Chapter 13 The Respiratory System

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Chapter 13The Respiratory System
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• Organs of the Respiratory system

• Nose
• Pharynx
• Larynx
• Trachea
• Bronchi
• Lungs alveoli

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• Function of the Respiratory System

• Gas exchanges between blood and external
  environment
• Exchange of gasses within lungs in the alveoli
• Passageways to the lungs purify, warm, and
  humidify the incoming air

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• Upper Respiratory Tract

Figure 13.2
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• The Nose

• Only visible part of the respiratory system
• Air enters through external nares (nostrils)
• Interior is nasal cavity divided by nasal septum

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• Anatomy of the Nasal Cavity

• Olfactory receptors located in mucosa on superior
  surface
• Cavity otherwise lined w/ respiratory mucosa
• - Moistens air
• - Traps incoming foreign particles

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• Anatomy of the Nasal Cavity

• Lateral walls have projections called conchae
• Increases surface area
• Increases air turbulence
• within the nasal cavity
• Nasal cavity separated from oral cavity by the
  palate
• Anterior hard palate (bone)
• Posterior soft palate (muscle)

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• Paranasal Sinuses

• Cavities in bones around nose
• - Frontal bone
• - Sphenoid bone
• - Ethmoid bone
• - Maxillary bone

• Functions
• - Lighten the skull
• - Resonance chambers for speech
• - Produce mucus that drains into the nasal cavity

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• Pharynx (Throat)

• Muscular passage from nasal cavity to larynx
• 3 regions of the pharynx
• Nasopharynx superior region behind
• nasal cavity
• Oropharynx middle region behind mouth
• Laryngopharynx inferior region attached
• to larynx
• Oro- laryngo- are common passageways for air
  and food

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• Structures of the Pharynx

• Auditory tubes enter the nasopharynx
• Tonsils of pharynx
• - Pharyngeal tonsil (adenoids) in nasopharynx
• - Palatine tonsils in oropharynx
• - Lingual tonsils at base of tongue

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• Larynx (Voice Box)

• Routes air and food into proper channels
• Helps in speech
• 8 rigid hyaline cartilages and spoon-shaped flap
  of elastic cartilage (epiglottis)

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• Structures of the Larynx

• Thyroid cartilage
• - Largest hyaline cartilage
• - Protrudes anteriorly (Adams apple)
• Epiglottis
• - Superior opening of the larynx
• - Routes food to the larynx and air toward the
  trachea

• Vocal cords (vocal folds)
• - Vibrates air to create sound (speech)
• Glottis opening between vocal cords

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• Trachea (Windpipe)

• Connects larynx with bronchi
• Lined with ciliated mucosa
• - Beat in opposite direction of incoming air
• - Expel mucus loaded with debris away from lungs
• Walls reinforced with C-shaped hyaline cartilage

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• Primary Bronchi

• Formed by division of trachea
• Enters lung at hilus (medial depression)
• Right bronchus is wider, shorter, and straighter
  than left
• Bronchi subdivide into smaller and smaller
  branches

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• Lungs

• Occupy most of thoracic cavity
• Apex is near clavicle (superior)
• Base rests on diaphragm (inferior portion)
• Each lung is divided into lobes by fissures
• Left lung two lobes
• Right lung three lobes

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• Coverings of the Lungs

• Pulmonary (visceral) pleura covers lung surface
• Parietal pleura lines walls of thoracic cavity
• Pleural fluid fills area between layers of pleura
  to allow gliding reduces friction

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• Respiratory Tree Divisions

• Primary bronchi
• Secondary bronchi
• Tertiary bronchi
• Bronchioli
• Terminal bronchioli

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• Alveoli

• Structure of alveoli
• Alveolar duct
• Alveolar sac
• Alveolus
• Gas exchange across membrane of alveoli

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• Respiratory Membrane (Air-Blood Barrier)

• Squamous epithelial
• Capillaries cover alveoli
• Blood not exposed to air

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• Gas Exchange

• Gas crosses membrane by diffusion
• - Oxygen enters the blood
• - Carbon dioxide enters the alveoli
• Macrophages add protection
• Surfactant
  coats inside
  alveolus

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• Events of Respiration

• Pulmonary ventilation moving air in and out of
  lungs
• External respiration gas exchange between blood
  and alveoli

3. Respiratory gas transport transport of gases
via the bloodstream 4. Internal respiration gas
exchange between blood and tissue cells
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• Pulmonary Ventilation

• Mechanical process based on volume changes in the
  thoracic cavity
• Volume changes pressure changes
• Gases go from high low pressure

• Two phases
• - Inspiration into lung
• - Expiration leaving lung

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• Inspiration

• Diaphragm intercostal muscles contract
• Thoracic cavity increases
• External air is pulled into the lungs due to an
  increase in intrapulmonary volume

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• Exhalation

• Passive process
• As muscles relax, air pushed out
• Forced expiration can occur mostly by contracting
  internal intercostal muscles to depress the rib
  cage

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• Pressure Differences in Thoracic Cavity

• Intrapleural space is always negative
  (intrapleural pressure)
• Differences in lung and pleural space pressures
  keep lungs from collapsing

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• Nonrespiratory Air Movements

• Caused by reflexes or voluntary actions
• Examples
• Cough and sneeze clears lungs of debris
• Laughing
• Crying
• Yawn
• Hiccup

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• Respiratory Volumes and Capacities

• Normal breathing 500 ml of air each breath (tidal
  volume TV)
• Many factors that affect respiratory capacity
• - Size
• - Sex
• - Age
• - Physical condition
• Residual volume of air after exhalation, about
  1200 ml of air remains in the lungs

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• Respiratory Volumes and Capacities

• Inspiratory reserve volume (IRV)
• Extra air forcibly taken in over tidal volume
• Usually between 2100 - 3200 ml
• Expiratory reserve volume (ERV)
• Amount of air that can be forcibly exhaled
• 1200 ml

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• Respiratory Volumes and Capacities

• Residual volume 1200 ml
• Air remaining in lung after expiration

• Vital capacity
• The total amount of exchangeable air
• Vital capacity TV IRV ERV
• Dead space volume
• Air in conducting zone never reaches alveoli
• About 150 ml

• Functional volume - Usually 350 ml
• Air that actually reaches the respiratory zone
• Spirometer tool that measures respiratory
  capacities

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• Respiratory Capacities