Untitled

• Respiratory system


  Consists of the paired lungs and a series of air passages that lead to the lungs. Within the lungs, the air passages branch into smaller tubes until the very smallest air spaces, called alveoli.
• Functions of the respiratory system

  • Air conduction
  • Air filtration
  • Gas exchange (respiration)
• Conducting portion


  Those parts of the respiratory system located outside as well as within the lungs
• Nasal cavities


  Two large air-filled spaces in the uppermost part of the respiratory system
• Larynx


  A hollow tubular organ containing cartilaginous framework
• Trachea


  A flexible air tube that extends from the larynx to the thorax, and in the mediastinum it divides into paired main bronchi
• Main (primary) bronchi


  Enter the root of the right or left lung. Within the lungs, the main bronchi undergo extensive branching to give rise to the bronchioles.
• Respiratory portion


  That part of the respiratory tract in which gas exchange occurs
• Respiratory bronchioles


  Involved in both air conduction and gas exchange
• Alveolar ducts


  Elongated airways openings to alveoli
• Tracheal wall


  • Consists of four definable layers: Mucosa, Submucosa, Cartilaginous layer, Adventitia
• Unique feature of the trachea

  • Presence of a series of C-shaped hyaline cartilages that are stacked one on top of each other to form a supporting structure, preventing collapse of the tracheal lumen and providing flexibility
• Tracheal epithelium


  Principal cell types are ciliated columnar cells and mucous (goblet) cells
• Ciliated cells


  • Most numerous of the tracheal cell types, provide a coordinated sweeping motion of the mucous coat toward the pharynx, serve as an important protective mechanism for removing small inhaled particles
• Mucous cells


  • Interspersed among the ciliated cells, contain mucinogen that is typically washed out in histological preparations
• إطار


  تمنع انهيار
• تظهر العديد من البروزات على السطح القمي
• الحركة التنظيفية المنسقة


  تقدم
• تعتبر آلية حماية مهمة
• إزالة الجزيئات الصغيرة التي تم استنشاقها
• تتخلل


  المواد المخاطية عادة
• لا توجد ألواح غضروفية في القصيبات
• Bronchiolar Structure


  1. Bronchioles branch repeatedly

  2. Bronchioles have no cartilage plates

  3. Bronchioles have ciliated columnar epithelium that transforms to simple ciliated columnar epithelium

  4. Goblet cells present in larger bronchioles but not in terminal bronchioles

  5. Smooth muscle layer present in bronchiole walls
• Alveolar ducts


  Elongated airways with almost no walls, only alveoli
• Alveolar sacs


  Spaces surrounded by clusters of alveoli
• Alveoli


  • Terminal air spaces of respiratory system, sites of gas exchange between air and blood
  • Surrounded and separated by thin connective tissue layer containing blood capillaries (alveolar septum)
  • Alveolar epithelium composed of type I and II alveolar cells
• Type I alveolar cells

  Extremely thin squamous cells, not capable of cell division
• Type II alveolar cells

  Cuboidal cells interspersed among type I cells, progenitor cells for type I cells, proliferate to restore type I and II cells after lung injury