A&P 2

• Hair, mucus, blood capillaries and cilia line the nasal cavity to filter, moisten, warm, and eliminate debris from the passing air.
• The nasal septum divides the nasal cavity into two chambers.
• The nose consists of the visible external nose and the internal nasal cavity.
• Air enters two openings in the nose called nare.
• Air then passes into the vestibule and through passages called the superior, middle, and inferior meatus. The bony wall of the meatuses is called the concha.
• Function of the nose: 1) filters air 2) warms air 3) moistens air 4) passage way for air 5) chemical examination of air.
• The pharynx is the passageway for food and air from the mouth to the esophagus. It consists of three parts: the oropharynx, the laryngopharynx, and the nasopharynx.
• Nasopharynx: receives air from the two internal nares. The pharyngeal tonsil (adenoid) lies at the back of the nasopharynx.
• Oropharynx: extends from the soft palate posteriorly to the epiglottis anteriorly. Receives both air and food from the oral cavity. The palatine and lingual tonsils are located here.
• Laryngopharynx: passes food to the esophagus and air to the larynx.
• Functions of the pharynx: 1)common pathway for respiratory and digestive tracks 2) speech production 3) warming, humidifying and filtering air.
• The pharynx is supported by muscles and has the potential to collapse while the nasal cavity is supported by bone.
• Larynx: receives air from the laryngopharynx and consists of several pieces of cartilage. The epiglottis, thyroid cartilage, arytenoid cartilage, and cricoid cartilage.
• Epiglottis: A flexible flap that covers the larynx during swallowing to prevent the entrance of food.
• Thyroid Cartilage: forms the Adam's apple and protects the front of the larynx.
• Arytenoid Cartilage: A bony structure that forms the vocal fold. False vocal cords allow breath to be held during periods and the true vocal cords contain elastic ligaments that allow the vocal folds to vibrate. This causes speech production.
• Cricoid Cartilage: a paired cuneiform cartilage and the paired corniculate cartilage supports the larynx.
• Function of the Larynx: 1) air passageway 2) filtration, warming and humidification of air 3) voice production.
• Trachea (windpipe): extends inferiorly from the larynx to the bronchi. It is composed of C-shaped rings of hyaline cartilage with fibrous connective tissue between them. The trachealis muscle surrounds it and keeps it open.
• The trachea is c-shaped with the opening posteriorly because it lies in front of the esophagus. The shape allows the esophagus to expand when swallowing.
• Function of the trachea: carries air from the bronchi to the lungs
• Bronchi: Two tubes that branch from the trachea to the left and right lungs.
• Each bronchus divides into smaller bronchioles, which carry air to the alveoli.
• Alveolar ducts: the final branches of the bronchial tree that have enlarged, bubble-like swellings along its length called alveoli.
• Alveoli are tiny sacs where gas exchange occurs between blood capillaries and inspired air.
• The walls of the alveoli consist of simple squamous epithelium (type I cells) and type II cells. Type I cells allow for efficient oxygen diffusion and type II cells secrete pulmonary surfactant that reduces surface tension.
• Capillaries surround the alveoli and have a very thin wall to allow for the exchange of gases.
• Function of the bronchi and alveoli: 1) distribution of air 2) exchange of gases 3) cleansing, warming, humidifying of air
• Lungs: A pair of cone-shaped organs that are located in the thoracic cavity. The right and left lungs are separated by the mediastinum and are divided into three and two lobes respectively.
• Each lung has an apex and a base. The apex is the top of the lung and the base is the bottom of the lung.
• The pleural membrane covers both surfaces of the lungs and lines the inside of the chest cavity. It consists of parietal pleura on the inner side of the rib cage and visceral pleura covering the outer layer of the lungs.
• Functions of the lungs: Gas exchange, ventilation, and respiration
• Functions of the respiratory system: Air distribution, gas exchange, filters, warms, and humidifies the air and regulates the PH balance in the blood.
• Oxygen in the air diffuses out of the lungs and into the blood, while carbon dioxide diffuses in the opposite direction.
• External respiration: Gas exchange between the atmosphere and the body tissues.
• Internal respiration: the process of gas exchange between the blood, interstitial fluid, and the cells.
• Cellular respiration: Energy in the cell is released in the form of ATP, using oxygen and glucose while producing waste.
• Thorax: The chest region, including the lungs, heart, and trachea.
• The thorax has 3 divisions, the left and right pleural cavity (contains the lungs) and the mediastinum.
• The parietal pleura is the outer layer of the lung and is attached to the diaphragm.