Respiratory System Part One

RESPIRATORY SYSTEM PART ONE 1- Respiratory Anatomy &

Physiology

General Respiratory Anatomy 

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The respiratory system is comprised of the upper airway and lower airway structures. The upper respiratory system filters, moistens and warms air during inspiration.  Upper airway - from the nose or mouth to the external opening of the vocal cords  Serves as a passage for food and inspired gas  Structures: mouth, nose, pharynx, larynx The lower respiratory system enables the movement and exchange of gases to regulate PO2, PCO2 and PH.  Conducts air to the gas exchange surface  Structures: trachea, carina, bronchi, alveolar sacs

Upper Respiratory 

Upper Respiratory  Nose and Sinuses  Warm, filter, and humidify air  First defense against foreign particles  Pharynx  Behind oral and nasal cavities  Nasopharynx  behind nose  soft palate, adenoids and eustachian tube  Oropharynx  from soft palate to base of tongue  palatine tonsils  Laryngopharynx  base of tongue to esophagus  where food and fluids are separated from air  bifurcation of larynx and esophagus

Upper Respiratory

 Larynx  Between

trachea and pharynx  Commonly called the voice box  Thyroid cartilage Adam's apple  Cricoid cartilage  

contains vocal cords the only complete ring in the airway

Upper Respiratory 

Glottis - opening between vocal cords

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Epiglottis - covers airway during swallowing

Lower Respiratory 

Lower Respiratory and Other Structures

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Trachea 

In neck, in front of esophagus

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Carries air to lungs

Lower Respiratory 

Mainstem bronchi  Right and left  Right more vertical, so right lung more likely to receive aspirate

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Conducting Airways  Lobar bronchi  surrounded by blood vessels, lymphatics, nerves  lined with ciliated, columnar epithelial cell

Lower Respiratory Bronchioles  no cartilage; collapse more easily  no cilia  do not participate in gas exchange Alveolar Ducts and Alveoli  Lungs contain approximately 300 million alveoli  Alveoli surrounded by capillary network  Gas exchange area (blood takes O2, gives off CO2)  Gas exchange happens at alveolar-capillary membrane  Held open by surfactant  Collapse of alveoli is called atelectasis 

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Lower Respiratory 

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Other Structures: Accessory muscles of respiration  Scalene muscles - elevate first two ribs

Sternocleidomastoid - raises sternum  Trapezius and pectoralis - stabilize shoulders  Abdominal muscles - put power into cough and assists with deep breathing  In infants - nasal flaring, sternal or intercostal retractions, grunting

Physiology

Physiology 

Ph regulation  Blood Ph (partial pressure of hydrogen in blood): a decrease in blood Ph stimulates respiration, both through the neurons of the brain's respiratory center and through the chemoreceptors in carotid arteries and aortic arch.  Blood PaCO2 (partial pressure of carbon dioxide in arterial blood): an increase in the PaCO2 results in decreased blood Ph, and stimulates respiration as described above.  Blood PaO2 (partial pressure of oxygen in arterial blood): a decrease in the PaO2 results in a decreased blood Ph, stimulating respiration as described above.  When arterial Ph rises or the arterial PaCO2 falls, hypoventilation occurs.