PowerPoint ® Lecture Slides prepared by Janice Meeking, Mount Royal College C H A P T E R Copyright © 2010 Pearson Education, Inc. 22 The Respiratory System: Part A – anatomy and histology

Copyright © 2010 Pearson Education, Inc. Major Functions of the Respiratory System To supply the body with oxygen and dispose of carbon dioxide Respiration – four distinct processes must happen Pulmonary ventilation (breathing): movement of air into and out of the lungs External respiration: O 2 and CO 2 exchange between the lungs and the blood Transport: O 2 and CO 2 in the blood Internal respiration: O 2 and CO 2 exchange between systemic blood vessels and tissues Respiratory system Circulatory system

Copyright © 2010 Pearson Education, Inc. Respiratory System – conducting and respiratory zone Consists of the respiratory and conducting zones Respiratory zone: Site of gas exchange Consists of respiratory bronchioles, alveolar ducts, and alveoli Conducting zone: Conduits for air to reach the sites of gas exchange Includes all other respiratory structures (e.g., nose, nasal cavity, pharynx, trachea) Respiratory muscles – diaphragm and other muscles that promote ventilation

Copyright © 2010 Pearson Education, Inc. Respiratory System – conducting and respiratory zone Conducting passageways carrying air to and from the alveoli Upper respiratory passages filter and humidify incoming air Lower passageways include delicate conduction passages and alveolar exchange surfaces The conducting passageways of the respiratory system (nasal cavity, trachea, bronchi and bronchioles) are lined by ciliated pseudostratified columnar ET, which includes mucus-secreting goblet cells. Because the passage of air depends on wide open passageways, the larger respiratory passages (trachea and bronchi) are supported by rings of cartilage. The respiratory regions are lined with simple squamous ET

Copyright © 2010 Pearson Education, Inc. Function of the Nose The only externally visible part of the respiratory system that functions by: Providing an airway for respiration Moistening and warming the entering air Filtering inspired air and cleaning it of foreign matter Serving as a resonating chamber for speech Housing the olfactory receptors

Copyright © 2010 Pearson Education, Inc. Paranasal Sinuses Sinuses in bones that surround the nasal cavity Sinuses lighten the skull and help to warm and moisten the air

Copyright © 2010 Pearson Education, Inc. Larynx (Voice Box) Attaches to the hyoid bone and opens into the laryngopharynx superiorly Continuous with the trachea posteriorly The functions of the larynx are: Air passage To act as a switching mechanism to route air and food into the proper channels To function in voice production

Copyright © 2010 Pearson Education, Inc. Framework of the Larynx Cartilages (hyaline) of the larynx Shield-shaped anterosuperior thyroid cartilage with a midline laryngeal prominence (Adam’s apple) Signet ring–shaped anteroinferior cricoid cartilage Three pairs of small arytenoid, cuneiform, and corniculate cartilages Epiglottis – elastic cartilage that covers the laryngeal inlet during swallowing Glottis is the superior opening of the larynx. It is guarded by the epiglottis (cartilage)

Copyright © 2010 Pearson Education, Inc. Vocal Ligaments Attach the arytenoid cartilages to the thyroid cartilage Composed of elastic fibers that form mucosal folds called true vocal cords The medial opening between them is the glottis They vibrate to produce sound as air rushes up from the lungs False vocal cords Mucosal folds superior to the true vocal cords Have no part in sound production

Copyright © 2010 Pearson Education, Inc. Voice Production Speech: release of expired air while opening and closing the glottis Pitch is determined by the length and tension of the vocal cords Loudness depends upon the force of air Chambers of pharynx, oral, nasal, and sinus cavities amplify and enhance sound quality Sound is “shaped” into language by muscles of the pharynx, tongue, soft palate, and lips

Copyright © 2010 Pearson Education, Inc. Trachea Flexible and mobile tube extending from the larynx into the mediastinum Composed of three layers Mucosa – ciliated pseudostratified columnar epithelium with goblet cells Submucosa – connective tissue with mucous glands, lymph nodes Adventitia – fibrous CT that contains C-shaped rings of hyaline cartilage

Copyright © 2010 Pearson Education, Inc. Trachea branches in the mediastinum into right and left primary bronchi Bronchi enter the lungs at the hilus Have C-shaped cartilaginous supporting rings The primary bronchi

Copyright © 2010 Pearson Education, Inc. System of tubes formed from the primary bronchi and their branches Primary bronchi branch into secondary or lobar bronchi Secondary bronchus goes to each lobe of the lungs Secondary bronchi branch into tertiary (segmental) bronchi Both secondary and tertiary bronchi are covered by overlapping plates of cartilage and not rings Cartilage in walls decrease and smooth muscle increase with branching The bronchial tree

Copyright © 2010 Pearson Education, Inc. Branching of the bronchi that are 1 mm or less in diameter and lack cartilage. Bronchioles are surrounded by smooth muscle that allows the change of diameter. Ultimately bronchioles branch into the final branch of the conducting division - terminal bronchioles with a diameter of mm Terminal bronchiole becomes respiratory bronchioles – the beginning of the respiratory division The bronchioles

Copyright © 2010 Pearson Education, Inc. Respiratory Zone Defined by the presence of alveoli; begins as terminal bronchioles feed into respiratory bronchioles Respiratory bronchioles lead to alveolar ducts, then to terminal clusters of alveolar sacs composed of alveoli Approximately 300 million alveoli: Account for most of the lungs’ volume Provide tremendous surface area for gas exchange

Copyright © 2010 Pearson Education, Inc. Respiratory Membrane This air-blood barrier is composed of: Alveolar and capillary walls Their fused basal laminas Simple squamous ET (type I) – most of the cells in the alveolus wall and are part of the respiratory membrane (allow gas exchange) Septal cells (type II ) – about 5% of the alveolar wall. The septal cells secret surfactant – a lipoprotein secretion that reduces the surface tension in the alveolus Alveolar Macrophage (dust cells) - patrol epithelium and engulf foreign particles

Copyright © 2010 Pearson Education, Inc. Pleurae Thin, double-layered serosa Parietal pleura Covers the thoracic wall and superior face of the diaphragm Continues around heart and between lungs Visceral, or pulmonary, pleura Covers the external lung surface Divides the thoracic cavity into three chambers The central mediastinum Two lateral compartments, each containing a lung

Copyright © 2010 Pearson Education, Inc. Dead Space Some of the inspired air does not contribute to the gas exchange in the alveoli Anatomical dead space – volume of the conducting respiratory passages (150 ml) Alveolar dead space – alveoli that cease to act in gas exchange due to collapse or obstruction Total dead space – sum of alveolar and anatomical dead spaces

Copyright © 2010 Pearson Education, Inc. Pulmonary Function Tests Spirometer – an instrument consisting of a hollow bell inverted over water, used to evaluate respiratory function Spirometry can distinguish between: Obstructive pulmonary disease – increased airway resistance Restrictive disorders – reduction in total lung capacity from structural or functional lung changes Total/minute ventilation – total amount of gas flow into or out of the respiratory tract in one minute Forced vital capacity (FVC) – gas forcibly expelled after taking a deep breath Forced expiratory volume (FEV) – the amount of gas expelled Increases in TLC, FRC, and RV may occur as a result of obstructive disease Reduction in VC, TLC, FRC, and RV result from restrictive disease

Copyright © 2010 Pearson Education, Inc. Nonrespiratory Air Movements Most result from reflex action Examples include: coughing, sneezing, crying, laughing, hiccupping, and yawning