Respiratory System PDF - Dr. Mohammed Elsalanty

Respiratory System Western University College of Optometry Dr. Mohammed Elsalanty  Conduction Portion – Nasal cavity – Nasopharynx – Larynx – Trachea – Bronchi – Bronchioles – Terminal bronchioles Respiratory Portion (gas exchange) – Respiratory bronc...

Respiratory System Western University College of Optometry Dr. Mohammed Elsalanty  Conduction Portion – Nasal cavity – Nasopharynx – Larynx – Trachea – Bronchi – Bronchioles – Terminal bronchioles Respiratory Portion (gas exchange) – Respiratory bronchioles – Alveolar ducts (sacs) – Alveoli  Nasal Cavity Anterior vestibule and internal nasal fossae Anterior vestibule lined by skin, with sebaceous and sweat glands and thick hair (vibrissae) Posteriorly, epithelium loses its keratin, then turns into respiratory epithelium (pseudostratified columnar ciliated with Goblet Cells) Superior turbinate and roof  olfactory mucosa  THIN SKIN RESPIRATORY keratinized Stratified Squamous Pseudostratified Ciliated Columnar Epithelium Epithelium with Goblet Cells Nasopharynx Respiratory epithelium Serous and mucous gland in the lamina propria Masses of lymphoid tissue (L) form the nasopharyngeal tonsil (adenoids if enlarged), a component of “Waldeyer ring”. Most prominent in children and young adults Patches of squamous epithelium occur with increasing age (and smokers). Eustachian Tube  Respiratory epithelium, turns columnar ciliated near the middle ear.  Larynx Box of cartilage connecting the pharynx to the trachea – Hyaline: Thyroid, cricoid, and most of arytenoids – Elastic: Epiglottis, cuneiform, corniculate, and tip of arytenoid Epiglottis: – Projects from anterior rim of larynx at the posterior end of the tongue – Stratified squamous epithelium (oral and most of laryngeal surfaces) – RE: lower part of laryngeal surface – Mucous and serous glands – Elastic cartilage underneath  Vestibular Folds (False Vocal Cords) Superior to the vocal cords Covered by Respiratory Epithelium  Vocal Folds (True Vocal Cords) Non-keratinized stratified squamous epithelium Has skeletal muscle (the vocalis), and the vocal ligament (a band of elastic fibers) Below the vocal cords, the lining epithelium changes back to respiratory epithelium  Serous Glands Trachealis Muscle Hyaline Cartilage Respiratory epithelium, with serous glands in the lamina propria Opening in the cartilage C-shape bridged by fibroelastic ligament and smooth muscle (trachealis) contracts during coughing  Effect of Smoking on Trachea Loss of cilia Basal cell hyperplasia Goblet cell hyperplasia Sub-epithelial inflammatory cell infiltration Altered gene expression  Bronchial Tree Two 1ry (main) bronchi Enter the lung at the hilum then branch: – Rt  Three bronchi – Lt  Two bronchi Continue to branch down  bronchioles  terminal bronchioles  Bronchi Similar to trachea except: – Less serous glands in lamina propria – Cartilage form irregular plates – Spiral smooth muscles in lamina propria, more extensive distally – Lymphocyte infiltration in lamina propria Trachea Bronchus  Bronchioles Diameter < 1mm, intralobular Epithelium varies from ciliated columnar w/ goblet cells to ciliated columnar or cuboidal Lamina propria: Smooth muscle and elastic fibers (NO CARTILAGE) NO GLANDS  RESPIRATORY PORTION OF THE RESPIRATORY SYSTEM Where exchange of gases takes place across alveolar blood-air barrier Includes: 1. Respiratory bronchioles 2. Alveolar ducts (sacs) 3. Alveoli 1 2 3 4  Respiratory Bronchioles Beginning of gas exchange Mucosa interrupted by alveolar extensions Ciliated cuboidal + Clara cells Alveoli lined with squamous cells Smooth muscle and elastic fibers in LP  Alveolar Ducts The tube wall is composed entirely of alveoli Network of smooth muscles (act like sphincters and appear like knops between alveoli) Matrix of elastic and reticular fibers  Alveoli Sac-like pockets, 200 µm in diameter Bud off the walls of respiratory bronchioles, alveolar ducts, and alveolar sacs Honeycomb formation Interalveolar septum has two layers of squamous epithelium sandwiching blood vessels, nerves, elastic and reticular fibrous network, and connective tissue cells  Inter Alveolar Septum Richest capillary network in the body Structural support from elastic and reticular fibers Leukocytes (esp. macrophages) may be found Blood-Air Barrier (0.1 – 1.5 μm thick): – Squamous cell (alveolar lining) – Fused basal laminae – Endothelial cell (capillary lining)