Respiratory System

• The major respiratory structures span the nasal cavity to the diaphragm
• Upper Airway


  The passage through which air enters and leaves the body
• A sagittal section of the upper airway and surrounding structures is illustrated
• Air passes through the upper airway


  1. External naris

  2. Nasal vestibule

  3. Nasal cavity

  4. Internal naris

  5. Nasopharynx

  6. Oropharynx

  7. Laryngopharynx

  8. Larynx

  9. Trachea
• Nasal cavity


  • Has raised nasal conchae and depressed meatuses that increase its surface area
  • Narrows at the internal naris that meets the nasopharynx
• Frontal sinus


  Hollowed out space within the frontal bone
• Sphenoidal sinus


  Hollowed out space within the sphenoid bone
• Air then passes by the tonsils as it moves through the nasopharynx above the uvula, the oropharynx posterior to the oral cavity, and the laryngopharynx before entering the larynx superior to the trachea
• Ciliated Pseudostratified Columnar Epithelium

  • The respiratory epithelium consists of a ciliated pseudostratified columnar epithelium featuring cilia at the apical surface facing the lumen of the airway and goblet cells that secrete mucus.
  • Seromucous glands embedded in the dense irregular connective tissue of the submucosa provide additional lubricating mucus.
• Pharynx


  A shared respiratory and digestive structure
• Divisions of the Pharynx


  • Nasopharynx
  • Oropharynx
  • Laryngopharynx
• Nasopharynx


  Found between the internal naris at the posterior of the nasal cavity and the soft palate
• Oropharynx


  Extends from the soft palate (posterior to the hard palate) to the superior surface of the open epiglottis where it is continuous with the inferior region of the pharynx: the laryngopharynx
• Laryngopharynx


  Anteriorly, opens into the larynx (which is superior to the trachea), whereas posteriorly, it enters the esophagus
• larynx

  • The larynx extends from the laryngopharynx and the hyoid bone to the trachea.

   
• Glottis

  •  The glottis inside the larynx includes the true vocal cords and the superior vestibular folds. A superior view shows the posterior of the tongue and the open epiglottis at the anterior.
  • The trachea is inferior to the glottis, visible beyond the opening of the V-shaped true vocal cords. The pyriform fossa is a depression lateral to the glottis at the base of the laryngopharnyx. The opening to the esophagus is posterior to the glottis.

   
• Trachea

  • The mucosa lines the lumen of the trachea and is comprised of ciliated pseudostratified columnar epithelium that contains goblet cells covering a lamina propria of connective tissue. The submucosa houses seromucous glands.
  • The C-shaped rings of hyaline cartilage are positioned deep to the mucosa with the opening at the posterior, which is spanned by the trachealis muscle and connective tissue.
  • The superficial layer of the trachea is adventitia. The esophagus is positioned posterior to the trachea.
• Bronchial Tree


  1. Trachea branches at the carina to the primary bronchi

  2. Primary bronchi branch into the secondary bronchi

  3. Secondary bronchi branch into the tertiary bronchi
• Primary bronchi


  Deliver air to each lung
• Secondary bronchi


  Deliver air to the lobes of each lung
• Tertiary bronchi


  Deliver air into the bronchopulmonary segments of each lobe
• Tracheal mucosa


  • Lined with ciliated pseudostratified columnar epithelium containing goblet cells
  • Covering a lamina propria of connective tissue that houses seromucous glands
• Tracheal structure


  • C-shaped rings of hyaline cartilage positioned deep to the mucosa with the opening at the posterior
  • Spanned by the trachealis muscle and connective tissue
  • Superficial layer is adventitia
• Esophagus


  Positioned posterior to the trachea
• Respiratory Zone


  1. Terminal bronchiole branches to respiratory bronchioles

  2. Respiratory bronchiole branches to alveolar ducts

  3. Alveolar ducts connect to alveolar sacs
• Alveolar sac


  A cluster of alveoli wrapped in a capillary bed where gas exchange occurs, appearing as if it was caught in a net
• Alveoli


  • Interconnected by way of alveolar pores
• Gas exchange


  1. Deoxygenated blood delivered to capillary bed in arteriole branched from pulmonary artery

  2. Oxygenated blood collected from capillary bed by venule draining to pulmonary vein
• Structure of Respiratory Zone

  • The alveolus is responsible for gas exchange.
  • A micrograph shows the alveolar structures within lung tissue.
• Normal & Bronchial Asthma Tissue

  • Normal lung tissue does not have the characteristics of lung tissue during
  • (b) an asthma attack, which include thickened mucosa, increased mucus-producing goblet cells, increased numbers of macrophages and mast cells, and eosinophil infiltrates.

   
• Left lung


  • Divided into two lobes
  • Less mass due to the cardiac notch
• Right lung


  • Divided into three lobes
• Separation of right lung lobes


  1. Right superior lobe separated from right middle lobe by right horizontal fissure

  2. Right middle lobe separated from right inferior lobe by right oblique fissure
• Separation of left lung lobe


  Left superior lobe separated from right inferior lobe by left oblique fissure
• Main (primary) bronchi


  Deliver air from the trachea into each lung
• Lobar (secondary) bronchi


  Deliver air into the lobes of each lung
• Segmental (tertiary) bronchi


  Deliver air into the bronchopulmonary segments of each lobe
• Parietal & Visceral Pleura of Lungs

  •  The pleural sac is formed by the parietal and visceral pleura of the lungs.
  • The parietal pleura is attached to the deep surface of the chest wall, which includes the ribs, sternum, thoracic vertebrae, connective tissue of the mediastinum, internal intercostal muscles, and the superior surface of the diaphragm.
  • The visceral pleura covers the superficial surface of the lobes of the lungs.
  • The pleural cavity is the potential space between the layers that is filled with lubricating serous fluid.
• Pneumothorax

  • caused by air in the pleural cavity, which increases pressure on the lung, causing it to collapse.
• Inspiration of Lungs

  • During inspiration, the diaphragm and external intercostal muscles contract, expanding the volume in the thoracic cavity, creating a pressure gradient with lower air pressure in the lungs that draws air in.