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Introduction Cells obtain oxygen and eliminate carbon dioxide. The respiratory system facilitates the exchange of gases between the air and the blood. Blood carries oxygen to peripheral tissues. Blood accepts the carbon dioxide from peripheral tissues. An Overview of the Respiratory System The Respiratory System Includes the nose, nasal cavity and sinuses, pharynx, larynx, trachea, and conducting passageways The respiratory tract consists of the following: Conduction portion Respiratory portion The respiratory bronchiles The alveoli Functions of the Respiratory System Providing an area for gas exchange Moving air to and from the exchange surface Protecting respiratory surfaces Defending the respiratory system and other tissues from invasion by pathogenic microorganisms Producing sounds involved in speaking, singing, or nonverbal communication Assisting in the regulation of blood volume, blood pressure, and the control of body fluid pH The Upper Respiratory System Structures in the head are part of the upper respiratory system. Nose Nasal cavity Paranasal sinuses Pharynx The Lower Respiratory System Structures in the neck and thoracic cavity are parts of the lower respiratory system Larynx Trachea Bronchi Bronchioles Alveoli The Trachea Also called the windpipe Walls contain cartilage rings Enters thoracic cavity anterior to esophagus Bifurcates at the carina The Primary Bronchi Wall structure similar to tracheal wall One per lung The right primary bronchus supplies the right lung, and the left supplies the left lung Right has a larger diameter and descends toward lung at steeper angle; easier for foreign objects to get lodged there The Lungs Lungs are divided into lobes: 3 lobes on right: superior, middle, and inferior 2 lobes on left: superior and inferior Bronchi branch out into smaller bronchioles. Bronchioles lead to alveoli. The Pleural Cavities and Pleural Membranes Parietal pleura lines the pleural cavity. Visceral pleura covers the lungs. Pleural fluid causes membranes to stick together but still slide on one another. Respiratory Muscles and Pulmonary Ventilation Inspiratory muscles Diaphragm External intercostal muscles Expiratory muscles Usually not needed due to elastic recoil of lungs and thoracic cavity Accessory respiratory muscles Inspiration Sternocleidomastoid, serratus anterior, pectoralis minor, and scalene muscles Expiration Transversus thoracis, oblique, and rectus abdominis muscles Internal intercostal muscles Aging and the Respiratory System Elastic tissue deteriorates, reducing the lungs’ ability to inflate and deflate. Movements of the rib cage are restricted by arthritic changes. Some degree of emphysema is normally found in individuals age 50–70.