1. The Respiratory System22
The Respiratory System

2. The Respiratory System
Basic functions of the respiratory system
Supplies body with oxygen
Disposes of carbon dioxide
Four processes involved in respiration
Pulmonary ventilation
External respiration
Transport of respiratory gases
Internal respiration

3. Functional Anatomy of the Respiratory System
Respiratory organs
Nose, nasal cavity, and paranasal sinuses
Pharynx, larynx, and trachea
Bronchi and smaller branches
Lungs and alveoli

4. Organs of the Respiratory System
Nasal cavity
Trachea
Carina of
trachea
Left main
(primary)
bronchus
Right main
Right lung
Parietal
pleura
Left lung
Alveoli
Bronchi
Nostril
Oral cavity
Pharynx
Larynx
Diaphragm
Figure 22.1

5. Organs of the Respiratory System
Divided into
Conducting zone
Respiratory zone

6. The Nose
Provides an airway for respiration
Moistens and warms air
Filters inhaled air
Resonating chamber for speech
Houses olfactory receptors

7. Size variation due to differences in nasal cartilages
The Nose
Size variation due to differences in nasal cartilages
Skin is thin—contains many sebaceous glands
Frontal bone
Nasal bone
Septal cartilage
Maxillary bone
(frontal process)
Lateral process of
septal cartilage
Minor alar
cartilages
Major alar
Dense fibrous
connective tissue
(b) External skeletal framework
Epicranius,
frontal belly
Ala of nose
Root and bridge
of nose
Dorsum nasi
Apex of nose
Philtrum
Naris (nostril)
(a) Surface anatomy
Figure 22.2

8. External nares—nostrils Divided by nasal septum
The Nasal Cavity
External nares—nostrils
Divided by nasal septum
Continuous with nasopharynx
Posterior nasal apertures—choanae

9. Two types of mucous membrane
Nasal Cavity
Two types of mucous membrane
Olfactory mucosa
Near roof of nasal cavity
Houses olfactory (smell) receptors
Respiratory mucosa
Lines nasal cavity
Epithelium is pseudostratified ciliated columnar

10. The Upper Respiratory Tract
Sphenoid sinus
Frontal sinus
Nasal meatuses
(superior, middle,
and inferior)
Nasopharynx
Uvula
Palatine tonsil
Isthmus of the
fauces
Posterior nasal
aperture
Opening of
pharyngotympanic
tube
Pharyngeal tonsil
Oropharynx
Laryngopharynx
Vocal fold
Esophagus
(c) Illustration
Nasal conchae
(superior, middle
Nasal vestibule
Nostril
Nasal cavity
Hard palate
Soft palate
Tongue
Lingual tonsil
Epiglottis
Hyoid bone
Larynx
Thyroid cartilage
Vestibular fold
Cricoid cartilage
Thyroid gland
Trachea
Cribriform plate
of ethmoid bone
Figure 22.3c

11. Cilia move contaminated mucus posteriorly
Respiratory Mucosa
Consists of
Pseudostratified ciliated columnar epithelium
Goblet cells within epithelium
Underlying layer of lamina propria
Cilia move contaminated mucus posteriorly

12. Superior and middle nasal conchae Inferior nasal conchae
Part of the ethmoid bone
Inferior nasal conchae
Separate bone
Project medially from the lateral wall of the nasal cavity
Particulate matter
Deflected to mucus-coated surfaces

13. Funnel-shaped passageway Connects nasal cavity and mouth
The Pharynx
Funnel-shaped passageway
Connects nasal cavity and mouth
Divided into three sections by location
Nasopharynx
Oropharynx
Laryngopharynx
Type of mucosal lining changes along its length

14. Superior to the point where food enters Only an air passageway
The Nasopharynx
Superior to the point where food enters
Only an air passageway
Closed off during swallowing
Pharyngeal tonsil (adenoids)
Located on posterior wall
Destroys entering pathogens
Contains the opening to the pharyngotympanic tube (auditory tube)
Tubal tonsil
Provides some protection from infection

15. Arch-like entranceway—fauces Epithelium
The Oropharynx
Arch-like entranceway—fauces
Extends from soft palate to the epiglottis
Epithelium
Stratified squamous epithelium
Two types of tonsils in the oropharynx
Palatine tonsils—in the lateral walls of the fauces
Lingual tonsils—covers the posterior surface of the tongue

16. Passageway for both food and air Epithelium
The Laryngopharynx
Passageway for both food and air
Epithelium
Stratified squamous epithelium
Continuous with the esophagus and larynx

17. The Larynx Three functions Voice production Provides an open airway
Routes air and food into the proper channels
Superior opening is
Closed during swallowing
Open during breathing

18. Nine Cartilages of the Larynx
Thyroid cartilage
Shield-shaped, forms laryngeal prominence (Adam’s apple)
Three pairs of small cartilages
Arytenoid cartilages
Corniculate cartilages
Cuneiform cartilages
Epiglottis
Tips inferiorly during swallowing

19. Vocal ligaments of the larynx
Vocal folds (true vocal cords)
Act in sound production
Vestibular folds (false vocal cords)
No role in sound production
Epithelium of the larynx
Stratified squamous—superior portion
Pseudostratified ciliated columnar—inferior portion

20. Anatomy of the Larynx Figure 22.5a, b Body of hyoid bone
Cricoid cartilage
Laryngeal prominence
(Adam’s apple)
Clavicle
Sternal head
Clavicular head
Sternocleidomastoid
Jugular notch
(a) Surface view
Body of hyoid bone
Epiglottis
Cricoid cartilage
Tracheal
cartilages
Thyroid cartilage
Laryngeal prominence
(Adam’s apple)
Cricothyroid ligament
Cricotracheal ligament
(b) Anterior view
Thyrohyoid
membrane
Figure 22.5a, b

21. Anatomy of the Larynx Figure 22.5c, d Epiglottis Hyoid bone Thyrohyoid
Thyroid
cartilage
Glottis
(c) Photograph of cartilaginous framework of the larynx, posterior view
Epiglottis
Corniculate cartilage
Arytenoid cartilage
Cricoid cartilage
Tracheal cartilages
Thyrohyoid
membrane
Epiglottis
Body of hyoid bone
Thyrohyoid membrane
Vestibular fold
(false vocal cord)
Vocal fold
(true vocal cord)
Cricothyroid ligament
Cricotracheal ligament
Fatty pad
Thyroid cartilage
Cuneiform cartilage
Corniculate cartilage
Arytenoid cartilage
Cricoid cartilage
Tracheal cartilages
Arytenoid muscle
(d) Sagittal section (anterior on the right)
Thyrohyoid
membrane
Figure 22.5c, d

22. Movements of the Vocal Folds
(a) Vocal folds in closed position; closed glottis
(b) Vocal folds in open position; open glottis
Base of tongue
Epiglottis
Vestibular fold
(false vocal cord)
Vocal fold
(true vocal cord)
Glottis
Inner lining of trachea
Cuneiform cartilage
Corniculate cartilage
Thyroid cartilage
Cricoid cartilage
Vocal ligaments
of vocal cords
Lateral
cricoarytenoid muscle
Arytenoid cartilage
Posterior
Anterior
Figure 22.6

23. Sphincter function of the larynx Innervation of the larynx
Voice production
Length of the vocal folds changes with pitch
Loudness depends on the force of air across the vocal folds
Sphincter function of the larynx
Valsalva’s maneuver—straining
Innervation of the larynx
Recurrent laryngeal nerves (branch of vagus)

24. Descends into the mediastinum
The Trachea
Descends into the mediastinum
C-shaped cartilage rings keep airway open
Carina
Marks where trachea divides into two primary bronchi
Epithelium
Pseudostratified ciliated columnar

25. The Trachea Figure 22.7 Mucosa Pseudostratified ciliated columnar
(b) Photomicrograph of the tracheal wall (250)
Hyaline cartilage
Lamina propria
(connective tissue)
Submucosa
Mucosa
Seromucous gland
in submucosa
Pseudostratified
ciliated columnar
epithelium
(a) Cross section of the trachea and esophagus
Hyaline cartilage
Submucosa
Mucosa
Seromucous gland
in submucosa
Posterior
Lumen of
trachea
Anterior
Esophagus
Trachealis
muscle
Adventitia
Figure 22.7

26. Bronchi in the Conducting Zone
Bronchial tree
Extensively branching respiratory passageways
Primary bronchi (main bronchi)
Largest bronchi
Right main bronchi
Wider and shorter than the left

27. Bronchi in the Conducting Zone
Trachea
Superior lobe
of right lung
Middle lobe
Inferior lobe
of left lung
Left main
(primary)
bronchus
Lobar
(secondary)
Segmental
(tertiary)
(a) The branching of the bronchial tree
Figure 22.8a

28. Bronchi in the Conducting Zone
Mucosa
Pseudostratified
epithelium
Lamina propria
Fibromusculo-
cartilaginous
layer
Cartilage plate
Smooth muscle
Lumen
(b) Photomicrograph of a bronchus (13)
Figure 22.8b

29. Bronchi in the Conducting Zone
Secondary (lobar) bronchi
Three on the right
Two on the left
Tertiary (segmental) bronchi
Branch into each lung segment
Bronchioles
Little bronchi, less than 1 mm in diameter
Terminal bronchioles
Less than 0.5 mm in diameter

30. Changes in Tissue Composition along Conducting Pathways
Supportive connective tissues change
C-shaped rings replaced by cartilage plates
Epithelium changes
First, pseudostratified ciliated columnar
Replaced by simple columnar, then simple cuboidal epithelium
Smooth muscle becomes important
Airways widen with sympathetic stimulation
Airways constrict under parasympathetic direction

31. Structures of the Respiratory Zone
Consists of air-exchanging structures
Respiratory bronchioles—branch from terminal bronchioles
Lead to alveolar ducts
Lead to alveolar sacs

32. Structures of the Respiratory Zone
Alveolar duct
Alveoli
Alveolar
sac
Respiratory
bronchioles
Terminal
bronchiole
(a)
Figure 22.9a

33. Structures of the Respiratory Zone
Alveolar
pores
duct
Respiratory
bronchiole
Alveoli
sac
(b)
Figure 22.9b

34. Structures of the Respiratory Zone
Alveoli
~300 million alveoli account for tremendous surface area of the lungs
Surface area of alveoli is ˜140 square meters

35. Structures of the Respiratory Zone
Structure of alveoli
Type I cells—single layer of simple squamous epithelial cells
Surrounded by basal lamina
Alveolar and capillary walls plus their basal lamina form
Respiratory membrane

36. Structures of the Respiratory Zone
Structures of alveoli (continued)
Type II cells—scattered among type I cells
Are cuboidal epithelial cells
Secrete surfactant
Reduces surface tension within alveoli
Alveolar macrophages

37. Anatomy of Alveoli and the Respiratory Membrane
Elastic
fibers
(a) Diagrammatic view of capillary-alveoli relationships
Smooth
muscle
Alveolus
Capillaries
Terminal bronchiole
Respiratory bronchiole
Figure 22.10a, b

38. Anatomy of Alveoli and the Respiratory Membrane
Alveolus
Capillary
Type II (surfactant-
secreting) cell
Type I cell
of alveolar wall
Endothelial cell nucleus
Macrophage
Alveoli (gas-filled
air spaces)
Red blood cell
in capillary
Alveolar pores
Capillary endothelium
Fused basement
membranes of the
alveolar epithelium
and the capillary
endothelium
Alveolar epithelium
Respiratory
membrane
Red blood
cell O2
CO2
Nucleus of type I
(squamous
epithelial) cell
(c) Detailed anatomy of the respiratory membrane
Figure 22.10c

39. The Respiratory Zone Features of alveoli Surrounded by elastic fibers
Interconnect by way of alveolar pores
Internal surfaces
A site for free movement of alveolar macrophages

40. Gross Anatomy of the Lungs
Major landmarks of the lungs
Apex, base, hilum, and root
Left lung
Superior and inferior lobes
Fissure—oblique
Right lung
Superior, middle, and inferior lobes
Fissures—oblique and horizontal

41. Gross Anatomy of the Lungs
Anterior View of Thoracic Structures
Trachea
Apex of lung
Thymus
Right superior lobe
Horizontal fissure
Right middle lobe
Oblique fissure
Right inferior lobe
Heart
(in mediastinum)
Diaphragm
Base of lung
Left
superior lobe
Cardiac notch
Oblique
fissure
Left inferior
lobe
Lung
Pleural cavity
Parietal pleura
Rib
Intercostal muscle
Visceral pleura
(a) Anterior view. The lungs flank mediastinal structures laterally.
Left
superior lobe
Oblique
fissure
Left inferior
lobe
(b) Photograph of medial view of the left lung
Left main
bronchus
Pulmonary
vein
Impression
of heart
Lobules
artery
Apex of lung
Hilum
Aortic
impression
Figure 22.11a, b

42. Bronchopulmonary Segments
Right
superior
lobe (3
segments)
middle
lobe (2
inferior lobe
(5 segments)
Left superior
lobe
(4 segments)
Left inferior
Right lung
Left lung
Figure 22.12

43. Blood Supply and Innervation of the Lungs
Pulmonary arteries
Deliver oxygen-poor blood to the lungs
Pulmonary veins
Carry oxygenated blood to the heart
Innervation
Sympathetic, parasympathetic, and visceral sensory fibers
Parasympathetic—constrict airways
Sympathetic—dilate airways

44. Transverse Cut through the Superior Thorax
(d) Transverse section through the thorax, viewed from above. Lungs, pleural
membranes, and major organs in the mediastinum are shown.
Esophagus
(in mediastinum)
Right lung
Parietal pleura
Visceral pleura
Pleural cavity
Pericardial
membranes
Sternum
Anterior
Posterior
Vertebra
Root of lung
at hilum
Left lung
Thoracic wall
Pulmonary trunk
Heart (in mediastinum)
Anterior mediastinum
Left main bronchus
Left pulmonary
artery
Left pulmonary vein
Figure 22.11d

45. A double-layered sac surrounding each lung
The Pleurae
A double-layered sac surrounding each lung
Parietal pleura
Visceral pleura
Pleural cavity
Potential space between the visceral and parietal pleurae
Pleurae help divide the thoracic cavity
Central mediastinum
Two lateral pleural compartments

46. Diagram of the Pleurae and Pleural Cavities
Trachea
Apex of lung
Thymus
Right superior lobe
Horizontal fissure
Right middle lobe
Oblique fissure
Right inferior lobe
Heart
(in mediastinum)
Diaphragm
Base of lung
Left
superior lobe
Cardiac notch
Oblique
fissure
Left inferior
lobe
Lung
Pleural cavity
Parietal pleura
Rib
Intercostal muscle
Visceral pleura
(a) Anterior view. The lungs flank mediastinal structures laterally.
Figure 22.11a

47. Location of Lungs in Thoracic Cavity
Rib
(a) Posterior view
Lung 10 11 12 9 8
(b) Anterior view
Clavicle
Nipple
Midaxillary
line
Midclavicular line
Infrasternal
angle at the
xiphisternal
joint
Costal margin
Parietal
pleura
Rib 3 7 6 5 4
Figure 22.13

48. The Mechanisms of Ventilation
Two phases of pulmonary ventilation
Inspiration—inhalation
Expiration—exhalation

49. Volume of thoracic cavity increases
Inspiration
Volume of thoracic cavity increases
Decreases internal gas pressure
Action of the diaphragm
Diaphragm flattens
Action of intercostal muscles
Contraction raises the ribs

50. Deep inspiration requires
Scalenes
Sternocleidomastoid
Pectoralis minor
Erector spinae—extends the back

51. Quiet expiration—chiefly a passive process
Inspiratory muscles relax
Diaphragm moves superiorly
Volume of thoracic cavity decreases
Forced expiration—an active process
Produced by contraction of
Internal and external oblique muscles
Transverse abdominis muscles

52. Changes in Thoracic Volume
Ribs are
elevated and
sternum flares
as external
intercostals
contract.
Diaphragm and intercostal muscles
contract (diaphragm descends and
rib cage rises). Thoracic cavity
volume increases.
Diaphragm moves
inferiorly during
contraction.
External
Changes in
superior-
inferior and
anterior-
posterior
dimensions
Changes
in lateral
(superior
view)
(a) Inspiration
Inspiratory muscles relax (diaphragm rises and
rib cage descends due to recoil of the costal
cartilages). Thoracic cavity volume decreases.
Ribs and
sternum are
depressed as
external
intercostals
relax.
External
Diaphragm moves
superiorly as it relaxes.
(b) Expiration
Figure 22.14

53. Changes in Thoracic Volume
At rest, no air
movement: Air
pressure in lungs is
equal to atmospheric
(air) pressure. Pressure
in the pleural cavity is
less than pressure in the
lungs. This pressure
difference keeps the
lungs inflated.
Inspiration: Inspiratory
muscles contract and increase
the volume of the thoracic and
pleural cavities. Pleural fluid in
the pleural cavity holds the
parietal and visceral pleura close
together, causing the lungs to
expand. As volume increases,
pressure decreases and air flows
into the lungs.
Expiration: Inspiratory
muscles relax, reducing thoracic
volume, and the lungs recoil.
Simultaneously, volumes of the
pleural cavity and the lungs
decrease, causing pressure to
increase in the lungs, and air
flows out. Resting state is
reestablished.
Trachea
Diaphragm
Lung
Air flows in
Air flows
out V P
Pleural
cavity
Thoracic
wall
Air
Main bronchi
Parietal
pleura
Visceral
Thoracic wall
At rest
Expanded 1 2 3
Figure 22.15

54. Neural Control of Ventilation
Most important respiratory center
VRG—ventral respiratory group
Located in reticular formation in the medulla oblongata
Neurons generate respiratory rhythm

55. Respiratory Centers in the Brain Stem
Pons
Ventral respiratory group (VRG)
contains rhythm generators
whose output drives respiration.
Pontine respiratory centers
interact with the medullary
respiratory centers to smooth
the respiratory pattern.
Medulla
To inspiratory
muscles
External intercostal
Diaphragm
Dorsal respiratory group (DRG)
integrates peripheral sensory
input and modifies the rhythms
generated by the VRG.
Figure 22.16

56. Neural Control of Ventilation
Respiratory center
Generates baseline respiration rate
In the reticular formation of the medulla oblongata
Chemoreceptors
Sensitive to rising and falling oxygen levels
Central chemoreceptors—located in medulla
Peripheral chemoreceptors
Aortic bodies
Carotid bodies

57. Location of Peripheral Chemoreceptors
Brain
Sensory nerve fiber in cranial nerve
IX (pharyngeal branch
of glossopharyngeal)
External carotid artery
Internal carotid artery
Carotid body
Common carotid artery
Cranial nerve X (vagus nerve)
Sensory nerve fiber in
cranial nerve X
Aortic bodies in aortic arch
Aorta
Heart
Figure 22.17

58. Disorders of Lower Respiratory Structures
Bronchial asthma
A type of allergic inflammation
Hypersensitivity to irritants in the air or to stress
Asthma attacks characterized by
Contraction of bronchiole smooth muscle
Secretion of mucus in airways

59. Disorders of Lower Respiratory Structures
Cystic fibrosis (CF)—inherited disease
Exocrine gland function is disrupted
Respiratory system affected by
Oversecretion of viscous mucus

60. Disorders of Lower Respiratory Structures
Chronic obstructive pulmonary disease (COPD)
Airflow into and out of the lungs is difficult
Obstructive emphysema
Chronic bronchitis
History of smoking

61. Disorders of Lower Respiratory Structures
Figure 22.18

62. Alveolar Changes in Emphysema
Figure 22.19

63. Disorders of Upper Respiratory Structures
Epistaxis—nosebleed

64. The Respiratory System Throughout Life
By week 4 of development
Olfactory placodes appear
Invaginate to form olfactory pits
Laryngotracheal bud
Forms trachea, bronchi, and bronchi subdivisions
Reaches functional maturity late in development
At birth, only one-sixth of alveoli are present
Those who begin smoking as teenagers
Lungs never fully develop
Additional alveoli never form

65. The Respiratory System Throughout Life
Frontonasal elevation
Olfactory placode
Stomodeum
(future mouth)
Future mouth
Eye
Trachea
Bronchial
buds
Pharynx
Foregut
Olfactory
placode
Esophagus
Liver
Laryngotracheal
bud
(a) 4 weeks: anterior
superficial view of
the embryo’s head
(b) 5 weeks: left lateral view of the developing lower
respiratory passageway mucosae
Figure 22.20

66. Aging of the Respiratory System
Number of glands in the nasal mucosa declines
Nose dries
Produces thickened mucus
Thoracic wall becomes more rigid
Lungs lose elasticity
Oxygen levels in the blood may fall