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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
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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
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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:
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 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.