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Cardiopulmonary Anatomy and
Physiology I
esp ra ory are rogram
University of Medicine and Dentistry
Professor Richard Clausell, MPA, RRT
Anatomy of the
Respiratory Tract The respiratory tract is divided into an upper and a lower
airway.
The upper airway includes: the nose
the oral cavity
the pharynx
The lower airway includes: the larynx
the tracheobronchial tree
the lung parenchyma
The Upper Airway
The upper airway consists of the nose, oral cavity, andpharynx.
The primary functions of the upper airway are: act as a conductor of air
prevent foreign materials from entering the tracheobronchialtree
serve as an important area involved in speech and smell.
heat and humidify inspired air
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The Nose
Top third is bony; lower two thirds is cartilage.
Nasal septum is cartilage in its anterior portion and
divides the nose into two nasal fossae or nares. The anterior portion of the nasal cavity is lined with skin
and contains hair follicles.
The Nose
Anterior third is lined with squamous, nonciliatedepithelium.
Posterior two thirds is covered with ciliated,pseudostratified, columnar epithelium containing manyserous an mucous g an s.
The primary functions of the nose are to humidify, heat,and filter the inspired a ir.
Two secondary functions are the sense of smell and aresonance chamber for phonation.
The Oral Cavity The oral cavity is involved in digestion, speech and
respiration.
The palate separates the nasal cavity from the oral cavity.
The anterior 2/3 has a bony skeleton and is called the
hard palate. The posterior third is composed of cartilage and is called
the soft palate.
The oral cavity also houses tonsils that serve certain
protective functions.
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The Pharynx
The pharynx is the space behind the oral and nasal cavities
and is subdivided into the nasopharynx, oropharynx and
laryngopharynx.
The nasopharynx is the area above the soft palate lined with
ci iate , pseu ostrati ie , co umnar epit e ium.
The Pharynx
The oropharynx extends from the soft palate to the base ofthe tongue and houses, the tonsils. It also houses the lingualtonsils and together play an important role in the pulmonarydefense system.
the opening of the esophagus and houses many of theimportant landmarks for intubation.
The Lower Airway
The lower airway starts at the level of the vocal cords.
Divided into three sections:
The larynx
Tracheobronchial Tree
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The Larynx
Lies between the upper and lower airways at the level of thefourth-sixth vertebrae.
The opening to the larynx is the glottis.
Composed of cartilage connected to one another by muscles.
The largest laryngeal cartilage is the V-shaped thyroidcartilage.
Below the thyroid cartilage is the ringlike cricoid cartilage.
The Larynx
The cricoid cartilage is the only complete ring in the
trachea and is the narrowest portion of the upper airway
in infants and small children.
4 Functions of the Larynx
To act as a gas-conducting channel connecting the upper and
lower airways.
To protect the lower airway from foreign substances.
To participate in the cough mechanism.
o participate in speec .
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The Tracheobronchial Tree
Functions as a system of conducting tubes, allowing passage of
gas to and from the lung parenchyma, where gas exchange
occurs.
Subdivided into two portions: central airways (bronchi) and
perip era airways ronc ioes .
Composed of three major layers: an epithelial lining, the lamina
propria and cartilaginous layer.
Tracheobronchial Tree
The epithelial layer is composed of pseudostratified,
ciliated, columnar epithelium with numerous mucous
and serous glands.
,
containing many small blood vessels, lymphatic vessels
and nerves. It also contains bronchial smooth muscle
which may contract, resulting in an acute increase in
airway resistance.
Tracheobronchial Tree
The cartilaginous layer provides structure for the airways and
progressively diminishes until it essentially disappears in
tubes of less than 1 mm in diameter.
The contents and functional significance of these layers
chan e as the diameters of the tubes become smaller..
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The Trachea
Generation 0
In the adult, the trachea is a tube 11 to 13 cm in length and1.5 to 2.5 cm in diameter.
It extends from the larynx to its bifurcation (the carina) atthe level of the the second costal cartilage or fifth thoracicvertebra.
Supported by 16 to 20 C-shaped cartilage.
Posterior wall is made up of muscle and sits anterior to theesophagus.
Main Stem Bronchi
First generation.
Structurally similar to the trachea.
The right main stem bronchus forms an approximately
25 de ree an le with the vertical axis and is wider and
shorter than the left.
The left main stem bronchus forms a 40 to 60 degree
angle.
In the infant, both main stem bronchi form equal angles
of approximately 55 degrees.
Lobar Bronchi
2nd Generation.
The right main stem bronchus divides into three lobar
branches: upper, middle and lower.
The left main stem bronchus divides into a upper andlower lobar bronchi.
The cartilage lose the characteristic horseshoe shape but
still provide rigidity under most circumstances.
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Segmental Bronchi
3rd Generation.
The lobar bronchi give rise to various branches called
segmental bronchi that are named according to the lung
.
Ten on the right and eight on the left.
Important to the application of postural drainage and
other chest physical therapy techniques.
Subsegmental Bronchi
Generations 4-9.
Each generation of segmental bronchi give rise to a numberof generations of subsegmental bronchi.
The total cross-sectional area increases with each generation.
The diameter decreases from about 4 mm to 1 mm.
Subsegmental Bronchi
The bronchi are surrounded by connective tissue containing
arteries, lymphatics and nerves until the diameter becomes
1mm or less.
Tubes greater than 1 mm diameter with connective tissue are
called bronchi and are res onsible for 80% of normal airwaresistance below the glottis.
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Bronchioles Generation 10-15
Tubes less than 1 mm without connective tissue are called
brochioles. Account for the other 20% of normal total airway resistance
below the glottis.
The tracheobronchial tree ends at approximately the 16thgeneration from the trachea.
Terminal Bronchioles
Generation 16-19.
Average diameter is approximately 0.5 mm.
Epithelium becomes flattened.
Mucous lands and cilia are scant.
Unique secretory cells called clara cells may produce somemucous.
Very important surfactant is found at the level of the terminalbrochioles. Pulmonary surfactant is a surface-activelipoprotein complex (phospholipoprotein) formed by type IIalveolar cells.
Lung Parenchyma
Lung parenchyma is composed of:
Respiratory Bronchioles
Alveolar Ducts
Alveolar Sacs
Primar Lobules
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Respiratory Bronchioles
Generation 20-23.
The terminal bronchioles give rise to respiratory bronchioleswhich serve as a transition to pure alveolar epithelium
ossessin maximum as exchan e ca abilit .
Lack cilia, mucous and serous glands.
Alveolar Ducts
Generation 24-27.
Alveolar ducts arise from the respiratory bronchiole.
About half of lung alveoli arise directly from the alveolar
ducts and are responsible for 35% of alveolar gas exchange.
Alveolar Sacs
Generation 28.
Alveolar sacs, also known as primary lobules, are thelast generation of the airways and are functionally the
same as alveolar ducts. The lung parenchyma is actually composed of
numerous primary lobules or functional units,approximately 130,000.
Each lobule has a diameter of 3.5 mm and containsapproximately 2,200 alveoli responsible forapproximately 65% of gas exchange.
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Alveolar Epithelium Alveolar type I cell: squamous pneumocyte
makes up 80-95% of alveolar surface
play integumentary role in the maintenance of the air-blood
barrier
,
extremely susceptible to injury
Alveolar Epithelium
Alveolar Type II cells: granular pneumocyte
cuboidal cell responsible for considerable metabolic and
enzymatic activity
primary source of pulmonary surfactant which decreases
surface tension of fluid that lines the alveoli
also may secrete other substances for clearance and degradation
of pulmonary secretions and cellular debris
Alveolar Epithelium
Alveolar Macrophages: Type III cells
mononuclear phagocytes
originate in bone marrow and migrate to lung where they
mature
does not function in as exchan e but is an im ortant as ect inlung defense removing bacteria and other foreign particles
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Defense Function
There are about 200 cilia per cell which lie almost
entirely within the fluid sol layer. Cilia movement makes the upper end of the hairlike
ro ection extend into the viscous el la er and ulls itforward.
The mucous blanket moves at an average rate of 2cm/min.
Cough mechanism also mobilizes the mucous blanket.
Factors That Effect Mucociliary
Clearance Smoking
Positive pressure ventilation
Dehydration
Anesthesia
High FIO2s
Disease processes
Cough Mechanism
A cough is a pulmonary defense mechanism thatattempts to maintain adequate bronchial hygiene in spiteof inadequate normal mechanisms.
It functions in the presence of abnormalities such ascop ous, ry or c mucous as we as poor c aryactivity.
The cough is the major defense against retainedsecretions and is often destroyed in pulmonary disease.
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Cough Mechanics
Cough consists of five separate mechanical components:
a deep breath an inspiratory pause
glottic closure
ncrease n ra oracc pressure
glottic opening
No matter how effective the cough may be mechanically,it must have an intact mucous blanket.
Clinical Manifestations
Common manifestations of retained secretions are: increased work of breathing
mucous plugging
hypoxemia
inadequate cough
atelectasis
pneumonia
Causes of Retained Secretions
Dehydration
Pulmonary Disease
Tracheal Foreign Body
Muscular Weakness Bulbar Malfunction
Abdominal Musculature Limitations
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Pulmonary Vascular System
The pulmonary vascular system can be viewed as an
independent vascular network with the purpose of
delivering blood to and from the lungs for gas exchange.
The pulmonary vascular system is composed of:
arteries -venules
arterioles -veins
capillaries
Arteries
The right ventricle of the heart pumps deoxygenated bloodinto the pulmonary artery.
Pulmonary arteries divide into the right and left branches,penetrating their respective lung through a region called thehilum.
The hilum is the part of the lung where the main stembronchi, vessels, and nerves enter.
Arterioles
The arterioles progressively get smaller and smaller as theyreach the pulmonary capillaries.
The pulmonary arteries supply nutrients to the respiratorybronchioles, alveolar ducts, and alveoli.
regulation of blood and are called the resistance vessels.
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Capillaries
The pulmonary arterioles give rise to a complex network of
capillaries that surround the alveoli. (p. 33) The capillaries are essentially an extension of the inner lining
of the larger vessels.
The capillaries are where gas exchange occurs and also have aselective permeability to water, electrolytes, and sugars.
Venules
After blood moves from the pulmonary capillaries, it enters
the pulmonary venules.
The venules are actually tiny veins continuous with the
capillaries.
,
the heart.
Veins
Veins contain one-way, flaplike valves that aid blood flow
back to the heart.
The valves open as long as the flow is toward the heart,
but close if flow moves away from the heart. (p. 35)
e ns are capa e o co ect ng a arge amount o oo
with very little pressure change and are also called
capacitance vessels.
The pulmonary veins then empty into the left atrium of
the heart.
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The Lymphatic System
Lymphatic vessels are found superficially around thelungs just beneath the visceral pleura.
e pr mary unc on o e ymp a c vesses s o
remove excess fluid and protein molecules that leak out
of the pulmonary capillaries.
Neural Control of the Lungs
The balance, or tone, of the bronchial and arteriolar
smooth muscle of the lungs is controlled by the ANS.
The ANS has two divisions: (1) the sympathetic nervous
system, w ic acce erates t e HR, constricts oo
vessels, relaxes bronchial smooth muscle and raises
blood pressure and (2) the parasympathetic nervous
system, which has the opposite effects.
Sympathetic Nervous System
When activated, neural transmitters, such epinephrine andnorepinephrine, are released.
These agents stimulate beta2 receptors in the bronchial
smooth muscles causin relaxation of the airwa s.
They also stimulate alpha receptors in bronchial smoothmuscles causing the pulmonary vascular system to constrict.
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Parasympathetic Nervous System
When the parasympathetic nervous system is activated, the
neural transmitter acetylcholine is released, causing
constriction of the bronchial smooth muscle.
Inactivity of either systems allows for the action of the other
to dominate the bronchial smooth muscle res onse.
The Lungs
The apex of each lung is somewhat pointed and the baseis broad and concave to accommodate the convexdiaphragm.
The mediastinal border of each lun is concave to fit theheart.
At the center of the mediastinal border is the hilum,where the mainstem bronchi, blood vessels, lymphvessels and nerves enter and exit the lungs.
Right and Left Lungs
The right lung is larger and heavier than the left.
It is divided into the upper, middle and lower lobes by
fissures.
The right lung is shorter than the left due to the liver
occupying the space directly below it.
The left lung is divided into an upper and a lower lobe.
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Mediastinum
The mediastinum is a cavity that contains organs and tissuesin the center of the thoracic cage between the right and left
lungs. It is bordered anteriorly by the sternum and posteriorly by
the thoracic vertebrae.
e me iastinum ouses t e trac ea, eart, major oovessels, various nerves, esophagus, thymus gland and lymphnodes.
Pleural Membranes
Two moist, slick-surfaced membranes, called the visceral and
parietal pleurae, are closely associated with the lungs.
The visceral pleura is firmly attached to the outer surface of
each lung.
The parietal pleura lines the inside of the thoracic surface of
the diaphragm, and the lateral portion of the mediastinum.
Pleural Membrane
The potential space between the visceral and parietal
pleura is called the pleural cavity.
The pleural layers are held together by a thin film of
serous fluid. This fluid allows the two membranes to glide over each
other during inspiration and expiration.
The potential space between the two membranes has a
subatmospheric pressure causing the two membranes to
adhere.
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Thorax
The thorax houses and protects the organs of thecardiopulmonary system.
Twelve thoracic vertebrae form the posterior midline borderof the thoracic cage.
The sternum forms the anterior burder of the chest.
The sternum is composed of the manubrium, body, andxiphoid process.
Thorax The twelve pairs of ribs form the lateral boundary of the
thorax.
The ribs attach directly to the thoracic vertebraeposteriorly and anteriorly to the sternum by way of thecostal cartilage.
,directly to the sternum.
Ribs 8-10 are called false ribs since they attach to thecartilage of the ribs above.
Ribs 11 and 12 are called floating ribs since they floatfreely anteriorly.
Diaphragm
The diaphragm is the major muscle of ventilation.
It is a dome-shaped muscle located between the thoracic
cavity and the abdominal cavity.
The dia hra m is com osed of two se arate musclesknown as the right and left hemidiaphragms.
The diaphragm is pierced by the esophagus, aorta, nerves
and inferior vena cava.
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Diaphragm
The phrenic nerve leaves the spinal cord between the 3rd
and 5th cervical vertebrae and supply the primary motorinnervation to the diaphragm.
The lower thoracic nerves also contribute to the motor
innervation of each hemidiaphragm.
When stimulated to contract, the diaphragm moves
downward and the lower ribs move upward and
outward.
Accessory Muscles of Ventilation
During normal breathing in healthy individuals, the
diaphragm alone can manage the task of moving gas in and
out of the lungs.
During vigorous exercise and during advanced stages of
COPD the accessor muscles are activated to assist the,
diaphragm.
Accessory Muscles of Inspiration
The accessory muscles of inspiration are those musclesthat are recruited to assist the diaphragm in creating asubatmospheric pressure in the lungs.
Major accessory muscles of inspiration include:sca ene musc es
sternocleidomastoid muscles
pectoralis major muscles
trapezius muscles
external intercostal muscles
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Scalene Muscles The scalene muscles are three separate muscles that function
as a unit.
They originate from the 2nd - 6th cervical vertebrae andinsert into the 1st and 2nd ribs.
When used as accessory muscles for inspiration, they elevatethe first and second ribs.
Sternocleidomastoid Muscles
The sternocleidomastoid muscles are located on each side of
the neck.
They originate from the sternum and clavicle and insert into
the mastoid process.
,
elevates the sternum increasing the A/P diameter of the
chest.
Pectoralis Major Muscles
The pectoralis major muscles are powerful, fan-shaped
muscles located on each side of the upper chest.
They originate from the clavicle and sternum and insert
into the upper part of the humerus.
When functioning as an accessory inspiratory muscle,
they elevate the chest, resulting in an increased A/P
diameter.
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Trapezius Muscles
The trapezius muscles are large, flat, triangular muscles that
are situated superficially in the upper back and neck.
When used as accessory inspiratory muscles of inspiration,they help to elevate the thoracic cage.
External Intercostal Muscles
The external intercostal muscles arise from the lower border
of each rib and insert into the upper border of the rib below.
The external intercostals contract during inspiration and pull
the ribs upward and outward, increasing both lateral and a/p
diameters of the thorax..
Accessory Muscles of Expiration
The accesory muscles of expiration are those muscles
that are recruited to assist in exhalation when airway
resistance increases.
When these muscles contract, they increase intrapleural
ressure and offset the increased airwa resistance.
Accessory muscles of expiration include:
abdominal muscles
internal intercostal muscles
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Abdominal Muscles
The abdominal muscles used as accessory muscles of
expiration include: rectus abdominis
external abdominis oblique
internal abdominis oblique
tranverse abdominis
When these muscles contract, they compress the
abdominal cavity, in turn, pushing the diaphragm into the
thoracic cage.
Internal Intercostal Muscles
The internal intercostal muscles run between the ribs
immediately beneath the external intercostal muscles.
The muscles arise from the inferior border of each rib
and insert into the superior border of the rib below.
These muscles contract during expiration and pull the
ribs downward and inward, decreasing both the lateral
and A/P diameter of the thorax.