The Respiratory System
Function of the lungs
• Ventilation (breathing)
• Gas Exchange
• The movement of oxygen and carbon dioxide
between lungs and tissues via blood
• Oxygen utilization
• The use of oxygen by cells to release energy
The respiratory acinus
• Cartilage is present to
level of proximal
bronchioles
• Beyond terminal
bronchiole gas
exchange occurs
• The distal airspaces
are kept open by
elastic tension in
alveolar walls
Lung Volume
• Lungs must stay open
• Atelectasis = accumulation of pleural fluid which
compresses the lung and collapses alveoli
• Asthma = spasm of bronchiolar smooth muscle narrows
the airway and constricts air flow
• Emphysema = insufficient respiratory membrane for gas
exchange
• Interstitial Fibrosis = an accumulation of fibrous tissue
stiffens the lung and prevents free flow of air and also
interferes with gas diffusion between blood and alveoli
Lung Volume
• Spirometry
• Diagnostic procedure that measures lung volumes and
capacities and flow rate of air going into and out of the
lungs
• Lung Diseases have typical spirometry patterns
• Generalized Diseases come in two categories
• Obstructive and Restrictive
• Obstructive = limitation of airflow
• Restrictive = limitation of lung expansion
Lung Volume
• Forced Vital Capacity (FVC)
• A volume measurement
• The amount of air expelled from maximum inspiration
to maximum expiration
• Patient takes the deepest breath possible and blows
out as much as possible, no timing involved
• Forced Expiratory Volume (FEV1)
• Rat measurement; the timed measurement of the
amount of air expelled from maximum inspiration in the
first second of effect
• Patient takes the deepest possible breath and breathes
out as hard as possible = amount expelled in first
second
Lung Volume
• FEV1/FVC = ratio is low in Obstructive disease
• Ratio is critical in separating obstructive and
restrictive lung disease
• In Obstructive disease
• The rate of air flowing out of the lungs is slowed
• The amount the patient can expel is low
• Lung volumes are usually normal
Lung Volume
• Restrictive disease
• The ratio of airflow to lung volume is usually near
normal
• Limits both volume and flow rate proportionally
• Both Obstructive and Restrictive Disease limits gas
exchange
• Arterial Oxygen levels are low and Carbon Dioxide
levels are high
Effect of pH on ventilation
• Normal level of HCO3- = 24 mEq/L
• Metabolic acidosis (HCO3- < 24) will + ventilation
• Metabolic alkalosis (HCO3- >24) will – ventilation
• Kidney regulates HCO3• Normal level of CO2 = 40 mmHg
• Respiratory acidosis (CO2 > 40) will + ventilation
• Respiratory alkalosis (CO2 < 40) will – ventilation
• Lung regulates CO2
Normal Lung Tissue
Static Lung Volumes
• Tidal Volume (500ml)
• amount of air moved in or out each breath
• Inspiratory Reserve Volume (3000ml)
• maximum vol. one can inspire above normal
inspiration
• Expiratory Reserve Volume (1100ml)
• maximum vol. one can expire below normal
expiration
• Residual Volume (1200 ml)
• volume of air left in the lungs after maximum
expiratory effort
Static Lung Capacities
• Functional residual capacity (RV+ERV)
• vol. of air left in the lungs after a normal expir., balance
point of lung recoil & chest wall forces
• Inspiratory capacity (TV+IRV)
• max. vol. one can inspire during an insp effort
• Vital capacity (IRV+TV+ERV)
• max. vol. one can exchange in a resp. cycle = max
exhaled volume
• Total lung capacity (IRV+TV+ERV+RV)
• the air in the lungs at full inflation
Patterns of Breathing
• Eupnea
• normal breathing (12-17 B/min, 500-600 ml/B)
• Hyperpnea
•  pulmonary ventilation matching  metabolic
demand
• Hyperventilation ( CO2)
•  pulmonary ventilation > metabolic demand
• Hypoventilation ( CO2)
•  pulmonary ventilation < metabolic demand
• Hypoperfusion
•  blood flow to alveoli< metabolic demand
Patterns of breathing (cont.)
• Tachypnea
•  frequency of respiratory rate
• Apnea
• Absense of breathing. e.g. Sleep apnea
• Dyspnea
• Difficult or labored breathing
• Orthopnea
• Dyspnea when recumbent, relieved when upright.
e.g. congestive heart failure, asthma, lung failure
General Signs and Symptoms of Respiratory
Disease
 Hypoxia : Decreased levels of oxygen in the tissues
 Hypoxemia : Decreased levels of oxygen in arterial blood
 Hypercapnia : Increased levels of CO2 in the blood
 Hypocapnia : Decreased levels of CO2 in the blood
 Cyanosis : Bluish discoloration of skin and mucous
membranes due to poor oxygenation of the blood
 Hemoptysis : Blood in the sputum
General Signs and Symptoms of Respiratory
Disease
• Cough
• Dyspnea
• Productive cough =
• Shortness of breath
raising fluid to the
• Airway obstruction
pharynx
• Decreased compliance
• Expectoration =
• Cyanosis
spitting
• Large quantities of
• Non-productive cough
unoxygenated
or hacking
blood
Areas Involved in Respiratory Tract Infections
• Upper respiratory tract
• Nose, sinuses, pharynx, epiglottis, and
larynx
• Filters, warms, moisturizes and channels air
• Lower respiratory tract
• Trachea, bronchi, lungs and pleurae
• Oxygenate blood and collects and discharges
carbon dioxide, produced by energy metabolism
Upper respiratory tract
Infections
The common cold
The most common viral pathogens for the “common cold” are
rhinovirus, parainfluenza virus, respiratory syncytial virus,
adenovirus and coronavirus.
 These viruses tend to have seasonal variations in their peak
incidence.
 They gain entry to the body through the nasal mucosa and the
surfaces of the eye. They are readily spread from person to person
via respiratory secretions.
 Manifestations of the common cold include:
 Rhinitis: Inflammation of the nasal mucosa
 Sinusitis: Inflammation of the sinus mucosa
 Pharyngitis: Inflammation of the pharynx and throat
 Headache
 Nasal discharge and congestion
Upper respiratory tract Infections
Influenza
• Influenza is a viral infection that can affect the upper or lower
respiratory tract.
• Three distinct forms of influenza virus have been identified: A, B
and C, of these three variants, type A is the most common and
causes the most serious illness.
• The influenza virus is a highly transmissible respiratory pathogen.
• Because the organism has a high tendency for genetic mutation,
new variants of the virus are constantly arising in different places
around the world. Serious pandemics (spread of infection across a
large region) of influenza are seen every 8 to 10 years as a result of
this genetic mutation .
Upper respiratory tract Infections
Influenza
• Symptoms of influenza infection:
 Headache
 Fever, chills
 Muscle aches
 Nasal discharge
 Unproductive cough
 Sore throat
• Influenza infection can cause marked inflammation of
the respiratory epithelium leading to acute tissue damage
and a loss of ciliated cells that protect the respiratory
passages from other organisms.
• As a result, influenza infection may lead to co-infection
of the respiratory passages with bacteria.
• It is also possible for the influenza virus to infect the
tissues of the lung itself to cause a viral pneumonia.
Upper respiratory tract
Infections
Influenza
Treatment of influenza:
 Bed rest, fluids, warmth
 Antiviral drugs
 Influenza vaccine :
 Provides protection against certain A and B influenza
strains that are expected to be prevalent in a certain year.
 The vaccine must be updated and administered yearly to be
effective but will not be effective against influenza strains
not included in the vaccine.
 The influenza vaccine is particularly indicated in elderly
people, in individuals weakened by other disease and in
health-care workers
Upper respiratory tract
Infections
Influenza
Drugs for Treating Influenza:
 Amantidine
 Used orally or by aerosol administration
 Effective only against type A influenza
 Inhibits viral fusion, assembly and release from the
infected host cell
 Neuraminidase inhibitors (Zanamavir, Oseltamivir)
 New drugs that can be used by inhalation
(Zanamavir) or orally (Oseltamivir)
 Effective against both type A and B influenza
 Inhibits the activity of viral neuraminidase enzyme
that is necessary for spread of the influenza virus
Types of Influenza Vaccinations
• Trivalent inactivated influenza vaccine (TIIV)
• Developed in the 1940s
• Administered by injection
• Live, attenuated influenza vaccine (LAIV)
• Approved for use in 2003
• Administered intranasally
Lower respiratory tract Infections
Pneumonia
• Pneumonia is a condition that involves inflammation of lower
lung structures such as the alveoli or interstitial spaces.
• It may be caused by bacteria or viruses such as pneumocystis
carinii.
•
The prevalence and severity of pneumonia have been
heightened in recent years due to the emergence of HIV as well
as antibiotic resistance.
• Pneumonia may be classified according to the pathogen that
is responsible for the infection.
•
There tend to be distinct organisms that cause pneumonia in
the hospital setting vs. the community setting.
Lower respiratory tract Infections
• Pathology:
Pneumonia
• Alveolar
• Bronchopneumonia (Streptococcus pneumoniae, Haemophilus
influenza, Staphylococcus aureus)
• Lobar (Streptococcus pneumoniae)
• Interstitial (Influenza virus, Mycoplasma pneumoniae)
• Pathogenesis:
• Inhalation of air droplets
• Aspiration of infected secretions or objects
• Hematogenous spread - causing infections away from the original site
Bronchopneumonia vs. Lobar Pneumonia
Bronchopneumonia
• Acute Inflammation in the walls of the bronchioles
Lobar Pneumonia
• Lobar pneumonia is a form of pneumonia that affects
a large and continuous area of the lobe of a lung
Bronchopneumonia
• Suppurative (pus) inflammation of lung tissue caused
by Staph, Strep, Pneumo & H. influenza
• Usually bilateral
• Lower lobes common, but can occur anywhere
• Complications:
• Abscess
• Empyema (is a collection of pus in the space between the lung
and the inner surface of the chest wall (pleural space).
• Dissemination
Bronchopneumonia
Bronchopneumonia
Bronchopneumonia
Bronchopneumonia:
Bronchopneumonia
Lower respiratory tract Infections
Pneumonia
Individuals Most at Risk for Pneumonia
 Elderly
 Those with viral infection
 Chronically ill
 AIDS or immunosuppressed patients
 Smokers
 Patients with chronic respiratory
bronchial asthma.
disease
e.g.
Potential Pathogens









Typical
Streptococcus pneumoniae
Hemophilus influenzae
Mycobacterium catarrhalis
Klebsiella pneumoniae
Atypical
Chlamydia pneumoniae
Legionella pneumophila
Mycoplasma pneumoniae.
Lower respiratory tract Infections
Pneumonia
Lobar Pneumonia
• Fibrinosuppurative consolidation – whole lobe
• Rare due to antibiotic treatment.
• ~95% - Strep pneumoniae
• The course runs in four stages:
• Congestion.
• Red Hepatization – Looks like the liver
• Gray Hepatizaiton
• Resolution
Lower respiratory tract Infections
Pneumonia
• Red hepatisation: (consolidation) describes lung tissue
with confluent acute exudation, containing neutrophils
and red cells, giving a red, firm, liver-like gross
appearance.
• Grey hepatisation: follows, as the red cells disintegrate
and the remaining fibrinosuppurative exudate persists,
giving a grey-brown appearance.
• Resolution: is the favourable final stage in which
consolidated exudate undergoes enzymatic and cellular
degradation and clearance; normal structure is restored.
Lobar pneumonia: whole
lobe(s) involved
grey hepatization
Lobar pneumonia
Red Hepatisation
Red Hepatisation
Lobar Pneumonia – Gray hep…
Lower respiratory tract Infections
Pneumonia
A second classification scheme for pneumonia is based on the
specific structures of the lung that the organisms infect and
includes typical and atypical pneumonia.
Typical pneumonia
• Usually bacterial in origin.
• Organisms replicate in the spaces of the alveoli.
Manifestations:
• Inflammation and fluid accumulation are seen in the alveoli.
• White cell infiltration and exudation can been seen on chest
radiographs.
• High fever, chest pain, chills, and malaise are present.
• Purulent sputum is present.
• Some degree of hypoxemia is present.
Lower respiratory tract Infections
Pneumonia
Atypical pneumonia
• Usually viral in origin.
• Organisms replicate in the spaces around the
alveoli.
Manifestations:
• Milder symptoms than typical pneumonia.
• Lack of white cell infiltration in alveoli.
• Lack of fluid accumulation in the alveoli.
• Not usually evident on radiographs.
• May make the patient susceptible to bacterial
pneumonia.
Lower respiratory tract Infections
Pneumonia
Treatment of pneumonia:
• Antibiotics if bacterial in origin. The health-care
provider should consider the possibility that
antibiotic-resistant organisms are present.
• Oxygen therapy for hypoxemia.
• A vaccine for pneumococcal pneumonia is
currently available and highly effective. This
vaccine should be considered in high-risk
individuals.
Lower respiratory tract Infections
Abscess
• An abscess is a complication of severe
pneumonia, most typically from virulent
organisms such as S. aureus.
• Abscesses are complications of
aspiration, where they appear more
frequently in the right posterior lung.
Lung Abscess:
• Focal suppuration with necrosis of lung tissue
• Organisms commonly cultured:
•
•
•
•
•
Staphylococci
Streptococci
Gram-negative
Anaerobes
Frequent mixed infections
• Mechanism:
• Aspiration
• Post pneumonic
• Septic embolism
• Neoplasms
• Productive Cough, Fever.
• Clubbing
• Complications: Systemic spread, septicemia.
Clubbing
Lung Abscess:
Abscess formation
Bronchopneumonia - Abscess
formation
Lung Abscess:
Lower respiratory tract Infections
Pulmonary Tuberculosis
• Caused by Mycobacterium tuberculosis.
• Transmitted through inhalation of infected droplets
• Primary
• Single granuloma within parenchyma and hilar lymph
nodes (Ghon complex).
• Infection does not progress (most common).
• Progressive primary pneumonia
• Miliary dissemination (blood stream).
Ghon complex
Forms of Tuberculosis
• M. tuberculosis hominis (human tuberculosis)
• Airborne infection spread by minute droplet nuclei
harbored in the respiratory secretions of persons
with active tuberculosis
• Living under crowded and confined conditions
increases the risk for spread of the disease.
• Bovine tuberculosis
• Acquired by drinking milk from infected cows;
initially affects the gastrointestinal tract
• Has been virtually eradicated in North America and
other developed countries
Tuberculosis
Granulomas
Ghon Complex
Mycobacterium Tuberculosis
Positive Tuberculin Skin Test
• Results from a cell-mediated immune response
• Implies that a person has been infected with M.
tuberculosis and has mounted a cell-mediated immune
response
• Does not mean the person has active tuberculosis
Induration
Question
•
a.
b.
c.
d.
Which of the following involves infection of
the entire respiratory tract?
Common cold
Pneumonia
Tuberculosis
Cancer
Answer
a. Common cold
b. Pneumonia: Pneumonia can involve all respiratory
tissues and, due to its virulence, is a major health risk.
c. Tuberculosis
d. Cancer
Chronic Obstructive Disease
• Asthma
• Chronic Bronchitis
• Emphysema
Asthma
• Extrinsic - response to inhaled antigen
• Intrinsic - non-immune mechanisms (cold,
exercise, aspirin)
Pathology of asthma
• Airway inflammation with mucosal edema
• Mucus plugging
Bronchial Asthma
A chronic inflammatory disorder characterised by
hyperreactive airways leading to episodic
reversible bronchoconstriction
Mucosal edema
Mucus plugs
Mucus plug/inflammation
Chronic Obstructive Pulmonary
Disease
• Chronic bronchitis
• Emphysema
A smoker’s disease
Due to particulate matter entering the lungs
Cor Pulmonale
• Right heart failure resulting from primary lung
disease and long-standing primary or secondary
pulmonary hypertension
• Involves hypertrophy and the eventual failure of
the right ventricle
• Manifestations include the signs and symptoms
of primary lung disease and the signs of rightsided heart failure.
COPD
• One of the top 5 causes of death in Europe/N. America
• Clinical course characterised by infective exacerbations
(Haemophilus influenzae, Streptococcus pneumoniae)
• Death by respiratory failure or heart failure (“cor
pulmonale”)
Chronic Bronchitis
Cough productive of sputum on most days for 3 months
of at least 2 successive years
• An epidemiological definition
• Does not imply airway inflammation
Chronic Bronchitis
• Chronic irritation
defensive
increase in mucus production with
increase in numbers of epithelial cells (esp
goblet cells)
• Poor relation to functional obstruction
• Role in sputum production and increased
tendency to infection
Chronic Bronchitis
• Non-reversible obstruction
• In some patients there may be a reversible
(“asthmatic”) component
Normal vs. Chronic Bronchitis
Small airways in Chronic Bronchitis
• More important than traditionally realized
• Goblet cell metaplasia, macrophage
accumulation and fibrosis around bronchioles
may generate functional obstruction
Emphysema
• Increase beyond the normal in the size of
the airspaces distal to the terminal
bronchiole
• Without fibrosis
The gas-exchanging compartment of the
lung
Emphysema (types)
• Centriacinar (centrilobular)
• Panacinar
• Others (e.g. localized around scars in the lung)
Centriacinar (centrilobular)
• Begins in the respiratory bronchioles and
spreads peripherally.
• Associated with long-standing cigarette
smoking and predominantly involves the
upper half of the lungs
Panacinar Emphysema
• Destroys the entire alveolus uniformly
and is predominant in the lower half of
the lungs.
• Generally is observed in patients with
homozygous a 1 antitrypsin (AAT)
deficiency.
• In people who smoke focal panacinar
emphysema at the lung bases may
accompany centriacinar emphysema.
Normal lung
• There are two
major types of
emphysema:
centrilobular
(centriacinar) and
panlobular
(panacinar).
• Centrilobular
emphysema
• "dirty holes”
• This pattern is typical
for smokers.
Remaining Airspaces are Dilated.
Centriacinar emphysema
Panacinar emphysema 2
Panacinar emphysema 1
Emphysema
• Difficult to diagnose in life (apart from late
disease – enlarged “barrel chest”)
• Radiology (CT) can show changes in lung
density
• Correlation with function known from autopsy
studies
Emphysema
• “Dilatation” is due to loss of alveolar walls (tissue
destruction)
• Appears as “holes” in the lung tissue
Emphysema
How do these changes relate to functional
deficit?
• Poorly at macroscopic level
• Better with microscopic measurement
Normal
Early emphysema
Emphysema Impairs Respiratory Function
• Diminished alveolar surface area for gas
exchange (decreased Tco)
• Loss of elastic recoil and support of small
airways leading to tendency to collapse with
obstruction
Loss of surface area
(emphysema)
As disease advances….
PaO2 leads to:
• Dyspnea and increased respiratory rate
• Pulmonary vasoconstriction (and pulmonary
hypertension)
Epidemiology of COPD
• Smoking
• Atmospheric pollution
• Genetic factors
Pathophysiology of Emphysema
High rate of emphysema in the rare genetic
condition of a 1 antitrypsin deficiency
• THE PROTEASE/ANTIPROTEASE
HYPOTHESIS
Elastic Tissue
• Sensitive to damage by elastases (enzymes
produced by neutrophils and macrophages)
 a 1 antitrypsin acts as an anti-elastase
Imbalance in either arm of this system
predisposes to destruction of elastic alveolar
walls (emphysema)
Tobacco smoke…..
•
•
•
•
Increases #’s of neutrophils and macrophages in lung
Slows transit of these cells
Promotes neutrophil degranulation
Inhibits a 1 antitrypsin
Classification and Spread of Fungi
• Yeasts
• Are round and grow by budding
• Molds
• Form tubular structures called hyphae
• Grow by branching and forming spores
• Dimorphic fungi
• Grow as yeasts at body temperatures and as molds at
room temperatures
• Mechanisms of fungal spread
• Inhalation of spores
Farmer’s Lung
Silo Filler’s Disease
Laboratory Tests to Diagnose Histoplasmosis
• Cultures
• Fungal stain
• Antigen
detection
• Serologic tests
for antibodies
Asbestos
• The dense white
encircling tumor
mass is arising
from the visceral
pleura and is a
mesothelioma.
Respiratory Disorders in the Neonate
• Respiratory distress syndrome
• Bronchopulmonary dysplasia
Respiratory Disorders in Children
• Upper airway infections
• Viral croup
• Spasmodic croup
• Epiglottis
• Lower airway infections
• Acute bronchiolitis
Impending Respiratory Failure in Infants and
Children
• Rapid breathing
• Exaggerated use of the accessory
muscles
• Retractions
• Nasal flaring
• Grunting during expiration
Question
•
a.
b.
c.
d.
The lungs are a common site of
secondary tumor development. Why?
Due to the highly vascular nature and
small capillaries
Due to the fragility of the cells
Due to the rapid replication of type I
alveolar cells
Due to dumb luck
Answer
a. Due to the highly vascular nature and small capillaries
b. Due to the fragility of the cells
c. Due to the rapid replication of type I alveolar cells
d. Due to dumb luck
Disorders of Ventilation and
Gas Exchange
Gases of Respiration
• Primary function of respiratory system
• Remove CO2
• Add of O2
• Insufficient exchange of gases
• Hypoxemia
• Hypercapnia
Hypoxemia
• Hypoxemia results from
• Inadequate O2 in the air
• Diseases of the respiratory system
• Dysfunction of the neurological system
• Alterations in circulatory function
• Mechanisms
• Hypoventilation
• Impaired diffusion of gases
• Inadequate circulation of blood through the pulmonary capillaries
• Mismatching of ventilation and perfusion
Manifestations of Hypoxemia
• Mild hypoxemia
• Metabolic acidosis
• Increase in heart rate
• Peripheral vasoconstriction
• Diaphoresis
• Increase in blood pressure
• Slight impairment of mental performance
Manifestations of Hypoxemia (cont.)
• Chronic hypoxemia
• Manifestations of chronic hypoxia may be insidious
in onset and attributed to other causes
• Compensation masks condition
• Increased ventilation
• Pulmonary vasoconstriction
• Increased production of red blood cells
• Cyanosis
Hypercapnia
• Increased arterial PCO2
• Caused by hypoventilation or mismatching of ventilation
and perfusion
• Effects
• Acid-base balance (decreased pH, respiratory acidosis)
• Kidney function
• Nervous system function
• Cardiovascular function
Causes of Disorders of Lung Inflation
• Conditions that produce lung compression or lung
collapse
• Compression of the lung by an accumulation of fluid
in the intrapleural space
• Complete collapse of an entire lung as in
pneumothorax
• Collapse of a segment of the lung as in atelectasis
Characteristics and Symptoms
of Pleural Pain
•
•
•
•
•
•
•
Abrupt in onset
Unilateral, localized to lower and lateral part of the chest
May be referred to the shoulder
Usually made worse by chest movements
Tidal volumes are kept small.
Breathing becomes more rapid.
Reflex splinting of the chest may occur.
Pleural Effusion
• Definition
• An abnormal collection of fluid in the pleural cavity
• Types of fluid
• Transudate
• Exudate
• Purulent drainage (empyema)
• Chyle
• Blood
Diagnosis and Treatment
of Pleural Effusion
• Diagnosis
• Chest radiographs, chest ultrasound
• Computed tomography (CT)
• Treatment: directed at the cause of the disorder
• Thoracentesis
• Injection of a sclerosing agent into the pleural cavity
• Open surgical drainage
Disorders of the Pleura
• Pleural effusion: abnormal collection of fluid in the pleural
cavity
• Transudate or exudate, purulent (containing pus), chyle,
or sanguineous (bloody)
• Hemothorax
• Pleuritis
• Chylothorax
• Atelectasis
• Empyema
Types of Pneumothorax
• Spontaneous pneumothorax
• Occurs when an air-filled blister on the lung surface
ruptures
• Traumatic pneumothorax
• Caused by penetrating or nonpenetrating injuries
• Tension pneumothorax
• Occurs when the intrapleural pressure exceeds
atmospheric pressure
Atelectasis
• Definition
• Incomplete expansion of a lung or portion of a lung
• Causes
• Airway obstruction
• Lung compression such as occurs in pneumothorax
or pleural effusion
• Increased recoil of the lung due to loss of pulmonary
surfactant
Types of Atelectasis
• Primary
• Present at birth
• Secondary
• Develops in the neonatal period or later in life
Question
•
a.
b.
c.
d.
Which of the following is a disorder caused by abnormal
accumulation of fluid in the pleural space?
Pneumothorax
Pleural effusion
Atelectasis
Hypercapnia
Answer
a. Pneumothorax
b. Pleural diffusion: Pleural diffusion can be caused by
transudate, exudate, chyle, or other fluid.
c. Atelectasis
d. Hypercapnia
Physiology of Airway Disease
• Upper respiratory tract
• Trachea and major bronchi
• Lower respiratory tract
• Bronchi and alveoli
• Creation of negative pressure
• Effects of CO2/pH
• Role of inflammatory
mediators
• Increase airway
responsiveness by
• Producing
bronchospasm
• Increasing mucus
secretion
• Producing injury to the
mucosal lining of the
airways
Functions of Bronchial Smooth Muscle
• The tone of the bronchial smooth muscles surrounding the airways
determines airway radius.
• The presence or absence of airway secretions influence airway
patency.
• Bronchial smooth muscle is innervated by the autonomic nervous
system.
• Parasympathetic: vagal control
• Bronchoconstrictor
• Sympathetic: 2-adrenergic receptors
• Bronchodilator
Factors Involved in the Pathophysiology of
Asthma
• Genetic
• Atopy
• Early vs. late phase
• Environmental
• Viruses
• Allergens
• Occupational exposure
Factors Contributing to the Development of
an Asthmatic Attack
•
•
•
•
•
•
•
Allergens
Respiratory tract infections
Exercise
Drugs and chemicals
Hormonal changes and emotional upsets
Airborne pollutants
Gastroesophageal reflux
Classifications of Asthma Severity
•
•
•
•
Mild intermittent
Mild persistent
Moderate persistent
Severe persistent
Question
•
a.
b.
c.
d.
e.
f.
g.
Which of the following have not been implicated in the development
of asthma?
Allergens
Respiratory tract infections
Diet
Drugs and chemicals
Hormonal changes and emotional upsets
Airborne pollutants
Gastroesophageal reflux
Answer
a. Allergens
b. Respiratory tract infections
c. Diet: Diet does not affect the respiratory tract other than via allergic
reactions.
d. Drugs and chemicals
e. Hormonal changes and emotional upsets
f. Airborne pollutants
g. Gastroesophageal reflux
Chronic Obstructive Airway Disease
•
•
•
•
Inflammation and fibrosis of the bronchial wall
Hypertrophy of the submucosal glands
Hypersecretion of mucus
Loss of elastic lung fibers
• Impairs the expiratory flow rate, increases air
trapping, and predisposes to airway collapse
• Alveolar tissue
• Decreases the surface area for gas exchange
Causes of Chronic Obstructive Airway
Disease
•
•
•
•
Chronic bronchitis
Emphysema
Bronchiectasis
Cystic fibrosis
• Bronchiectasis occurs
when there is obstruction or
infection with inflammation
and destruction of bronchi
so that there is permanent
Pulmonary Fibrosis
• The alveolitis that
produces fibroblast
proliferation and
collagen deposition is
progressive over time.
• Sarcoidosis
Honeycomb Lung
Characteristics of Type A Pulmonary
Emphysema
•
•
•
•
•
•
•
•
Smoking history
Age of onset: 40–50 years
Often dramatic barrel chest
Weight loss
Decreased breath sounds
Normal blood gases until late in disease process
Cor pulmonale only in advanced cases
Slowly debilitating disease
Characteristics of Type B Chronic Bronchitis
•
•
•
•
•
•
Smoking history
Age of onset 30–40 years
Barrel chest may be present
Shortness of breath predominant early symptom
Rhonchi often present
Sputum frequent early manifestation
Characteristics of Type B Chronic Bronchitis
(cont.)
•
•
•
•
Often dramatic cyanosis
Hypercapnia and hypoxemia may be present
Frequent cor pulmonale and polycythemia
Numerous life-threatening episodes due to acute
exacerbations
Types of Chronic Obstructive Pulmonary
Disease
• Emphysema
• Enlargement of air spaces and destruction of lung
tissue
• Types: centriacinar and panacinar
• Chronic obstructive bronchitis
• Obstruction of small airways
Bronchiectasis
• Permanent dilation of the bronchi and bronchioles
• Secondary to persisting infection or obstruction
• Manifestations
• Atelectasis
• Obstruction of the smaller airways
• Diffuse bronchitis
• Recurrent bronchopulmonary infection
• Coughing; production of copious amounts of foulsmelling, purulent sputum; hemoptysis
• Weight loss and anemia are common.
Cystic Fibrosis
• Definition
• An autosomal-recessive disorder involving
fluid secretion in the exocrine glands and the
epithelial lining of the respiratory,
gastrointestinal, and reproductive tracts
• Cause
• Mutations in a single gene on the long arm of
chromosome 7 that encodes for the cystic
fibrosis transmembrane regulator (CFTR),
which functions as a chloride (Cl-) channel in
epithelial cells
Manifestations of Cystic Fibrosis
•
•
•
•
•
•
•
Pancreatic exocrine deficiency
Pancreatitis
Elevation of sodium chloride in the sweat
Excessive loss of sodium in the sweat
Nasal polyps
Sinus infections
Cholelithiasis
Diffuse Interstitial Lung Diseases
• Definition
• A diverse group of lung disorders that
produce similar inflammatory and fibrotic
changes in the interstitium or interalveolar
septa of the lung
• Types
• Sarcoidosis
• Occupational lung diseases
• Hypersensitivity pneumonitis
• Lung diseases caused by exposure to toxic
drugs
Occupational Lung Diseases
• Pneumoconioses
• Caused by inhalation of inorganic dusts and
particulate matter
• Hypersensitivity diseases
• Caused by inhalation of organic dusts and
related occupational antigens
• Byssinosis: occurs in cotton workers; has
characteristics of the pneumoconioses and
hypersensitivity lung disease
Pulmonary Embolism
• Development
• A blood-borne substance lodges in a branch
of the pulmonary artery and obstructs the flow
• Types
• Thrombus: arising from deep vein
thrombosis
• Fat: mobilized from the bone marrow after a
fracture or from a traumatized fat depot
• Amniotic fluid: enters the maternal
circulation after rupture of the membranes at
the time of delivery
Pulmonary Embolism
Saddle Embolus
Pulmonary Hypertension
• A disorder
characterized by an
elevation of pressure
within the pulmonary
circulation
• Pulmonary arterial
hypertension
• Signs and symptoms of
secondary pulmonary
hypertension
• Dyspnea and fatigue
• Peripheral edema
• Ascites
• Signs of right heart
failure (cor
pulmonale)
Causes of Acute Respiratory Distress
Syndrome
• Aspiration of gastric contents
• Major trauma (with or without fat emboli)
• Sepsis secondary to pulmonary or nonpulmonary infections
• Acute pancreatitis
• Hematologic disorders
• Metabolic events
• Reactions to drugs and toxins
Causes of Respiratory Failure
• Impaired ventilation
• Upper airway obstruction
• Weakness of paralysis of respiratory muscles
• Chest wall injury
• Impaired matching of ventilation and
perfusion
• Impaired diffusion
• Pulmonary edema
• Respiratory distress syndrome
Treatment of Respiratory Failure
• Respiratory supportive care directed toward
maintenance of adequate gas exchange
• Establishment of an airway
• Use of bronchodilating drugs
• Antibiotics for respiratory infections
• Ensure adequate oxygenation
Question
• Which of the following has been implicated as a
causative factor in right ventricular failure?
a. Cor pulmonale
b. Pneumothorax
c. Cystic fibrosis
d. Acute respiratory distress syndrome
Answer
a. Cor pulmonale: Cor pulmonale will result in
right ventricle failure due to the increase in
workload.
b. Pneumothorax
c. Cystic fibrosis
d. Acute respiratory distress syndrome
Question
•
a.
b.
c.
d.
e.
The most common port of entry for cold
viruses is _______.
Inhalation
Small cuts
Food
Conjunctival surface of the eyes
Fingers
Answer
•
a.
b.
c.
d.
e.
The most common port of entry for cold
viruses is _______.
Inhalation
Small cuts
Food
Conjunctival surface of the eyes
Fingers
Factors Affecting the Signs and Symptoms of
Respiratory Tract Infections
• The function of the structure
involved
• The severity of the infectious
process
• The person’s age and general
health status
Rhinitis and Sinusitis
• Rhinitis
• Inflammation of the nasal mucosa
• Sinusitis
• Inflammation of the paranasal
sinuses
Types of Sinuses
• Paranasal sinuses
• Air cells connected by narrow openings
or ostia with the superior, middle, and
inferior nasal turbinates of the nasal
cavity
• Maxillary sinus
• Inferior to the bony orbit and superior to
the hard palate
• Its opening is located superiorly and
medially in the sinus, a location that
impedes drainage.
• Frontal sinuses
• Open into the middle meatus of the
nasal cavity
Transmission of Common Cold
• Viral infection of the upper respiratory tract
• Rhinoviruses, parainfluenza viruses,
respiratory syncytial virus,
coronaviruses, and adenoviruses
• Fingers are the greatest source of spread
• Coughing, sneezing
• The nasal mucosa and conjunctival
surface of the eyes are the most
common portals of entry for the virus.
Types of Sinuses (cont.)
• Sphenoid sinus
• Just anterior to the pituitary fossa
behind the posterior ethmoid sinuses
• Its paired openings drain into the
sphenoethmoidal recess at the top of
the nasal cavity.
• Ethmoid sinuses
• Comprise 3–15 air cells on each side,
with each maintaining a separate path
to the nasal chamber
Allergic Rhinosinusitis
• Occurrence
• Occurs in conjunction with allergic
rhinitis
• Mucosal changes are the same as
allergic rhinitis
• Symptoms
• Nasal stuffiness, itching and burning of
the nose, frequent bouts of sneezing,
recurrent frontal headache, watery
nasal discharge
• Treatment
• Oral antihistamines, nasal
decongestants, and intranasal cromolyn
Answer
a. Inhalation
b. Small cuts
c. Food
d. Conjunctival surface of the eyes: The eyes and the nasal
mucosa are the most common ports of entry.
e. Fingers
Types of Influenza Viruses
• Type A
• Most common type
• Can infect multiple species
• Causes the most severe disease
• Further divided into subtypes based on
two surface antigens: hemagglutinin (H)
and neuraminidase (N)
• Type B
• Has not been categorized into subtypes
Lung Cancer
• Causative factors
• Smoking
• Asbestos
• Familial
predisposition
• Primary lung
tumors (95%) vs.
bronchial,
glandular,
lymphoma
• Secondary via
metastasis
Categories of Bronchogenic Carcinomas
• Squamous cell lung carcinoma (25–40%)
• Closely related to smoking
• Adenocarcinoma (20–40%)
• Most common in North America
• Small cell carcinoma (20–25%)
• Small round to oval cells, highly malignant
• Large cell carcinoma (10–15%)
• Large polygonal cells, spread early in
development
Squamous Cell Carcinoma
• This is another
sqamous cell
carcinoma that
extends from hilum to
pleura.
• The black areas
represent anthracotic
pigment trapped in
the tumor.
Adenocarcinoma
Bronchioalveolar Carcinoma
Categories of the Manifestation of Lung
Cancer
• Those due to involvement of the lung and
adjacent structures
• The effects of local spread and metastasis
• The nonmetastatic paraneoplastic manifestations
involving endocrine, neurologic, and connective
tissue function
• Nonspecific symptoms such as anorexia and
weight loss
Metastatic Lung Cancer
Classifications of Rhinosinusitis
• Acute rhinosinusitis
• May be of viral, bacterial, or mixed viralbacterial origin
• May last from 5 to 7 days up to 4 weeks
• Subacute rhinosinusitis
• Lasts from 4 weeks to less than 12
weeks
• Chronic rhinosinusitis
• Lasts beyond 12 weeks
Control of Breathing
• Respiratory center
• Pacemaker center
• Pneumotaxic center
• Apneustic center
• Phrenic nerve
Control of Breathing (cont.)
• Automatic regulation of ventilation
• Controlled by input from two types of
sensors or receptors
• Chemoreceptors: monitor blood
levels of oxygen and carbon dioxide
and adjust ventilation to meet the
changing metabolic needs of the
body
• Lung receptors: monitor breathing
patterns and lung function
Control of Breathing (cont.)
• Voluntary regulation of ventilation
• Integrates breathing with voluntary acts
such as speaking, blowing, and singing
• These acts, initiated by the motor and
premotor cortex, cause a temporary
suspension of automatic breathing.
Cough Reflex
• Neurally mediated reflex that protects the
lungs
• Accumulation of secretions
• Entry of irritating and destructive
substances
Cheyne-Stokes
• Abnormal pattern of breathing
• Characterized by oscillation of
ventilation between apnea and
hyperpnea
• Compensate for changing serum partial
pressures
Mechanisms Involved in Dyspnea
• Stimulation of lung receptors
• Increased sensitivity to changes
in ventilation perceived through
central nervous system
mechanisms
• Reduced ventilatory capacity or
breathing reserve
• Stimulation of neural receptors in
the muscle fibers of the
intercostals and diaphragm and
of receptors in the skeletal joints
• Associated conditions
• Primary lung
diseases
• Heart disease
• Neuromuscular
disorders
Question
•
a.
b.
c.
d.
e.
Which of the following accurately
describes your breathing pattern after
running to class?
Cheyne-Stokes
Normal
Dyspnea
Eupnea
Hypoxemia
Answer
a. Cheyne-Stokes
b. Normal
c. Dyspnea: Dyspnea is simply labored
breathing; it is not necessarily
pathological in nature.
d. Eupnea
e. Hypoxemia
Stages of Lung Development
•
•
•
•
•
Embryonic period
Pseudoglandular period
Canicular period
Saccular period
Alveolar period
Function of the Respiratory System
• Gas exchange
• Oxygen from air to lungs
• Carbon dioxide from blood to
atmosphere
• Host defense
• Barrier to outside environment
• Metabolic organ
• Synthesizes and metabolizes different
components
Structural Organization of the
Respiratory System
• Consists of the air passages and the lungs
• Divided into two parts by function:
• Conducting airways, through which air
moves as it passes between the
atmosphere and the lungs
• Respiratory tissues of the lungs,
where gas exchange takes place
Structures of the Airways
• Conducting
• Nasal passages
• Mouth and
pharynx
• Larynx
• Trachea
• Bronchi
• Bronchioles
• Mucociliary blanket
• Respiratory tissues
• Alveolar bundle
• Respiratory
membrane
Ventilation
• Depends on the conducting airways
• Nasopharynx and oropharynx
• Larynx
• Tracheobronchial tree
• Function
• Moves air out of the lungs but does not
participate in gas exchange
Structure and Function of the Larynx
• Structure
• Connects the oropharynx with the
trachea
• Located in a strategic position between
the upper airways and the lungs
• Functions
• Helps produce speech
• Protects the lungs from substances
other than air
Structures of the Lungs
• Soft, spongy, cone-shaped organs located
side by side in the chest cavity
• Separated from each other by the
mediastinum and its contents
• Divided into lobes (3 in the right lung, 2
in the left)
• Apex: upper part of the lung; lies against
the top of the thoracic cavity
• Base: lower part of the lung; lies against
the diaphragm
Composition of the Alveolar Structures
• Type I alveolar cells
• Flat, squamous epithelial cells across
which gas exchange takes place
• Type II alveolar cells
• Produce surfactant, a lipoprotein
substance that decreases the surface
tension in the alveoli and allows for
greater ease of lung inflation
Normal Lung
Lung Circulation
• Pulmonary circulation
• Arises from the pulmonary artery
• Provides for the gas exchange function of the
lungs
• Bronchial circulation
• Arises from the thoracic aorta
• Supplies the lungs and other lung structures
with oxygen
• Distributes blood to the conducting airways
• Warms and humidifies incoming air
Ventilation and Gas Exchange
• Ventilation
• The movement of gases into and out of
the lungs
• Inspiration
• Air is drawn into the lungs as the
respiratory muscles expand the chest
cavity.
• Expiration
• Air moves out of the lungs as the chest
muscles recoil and the chest cavity
becomes smaller.
Question
•
Which of the following is directly
responsible for gas exchange?
a. Trachea
b. Bronchi
c. Bronchial circulation
d. Pulmonary circulation
e. Respiratory membrane
Answer
a.
b.
c.
d.
e.
Trachea
Bronchi
Bronchial circulation
Pulmonary circulation
Respiratory membrane: The respiratory
membrane is the anatomical site of gas
exchange in the lungs. It is located in the
alveoli.
Properties of Gases
• Respiratory pressures
• Atmospheric pressure
• Partial pressures
• Humidity
• Temperature effects
Respiratory Pressures
• Intrapulmonary pressure or alveolar
pressure
• Pressure inside the airways and alveoli
of the lungs
• Intrapleural pressure
• Pressure in the pleural cavity
• Intrathoracic pressure
• Pressure in the thoracic cavity
Lung Compliance
• Lung compliance
• C = ΔV/ΔP
• The change in lung volume (ΔV) that
can be accomplished with a given
change in respiratory pressure (ΔP)
Airway Resistance
• The volume of air that moves into and
out of the air-exchange portion of the
lungs
• Directly related to the pressure
difference between the lungs and the
atmosphere
• Inversely related to the resistance the
air encounters as it moves through the
airways
Lung function tests
• Tidal volume (TV): it is the amount of gas inhaled or exhaled
with each resting breath.
• Residual volume (RV): it is the amount of gas remaining in the
lungs at the end of maximum exhalation.
• Vital capacity (VC): it is the total amount of gas that can
exhaled following maximum inhalation.
• Total lung capacity (TLC): it is the amount of gas in the lung
at the end of maximum inhalation.
TLC = RV+ VC
Pulmonary Function Studies
• Maximum voluntary ventilation
• The volume of air a person can move
into and out of the lungs during
maximum effort lasting for 12–15
seconds
• Forced expiratory vital capacity (FVC)
• Involves full inspiration to total lung
capacity followed by forceful maximal
expiration
Pulmonary Function Studies (cont.)
• Forced expiratory volume (FEV)
• The expiratory volume achieved in a
given time period
• Forced inspiratory vital flow (FIF)
• The respiratory response during rapid
maximal inspiration
Processes of Pulmonary Gas Exchange
• Ventilation
• The flow of gases into and out of the
alveoli of the lungs
• Perfusion
• The flow of blood in the adjacent
pulmonary capillaries
• Diffusion
• Transfer of gases between the alveoli
and the pulmonary capillaries
Types of Dead Space
• Anatomic dead space
• That contained in the conducting
airways
• Alveolar dead space
• That contained in the respiratory portion
of the lung
• Physiologic dead space
• The anatomic dead space plus the
alveolar dead space
Matching Ventilation and Perfusion
• Required for exchange of gases between
the air in the alveoli and the blood in
pulmonary capillaries
• Two factors interfere with the process:
• Dead air space and shunt
• The blood oxygen level reflects the mixing
of blood from alveolar dead space and
physiologic shunting areas as it moves into
the pulmonary veins.
Factors Affecting Alveolar–Capillary Gas
Exchange
• Surface area available for diffusion
• Thickness of the alveolar-capacity
membrane
• Partial pressure of alveolar gases
• Solubility and molecular weight of the gas
Oxygen and Carbon Dioxide Transport
•
PO2 of arterial blood normally is above 80
mm Hg.
1. In chemical combination with
hemoglobin
– 98–99%
– Oxyhemoglobin
– Binding affinity of hemoglobin for
oxygen
2. In the dissolved state
Oxygen and Carbon Dioxide Transport (cont.)
• The PCO2 is in the range of 35–45 mm
Hg.
• Dissolved in carbon dioxide (10%)
• Attached to hemoglobin (30%)
• Bicarbonate (60%)
• Acid-base balance is influenced by
the amount of dissolved carbon
dioxide and the bicarbonate level in
the blood
Dead Space
• Area where gas exchange cannot occur
• Includes most of airway volume
• Anatomical dead space (=150 ml)
• Airways
• Physiological dead space
• = anatomical + non functional alveoli
• Calculated using a pure O2 inspiration and
measuring nitrogen in expired air (fig 37-7)
• % area X Ve
Alveolar Volume
• Alveolar volume (2150 ml) = FRC (2300 ml)- dead space
(150 ml)
• At the end of a normal expiration most of the FRC is at the
level of the alveoli
• Slow turnover of alveolar air (6-7 breaths)
• Rate of alveolar ventilation
• Va = RR (Vt-Vd)
Types of Shunts
• Anatomic shunt
• Blood moves from the venous to the arterial side of the
circulation without moving through the lungs
• Physiologic shunt
• Mismatching of ventilation and perfusion with the lung
• Results in insufficient ventilation to provide the oxygen
needed to oxygenate the blood flowing through the
alveolar capillaries
Matching Ventilation and Perfusion
• Required for exchange of gases between the air in the
alveoli and the blood in pulmonary capillaries
• Two factors interfere with the process:
• Dead air space and shunt
• The blood oxygen level reflects the mixing of blood from
alveolar dead space and physiologic shunting areas as it
moves into the pulmonary veins.
Ventilation-Perfusion Defects
• Alveoli that are ventilated but not perfused
is ventilatory “dead space”
• Alveoli that are perfused but not ventilated
leads to “shunting” of non-oxygenated
blood from pulmonary to systemic
circulation ( a mechanism of cyanosis)
ANS influence on pulmonary
vascular smooth muscle
• SNS + will cause a mild
vasoconstriction
• 3 Hz to 30 Hz  pulmonary arterial BP
about 30%
• Mediated by alpha receptors
• With alpha blockage response abolished and at
30 Hz. vasodilatation observed as beta receptors
are unmasked
• Parasympathetic + will cause a mild
vasodilatation
• (major constrictor effect on pulmonary
vascular smooth muscle is low alveolar
O2)