Respiratory System

• Respiratory System


  The system responsible for breathing and gas exchange in the body
• Parts of the Respiratory System

  • Upper Respiratory
  • Lower Respiratory
• Upper Respiratory


  • Nose
  • Nasal cavity
  • Pharynx
  • Associated structures
• Lower Respiratory


  • Larynx
  • Trachea
  • Bronchi
  • Lungs
• Functions of the Upper Respiratory

  • Passageway for respiration
  • Receptors for smell
  • Filters incoming air to filter larger foreign material
  • Moistens and warms incoming air
  • Resonating chambers for voice
• Functions of the Lower Respiratory

  • Larynx: maintains an open airway, routes food and air appropriately, assists in sound production
  • Trachea: transports air to and from lungs
  • Bronchi: branch into lungs
  • Lungs: transport air to alveoli for gas exchange
• Nose


  Provides entrance for air, has two portions: external nares (choanae) and internal nares
• Nasal Cavity


  Entrance of the respiratory system, lined with sticky mucus membrane and contains cilia, divided medially by the nasal septum
• Trachea


  A long tube connecting the mouth and nasal cavity to the rest of the respiratory system
• Bronchus


  The trachea branches off into two bronchi, one entering each lung
• Bronchioles


  Each bronchus divides into smaller tubes called bronchioles, which the air passes through
• Alveoli


  Located at the end of each bronchiole, air sacs which facilitate gas exchange, millions in the lungs
• Alveoli Features


  • They have thin walls to reduce the distance for diffusion
  • The walls are only one cell thick
  • They have a large surface area which is moist so gases can dissolve and diffuse across
  • They are surrounded by capillaries, so alveoli have a rich blood supply
• Respiratory Cycle


  1. Breathing (ventilation): air in to and out of lungs

  2. External respiration: gas exchange between air and blood

  3. Internal respiration: gas exchange between blood and tissues

  4. Cellular respiration: oxygen use to produce ATP, carbon dioxide as waste
• Respiratory Cycle Control


  • Carotid and aortic bodies: sensitive to carbon dioxide, pH, and oxygen levels
  • Conscious control: resides in higher brain centers; ability to modify breath is limited
  • Respiratory center in the medulla oblongata: establishes basic breathing pattern
  • Chemical receptors: monitor carbon dioxide, hydrogen ions, and oxygen levels
  • Medulla: sensitive to hydrogen ions in cerebrospinal fluid resulting from carbon dioxide in blood
• Inspiration


  Diaphragm contracts, pulling muscle down, intercostal muscles contract elevating chest wall and expanding volume of chest, lowering pressure in lungs, pulling in air
• Expiration


  Muscles relax, diaphragm resumes dome shape, intercostal muscles allow chest to lower resulting in increase of pressure in chest and expulsion of air
• Gas Exchange


  • Gases diffuse according to their partial pressures
  • External respiration: gases exchanged between air and blood
  • Internal respiration: gases exchanged with tissue fluids
  • Oxygen transport: bound to hemoglobin in red blood cells or dissolved in blood plasma
  • Carbon dioxide transport: dissolved in blood plasma, bound to hemoglobin, or in the form of plasma bicarbonate
• Pharynx


  Funnel shaped tube, wall composed of skeletal muscles lined with mucus membrane, has 3 regions: nasopharynx, oropharynx, laryngopharynx
• Larynx


  Voice box, conducts air into lower respiratory tract, produces voice, contains muscles that connect cartilage to other structures and to one another
• Trachea


  Flexible cylindrical tube
• Lungs


  Occupy most of the space in the thoracic cavity, left lung divided into 2 lobes, right lung divided into 3 lobes, blood supply is the pulmonary circulation
• Asthma


  A chronic inflammatory disease of the airways in which many cells/cellular elements play a role, causing recurrent episodes of wheezing, breathlessness, chest tightness, and coughing
• Asthma Pathophysiology


  • Chronic airway inflammation results in increased smooth muscle cell proliferation and hypertrophy leading to thickening of the airway wall, increased mucous production, and airway edema, resulting in partial airway obstruction and difficulty in airflow movement
  • Presence of inflammatory mediators may increase airway reactivity and induce bronchospasm (contraction of smooth muscle surrounding medium-sized bronchi and bronchioles)
• Asthma Symptoms


  • Wheezing
  • Rapid breathing and shortness of breath
  • Coughing
  • Chest tightness
  • Hyperinflation of thorax
• Asthma Types


  • Extrinsic (usually begins in childhood, associated with atopy)
  • Intrinsic (more common in adults, not associated with atopy, may have nasal polyps, asprin sensitivity, sinusitis)
• Asthma Triggers


  • Pollen
  • House dust mites
  • Pet dander
  • Cockroach antigens
  • Cigarette smoke
  • Perfume and other chemicals
  • Viral infections
  • Cold air
  • Exercise
  • Aspirin
• Asthma Diagnosis


  Made on the basis of spirometry: Spirometry measurements (FEV 1 , FVC, FEV 1 /FVC) taken before and after the patient inhales a short-acting bronchodilator
• Asthma Diagnosis Indicators


  • Symptoms occur or worsen in the presence of exercise, viral infection, animals with fur or feathers, house-dust mites, mold, pollen, smoke, changes in weather, strong emotional expression
  • Symptoms occur or worsen at night, awakening the patient
• Asthma Treatment Goals


  • Prevent chronic symptoms
  • Maintain normal/near normal pulmonary function
  • Maintain normal activity level
  • Prevent recurrent exacerbations
  • Minimize need of ER/hospital admissions
  • Meet patients' expectations of and satisfaction with care
• Asthma Medications


  • Quick relievers: short-acting beta 2 agonist inhalers
  • Long-term controllers: inhaled corticosteroids, long acting beta 2 agonist inhalers, oral beta 2 agonists, Theophylline, cromolyn/nedcromil, leukotriene modifiers