LUNGS ORAL CAVITY PHARYNX PARANASAL CAVITIES NASAL CAVITY NOSE UPPER RESPIRATORY SYSTEM LOWER RESPIRATORY SYSTEM LARYNX TRACHEA BRONCHI THE NOSE Air enters through two openings, THE EXTERNAL NARES or NOSTRILS. Just inside each nostril is an expanded VESTIBULE containing coarse hairs. A midsagittal NASAL SEPTUM divides the NASAL CAVITY. The maxillary, nasal, frontal, ethmoid and sphenoid bones form the lateral and superior walls of the nasal cavity. The HARD and SOFT PALATES form the floor of the cavity. ( the posterior part of the soft palate is the UVULA ) The external portion of the nose is composed of cartilage that forms the BRIDGE and the TIP of the nose. Posteriorly the INTERNAL NARES open into the nasopharynx. THE PHARYNX Is a chamber shared by the digestive and respiratory systems. It extends between the internal nares and the entrances to the larynx and esophagus. A stratified squamous epithelium lines the pharynx. THE THROAT OR PHARYNX IS DIVIDED IN THREE REGIONS 1. Upper NASO-PHARYNX 2. Middle OROPHARYNX 3. Lower LARYNGOPHARYNX THE NASOPHARYNX LIES SUPERIOR TO THE SOFT PALATE SERVES A PASSAGEWAY FOR AIRFLOW FROM NASAL CAVITY IT CONTAINS THE PHARYNGEAL TONSILS ( adenoids ) IN POSTERIOR WALL, AND THE OPENNINGS OF THE EUSTACHIAN TUBES ( auditory tubes ) THE OROPHARYNX EXTENDS FROM THE SOFT PALATE DOWN TO THE EPIGLOTTIS ( base of the tongue ) IT CONTAINS THE PALATINE AND LINGUAL TONSILS. THE LARYNGOPHARYNX INCLUDES THE NARROW ZONE BETWEEN THE HYOID BONE AND THE ENTRANCE TO THE ESOPHAGUS. THE LARYNX JOINS THE LARYNGOPHARYNX WITH THE TRACHEA. IT CONSISTS OF CARTILAGES IT IS ALSO CALLED THE VOICE BOX. THE THREE MAIN CARTILAGES ARE: THROID CARTILAGE ( Adamss apple ), EPIGLOTTIS, AND CRICOID CARTILAGE. THE EPIGLOTTIS IS A PIECE OF ELASTIC CARTILAGE THAT FALLS OVER THE OPENING ( GLOTTIS ) DURING SWALLOWING TO PREVENT INGESTED FOOD FROM ENTERING THE RESPIRATORY TRACT. THE LARYNX TWO PAIRS OF FOLDS SPAN THE GLOTTAL OPENING. FALSE VOCAL CORDS ARE INELASTIC BUT THE TENSION IN THE VOCAL CORDS CAN BE ADJUSTED BY VOLUNTARY MUSCULAR MOVEMENTS. DURING EXPIRATION AIR FLOWING THROUGH THE LARYNX VIBRATES THE VOCAL CORDS ( TRUE VOCAL CORDS ) AND PRODUCES SOUND WAVES. COUGHING AND LARYNGEAL SPASMS ARE PROTECTIVE REFLEXES THAT PROTECT THE GLOTTIS AND TRACHEA FROM FOREIGN OBJECTS AND IRRITANTS. THE TRACHEA IS A TUBULAR STRUCTURE WITH 4.25 in. IN LENGTH AND 1 in. IN DIAMETER. AT ITS CAUDAL LIMIT THE TRACHEA DIVIDES TO FORM THE PRIMARY BRONCHI. LIES ANTERIOR TO THE ESOPHAGUS THE TRACHEA ALONG THE LENGTH OF THE TRACHEA ARE C-SHAPED PIECES OF HYALINE CARTILAGE (TRACHEAL CARTILAGES) THE TRACHEAL MUSCLE HOLDS THE TWO SIDES OF THE C-SHAPED CARTILAGE TOGETHER POSTERIORLY TRACHEA IS LINED WITH PSEUDOSTRATIFIED CILIATED COLUMNAR EPITHELIUM THE TRACHEA BRANCHES WITHIN THE MEDIASTINUM, FORMING THE LEFT AND RIGHT PRIMARY BRONCHI LEFT AND RIGHT PRIMARY BRONCHI ( extrapulmonary bronchi ) EACH BRONCHUS ENTERS A LUNG AT A GROOVE, THE HILUS. EACH BRONCHUS BRANCHES INTO INCREASINGLY SMALLER PASSAGEWAYS TO CONDUCT AIR INTO THE LUNGS SECONDARY BRONCHI ( intrapulmonary bronchi ) AS THERE ARE LOBES OF EACH LUNG THE SMALLEST PASSAGEWAYS ARE THE BRONCHIOLES THE LUNGS ARE A PAIR OF CONE SHAPED ORGANS LYNING IN THE PLEURAL CAVITIES. THE APEX IS THE CONICAL TOP OF EACH LUNG, AND THE BROAD INFERIOR PORTION IS THE BASE. EACH LUNG HAS A HILUS, A MEDIAL SLIT WHERE THE BRONCHIAL TUBES, VASCULARIZATION, LYMPHATICS, AND NERVES REACH THE LUNG. EACH LUNG IS DIVIDED INTO LOBES BY DEEP FISURES Right Lung IS DIVIDED IN THREE LOBES ( SUPERIOR, MIDDLE and INFERIOR ) LEFT LUNG IS DIVIDE BY AN OBLIQUE FISSURE INTO SUPERIOR AND INFERIOR LOBES THE PLEURAL CAVITIES The thoracic cavity is bounded by the ribcage and the muscular diaphragm. The mediastinum divides the region into TWO PLEURAL CAVITIES. The pleural cavity is lined with a serous membrane, THE PLEURA. PARIETAL PLEURA lines the thoracic wall, diaphragm, and mediastinum. VISCERAL PLEURA covers the surfaces of the lungs. Alveoli THE ALVEOLAR WALLS ARE MADE OF SIMPLE SQUAMOUS PULMONARY EPITHELIUM SCATTERED AMONG EPITHELIUM ARE SURFACTANT CELLS THAT SECRETE AN OIL COATING TO PREVENT THE ALVEOLI FROM STICKING TOGETHER AFTER EXHALATION. ALSO IN THE ALVEOLAR WALL ARE MACROPHAGES THAT PHAGOCYTIZE DEBRIS OR POTENTIAL PATHOGENS PULMONARY CAPILLARIES COVER THE EXTERIOR OF THE ALVEOLI