Respiratory

• Respiration


  The process of bringing in oxygen and removing carbon dioxide for body tissues
• Larger organisms

  • Need specialized organs to bring in oxygen and remove carbon dioxide
  • Land-dwelling animals have lungs for gas exchange
  • Aquatic species have gills
• All cells must capture oxygen to derive energy from food
• The body must dispose of carbon dioxide generated from metabolism
• Respiratory system


  • Defends against invasion of airborne microorganisms
  • Produces sounds that make speech possible
  • Regulates blood volume and pressure
  • Assists in controlling body fluid pH

  
• The respiratory system is responsible for the intake of oxygen and the disposal of carbon dioxide from the body's metabolism

  
• Structures of the Respiratory System


  • Nose, nasal cavity, sinuses
  • Pharynx (throat), larynx (voice box), trachea (windpipe)
  • Bronchi, bronchial tubes, bronchioles, alveoli
  • Lungs

  
• Nose and Nasal Cavity

  • Air enters through nostrils, hairs trap dust and particles
  • Sinuses help insulate, reduce weight, and allow voice resonance
  • Mucous membrane and cilia trap foreign particles
  • Mucous moistens and capillaries warm the air, preparing it for the lungs
• Pharynx and Larynx

  • Air travels from nasal cavities to pharynx, protected by uvula during swallowing
  • Air travels from pharynx to larynx (voice box), vocal cords make sounds
  • Larynx is covered by epiglottis during swallowing

  
• Trachea

  • Tube from larynx to lungs, with rings of cartilage to prevent collapse
  • Lined with ciliated mucous membrane to trap particles and move mucous to pharynx
• Lungs

  • Trachea branches into bronchi, then bronchial tubes, bronchioles, and alveoli
  • Alveoli are where gas exchange takes place
  • Lungs fill thoracic cavity, separated from abdomen by diaphragm
  • Covered by 2-layered pleural membrane with lubricating fluid

  
• Steps in Respiration

  1. Inhalation - air movement into lungs

  2. Exhalation - air movement out of lungs

  3. Pressure differentials between lungs and environment control respiratory cycle

  4. No air movement when pressure inside and outside lungs is equal

  5. Diaphragm contraction enlarges thoracic cavity, decreasing lung pressure and drawing in air

  6. Relaxation of respiratory muscles reduces thoracic cavity, increasing pressure and expelling air

  
• Gas Exchange during Breathing

  • Occurs at alveolar surface with rich capillary supply
  • Oxygen moves from alveoli into capillaries down concentration gradient
  • Oxygen binds to hemoglobin in red blood cells
  • Carbon dioxide moves from capillaries into alveoli down concentration gradient to be expelled

  
• Diseases of the Respiratory System


  • Asthma - bronchioles spasm, constricting airflow
  • Bronchitis - bronchioles swell and clog with mucous, more common in smokers
  • Emphysema - lungs lose elasticity, alveolar damage decreases respiratory surface area, causes breathing difficulties, smoking increases risk
  • Lung cancer