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The Respiratory System

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The Respiratory System

  1. 1. The Respiratory System
  2. 2.  Oversees gas exchanges (oxygen and carbon dioxide) between the blood and external environment  Exchange of gases takes place within the lungs in the alveoli (only site of gas exchange, other structures passageways  Passageways to the lungs purify, warm, and humidify the incoming air  Shares responsibility with cardiovascular system Function of the Respiratory System
  3. 3.  Nose  Pharynx  Larynx  Trachea  Bronchi  Lungs – alveoli Organs of the Respiratory System
  4. 4. Upper Respiratory Tract
  5. 5. The Nose • The only externally visible part of the respiratory system • Air enters the nose through the external nares (nostrils) • The interior of the nose consists of a nasal cavity divided by a nasal septum
  6. 6.  Olfactory receptors are located in the mucosa on the superior surface  The rest of the cavity is lined with respiratory mucosa Moistens air Traps incoming foreign particles Anatomy of the Nasal Cavity
  7. 7.  Lateral walls have projections called conchae Increases surface area Increases air turbulence within the nasal cavity  The nasal cavity is separated from the oral cavity by the palate Anterior hard palate (bone) Anatomy of the Nasal Cavity
  8. 8.  Cavities within bones surrounding the nasal cavity  Frontal bone  Sphenoid bone  Ethmoid bone  Maxillary bone Paranasal Sinuses
  9. 9. Lighten the skull Act as resonance chambers for speech Produce mucus that drains into the nasal cavity Functions of the Paranasal Sinuses
  10. 10.  Muscular passage from nasal cavity to larynx  Three regions of the pharynx  Nasopharynx – superior region behind nasal cavity  Oropharynx – middle region behind mouth  Laryngopharynx – inferior region attached to larynx  The oropharynx and laryngopharynx are common passageways for air and food Pharynx (Throat)
  11. 11. Pharynx (Throat)
  12. 12. Upper Respiratory Tract
  13. 13.  Auditory tubes enter the nasopharynx  Tonsils of the pharynx  Pharyngeal tonsil (adenoids) in the nasopharynx  Palatine tonsils in the oropharynx  Lingual tonsils at the base of the tongue Structures of the Pharynx
  14. 14.  Routes air and food into proper channels  Plays a role in speech  Made of eight rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage (epiglottis) Larynx (Voice Box)
  15. 15.  Thyroid cartilage  Largest hyaline cartilage  Protrudes anteriorly (Adam’s apple)  Epiglottis  Superior opening of the larynx  Routes food to the larynx and air toward the trachea Structures of the Larynx
  16. 16.  Vocal cords (vocal folds)  Vibrate with expelled air to create sound (speech)  Glottis – opening between vocal cords Structures of the Larynx
  17. 17.  Connects larynx with bronchi  Lined with ciliated mucosa  Beat continuously in the opposite direction of incoming air  Expel mucus loaded with dust and other debris away from lungs  Walls are reinforced with C-shaped hyaline cartilage Trachea (Windpipe)
  18. 18. Tracheotomy
  19. 19.  Formed by division of the trachea  Enters the lung at the hilus (medial depression)  Right bronchus is wider, shorter, and straighter than left  Bronchi subdivide into smaller and smaller branches Primary Bronchi
  20. 20.  Occupy most of the thoracic cavity  Apex is near the clavicle (superior portion)  Base rests on the diaphragm (inferior portion)  Each lung is divided into lobes by fissures  Left lung – two lobes  Right lung – three lobes Lungs
  21. 21. Lungs
  22. 22.  Pulmonary (visceral) pleura covers the lung surface  Parietal pleura lines the walls of the thoracic cavity  Pleural fluid fills the area between layers of pleura to allow gliding Coverings of the Lungs
  23. 23.  Primary bronchi  Secondary bronchi  Tertiary bronchi  Bronchioli  Terminal bronchioli Respiratory Tree Divisions
  24. 24. Respiratory Tree Divisions
  25. 25. • Smallest branches of the bronchi • All but the smallest branches have reinforcing cartilage • Terminal bronchioles end in alveoli Bronchioles
  26. 26.  Structures  Respiratory bronchioli  Alveolar duct  Alveoli  Site of gas exchange Respiratory Zone
  27. 27.  Structure of alveoli  Alveolar duct  Alveolar sac  Alveolus  Gas exchange Alveoli
  28. 28.  Thin squamous epithelial layer lining alveolar walls  Pulmonary capillaries cover external surfaces of alveoli Respiratory Membrane (Air-Blood Barrier)
  29. 29.  Gas crosses the respiratory membrane by diffusion Oxygen enters the blood Carbon dioxide enters the alveoli  Macrophages add protection  Surfactant coats gas-exposed alveolar surfaces Gas Exchange
  30. 30. Gas exchange
  31. 31.  Pulmonary ventilation – moving air in and out of the lungs  External respiration – gas exchange between pulmonary blood and alveoli  Respiratory gas transport – transport of oxygen and carbon dioxide via the bloodstream  Internal respiration – gas exchange between blood and tissue cells in systemic capillaries Events of Respiration
  32. 32.  Completely mechanical process  Depends on volume changes in the thoracic cavity  Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure Mechanics of Breathing (Pulmonary Ventilation)
  33. 33.  Two phases Inspiration – flow of air into lung Expiration – air leaving lung Mechanics of Breathing (Pulmonary Ventilation)
  34. 34.  Diaphragm and intercostal muscles contract  The size of the thoracic cavity increases  External air is pulled into the lungs due to an increase in intrapulmonary volume Inspiration
  35. 35. Inspiration
  36. 36.  Largely a passive process which depends on natural lung elasticity  As muscles relax, air is pushed out of the lungs  Forced expiration can occur mostly by contracting internal intercostal muscles to depress the rib cage Exhalation
  37. 37. Exhalation
  38. 38.  Can be caused by reflexes or voluntary actions  Examples  Cough and sneeze – clears lungs of debris  Laughing  Crying  Yawn  Hiccup Nonrespiratory Air Movements
  39. 39.  Normal breathing moves about 500 ml of air with each breath (tidal volume [TV])  Many factors that affect respiratory capacity  A person’s size  Sex  Age  Physical condition  Residual volume of air – after exhalation, about 1200 ml of air remains in the lungs Respiratory Volumes and Capacities
  40. 40.  Residual volume Air remaining in lung after expiration About 1200 ml Respiratory Volumes and Capacities
  41. 41.  Vital capacity The total amount of exchangeable air Vital capacity = TV + IRV + ERV Dead space volume  Air that remains in conducting zone and never reaches alveoli  About 150 ml Respiratory Volumes and Capacities
  42. 42.  Functional volume Air that actually reaches the respiratory zone Usually about 350 ml  Respiratory capacities are measured with a spirometer Respiratory Volumes and Capacities
  43. 43. Respiratory Capacities
  44. 44.  Sounds are monitored with a stethoscope  Bronchial sounds – produced by air rushing through trachea and bronchi  Vesicular breathing sounds – soft sounds of air filling alveoli Respiratory Sounds
  45. 45.  Oxygen movement into the blood The alveoli always has more oxygen than the blood Oxygen moves by diffusion towards the area of lower concentration Pulmonary capillary blood gains oxygen External Respiration
  46. 46.  Carbon dioxide movement out of the blood  Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli  Pulmonary capillary blood gives up carbon dioxide  Blood leaving the lungs is oxygen-rich and carbon dioxide-poor External Respiration
  47. 47.  Oxygen transport in the blood Inside red blood cells attached to hemoglobin (oxyhemoglobin [HbO2]) A small amount is carried dissolved in the plasma Gas Transport in the Blood
  48. 48.  Carbon dioxide transport in the blood Most is transported in the plasma as bicarbonate ion (HCO3 –) A small amount is carried inside red blood cells on hemoglobin, but at different binding sites than those of oxygen Gas Transport in the Blood
  49. 49.  Exchange of gases between blood and body cells  An opposite reaction to what occurs in the lungs Carbon dioxide diffuses out of tissue to blood Oxygen diffuses from blood into tissue Internal Respiration
  50. 50. Internal Respiration
  51. 51. A Summary of External Respiration, Gas Transport, and Internal Respiration
  52. 52.  Activity of respiratory muscles is transmitted to the brain by the phrenic and intercostal nerves  Neural centers that control rate and depth are located in the medulla  The pons appears to smooth out respiratory rate  Normal respiratory rate (eupnea) is 12–15 respirations per minute  Hypernia is increased respiratory rate often due to extra oxygen needs Neural Regulation of Respiration
  53. 53. Neural Regulation of Respiration
  54. 54.  Physical factors  Increased body temperature  Exercise  Talking  Coughing  Volition (conscious control)  Emotional factors Factors Influencing Respiratory Rate and Depth
  55. 55.  Chemical factors Carbon dioxide levels  Level of carbon dioxide in the blood is the main regulatory chemical for respiration  Increased carbon dioxide increases respiration  Changes in carbon dioxide act directly on the medulla oblongata Factors Influencing Respiratory Rate and Depth
  56. 56.  Chemical factors (continued) Oxygen levels  Changes in oxygen concentration in the blood are detected by chemoreceptors in the aorta and carotid artery  Information is sent to the medulla oblongata Factors Influencing Respiratory Rate and Depth
  57. 57. Respiratory Diseases
  58. 58.  Exemplified by chronic bronchitis and emphysema  Major causes of death and disability in the United States Chronic Obstructive Pulmonary Disease (COPD)
  59. 59.  Features of these diseases Patients almost always have a history of smoking Labored breathing (dyspnea) becomes progressively more severe Coughing and frequent pulmonary infections are common Chronic Obstructive Pulmonary Disease (COPD)
  60. 60.  Features of these diseases (continued) Most victims retain carbon dioxide, are hypoxic and have respiratory acidosis Those infected will ultimately develop respiratory failure Chronic Obstructive Pulmonary Disease (COPD)
  61. 61.  Alveoli enlarge as adjacent chambers break through  Chronic inflammation promotes lung fibrosis  Airways collapse during expiration  Patients use a large amount of energy to exhale  Over inflation of the lungs leads to a permanently expanded barrel chest  Cyanosis appears late in the disease Emphysema
  62. 62.  Mucosa of the lower respiratory passages becomes severely inflamed  Mucus production increases  Pooled mucus impairs ventilation and gas exchange  Risk of lung infection increases  Pneumonia is common  Hypoxia and cyanosis occur early Chronic Bronchitis
  63. 63. Chronic Obstructive Pulmonary Disease (COPD)
  64. 64. Hypoxia
  65. 65.  Accounts for 1/3 of all cancer deaths in the United States  Increased incidence associated with smoking  Three common types  Squamous cell carcinoma  Adenocarcinoma  Small cell carcinoma Lung Cancer
  66. 66. Lung Cancer
  67. 67.  Apparently healthy infant stops breathing and dies during sleep  Some cases are thought to be a problem of the neural respiratory control center  One third of cases appear to be due to heart rhythm abnormalities SIDS (Sudden Infant Death Syndrome)
  68. 68.  Chronic inflamed hypersensitive bronchiole passages  Response to irritants with dyspnea, coughing, and wheezing Asthma
  69. 69. • Using an Inhaler Asthma and Inhalers
  70. 70.  Lungs are filled with fluid in the fetus  Lungs are not fully inflated with air until two weeks after birth  Surfactant that lowers alveolar surface tension is not present until late in fetal development and may not be present in premature babies Developmental Aspects of the Respiratory System
  71. 71.  Important birth defects  Cystic fibrosis – oversecretion of thick mucus clogs the respiratory system  Cleft palate Developmental Aspects of the Respiratory System
  72. 72.  Elasticity of lungs decreases  Vital capacity decreases  Blood oxygen levels decrease  Stimulating effects of carbon dioxide decreases  More risks of respiratory tract infection Aging Effects
  73. 73.  Newborns – 40 to 80 respirations per minute  Infants – 30 respirations per minute  Age 5 – 25 respirations per minute  Adults – 12 to 18 respirations per minute  Rate often increases somewhat with old age Respiratory Rate Changes Throughout Life