respiratory

• The respiratory system is the set of organs that allows a person to breathe and exchange oxygen and carbon dioxide throughout the body
• Passage of air into the lungs for oxygen supply is called inhalation
• Passage of air out of the lungs to expel carbon dioxide is called exhalation
• This process is collectively called breathing or ventilation
• Organs involved in breathing include the nose, throat, larynx, trachea, bronchi, and lungs
• The respiratory system aids in the exchange of gases between the air and blood, and between the blood and the body’s cells
• Most organs help distribute air, but only alveoli and alveolar ducts are responsible for gas exchange
• Functions of the respiratory system include air distribution, gas exchange, filtration, warming and humidifying incoming air, playing a role in speech, the sense of smell, and helping the body maintain homeostasis and pH regulation
• The respiratory system is divided into the upper respiratory tract (nose, pharynx, larynx) and lower respiratory tract (larynx, trachea, bronchi, lungs)
• Nasal cavity warms, filters, and humidifies air
• Sinuses help make the skull lighter
• The pharynx functions as a passageway for air and food, provides a resonating chamber for speech sounds, and houses the tonsils
• Pharynx consists of nasopharynx, oropharynx, and laryngopharynx
• The larynx is a passageway connecting the pharynx and trachea
• Contains vocal folds that produce sound when they vibrate
• Lower respiratory tract includes the trachea, lungs, and bronchial tree segments
• Trachea is the main airway to the lungs
• Bronchi branch from the trachea into each lung to supply air
• Lungs provide oxygen to capillaries and exhale carbon dioxide
• Diaphragm is the main respiratory muscle for breathing
• Pleural membrane encloses and protects the lungs
• Parietal pleura lines the thoracic cavity wall
• Visceral pleura covers the lungs
• Pleural cavity contains lubricating fluid for membrane movement
• Alveoli are sac-like structures for gas exchange
• Type I alveolar cells are for gas exchange, Type II alveolar cells secrete alveolar fluid
• Surfactant lowers surface tension to prevent alveoli collapse
• Alveolar macrophages remove dust and debris in alveolar spaces
• Respiratory membrane consists of alveolar cells, basement membranes, and capillary endothelium
• Pulmonary ventilation involves air flow between atmosphere and alveoli due to pressure changes from respiratory muscle contraction and relaxation
• Includes inspiration (inhalation) and expiration (exhalation)
• Respiratory physiology involves internal and external respiration
• Internal respiration is gas exchange between interstitial fluid and cells
• External respiration is gas exchange between interstitial fluid and external environment
• Steps of external respiration include pulmonary ventilation, gas diffusion, and transport of oxygen and carbon dioxide
• Factors affecting pulmonary ventilation include decreased compliance, airway resistance, scar tissue in the lungs, pulmonary edema, surfactant deficiency, and impeded expansion
• Quiet breathing (eupnea) uses the diaphragm
• Airway Resistance:

  • The rate of air flow through the airways depends on both the pressure difference and the resistance
• Mechanisms of Breathing:

  • Quiet breathing (eupnea) uses the diaphragm and external and internal intercostal muscles
  • Forced breathing (hyperpnea) uses accessory muscles
• Breathing Patterns and Respiratory Movements:

  • Tidal Volume (VT) is the volume of one breath
  • Minute Ventilation (MV) is the total volume of air inhaled and exhaled each minute, calculated as respiratory rate multiplied by tidal volume
  • Alveolar Ventilation Rate is the volume of air per minute that reaches the alveoli and other respiratory portions
  • Inspiratory Reserve Volume is additional inhaled air more than the tidal volume
  • Expiratory Reserve Volume is the air excess of tidal volume that is exhaled