry unproductive cough or if cough is unduly tiring,disturbs sleep or is hazardous. mainly used for unproductive cough. antitussives

antitussives:

antitussives a)opioids ~ codeine ~pholcodeine ~morphine ~ethylmorphine b)non-opioids ~noscapine ~dextromethorphan ~oxeladin ~chlophedianol c)antihistamine ~ chlorpheniramine ~diphenhydramine ~promethazine

nasal decongestant:

A decongestant (or nasal decongestant) is a type of pharmaceutical drug that is used to relieve nasal congestion in the upper respiratory tract. The active ingredient in most decongestants is either pseudoephedrine or phenylephrine (the latter of which has disputed efficacy). These are alpha-agonists which on topical application as dilute solution (0.05-0.1%) produce local vasoconstriction. Regular use of these agents for long periods should be avoided because mucosal ciliary function is impaired: atrophic rhinitis and anosmia can occur due to persistent vasoconstriction. nasal decongestant

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Common decongestants include: Ephedrine Levomethamphetamine Naphazoline Oxymetazoline Phenylephrine Phenylpropanolamine Propylhexedrine Synephrine Tetrahydrozoline Xylometazoline Pseudoephedrine—controlled in some jurisdictions for over the counter use Tramazoline

bronchodilators:

bronchodilators A bronchodilator is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lungs. Bronchodilators may be endogenous (originating naturally within the body), or they may be medications administered for the treatment of breathing difficulties. They are most useful in obstructive lung diseases, of which asthma and chronic obstructive pulmonary disease are the most common conditions Bronchodilators are either short-acting or long-acting

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The bronchodilators are divided in short- and long-acting groups. Short-acting bronchodilators are used for relief of bronchoconstriction, while long-acting bronchodilators are predominantly used as preventers. Short-acting bronchodilators include: Salbutamol/albuterol (Proventil or Ventolin) Levosalbutamol/levalbuterol Pirbuterol Epinephrine Racemic Epinephrine (Asthmanefrin, Primatene Mist Replacement) Ephedrine (Bronkaid) Terbutaline

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Long-acting bronchodilators include Salmeterol (Serevent) Clenbuterol (Spiropent) Formoterol Bambuterol Indacaterol

leukotriene antagonists:

since it was realized that cystenyl leukotrienes (LT-C 4 /D 4 ) are important mediators of bronchial asthma,effords were made to develop their antagonists and synthesis inhibitors. two cystenyl LT 1 receptor antagonists montelukast and zafirlukast have recently become available leukotriene antagonists

mast cell stabilizers:

Mast cell stabilizers are cromone medications used to prevent or control certain allergic disorders. They block a calcium channel essential for mast cell degranulation, stabilizing the cell and thereby preventing the release of histamine and related mediators. mast cell stabilizers

examples of mast cell stabilizers:

examples of mast cell stabilizers sodium cromoglycate nedocromil sodium ketotifen Cromoglicic acid

CORTICOSTEROIDS:

these benefit by reducing bronchial hyperreactivity,mucosal edema and by supperssing inflammatory response to AG:AB reaction or other trigger stimuli. it was realised that asthma is an iinflammatory disease,the attending inflammatory response is suppressed by glucocorticoids. CORTICOSTEROIDS

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