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Functional Anatomy of the Respiratory System
Respiration
Functional Anatomy of
the Respiratory System
• function - supply body with O2 and dispose of CO2
• respiration - process of gas exchange between the
atmosphere and cells
a. pulmonary ventilation (breathing) - movement of
air into and out of the lungs
b. external respiration - gas exchange between the
blood and air in lungs (O2 in, CO2 out)
c. gas transport - blood carries O2 to tissue cells and
picks up CO2
d. internal respiration - gas exchange between
blood and body cells (O2 out, CO2 in)
• also involved in the sense of smell and with speech
Respiratory Tract
• functional divisions
a. respiratory zone - site of gas exchange
includes bronchioles, alveolar ducts, alveoli
b. conducting zone - allow air to reach respiratory zone
includes nose, nasal cavity, paranasal sinuses,
pharynx, larynx, trachea, bronchi, lungs
• structural divisions
a. upper tract
includes nose, nasal cavity, paranasal sinuses, pharynx
strep throat, colds, allergies, sinus infection
b. lower tract
includes larynx, trachea, bronchial tree, lungs
pneumonia, laryngitis, bronchitis
Nose & Nasal Cavity
• functions - produce mucus, filter, warm, and moisten
incoming air, resonating chamber for speech, houses
olfactory (smell) receptors
• nose
bone and cartilage support nose internally
nostrils (nares) provide openings for air to pass
hairs prevent entry of large particles
• nasal cavity
nasal septum divides cavity into right and left
nasal conchae creates passageways, supports
mucous membranes, increases surface area
Functional Anatomy of the Respiratory System
Mucous Membranes
• mucous - structure that secretes mucus
• mucus - sticky substance
• pseudostratified ciliated epithelium
lining nose and nasal cavity
• extensive network of blood vessels
• air passing over membrane is heated to
within 1 of body temperature (98.6 F) by
blood vessels
• air is moistened as water evaporates
from membrane
• sticky mucus traps dust and other small particles
• cilia push a thin layer of mucus with entrapped particles
toward pharynx (throat)
Paranasal Sinuses
• functions - same as nose and nasal cavity, lighten
skull
• air-filled spaces located within the maxilla, frontal,
ethmoid, and sphenoid bones
• open to nasal cavity
• mucous membrane lines sinuses and are continuous
with nasal cavity
swallowed - stomach acid destroys microorganisms
expectorated - spit or blown out
• sensory nerve endings trigger a sneeze when they come in
contact with an irritant
Pharynx
• functions: passageway for food/liquid to esophagus
and air to larynx
• commonly referred to as the throat
• passageway connecting nasal cavity to larynx and
oral cavity to esophagus
• three divisions: nasopharynx (behind nose),
oropharynx (behind mouth), laryngopharynx/
hypopharynx (behind larynx)
Vocal Cords, Glottis, & Epiglottis
• vocal cords housed in larynx
false vocal cords - upper pair of folds within larynx
produces NO sound, but help close airway during
swallowing
true vocal cords - lower pair of folds in larynx
produces sound through vibration
• glottis - triangular slit/opening in vocal cords
muscles in false vocal cords close glottis when
swallowing
• epiglottis - flaplike structure that closes over larynx
during swallowing to prevent food/liquid from
entering airways
Larynx
• functions - air passageway, prevents food from
entering lower respiratory tract, voice production
• commonly referred to as the voice box
• composed of muscle and cartilage bound by
elastic tissue
Functional Anatomy of the Respiratory System
Trachea
• functions - air passageway, cleans, warms, and
moistens incoming air
• commonly referred to as the windpipe
• flexible, cylindrical tube about 2 cm in diameter and
10-12 cm in length
• extends downward in front of esophagus into
thoracic cavity
• splits into right and left bronchi
• about 20 C-shaped pieces of hyaline cartilage keep
trachea from collapsing
• backside composed of smooth muscle and
connective tissue to allow esophagus to expand
when swallowing food
Bronchial Tree
• functions - air passageways connecting trachea with
alveoli; cleans, warms and moistens incoming air
• branched airways leading from the trachea to the
microscopic air sacs (alveoli) of the lungs
• cartilage line bronchial tree (like trachea), but as
branching gets smaller smooth muscle becomes
more prominent
• primary bronchi
secondary bronchi
bronchioles
alveolar ducts
alveolar sacs
alveoli
• alveoli - simple squamous epithelial cells through
which gases can easily be exchanged (diffusion)
increase surface area of lungs (1/2 size of a tennis court)
about 300 million
Lungs & Pleurae
soft, spongy, cone-shaped organs in thoracic cavity
mediastinum - separates right and left lung
diaphragm - muscle underneath lungs
suspended by a bronchus and some large blood
vessels
• pleurae - membrane that surrounds each lung
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serous fluid in between the membranes reduces
friction while breathing
• right lung is larger and divided
into 3 lobes
• left lung is smaller and divided
into 2 lobes