The Respiratory System Basic functions of the respiratory system Breathing (Pulmonary Ventilation) – movement of air in and out of the lungs Inhalation (inspiration) draws gases into the lungs. Exhalation (expiration) forces gases out of the lungs. Gas Conditioning – as gases pass through the nasal cavity and paransal sinuses, inhaled air becomes turbulent. The gases in the air are • warmed to body temperature • humidified • cleaned of particulate matter Gas Exchange - respiration • Supplies body with oxygen • Disposes of carbon dioxide Produces Sounds Protects respiratory surfaces Site for olfactory sensation

Respiration Respiration – four distinct processes must happen Pulmonary ventilation – moving air into and out of the lungs External respiration – gas exchange between the lungs and the blood Transport – transport of oxygen and carbon dioxide between the lungs and tissues Internal respiration – gas exchange between systemic blood vessels and tissues

Functional Anatomy of the Respiratory System Respiratory organs Nose, nasal cavity, and paranasal sinuses Pharynx, larynx, and trachea Bronchi and smaller branches Lungs and alveoli

Organs of the Respiratory System Figure 21.1

Respiratory System Consists of Respiratory muscles – diaphragm and other muscles that promote ventilation Respiratory zone – site of external respiration – respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli. Conducting zones Provides rigid conduits for air to reach the sites of gas exchange Includes nose, nasal cavity, pharynx, trachea Air passages undergo 23 orders of branching in the lungs

The Nose Provides an airway for respiration Moistens and warms air Filters inhaled air Resonating chamber for speech Houses olfactory receptors Skin is thin – contains many sebaceous glands

The Nasal Cavity External nares – nostrils Divided by – nasal septum Vestibule - anterior opening Continuous with nasopharynx Two types of mucous membrane Olfactory mucosa - Near roof of nasal cavity, houses olfactory (smell) receptors Respiratory mucosa - Lines nasal cavity Epithelium is pseudostratified ciliated columnar Goblet cells within epithelium Underlying layer of lamina propria has glands that contribute to the mucus layer and blood vessels that warm the air. Cilia move contaminated mucus posteriorly

Nasal Cavity

Nasal Conchae 3 paired bony projections along the lateral walls of the nasal cavity Superior and middle nasal conchae - part of the ethmoid bone Inferior nasal conchae - separate bone Function - Particulate matter deflected to mucus-coated surfaces

The Paranasal Sinuses Figure 7.11a, b

The Pharynx Funnel-shaped passageway Connects nasal cavity and mouth Shared by the digestive and respiratory systems Divided into three sections by location Nasopharynx – superior portion, Oropharynx – continuous with the oral cavity Laryngopharynx – between the hyoid bone and the esophagus Type of mucosal lining changes along its length

The Nasopharynx Superior to the point where food enters Only an air passageway Closed off during swallowing Epithelium consists of ciliated pseudostratified epithelium that moves mucus

The Oropharynx Arch-like entranceway – fauces Extends from soft palate to the epiglottis Epithelium - stratified squamous epithelium Two types of tonsils in the oropharynx Palatine tonsils – in the lateral walls of the fauces Lingual tonsils – covers the posterior surface of the tongue

The Laryngopharynx Passageway for both food and air Epithelium - stratified squamous epithelium Continuous with the esophagus and larynx

The Larynx Prevent food and drink from entering the trachea Passageway for air Produces Sound It connects the pharynx to the trachea Epithelium of the larynx Stratified squamous – superior portion Pseudostratified ciliated columnar – inferior portion

Nine Cartilages of the Larynx Thyroid cartilage - shield-shaped, forms laryngeal prominence (Adam’s apple) Three pairs of small cartilages Arytenoid cartilages Corniculate cartilages Cuneiform cartilages Epiglottis - tips inferiorly during swallowing

The Larynx Vocal ligaments of the larynx Vocal folds (true vocal cords) - act in sound production Vestibular folds (false vocal cords) - no role in sound production Voice production Length of the vocal folds changes with pitch Loudness depends on the force of air across the vocal folds

The Trachea Descends into the mediastinum C-shaped cartilage rings keep airway open Carina - marks where trachea divides into two primary bronchi Epithelium - pseudostratified ciliated columnar

The Trachea Figure 21.7a, b

Bronchi in the Conducting Zone Bronchial tree - extensively branching respiratory passageways Primary bronchi (main bronchi) Largest bronchi Right main bronchi - wider and shorter than the left Secondary (lobar) bronchi Three on the right Two on the left Tertiary (segmental) bronchi - branch into each lung segment Bronchioles - little bronchi, less than 1 mm in diameter Terminal bronchioles - less than 0.5 mm in diameter

Tissue Composition of Conducting Zone Changes along pathway Supportive connective tissues change C-shaped rings – trachea, primary bronchi Replaced by cartilage plates, secondary & tertiary bronchi Epithelium changes First, pseudostratified ciliated columnar – trachea Replaced by simple columnar - bronchi Then simple cuboidal epithelium - bronchioles and terminal bronchioles Smooth muscle becomes important at the bronchioles - controlled by the ANS (bronchoconstriction and bronchodilation).

Lobes and Surfaces of the lungs Right lung has three lobes Left lung has two lobes Concavity on medial surface = cardiac notch Bronchi enter the lungs at the hilus

The Pleurae A double-layered sac surrounding each lung Parietal pleura Visceral pleura Pleural cavity - potential space between the visceral and parietal pleurae Pleurae help divide the thoracic cavity Central mediastinum Two lateral pleural compartments

Structures of the Respiratory Zone Consists of air-exchanging structures Respiratory bronchioles – branch from terminal bronchioles Lead to alveolar ducts Lead to alveolar sacs

Structures of the Respiratory Zone Figure 21.9b

Features Of Alveoli Alveoli cell types Type I cells site of gas exchangeand Type II cells - secrete surfactant Macrophages Surrounded by basal laminae and elastic fibers Interconnect by way of alveolar pores Internal surfaces - site for free movement of alveolar macrophages Figure 21.10b