1Chapter 22.Respiratory SystemOverview• Respiratory anatomy• Respiration• Respiratory musculature• Ventilation, lung volumes and capacities• Gas exchange and transport–O2–CO2• Respiratory centers • Chemoreceptor reflexes• Respiratory DiseasesOxygen• Is obtained from the air by diffusion across delicate exchange surfaces of lungs• Is carried to cells by the cardiovascular system which also returns carbon dioxide to the lungs Functions of the Respiratory System• Supplies body with oxygen and get rid of carbon dioxide• Provides extensive gas exchange surface area between air and circulating blood• Moves air to and from exchange surfaces of lungs• Protects respiratory surfaces from outside environment• Produces sounds• Participates in olfactory senseFigure 23–1Components of the Respiratory SystemOrganization of the Respiratory System• Upper respiratory system– Nose, nasal cavity, sinuses, and pharynx• Lower respiratory system– Larynx, trachea, bronchi and lungs2The Respiratory Tract• Conducting zone:–from nasal cavity to terminal bronchioles– conduits for air to reach the sites of gas exchange• Respiratory zone:– the respiratory bronchioles, alveolar ducts, and alveoli– sites of gas exchange The Respiratory EpitheliumFigure 23–2Respiratory Epithelia• Changes along respiratory tract• Nose, nasal cavity, nasopharynx = pseudostratifiedciliated columnar epithelium• Oropharynx, laryngopharynx = stratified squamousepitheium• Trachea, bronchi = pseudostratified ciliated columnar epithelium• Terminal bronchioles = cuboidal epithelium• Respiratory bronchioles, alveoli = simple squamousepithelium• Think about why each part has the lining that it does– For example, in alveoli• walls must be very thin (< 1 µm) • surface area must be very great (about 35 times the surface area of the body)– In lower pharynx• walls must be tough because food abrades themThe Respiratory Mucosa• Consists of:– epithelial layer–areolarlayer• Lines conducting portion of respiratory system • Lamina propria– Areolar tissue in the upper respiratory system, trachea, and bronchi (conducting zone)– Contains mucous glands that secrete onto epithelial surface– In the conducting portion of lower respiratory system, contains smooth muscle cells that encircle lumen of bronchiolesRespiratory Defense System• Series of filtration mechanisms removes particles and pathogens• Hairs in the nasal cavity• Goblet cells and mucus glands: produce mucus that bathes exposed surfaces• Cilia: sweep debris trapped in mucus toward the pharynx (mucus escalator)• Filtration in nasal cavity removes large particles• Alveolar macrophages engulf small particles that reach lungs Upper Respiratory TractFigure 23–33Upper Respiratory Tract• Nose :– Air enters through nostrils or external nares into nasal vestibule– Nasal hairs in vestibule are the first particle filtration system•Nasal Cavity :– Nasal septum divides nasal cavity into left and right– Mucous secretions from paranasal sinus and tears clean and moisten the nasal cavity– Meatuses Constricted passageways in between conchae that produce air turbulence:• Warm (how?) and humidify incoming air (bypassed by mouth breathing)• trap particles • Air flow: from external nares to vestibule to internal naresthrough meatuses, then to nasopharynxThe Pharynx• A chamber shared by digestive and respiratory systems that extends from internal nares to the dual entrances to the larynx and esophagus at the C6 vertebrae• Nasopharynx– Superior portion of the pharynx (above the soft palate) contains pharyngeal tonsils; epithelium?• Oropharynx– Middle portion of the pharynx, from soft palate to epiglottis; contains palatine and lingual tonsils; communicates with oral cavity; epithelium?• Laryngopharynx– Inferior portion of the pharynx, extends from hyoid bone to entrance to larynx and esophagus Lower Respiratory Tract• Air flow from the pharynx enters the larynx, continues into trachea, bronchial tree, bronchioles, and alveoliAnatomy of the LarynxFigure 23–4Cartilages of the Larynx• 3 large, unpaired cartilages form the body of the larynx (voice box)– thyroid cartilage (Adam’s apple)• hyaline cartilage• Forms anterior and lateral walls of larynx• Ligaments attach to hyoid bone, epiglottis, and other laryngeal cartilages– cricoid cartilage• hyaline cartilage• Form posterior portion of larynx• Ligaments attach to first tracheal cartilage– the epiglottis• elastic cartilage•Covers glottis during swallowing• Ligaments attach to thyroid cartilage and hyoid boneSmall Cartilages of the Larynx• 3 pairs of small hyaline cartilages:–arytenoidcartilages– corniculate cartilages– cuneiform cartilages• Corniculate and arytenoid cartilages function in opening and closing the glottis and the production of sound4Larynx Functions• To provide a patent airway• To function in voice production• To act as a switching mechanism to route air and food into the proper channels– Thyroid and cricoid cartilages support and protect the glottis and the entrance to trachea– During swallowing the larynx is elevated and the epiglottis folds back over glottis prevents entry of food and liquids into respiratory tract Sphincter Functions of Larynx• The larynx is closed during coughing, sneezing, and Valsalva’s maneuver • Valsalva’s maneuver– Air is temporarily held in the lower respiratory tract by closing the glottis – Causes intra-abdominal pressure to rise when abdominal muscles contract– Helps to empty the rectum– Acts as a splint to stabilize the trunk when lifting heavy loads• Glottis also “closed” (covered) by epiglottis during swallowingThe GlottisFigure 23–5Sound Production• Air passing through glottis:– vibrates vocal folds and produces sound waves• Sound is varied by:– tension on vocal folds– voluntary muscles position cartilagesAnatomy of the TracheaFigure 23–6The Trachea • Extends from the cricoid cartilage into mediastinum where it branches into right and left bronchi• Has mucosa, submucosa which contains mucous glands, and adventitia• Adventita made up of 15–20 C-shaped tracheal cartilages (hyaline) strengthen and protect airway– Ends of each tracheal cartilage are connected by an elastic ligament and trachealis muscle where trachea contacts esophagus. Why?5The Primary Bronchi• Right and left