Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Chapter 26: Anatomy of the Respiratory System
Anatomy & Physiology
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Structural Plan of the Respiratory System
Structure determined by respiratory system functions of air distributor and gas exchanger—supplying oxygen and removing carbon dioxide from cells (Figure 26-1)
Alveoli—sacs that serve as gas exchangers; all other parts of respiratory system serve as air distributors
The respiratory system also warms, filters, and humidifies air
Respiratory organs involved in speech, homeostasis of body pH, and olfaction
2
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 3
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Structural Plan of the Respiratory System
The respiratory system is divided into two structural divisions
Upper respiratory tract—the organs are located outside the thorax and consist of the nose, nasopharynx, oropharynx, laryngopharynx, and larynx
Lower respiratory tract—the organs are located within the thorax and consist of the trachea, the bronchial tree, and the lungs
Accessory structures include the oral cavity, rib cage, and diaphragm
4
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Upper Respiratory Tract Nose
Structure of the nose—external portion consists of a bony and cartilaginous frame covered by skin containing sebaceous glands
The two nasal bones meet and are surrounded by the frontal bone to form the root
The nose is surrounded by the maxilla (Figure 26-2)
5
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 6
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Upper Respiratory Tract Nose (cont)
Internal portion of the nose (nasal cavity) lies over the roof of the mouth, separated by the palatine bones
Cleft palate—condition in which the palatine bones fail to unite completely and only partially separate the nose and the mouth, thereby producing difficulty swallowing
Cribriform plate—separates the roof of the nose from the cranial cavity
Septum—separates the nasal cavity into right and left cavities; it consists of four structures: the perpendicular plate of the ethmoid bone, the vomer bone, the vomeronasal cartilages, and the septal nasal cartilage
7
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Upper Respiratory Tract Nose (cont)
Each nasal cavity is divided into three passageways: superior, middle, and inferior meatuses (Figure 26-3)
Anterior (external) nares—external openings to the nasal cavities; open into the vestibule
Sequence of airflow through the nose into the pharynx—anterior nares to the vestibule to all three meatuses simultaneously and then to the posterior (internal) nares
8
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 9
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Upper Respiratory Tract Nose (cont)
Nasal mucosa Air passes over respiratory
mucosa, which contains a rich blood supply (Figure 26-4)
Olfactory epithelium—special sensory membrane containing many olfactory nerve cells and a rich lymphatic plexus
10
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 11
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Upper Respiratory Tract Nose (cont)
Paranasal sinuses Four pairs of air-containing
spaces that open or drain into the nasal cavity
Each is lined with respiratory mucosa (Figure 26-5)
12
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 13
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Upper Respiratory Tract Nose (cont)
Functions of the nose Provides a passageway for air
traveling to and from the lungs Filters the air, aids speech, and
makes possible the sense of smell
14
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Upper Respiratory Tract Pharynx (throat)
Structure of pharynx Tubelike structure extending from
the base of the skull to the esophagus
Made of muscle and divided into three parts (Figure 26-3)—nasopharynx, oropharynx, and laryngopharynx
15
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Upper Respiratory Tract Pharynx (cont)
Pharyngeal tonsils
• Located in the nasopharynx•Called adenoids when they become
enlarged Oropharynx contains two pair of organs—the
palatine tonsils (most commonly removed in tonsillectomy) and the lingual tonsils (rarely removed)
Functions of the pharynx—pathway for the respiratory and digestive tracts
16
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Upper Respiratory Tract Larynx (Figures 26-6 and 26-7)
Location of larynx—positioned between the root of the tongue and the upper end of the trachea
Structure of larynx
•Consists of cartilages attached to each other by muscle • Lined by a ciliated mucous membrane,
which forms two pairs of folds (Figure 26-8)— vestibular folds (false vocal folds) and vocal folds
17
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 18
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 19
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 20
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Upper Respiratory Tract Larynx (cont)
Cartilages (framework) of the larynx—formed by nine cartilages
• Single laryngeal cartilages—the three largest cartilages: the thyroid cartilage, the epiglottis, and the cricoid cartilages• Paired laryngeal cartilages—three
pairs of smaller cartilages: the arytenoid, the corniculate, and the cuneiform cartilages
21
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Upper Respiratory Tract Larynx (cont)
Muscles of the larynx Intrinsic muscles both insert and
originate within the larynx Extrinsic muscles insert in the
larynx but originate on some other structure
Functions of the larynx—forms part of the airway to the lungs and produces the voice
22
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Lower Respiratory Tract Trachea—often called “windpipe” (Figure 26-10)
Structure of trachea Extends from the larynx to the primary bronchi Wall composed of (outer) adventitia, (middle)
smooth muscle and C-shaped cartilage rings, (inner) respiratory mucosa; posterior wall is very elastic (Figure 26-11)
Incomplete rings and posterior elasticity allows esophagus to expand into trachea during swallowing
Functions of trachea—furnishes part of the open airway to the lungs; obstruction causes death
23
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 24
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 25
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Lower Respiratory Tract Bronchi and alveoli
Structure of bronchi Lower end of the trachea divides into
two primary bronchi, one on the right and one on the left
Primary bronchi enter the lung and divide into secondary bronchi, which branch into bronchioles and eventually divide into alveolar ducts and alveoli
23 levels of branching (Figure 26-12)
26
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 27
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Lower Respiratory Tract Bronchi and alveoli (cont)
Structure of alveoli—the primary gas exchange structures
Respiratory membrane—the barrier between which gases are exchanged by alveolar air and blood (Figure 26-15)
Respiratory membrane consists of the alveolar epithelium, the capillary endothelium, and their joined basement membranes
Surfactant—a component of the fluid coating the respiratory membrane that reduces surface tension; produced by type II cells
28
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 29
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Lower Respiratory Tract Bronchi and alveoli (cont)
Functions of bronchi and alveoli Distribute air to the lung’s interior;
23 levels of branching are optimal for oxygen transfer to the blood
Mucus blanket cleans the airways as it is moved upward by the ciliary escalator
30
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Lower Respiratory Tract Lungs
Structure of the lungs—cone-shaped organs extending from the diaphragm to above the clavicles (Figure 26-17)
Hilum—slit on the lung’s medial surface where the primary bronchi and pulmonary blood vessels enter
Base—the inferior surface of the lung that rests on the diaphragm
Costal surface—lies against the ribs
31
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 32
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Lower Respiratory Tract Structure of the lungs (cont)
Left lung is divided into two lobes—superior and inferior
Right lung is divided into three lobes—superior, middle, and inferior
Lobes are further divided into functional units—bronchopulmonary segments
Ten segments in the right lung Eight segments in the left lung
Functions of the lungs—air distribution and gas exchange
33
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Lower Respiratory Tract Thorax (Figure 26-18)
Structure of the thoracic cavity—three divisions divided by the pleura
Pleural divisions—the part occupied by the lungs
Mediastinum—part occupied by the esophagus, trachea, large blood vessels, and heart
Functions of the thorax—brings about inspiration and expiration
34
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. 35
Mosby items and derived items © 2013, 2010, 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.
Cycle of Life: Respiratory System Respiration may be affected by
developmental defects, age-related structural changes, or loss of function throughout the life cycle
Age-related changes affect lung capacity, make ventilation difficult, or reduce the oxygen- or carbon dioxide–carrying capacity of blood
Respiratory efficiency is reduced in old age as a result of changes in ribs, respiratory muscles, and hemoglobin levels
36