1. Chapter 24 The Respiratory System
Copyright 2009, John Wiley & Sons, Inc.

2. Copyright 2009, John Wiley & Sons, Inc.
Introduction
Principal functions associated with the respiratory system
gas transport and gas exchange.
The respiratory system also participates in
regulating blood pH, contains receptors for the sense of smell, filters inhaled air, produces sounds, and rids the body
of small amounts of water and heat in exhaled air.
Copyright 2009, John Wiley & Sons, Inc.

3. Respiratory system Anatomy
The respiratory system consists of the nose, pharynx (throat), larynx (voice box), trachea (windpipe), bronchi, and lungs
The respiratory system consists of two parts:
(1) The upper respiratory system includes the nose, pharynx, and associated structures.
(2) The lower respiratory system includes the larynx, trachea, bronchi, and lungs.
Functionally, the respiratory system also consists of two parts:
(1) The conducting zone: includes the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles
(2) The respiratory zone: includes the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli, and they are the main sites of gas exchange between air and blood.
Copyright 2009, John Wiley & Sons, Inc.

4. Respiratory System Anatomy (Fig. 24.1)
Copyright 2009, John Wiley & Sons, Inc.

5. Copyright 2009, John Wiley & Sons, Inc.
Nose
The nose is divided into external and internal portions.
The external nose, the skin and muscle-covered portion of the nose nasal aperture, bordered laterally and inferiorly by the maxillary bones and superiorly by the nasal bones.
Cartilaginous framework of the external nose.
Three larger cartilages—the unpaired septal nasal cardtilage and the paired major alar cartilages—and a series of smaller cartilages—the minor alar cartilages.
The entryways into the external nose are the external nares or nostrils, which lead into the cavities, called the nasal vestibules.
This skin has numerous hairs, with sebaceous and sweat glands that secrete onto its surface.
The internal nose is a large cavity in the anterior aspect of the skull that lies inferior to the nasal bone and superior to the mouth. Anteriorly, the internal nose merges with the external nose, and posteriorly it communicates
with the pharynx through two openings called the internal nares
or choanae.
Copyright 2009, John Wiley & Sons, Inc.

6. Copyright 2009, John Wiley & Sons, Inc.
Nose (Figure 24.2
Copyright 2009, John Wiley & Sons, Inc.

7. Copyright 2009, John Wiley & Sons, Inc.
Paranasal sinuses
Paranasal sinuses (frontal, sphenoidal, maxillary, and ethmoidal paranasal sinuses) and the nasolacrimal ducts which drain tears from the lacrimal glands, open into the internal nose.
The lateral walls of the internal nose are formed by the ethmoid, maxillae, lacrimal, palatine, and inferior nasal conchae bones; Palatine bones and palatine processes of the maxillae, constitute the hard palate, and form the floor of the internal nose.
The nasal cavity, is divided by an intermediate nasal septum into right and left halves.
The nasal septum is formed by the septal nasal cartilage, attaches to the vomer and perpendicular plate of the ethmoid bone.
Copyright 2009, John Wiley & Sons, Inc.

8. Paranasal Sinuses (Figure 24.2 d)
Copyright 2009, John Wiley & Sons, Inc.

9. Copyright 2009, John Wiley & Sons, Inc.
Conchae
The conchae, the bony nasal septum, subdivide each side of the nasal cavity into a series of groovelike passageways—the superior, middle, and inferior meatuses .
Mucous membrane lines the nasal cavity and its shelves.
As inhaled air whirls around the conchae and meatuses, it is warmed by blood circulating in the capillaries.
Mucus secreted by the goblet cells moistens the air and traps dust particles.
Drainage from the nasolacrimal ducts and secretions from the
paranasal sinuses also help moisten the air.
The cilia move the mucus and trapped dust particles toward the pharynx
Copyright 2009, John Wiley & Sons, Inc.

10. Copyright 2009, John Wiley & Sons, Inc.
Pharynx
The pharynx, or throat, is a funnel-shaped tube about 13 cm (5 in)
The pharynx functions: as a passageway for air and food, provides a resonating chamber for speech sounds, and houses the tonsils, which participate in immunological reactions against foreign invaders.
The pharynx can be divided into three anatomical regions: (1) nasopharynx, (2) oropharynx, and (3) laryngopharynx.
Copyright 2009, John Wiley & Sons, Inc.

11. Copyright 2009, John Wiley & Sons, Inc.
Pharynx
The nasopharynx, lies posterior to the nasal cavity and extends to the plane of the soft palate.
The oropharynx, posterior to the oral cavity and extends from the soft palate inferiorly to the level of the hyoid bone. Two pairs of tonsils, the palatine and lingual tonsils, are found in the oropharynx.
The laryngopharynx , or hypopharynx, begins at the level of the hyoid bone and ends at the larynx. The laryngopharynx is both a respiratory and a digestive pathway and is lined by nonkeratinized stratified squamous epithelium.
Most of the muscles of the pharynx are innervated by nerve branches from the pharyngeal plexus supplied by the glossopharyngeal (IX) and vagus (X) nerves.
Copyright 2009, John Wiley & Sons, Inc.

12. Copyright 2009, John Wiley & Sons, Inc.
Larynx
The larynx, or voice box, connects the laryngopharynx with the trachea. It lies in the midline of the neck anterior to the fourth through sixth cervical vertebrae (C4–C6).
The wall of the larynx is composed of nine pieces of cartilage:Three occur singly (thyroid cartilage, epiglottis, and cricoid cartilage), and three occur in pairs (arytenoid, cuneiform, and corniculate cartilages).
The arytenoid cartilages are the most important because they influence the positions and tensions of the vocal folds (true vocal cords).
The extrinsic muscles of the larynx connect the cartilages to other structures in the throat; the intrinsic muscles connect the
cartilages to each other.
Copyright 2009, John Wiley & Sons, Inc.

13. Copyright 2009, John Wiley & Sons, Inc.
Larynx
The thyroid cartilage (Adam’s apple) consists of two fused plates of hyaline cartilage that form the anterior wall of the larynx
The ligament that connects the thyroid cartilage to the hyoid bone just superior to it is called the thyrohyoid membrane.
The epiglottis composed of elastic cartilage that is covered with epithelium. The “stem” of the epiglottis is the tapered inferior portion that is attached to the anterior rim of the thyroid cartilage and hyoid bone.
During swallowing, the pharynx and larynx rise.
Elevation of the larynx causes the epiglottis to move down and form a lid
over the opening into the larynx, closing it off.
The narrowed passageway through the larynx is called the glottis.
The glottis consists of a pair of folds of mucous membrane, the vocal folds in the larynx, and the space between them called the rima glottidis
Copyright 2009, John Wiley & Sons, Inc.

14. Copyright 2009, John Wiley & Sons, Inc.
Larynx (Fig. 24.3)
Copyright 2009, John Wiley & Sons, Inc.

15. Copyright 2009, John Wiley & Sons, Inc.
Larynx Cartilage
The cricoid cartilage is a ring of hyaline cartilage that forms the inferior wall of the larynx. It is attached the trachea by the cricotracheal ligament.
The thyroid cartilage is connected to the cricoid cartilage by the cricothyroid ligament.
The paired arytenoid cartilages a triangular shape composed of hyaline cartilage located at the posterior, superior border of the cricoid cartilage.
The paired corniculate cartilages, horn-shaped pieces of elastic cartilage, are located at the apex of each arytenoid cartilage.
The paired cuneiform cartilages, clubshaped elastic cartilages anterior to the corniculate cartilages, support the vocal folds and lateral aspects of the epiglottis.
The lining of the larynx superior to the vocal folds is nonkeratinized
stratified squamous epithelium.
The lining of the larynx inferior to the vocal folds is pseudostratified ciliated columnar epithelium consisting of ciliated columnar cells, goblet cells, and basal cells. The mucus secreted by these cells helps trap dust not removed in the upper passages.
Copyright 2009, John Wiley & Sons, Inc.

16. Copyright 2009, John Wiley & Sons, Inc.
Trachea
The trachea, or windpipe, is a tubular passageway for air that is about 12 cm (5 in.) long and 2.5cm (1in.) in diameter.
It is located anterior to the esophagus and extends from the larynx to the superior border of the fifth thoracic vertebra (T5), where it divides into the right and left primary bronchi.
The layers of the tracheal wall, from deep to superficial, are (1) the mucosa, (2) the submucosa, (3) the media, or middle tunic, and (4) the adventitia.
The mucosa consists of an epithelial layer of pseudostratified ciliated columnar epithelium and an underlying layer of lamina propria that contains elastic and reticular fibers.
The epithelium consists of ciliated columnar cells and goblet cells that reach the luminal surface, plus basal cells that do not.
The submucosa consists of areolar connective tissue that contains seromucous glands and their ducts.
The middle tunic the 16–20 incomplete, horizontal rings of hyaline cartilage resemble the letter
Copyright 2009, John Wiley & Sons, Inc.

17. Copyright 2009, John Wiley & Sons, Inc.
Trachea
Smooth muscle fibers of the called the trachealis muscle, and elastic
connective tissue that allow the diameter of the trachea to change during inhalation and exhalation.
The solid C-shaped cartilage rings provide a semirigid support so that the tracheal wall does not collapse inward and obstruct the air passageway.
The smooth muscle and glands of the trachea are innervated
parasympathetically via the vagus (X) nerves
Copyright 2009, John Wiley & Sons, Inc.

18. Copyright 2009, John Wiley & Sons, Inc.
Bronchial Tree (Fig. 24.6a)
Copyright 2009, John Wiley & Sons, Inc.

19. Copyright 2009, John Wiley & Sons, Inc.
Lungs
The lungs are paired coneshaped organs in the thoracic cavity.
Separated from each other by the heart and other structures in the mediastinum, which separates the thoracic cavity into two anatomically distinct chambers.
The Lungs are surrounded by a protective, double-layered serous membrane called the pleural membrane.
The superficial layer lines the wall of the thoracic cavity and is called the
parietal pleura; and the visceral pleura, is attached to the lungs themselves . Between the visceral and parietal pleurae is a small space, the pleural cavity, which contains a small amount of lubricating fluid secreted by the two layers.
Inflammation of the pleural membrane, called pleurisy or pleuritis,.
Copyright 2009, John Wiley & Sons, Inc.

20. Copyright 2009, John Wiley & Sons, Inc.
Lungs
The broad inferior portion of the lung, the base, is concave and fits over the convex area of the diaphragm. The narrow superior portion of the lung is the apex. The surface of the lung lying against the ribs, the costal surface, matches the rounded curvature of the ribs. The mediastinal (medial) surface of each lung contains a region, the hilum, through which bronchi,
pulmonary blood vessels, lymphatic vessels, and nerves enter and exit
Copyright 2009, John Wiley & Sons, Inc.

21. Copyright 2009, John Wiley & Sons, Inc.
Alveoli
Alveoli and alveolar sacs are cupshaped outpouching lined by simple squamous epithelium and supported by a thin elastic basement membrane; an alveolar sac consists of two or more alveoli that share a common opening.
The walls of alveoli consist of two types of alveolar epithelial cells:
Type I alveolar cells, are simple squamous epithelial cells that form a
nearly continuous lining of the alveolar wall and are the main sites
of gas exchange.
Type II alveolar cells, also called septal cells, are found between type I alveolar cells. Type II alveolar cells, are rounded or cuboidal epithelial cells with free surfaces containing microvilli, they secrete alveolar fluid. In the alveolar fluid is surfactant, a complex mixture of phospholipids and lipoproteins. surfactant lowers the surface tension of alveolar fluid.
In the alveolar wall are alveolar macrophages, wandering phagocytes that remove fine dust particles and other debris in the alveolar spaces
Copyright 2009, John Wiley & Sons, Inc.

22. Microscopic Anatomy of Lungs (Figure 24.10)
Copyright 2009, John Wiley & Sons, Inc.

23. Copyright 2009, John Wiley & Sons, Inc.
Respiratory Membrane
The exchange of O2 and CO2 between the air spaces in the
lungs and the blood takes place by diffusion across the alveolar and capillary walls, which together form the respiratory membrane.
Extending from the alveolar air space to blood plasma, the respiratory membrane consists of four layers:
1. A layer of type I and type II alveolar cells and associated alveolar
macrophages that constitutes the alveolar wall.
2. An epithelial basement membrane underlying the alveolar wall.
3. A capillary basement membrane that is often fused to the epithelial basement membrane.
4. The endothelial cells of the capillary.
The respiratory membrane is very thin 0.5 mm thick
It has been estimated that the lungs contain 300 million alveoli, providing an immense surface area of 70 m2
Copyright 2009, John Wiley & Sons, Inc.

24. Copyright 2009, John Wiley & Sons, Inc.
Alveolus (Fig )
Copyright 2009, John Wiley & Sons, Inc.