Download Respiratory System

Respiratory System
Dr. Michael P. Gillespie
Functions
 Gas exchange.
 Regulation of blood ph.
 Contains receptors for the sense of smell.
 Filters inspired air.
 Produces sounds.
 Rids the body of some water and heat in
expired air.
Gas Exchange
 Cells use oxygen (O2) for metabolic reactions
that release energy from nutrient molecules
and produce ATP.
 These reactions release carbon dioxide
(CO2).
 The cardiovascular system and the
respiratory system cooperate to supple O2
and eliminate CO2.
Components
 Nose.
 Pharynx (throat).
 Larynx (voice box).
 Trachea (windpipe).
 Bronchi.
 Lungs.
Upper Respiratory System
 Nose.
 Pharynx.
 Associated structures.
Lower Respiratory System
 Larynx.
 Trachea.
 Bronchi.
 Lungs.
Functional Divisions
 Conducting portion.


Interconnecting cavities and tubes both outside and
within the lungs that filter, warm, moisten air and
conduct it into the lungs.
Nose, pharynx, larynx, trachea, bronchi, bronchioles, and
terminal bronchioles.
 Respiratory portion.


Tissues within the lungs where gas exchange occurs.
Respiratory bronchioles, alveolar ducts, alveolar sacs,
and alveoli.
Otorhinolaryngology
 Diagnosis and treatment of the ears, nose and
throat.
Pulmonologist
 Diagnosis and treatment of disease of the
lungs.
Nose
 External and internal portions.
External Nose
 Supporting framework of bone and hyaline
cartilage covered with muscle and skin and
lined with a mucous membrane.
 Frontal bone, nasal bones, and maxillae form
the bony framework.
External Nose
 The cartilaginous framework consists of
the septal cartilage, lateral nasal cartilages,
and alar cartilages.
External Nose
 The two openings are the external nares or
nostrils.
 Functions:



Warming, moistening, and filtering incoming air.
Detecting olfactory stimuli.
Modifying speech vibrations as they pass through large,
hollow, resonating chambers.

Resonance refers to prolonging, amplifying, or modifying a
sound by vibration.
Internal Nose
 A large cavity in the anterior aspect of the skull.
 Lies inferior to the nasal bone and superior to the
mouth.
 The internal nares or choanae provide
communication between the external nose and the
pharynx.
 Ducts from the paranasal sinuses and the
nasolacrimal ducts also open into the internal nose.
Internal Nose
 Lateral walls: ethmoid, maxillae, lacrimal,
palatine, and inferior nasal conchae bones.
 Floor: the hard palate which consists of the
palatine bones and the palatine process of the
maxillae.
Internal Nose
 Nasal cavity – the space within the internal
nose.
 The anterior portion just inside the nostrils is
called the vestibule.
 The nasal septum divides the cavity into
right and left sides.

Primarily hyaline cartilage, but also the vomer,
and perpendicular plate.
Air Filtration
 The vestibule is lined by skin containing coarse
hairs, which filter out large dust particles.
 Three shelves are formed by the superior, middle,
and inferior conchae.
 The conchae divide the nasal septum into groove
like passageways called the superior, middle, and
inferior meatuses.
 A mucous membrane lines the cavity and its
shelves.
Air Filtration
 The arrangement of the conchae and
meatuses increases surface area in the
internal nose. It traps water droplets during
exhalation to prevent dehydration.
 The olfactory receptors line the superior
nasal conchae and adjacent septum
(olfactory epithelium).
Air Filtration
 Inspired air is warmed by blood in the
capillaries.
 Mucous secreted by goblet cells moistens the
air and traps dust particles.
 Cilia move the mucous and trapped particles
towards the pharynx to be swallowed or spit
out.
Rhinoplasty
 “Nose job”.
 The structure of the external nose is altered.
 Often performed for cosmetic reasons.
 Sometimes performed to repair a fractured
nose or a deviated septum.
Pharynx
 The pharynx or throat is a funnel shaped tube
about 13 cm long.
 It starts at the internal nares and extends to
the cricoid cartilage (the most inferior
cartilage of the larynx).
Pharynx
 Its wall is composed of skeletal muscles and
it is lined with a mucous membrane.
Pharynx
 Functions:



Passageway for air and food.
Resonating chamber for speech sounds.
Houses the tonsils (participate in immune responses).
 Anatomical regions:



Nasopharynx.
Oropharynx.
Laryngopharynx.
Nasopharynx
 The nasopharynx is the superior portion of the
pharynx.
 Extends from the posterior nasal cavity to the soft
palate.
 5 openings in its wall:



2 internal nares.
Eustachian tubes (a.K.A. Auditory or
pharyngotympanic).
Opening into the oropharynx.
Nasopharynx
 Pharyngeal tonsils.
 The nasopharynx is lined with
pseudostratified ciliated columnar
epithelium, which moves mucous down
towards the inferior part of the pharynx.
 The eustachian tubes help to equalize air
pressure between the pharynx and middle
ear.
Oropharynx
 The intermediate portion of the pharynx.
 Extends from the soft palate to the hyoid bone.
 One opening – the fauces (throat), the opening from
the mouth.


Common passageway for air, food, and drink.
Lined with nonkeratinized stratified squamous
epithelium to withstand abrasion from food particles.
 Palatine and lingual tonsils are found here.
Laryngopharynx
 Inferior portion of the pharynx.
 Otherwise known as the hypopharynx.
 Opens to the esophagus posteriorly and the
larynx anteriorly.
 Both a respiratory and a digestive pathway.
 Lined with nonkeratinzed stratified
squamous epithelium.
Larynx
 Voice box.
 A short passageway that connects the
laryngopharynx with the trachea.
 Lies in the midline of the neck anterior to the
4th through 6th cervical vertebrae.
Larynx
 Composed of 9 pieces of cartilage.
 Thyroid cartilage (Adam’s apple).
Larynx
 Epiglottis – a large leaf shaped piece of
elastic cartilage.

During swallowing, the epiglottis closes off the
glottis (vocal cords) and prevents food from
entering the larynx and airways inferior to it. It
shunts food to the esophagus.
Larynx
 Cricoid cartilage.


A ring of cartilage that forms the inferior wall of
the larynx.
This cartilage serves as the landmark for making
an emergency airway (tracheostomy).
Voice Production
 The mucous membrane of the larynx forms
two pairs of folds.


Ventricular folds (false vocal cords) – superior.
Vocal folds (true vocal cords) – inferior.
 If air is directed against the vocal folds they
vibrate and produce sounds (phonation).
Voice Production
 The greater the pressure of the air, the louder the
sound.
 Pitch is controlled by tension on the vocal folds. If
they are pulled taught, the pitch raises. Decreasing
muscular tension results in lower sounds.
 Vocal folds are usually thicker and longer in males
than in females resulting in a lower pitch.
Laryngitis & Cancer Of The
Larynx
 Laryngitis is an inflammation of the larynx.
 It is often caused by a respiratory infection or
irritants such as cigarettes or smoke.
Laryngitis & Cancer Of The
Larynx
 Chronic inflammation in long term smokers
can cause a permanent hoarseness.
 Cancer of the larynx is found almost
exclusively in smokers.
 Treatment consists of radiation therapy and /
or surgery.
Trachea
 The trachea (windpipe) is a tubular
passageway for air that is about 12 cm long
and 2.5 cm in diameter.
Trachea
 It is anterior to the esophagus and extends
from the larynx to the superior border of the
5th thoracic vertebra where it branches to
form bronchi.
Trachea
 Layers:

Mucosa.



Submucosa.
Hyaline cartilage.




Pseudostratified ciliated columnar epithelium and goblet cells.
16 – 20 incomplete, horizontal rings that resemble the letter C.
The open part of each ring faces the esophagus and allows slight
expansion of the esophagus into the trachea during swallowing.
The solid C shaped ring prevents collapse of the trachea.
Adventitia.

Areolar connective tissue that joins the trachea to the surrounding
tissues.
Tracheostomy & Intubation
 Several conditions can block airflow:



A crushing injury to the chest.
Inflammation of the mucous membrane causing
swelling.
Vomit or another foreign object may be aspirated
into it.
 If the obstruction is superior to the larynx, a
tracheostomy may be performed.
Tracheostomy & Intubation
 A tracheostomy is an operation to make an opening
into the trachea.
 Intubation involves inserting a tube into the mouth
or nose and passing it inferiorly through the larynx
or trachea. The tube pushes any flexible
obstruction out of the way. Mucous can be
suctioned through the tube and the lumen provides
a passageway for air.
Bronchi
 The trachea divides into a right primary bronchus
and a left primary bronchus at the superior border
of T5.
 Carina – the ridge where the trachea branches into
the right and left bronchi. The mucous membrane
is the most sensitive here and triggers the cough
reflex.
 Upon entering the lungs, the primary bronchi divide
into secondary (lobar) bronchi – one for each lobe
of the lung. 3 on the right and 2 on the left.
Bronchi
 They then branch to tertiary (segmental)
bronchi and eventually bronchioles.
 Terminal bronchioles are the smallest branch.
 This branching is referred to as the bronchial
tree.
Bronchial Control
 The amount of cartilage decreases as we
move down the bronchial tree and the
amount of smooth muscle increases.
 With no supporting cartilage, muscle spasms
can close of the airways as in an asthma
attack.
Bronchial Control
 Sympathetic nerve stimulation causes
relaxation of the smooth muscles of the
bronchioles through release of epinephrine
and norepinephrine.
 The parasympathetic division of the ANS
and mediators of allergic reactions such as
histamine cause contraction of bronchiolar
smooth muscle.
Lungs
 Trauma to the chest which causes one lung to
collapse may not affect the other as they are
in two distinct chambers.
 There are two layers of the pleural
membrane:


Visceral pleura and parietal pleura.
The pleural cavity is the space between these
membranes and is filled with serous fluid.
Lungs
 Pleurisy or pleuritis is an inflammation of the
pleural membrane.
 Pleural effusion is an accumulation of fluid
in the pleural space due to persistence of
inflammation.
Surface Anatomy Of The
Lungs
 Base.
 Apex.
 Costal surface.
 Mediastinal (medial) surface.
 Hilus.
 Root.
 Cardiac notch.
Lobes, Fissures, & Lobules
 The lungs are divided into lobes by fissures.
 Each lung has an oblique fissure. The right lung
also has a horizontal fissure.
 The left lung has a superior and an inferior lobe.
The right lung has these as well as a middle lobe.
 Each lobe receives its own secondary (lobar)
bronchus.
Lobes, Fissures, & Lobules
 Superior, middle, and inferior bronchi on the
right and superior and inferior bronchi on the
left.
 The tertiary (segmental) bronchi arise from
the lobar bronchi and supply a
bronchopulmonary segment.
Lobes, Fissures, & Lobules
 Terminal bronchioles are called respiratory
bronchioles.
 Respiratory bronchioles are subdivided into
alveolar ducts.
 There are about 25 orders or branching from
the trachea to the alveolar ducts.
Alveoli
 The alveoli and alveolar sacs surround the
opening of the alveolar ducts.
 An alveolus is a cup-shaped outpouching
lined by simple squamous epithelium.
Alveoli
 An alveolar sac consists of 2 or more alveoli that
share a common opening.
 Type I and type II alveolar cells line the alveolar
wall along with alveolar macrophages (dust cells).
 Type II alveolar cells secrete alveolar fluid with
surfactant. Surfactant lowers the surface tension of
the alveolar fluid and prevents the alveoli from
collapsing.
Respiratory Membrane
 The alveolar walls and capillary walls form the
respiratory membrane.
 Exchange of O2 and CO2 takes place here.
 The respiratory membrane is very thin, which
allows for rapid diffusion of gases.
 The lungs contain an estimated 300 million alveoli,
providing a surface area of about 70m2 for the
exchange of gases.
Nebulization
 Nebulization is a treatment that administers
medication in the form of droplets suspended in air
to the respiratory tract.
 The patient inhales the medication as a fine mist.
 Various drugs are used. Some relax the smooth
muscles of the respiratory tract, some reduce the
thickness of mucous, and antibiotics are used.
Blood Supply To The Lungs
 Deoxygenated blood passes from the right
ventricle into the pulmonary trunk, which
divides into a left and right pulmonary artery.
 Four pulmonary veins return oxygenated
blood to the left atrium.
Blood Supply To The Lungs
 Pulmonary blood vessels constrict in the
presence of hypoxia (low O2) unlike blood
vessels elsewhere in the body. This shunts
blood from poorly ventilated areas of the
lung to well-ventilated regions.
 This is known as ventilation-perfusion
coupling because the perfusion (blood flow)
matches the ventilation (air flow) to an area.
Blood Supply To The Lungs
 Bronchial arteries, which branch from the
aorta, deliver oxygenated blood to the lungs.
 This blood peruses the walls of the bronchi
and bronchioles.
Pulmonary Ventilation
 Respiration (gas exchange) occurs in 3 steps:



Pulmonary ventilation (breathing) – the mechanical flow
of air into (inhalation) and out of (exhalation) the lungs.
External respiration – the exchange of gases between the
air spaces of the lungs and the blood in the capillaries.
Internal respiration – the exchange of gases between the
blood in systemic capillaries and tissue cells.
 Pulmonary ventilation (breathing) is the process by
which gases flow between the atmosphere and the
lung alveoli.
Inspiration & Expiration
Pressure Changes During
Pulmonary Ventilation
 Air moves into the lungs when air pressure in
the atmosphere is greater than air pressure in
the lungs.
 Air moves out of the lungs when the pressure
inside the lungs is greater than the pressure in
the atmosphere.
Inhalation
 Breathing in is called inhalation (inspiration).
 Increasing the volume of the lungs causes
inhalation.
 Contraction of the diaphragm and the
external intercostals expands the lungs.
Boyles Law
 The pressure of a gas in a closed container is
inversely proportional to the volume of the
container.
 If the size of a closed container increases, the
pressure inside the container decreases.
 If the size of a closed container decreases,
the pressure inside the container increases.
Muscles Of Inhalation
 The most important muscle of inhalation is
the diaphragm.
 The next most important muscles in
inhalation are the external intercostals.
Exhalation
 Breathing out is called exhalation
(expiration).
 Elastic recoil of the chest wall and lungs
causes exhalation.


Recoil of the elastic fibers that were stretched
during inhalation.
The inward pull from surface tension of the film
of alveolar fluid.
Active Exhalation
 Exhalation becomes active only during
forceful breathing such as when playing a
wind instrument or during exercise.
 The muscle of exhalation then contract.


Abdominals.
Internal intercostals.
Factors Affecting Pulmonary
Ventilation
 Surface tension of alveolar fluid. A
deficiency in surfactant in premature infants
causes respiratory distress syndrome.
Factors Affecting Pulmonary
Ventilation
 Compliance of lungs refers to how much effort is
required to stretch the lungs.

Decreased compliance results from scar tissue (TB),
excess fluid (pulmonary edema), a deficiency in
surfactant, or paralysis of muscles of inspiration.
 Airway resistance – any condition that narrows or
obstructs airways increases resistance.

Chronic obstructive pulmonary disorders (COPD) such
as asthma, emphysema, or bronchitis increase airway
resistance.
Breathing Patterns
 Eupnea – a normal pattern of quiet breathing.
 Costal breathing – shallow (chest) breathing. An
upward and outward movement of the chest due to
contraction of the external intercostal muscles.
 Diaphragmatic breathing – deep (abdominal)
breathing consisting of outward movement of the
abdomen from contraction and descent of the
diaphragm.
Modified Respiratory
Movements
 Coughing
 Sneezing
 Sighing
 Yawning
Modified Respiratory
Movements
 Sobbing
 Crying
 Laughing
 Hiccuping
 Valsalva maneuver
Lung Volumes & Capacities
 Tidal volume (VT)– the volume of one breath.
 Minute ventilation (MV) is the volume of inhaled
and exhaled air in one minute. It is determined by
multiplying the respiratory rate by the tidal volume.
 A spirometer or respirometer are utilized to
measure the volume of air used.
 A spirogram is the record of this volume.
Lung Volumes & Capacities
 Typically, about 70% of the tidal volume
reaches the respiratory portion of the
respiratory system. The remaining airways
are known as the anatomic dead space.
 By inhaling deeply, you can take in
additional air (inspiratory reserve volume).
Lung Volumes & Capacities
 The expiratory reserve volume is the
additional air from a forced exhale.
 Even after a forced breath, some air remains.
This is the residual volume.
Lung Volumes & Capacities
 The inspiratory capacity is the sum of the tidal
volume and the inspiratory reserve volume.
 The functional residual capacity is the sum of
residual volume and expiratory reserve volume.
 Vital capacity is the sum of inspiratory reserve
volume, tidal volume, and expiratory reserve
volume.
 Total lung capacity is the sum of vital capacity and
residual volume.
External Respiration
 External respiration or pulmonary gas exchange is
the diffusion of O2 from air in the alveoli of the
lungs to blood in pulmonary capillaries and the
diffusion of CO2 in the opposite direction.
 External respiration converts deoxygenated blood
coming from the right side of the heart into
oxygenated blood that returns to the left side of the
heart.
 External respiration occurs only in the lungs.
Internal Respiration
 Internal respiration or systemic gas exchange
is the exchange of CO2 and O2 between the
systemic capillaries and tissue cells.
 Internal respiration occurs in tissues
throughout the body.
Oxygen Transport
 Oxygen does not dissolve easily in water.
 Most of the blood O2 is bound to
hemoglobin.
 Oxygen and hemoglobin bind in an easily
reversible reaction to form oxyhemoglobin.
Carbon Monoxide Poisoning
 Carbon monoxide CO is a colorless and
odorless gas found in exhaust fumes from
automobiles, gas furnaces, space heaters, and
tobacco smoke.
 CO binds to hemoglobin about 200 times as
strong as O2 and uses up the available
hemoglobin molecules.
Carbon Monoxide Poisoning
 Bright, cherry red color of the lips is a sign.
 Administering pure oxygen speeds up the
dissociation of CO from hemoglobin and can
save a persons life.
Respiratory Center
 The respiratory center in the brain stem controls the
basic rhythm of respiration.
 3 areas:

Medullary rhythmicity area – controls the basic rhythm.



Inspiratory and expiratory areas.
Pneumotaxic area – impulses turn off the inspiratory area
before the lungs become too full.
Apneustic area – activates the inspiratory center and
prolongs inspiration.
Chemoreceptor Regulation
 Chemoreceptors regulate the levels of O2 and
CO2.
 Central chemoreceptors are located in the
medulla oblongata.
 Peripheral chemoreceptors are located in the
aortic bodies and carotid bodies.
Hypoxia
 A deficiency of O2 at the tissue level.
 4 types:




Hypoxic hypoxia – low PO2 in arterial blood from high
altitude, airway obstruction or fluid in the lungs.
Anemic hypoxia – too little hemoglobin due to
hemorrhage, anemia, CO poisoning.
Ischemic hypoxia – blood flow to a tissue is reduced.
Histotoxic hypoxia – tissues cannot use O2 properly due
to some toxic agent (I.E. Cyanide poisoning).
Influences On Respiration
 See page 840 in text.