The Respiratory System

The Respiratory System

1.     The Upper Respiratory Tracts:

·         Nose

·        Pharynx

2.     The Lower Respiratory Tracts

·        Larynx

·        Trachea

·        Bronchi

·        Lungs

The Respiratory System is divided also into

1.     Conducting Portions: nose, pharynx, larynx, trachea, bronchi, bronchioles and terminal bronchioles.

2.     Respiratory Portions: respiratory bronchioles, alveolar ducts, alveolar sacs and alveoli.

 

The Nose

·        septal cartilage: the inferior anterior nasal septum.

·        lateral cartilages: inferior anterior to the nasal bones.

·        alar cartilage: inferior portion of the nasal walls ( the swelled part).

·        External nares = nostrils: external openings of the nose.

·        Internal nares = choanae: between the pharynx and the internal nose.

·        Nasal cavity: space of the internal nose.

·        Superior,  middle and inferior meatuses: groovelike passage ways in the lateral walls of the nasal cavity made by the superior, middle and inferior nasal chonchae.

      

       The Pharynx

·        Nasopharynx: posterior to the nasal cavity down to the plane of soft palate.( 5 openings)

·        Oropharynx: from the soft palate down to the level of hyoid bone.

·        Laryngopharynx: from the level of hyoid bone down to the esophagus.

      

    

  The Larynx

·        9 pieces of Cartilage:

·        Thyroid  cartilage(Adam's Apple): the anterior wall of the larynx.

·        Epiglottis: the stem is attached to the thyroid cartilage while the leaf is free to control the opening and closing of the trachea.

·        Cricoid Cartilage: the inferior part of the larynx attached to the 1^st  ring of tracheal cartilage. 

·        2Arytenoid Cartilages: at the posterior superior borders of the cricoid cartilage, attached with  the vocal cords and the pharyngeal intrinsic muscles.

·        2Corniculate Cartilages: located at the apex of the arytenoid cartilages.

·        2Cuneiform Cartilages: anterior to the corniculate cartilages supporting the folds between the arytenoids and the epiglottis.

·        The vocal cords: the false vocal cords( ventricular folds)

                            the true vocal cords( vocal folds)

       the space between the two folds is the vestibule

     

       The Trachea

                It is located anterior to the esophagus, extends from the larynx down to the level of T5 where it divides into two primary bronchi( right and left). It contains C-shaped ring of hyaline cartilage.

      

       The Bronchi

             Start at the level of the superior border of T5 forming the carina. The right and the left bronchi enter the right and the left lung respectively at the hilus, where each one branches into two secondary bronchi inside each lung. Each secondary bronchus gives number of tertiary bronchi which will divide into smaller terminal bronchioles.

       The Lungs

       The two lungs are enveloped by two serous membranes; the parietal pleura lines the internal wall of thoracic cavity and the visceral pleura covers the lungs themselves. The pleural cavity is a space between the two pleural layers. The lungs extend from the diaphragm up to the level superior of the clavicle. The base of each  lung is directed inferiorly while the apex is directed superiorly. The hilus; at the mediastenal surface of each lung; is the point where the pulmonary blood vessels, lymphatic vessels, nerves and the bronchi enter and exit the lung. The left lung contains a concavity; the cardiac notch.

          The right lung is divided into three lobes; the superior, the  middle and the inferior lobes by the horizontal fissure and the oblique fissure. The left lung is divided into the superior and inferior lobes by the oblique fissure only. Each lobe receives its own secondary bronchus.                     

·  Bronchopulmonary segment: the segment of the lung tissue supplied by one tertiary bronchus.

·  Lobules: small components of the bronchopulmonary segment.

·  Respiratory bronchioles: microscopic subdivisions of the terminal bronchioles.

·  Alveolar ducts: subdivisions of the respiratory bronchioles.

·  Alveolus: cup shaped outpouching lined by simple squamous epithelium where the gaseous exchange occures.