The respiratory system includes the nose, pharynx, larynx, trachea, bronchi, and lungs. The nose and pharynx warm and humidify incoming air before it reaches the lungs. The trachea branches into bronchi which further divide into bronchioles and terminate in alveoli in the lungs. Gas exchange occurs across the thin alveolar membranes, and respiration is controlled by the medulla, chemoreceptors, and mechanical stretch receptors. Major respiratory disorders include COPD and lung cancer.

1. THE RESPIRATORY SYSTEM

2. Functional Anatomy of the Respiratory System
• Organs include:
• Nose
• Pharynx
• Larynx
• Trachea
• Bronchi
• Lungs (alveoli)
• Conducting passageways:
1. Upper respiratory tract
• nose to larynx
2. Lower respiratory tract
• trachea to alveoli
• Purify, humidify, and warm incoming air

3. The Nose
• Air enters the nose by passing
through the nostrils.
• Nasal cavity
• chamber within the nose
• separated from oral cavity by
palate
• lined with mucosa
• Respiratory mucosa
• warms, filters and moistens
incoming air

4. Nose
• Ciliated cells of nasal mucosa
create gentle current that moves
sheet of contaminated mucus
posteriorly toward the throat
• Conchae
• three mucosa-covered lobes in the
lateral walls of nasal cavity
• greatly increase the surface area
of the mucosa exposed to the air
• increase air turbulence

5. Cleft Palate
• genetic defect
• failure of the bones forming the
palate to fuse medially
• results in breathing difficulty
• problems with oral cavity
functions such as nursing and
speaking

6. Nose
• The nasal cavity is surrounded
by a ring of paranasal sinuses.
• Paranasal sinuses
• lighten the skull and act as
resonance chambers for speech
• produce mucus which drains
into the nasal cavities
• Nasolacrimal ducts
• drain tears from the eyes
• empty into the nasal cavities

7. Rhinitis
• caused by cold viruses and
various allergens
• inflammation of the nasal
mucosa
• excessive mucus produced
results in nasal congestion and
postnasal drip
• nasal cavity infections often
spread

8. Sinusitis
• sinus inflammation
• difficult to treat and can cause
marked changes in voice quality
• result is a partial vacuum and a
sinus headache localized over
the inflamed area

9. The Pharynx (throat)
• mucosa-lined, muscular tube
• passageway for food and air
• Three regions:
• Nasopharynx
• Oropharynx
• Laryngopharynx
• Air enters nasopharynx then
descends through oropharynx and
laryngopharynx.
• Food enters the mouth, travels
along with air through the
oropharynx and laryngopharynx.

10. Pharynx
• Pharyngotympanic tubes
• drain the middle ears and open into
nasopharynx
• Ear infections may follow a sore throat
• Tonsils
• clusters of lymphatic tissue
• play a role in protecting the body from
infection

11. Tonsilitis
• Pharyngeal tonsil becomes
inflamed and swollen during a
bacterial infection
• Obstruction in the nasopharynx
forces the person to breathe
through the mouth.
• Mouth breathing makes the air not
properly moistened, warmed, or
filtered.

12. The Larynx (voice box)
• routes air and food into the proper
channels
• most prominent hyaline cartilage
is the thyroid cartilage (Adam’s
apple)
• connects the pharynx with
trachea

13. Larynx
• Epiglottis
• protects the superior opening of
the larynx
• forming lid over larynx’s opening
when swallowing
• larynx is pulled upward and the
epiglottis tips when swallowing
• Cough reflex is triggered to
prevent substance from
continuing into the lungs.

14. Larynx
• Vocal cords
• vibrate with expelled air
• vibration allows speaking
• Glottis
• between the vocal folds and the
slitlike passageway

15. The Trachea (windpipe)
• extends from the larynx to the
main bronchi
• smooth-muscle tube line with
ciliated mucosa and reinforced
with C-shaped cartilaginous rings
• open parts of rings abut
esophagus and allow it to expand
anteriorly when swallowing food
• solid portions support the trachea
walls and keep it patent

16. Trachea
• Many people have
suffocated after choking
on a piece of food that
suddenly closed off the
trachea.
• Heimlich maneuver
• air in a person’s own lungs
is used to expel an
obstructing piece of food
• cracked ribs are a distinct
possibility when it is done
incorrectly

17. Trachea
• lined with ciliated mucosa
• cilia propel this mucus away from
the lungs to the throat
• Smoking inhibits and ultimately
destroys the cilia.

18. The Main Bronchi
• result from the subdivision of
the trachea
• each plunges in the hilum of
the lung on its side
• Smaller subdivisions of the
main bronchi within the lungs
are direct routes to the air
sacs.

19. Lungs
• Apex
• narrow superior portion of each
lung
• Base
• broad lung area resting on the
diaphragm
• Pulmonary (Visceral) Pleura
• covers the surface of each lung
• Parietal Pleura
• lines the walls of thoracic cavity
• Pleural membranes produce
pleural fluid which allows lungs
to glide over thorax wall during
breathing.

20. Pleurisy
• inflammation of the pleurae
• caused by insufficient secretion
of pleural fluid
• pleural surfaces become dry
and rough, resulting in friction
and stabbing pain with each
breath
• The pleurae may produce
excessive amounts of fluid
which exerts pressure on the
lungs.

21. The Bronchial Tree
• main bronchi subdivide into smaller
and smaller branches ending in
bronchioles (smallest)
• All but the smallest branches have
reinforcing cartilage in their walls.

22. Respiratory Zone Structure
• terminal bronchioles lead into
respiratory zone
• includes the respiratory
bronchioles, alveolar ducts,
alveolar sacs, and alveoli, is
the only site of gas exchange
• All other respiratory passages
are conducting zone
structures that serve as
conduits to and from the
respiratory zone.

23. Alveoli
• millions clustered inside the
lungs that resembles bunches
of grapes
• composed largely of a single,
thin layer of simple squamous
epithelial cells
• walls are very thin (thinner than
tissue paper)
• Alveolar pores
• connect neighboring air sacs and
provide alternative routes for air

24. Alveoli
• external surfaces are covered
with pulmonary capillaries
• alveolar and capillary walls
construct respiratory membrane
(air-blood barrier)
• Respiratory membrane has gas
(air) flowing past on one side and
blood flowing past on the other.
• Gas exchange occurs by simple
diffusion through the respiratory
membrane.

25. Alveoli
• Alveolar Macrophages
• also known as dust cells
• wander in and out of the
alveoli picking up bacteria,
carbon particles, and other
debris
• Surfactant-secreting Cells
• produce a lipid molecule
(surfactant) which coats the
gas-exposed alveolar
surfaces

26. Respiratory Physiology
Four distinct events of respiration:
1. Pulmonary ventilation
• air move into and out of the lungs (breathing)
2. External respiration
• gas exchanges are being made between the blood and the body exterior
3. Respiratory gas transport
• oxygen and carbon dioxide are transported to and from the lungs and tissue cells
4. Internal respiration
• gas exchange occurs between the blood and cells inside the body

27. Respiratory Physiology
• Gas travels from high pressure to low-
pressure areas.
• Atmospheric pressure – outside the body
• Intrapulmonary pressure – inside the lungs
• Intrapleural pressure – between the pleurae
• Inspiration
• inspiratory muscles contract, intrapulmonary
volume increases, its pressure decreases, air
rushes in
• Expiration
• inspiratory muscles relax, the lungs recoil, air
rushes out

28. Respiratory Physiology
• Air volumes exchanged during
breathing:
• Tidal Volume (TV)
• normal quiet breathing (500 ml)
• Inspiratory Reserve Volume (IRV)
• air forcibly inhaled above tidal volume
• Expiratory Reserve Volume (ERV)
• air forcibly exhaled beyond tidal volume
• Vital Capacity (VC)
• total amount of exchangeable air
• Residual volume allows gas
exchange to go on continually.

29. Respiratory Physiology
• Non-respiratory air movements
• voluntary or reflex activities that
move air into or out of the lungs
• Examples:
• Coughing
• Sneezing
• Laughing
• Crying
• Hiccupping
• Yawning

30. Control of Respiration
Nervous control:
• Medulla and Pons
• neural centers for control of
respiratory rhythm
• Medulla
• respiratory rate “pacemaker”
• Stretch receptors
• notify neural centers of
excessive overinflation

31. Control of Respiration
• Physical factors modify both
rate and depth of breathing
• Examples:
• Increased body temperature
• Exercise
• Speech
• Singing

32. Control of Respiration
• Volition
• conscious controlling of breathing that
does not interfere with homeostasis
• Emotional factors can modify
breathing.
• Examples:
• Fear
• Anger
• Excitement

33. Control of Respiration
Chemical factors:
• Changes in carbon dioxide levels and decreased blood pH
are the most important stimuli affecting respiratory rhythm and
depth.
• Carbon dioxide acts directly on the medulla via its effect on
reducing the pH of blood and brainstem tissue.
• A rising level of carbon dioxide results in faster, deeper breathing;
falling levels lead to shallow, slow breathing.

34. Respiratory Disorder
• The major respiratory disorders:
• COPD (emphysema and chronic
bronchitis)
• Lung cancer
• Cigarette smoking is a significant
cause of respiratory disorder.
• Emphysema
• permanent destruction and
enlargement of alveoli
• lungs lose their elasticity, and
expiration becomes an active process

35. Respiratory Disorder
• Chronic bronchitis
• excessive production and pooling of
mucus in lower respiratory
passageways
• severely impairs ventilation and gas
exchange
• Lung cancer
• extremely aggressive and
metastasizes rapidly
• Three most common lung cancers:
• Adenocarcinoma
• Squamous cell carcinoma
• Small cell carcinoma