Respiratory System
Anatomy & Physiology
Function and Functional
Anatomy
Function: to supply the body with
oxygen (O) and dispose it of carbon
dioxide(CO2)
 Functional Anatomy: there are 2 zones
of the respiratory system

I. Conducting Zone
II. Respiratory Zone
Upper and Lower Respiratory
Tracts
I. Conducting Zone

Function: to warm, cleanse and humidify
incoming air
 Structures of the conducting zone
–
–
–
–
–
–
Nose
Pharynx
Larynx
Trachea
Primary bronchii
Lungs
I. Conducting Zone: Nose

A&P of the nose:
– External nares: nostrils; where air enters
– Nasal cavity: interior of the nose
– Nasal septum: splits the n. cavity into 2;
contains:
• Mucosa: warms air and traps bacteria
• Cilia: moves particles to throat to be digested
• Olfactory receptors: nerve endings to detect
smell
I. Conducting Zone: Nose

There are 3 main nasal structures:
– Conchae: mucosa covered projections; increases
surface area and creates air turbulence within
nose
– Palate: separates nasal and oral cavities
• Hard palate: bony anterior section
• Soft palate: non-bony posterior section
– Paranasal sinuses:
• Lightens the skull
• Resonance chambers for speech
• Produces mucus to drain into nasal cavity
Paranasal Sinuses
I. Conducting Zone: Pharynx
AKA the throat
 Muscular passageway for both food and
air
 About 5 inches long
 Houses the tonsils (clusters of lymphatic
tissue)

I. Conducting Zone: Pharynx

3 parts to the pharynx:
– Nasopharynx: meets the auditory tube
from ear; houses pharyngeal (adenoids)
tonsils
– Oropharynx: palantine tonsils @ end of
soft palate
– Laryngopharynx: lingual tonsils @ base of
tongue
I. Conducting Zone: Larynx

AKA voice box
 Located inferior to pharynx
 Function: routes air and food into proper
tubes
 Formed from 8 rigid hyaline cartilages and
the epiglottis
– Epiglottis: a flap of elastic cartilage; closes larynx
while swallowing; open during breathing
Larynx
I. Conducting Zone: Larynx
– Thyroid Cartilage: AKA adam’s apple; the
largest of the 8 cartilaginous rings
– Larynx holds the vocal folds (cords)
• Vibrate with expelled air producing sound
• Vocal folds surround glottis
• Glottis: slit-like passageway in the larynx
I. Conducting Zone: Trachea &
Primary Bronchi

Trachea
– AKA the windpipe
– ~4 inches long
– Lined with ciliated
mucus
– Cilia beats to propel
dust and bacteria
away from lungs

Primary Bronchi
– There are 2; right
and left
– Runs from trachea to
lungs
– Air @ this point is
warmed, humidified
and cleansed
I. Conducting Zone: Lungs
Large paired organs
 Apex: narrow, superior region, lying
posterior to clavicles
 Base: broad and inferior region; rests
on diaphragm
 Lungs divided into lobes and fissures

I. Conducting Zone: Lungs

Right Lung:
– 3 lobes
– 2 fissures
• Horizontal
• Oblique

Left Lung:
– 2 lobes
Lungs
I. Conducting Zone: Lungs
Visceral Pleura: serous membrane
surrounding each lung
 Parietal Pleura: serous membrane
lining the wall of the thoracic cavity

– Both work to produce pleural fluid allowing
for reduced friction b/n lung and wall;
allows lungs to cling to wall
II. Respiratory Zone
Function: Where gas exchange takes
place
 Structures of the respiratory zone:

– Respiratory bronchioles
– Alveolar ducts
– Alveolar sacs
– Alveoli
II. Respiratory Zone:
Bronchioles

Respiratory Tree
– Primary bronchi branch off into right and
left lungs
– They then further divide into secondary
and tertiary bronchi---ends at bronchioles
– Bronchioles: the smallest of conducting
zone passageways leading to the
respiratory zone
Respiratory Tree
II. Respiratory Zone: Alveoli

Alveoli: small air sacs
– Surrounded by alveolar sacs and
connected by alveolar ducts—resembles
grapes
– Only site of gas exchange
– Millions per lung
– Walls made of squamos epithelial tissue
Respiratory Membrane

AKA Air-Blood Barrier
– External surfaces of alveoli covered by
pulmonary capillaries
– Alveolar walls + capillary walls =
respiratory membrane
Respiratory Membrane: Gas
Exchange

Simple Diffusion: exchange of gasses
across the vessel walls---DOWN the
concentration gradient
– Alveoli: holds air-CO2,
O2
– Pulmonary Capillaries: holds blood
CO2
O2
– Oxygen exchange occurs from alveoli to
capillaries
– Carbon dioxide exchange occurs from
capillaries to alveoli
Respiration

Divided into 4 different events:
1.
2.
3.
4.
Pulmonary Ventilation
External Respiration
Respiratory Gas Exchange
Internal Respiration
Respiration: Pulmonary
Ventilation

AKA breathing
 Definitions:
– Atmospheric pressure: pressure outside the body
– Intrathoracic/intrapulmonary pressure: pressure
within the thoracic cavity/lungs

Pressure is dependant on volume
– Volume changes within thoracic cavity leads to
pressure changes, leading to the flow of gases to
equalize the pressure
Respiration: Pulmonary
Ventilation

A.
There are 2 parts to pulmonary
ventilation:
Inspiration
– Inspiratory muscles: the diaphragm and
intercostal muscles
– Diaphragm contracts—moves inferiorly
– Intercostals contract and lift rib cage;
pushes sternum anteriorly
Inspiration
Respiration: Pulmonary
Ventilation

Inspiration continued
– Intrapulmonary volume increases
– Intrapulmonary pressure decreases
• Pressure less than atm. pressure
– Air moves into lungs from outside of body
until pressure inside cavity = atm. pressure
Respiration: Pulmonary
Ventilation
B.
Expiration AKA exhalation
– A passive process in healthy people
– Inspiratory muscles relax, descending rib
cage---lungs recoil
– Thoracic and intrapulmonary volume
decreases
– Intrapulmonary pressure increases above
atm. pressure—forcing air out of the body
Respiration: Pulmonary
Ventilation

Forced Expiration
– If respiratory passageways are impeded,
expiration is an active process and
muscles have to contract to decrease the
volume of the cavity
• Asthma
• Bronchitis
• Pneumonia
Expiration
Respiration: External
Respiration

The actual exchange of gas between
alveoli and capillaries in the lungs
– Oxygen from alveoli to capillaries
– Carbon dioxide from capillaries to alveoli
– Blood going back to heart and out to body
is oxygen rich and carbon dioxide poor
Respiration: Respiratory Gas
Transport

The transport of respiratory gases
throughout the body
– Oxyhemoglobin Complex: oxygen
attaches to hemoglobin on RBC’s;
transports oxygen through body
– Some oxygen carried in plasma
– Carbon dioxide transported in plasma as a
bicarbonate ion (HCO3-); some carried on
hemoglobin
Respiration: Internal Respiration

The exchange of gases occurring
between blood in capillaries and tissue
cells----opposite of exchange in lungs
– Oxygen from capillaries to body cells
– Carbon dioxide from body cells to
capillaries
– Venous blood back to heart is oxygen-poor
and carbon dioxide-rich
Internal and External Respiration
Respiratory Volumes and
Capacities

Tidal Volume (TV):
normal quiet
breathing
– ~500ml moves into
and out of lungs with
each breath

Inspiratory
Reserve Volume
(IRV): amount of air
taken in forcibly over
TV
– ~2100-3200 ml
Respiratory Volumes and
Capacities

Expiratory Reserve  Residual Volume:
Volume (ERV):
after strenuous
amount of air
expiration
forcibly exhaled over
– ~1200 ml air remains
in lungs & cannot be
tidal expiration
– ~ 1200ml
expelled voluntarily
– Allows for continuous
gas exchange
between breaths
Respiratory Volumes and
Capacities

Vital Capacity (VC):  Dead Space
the total amount of
Volume: air that
exchangeable air
enters the resp. tract
& remains in the
– ~4800 ml in healthy
males
conducting zone—
– VC =TV+IRV+ERV
never reaches
alveoli
– ~150 ml
Respiratory Control Centers

Located in medulla and pons of brain
stem
– Inspiratory and expiratory centers in
medulla keep respiration rate ~ 12-18
breaths per minute
Receptors Influencing
Respiration

Chemoreceptors
– Located in carotid and aorta arteries
– Detect rising carbon dioxide levels and low
oxygen levels in blood

Pulmonary Stretch Receptors
– Located in pulmonary airways and alveoli
of the lungs
Types of Breathing
Eupnea: normal respiratory rate
 Dyspnea: labored/difficulty breathing
 Orthopnea: dyspnea relieved by sitting
upright
 Apnea: momentary cessation of
breathing

Types of Breathing
Types of Breathing
Hyperventilation: rapid and deep
breathing (too much oxygen/too little
carbon dioxide)
 Hypoventilation: slow and shallow
breathing (too little oxygen/too much
carbon dioxide)
