Week 1 - Anatomy of the Respiratory System

8/3/2019 Week 1 - Anatomy of the Respiratory System

1/22

5/31/20

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


2/22

5/31/20

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.


3/22

5/31/20

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


4/22

5/31/20

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 .


5/22

5/31/20

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.


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.


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..


6/22

5/31/20

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.


7/22

5/31/20

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.


8/22

5/31/20

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


9/22

5/31/20

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.


10/22

5/31/20

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


11/22

5/31/20

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.


12/22

5/31/20

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


13/22

5/31/20

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.


14/22

5/31/20

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.


15/22

5/31/20

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.


16/22

5/31/20

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.


17/22

5/31/20

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.


18/22

5/31/20

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.


19/22

5/31/20

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


20/22

5/31/20

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.


21/22

5/31/20

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


22/22

5/31/20

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.

Documents

Week 1 - Anatomy of the Respiratory System