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Essentials of Pathophysiology
CHAPTER 22
RESPIRATORY TRACT INFECTIONS,
NEOPLASIA, AND
CHILDHOOD DISORDERS
PRE LECTURE QUIZ
True/False
F

T

F

T

T
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Bacteria are the most frequent cause of respiratory tract
infections.
Influenza is a viral infection that can affect the upper and
lower respiratory tracts and is transmitted by aerosol or
direct contact.
Primary tuberculosis represents either reinfection from
inhaled droplet nuclei or reactivation of a previously
healed primary lesion.
Typical pneumonias result from infection by bacteria.
Acute bronchiolitis is a viral infection that has a peak
incidence at 3 to 6 months of age and is most commonly
caused by the respiratory syncytial virus (RSV).
PRE LECTURE QUIZ

epiglottitis

Mycobacterium

Lung
rapid
upper


The common cold is a viral infection of the
__________ respiratory tract.
One distinguishing feature of influenza is __________
onset.
Tuberculosis is an infectious disease caused by
__________ tuberculosis, a rod-shaped aerobic
bacterium that is resistant to destruction and can
persist in necrotic and calcified lesions for prolonged
periods and remain capable of reinstating growth.
__________ cancer is the leading cause of cancer
deaths among men and women in the United States.
Acute __________ is a dramatic, potentially fatal
condition characterized by inflammatory edema of the
supraglottic area, including the epiglottis and
pharyngeal structures, that comes on suddenly and
carries the risk of complete obstruction.
UPPER RESPIRATORY
VIRUSES IN ADULTS



Common cold
Rhinosinusitis
Influenza
Catarrh- Excessive mucus secretion
THE COMMON COLD

Rhinoviruses


Parainfluenza viruses


Occur in children younger than 3
Respiratory syncytial virus


Occur in early fall and late spring
in persons between ages 5 and 40
Occurs in winter and spring in
children younger than 3
Coronaviruses and adenoviruses

Occur in winter and spring
: any of a family
(Adenoviridae) ofDNA
viruses shaped like a 20sided polyhedron, causing
respiratory diseases (as
catarrh), and including
some capable of inducing
malignant tumors
:any of various singlestranded, RNA-containing
viruses that cause
respiratory infection in
humans and resemble a
crown when viewed under
an electron microscope
because of their petalshaped projections.
RHINOSINUSITIS (SINUSITIS)
Infection or allergy obstructs
sinus drainage
 Acute: facial pain,
headache, purulent nasal
discharge, decreased sense
of smell, fever
 Chronic: nasal obstruction,
fullness in the ears,
postnasal drip, hoarseness,
chronic cough, loss of taste
and smell, unpleasant
breath, headache

INFLUENZA
In the United States, approximately 36,000
persons die each year of influenza-related
illness
 Transmission is by aerosol (three or more
particles) or direct contact
 Upper respiratory infection (rhinotracheitis)



Viral pneumonia


Like a common cold with profound malaise
Fever, tachypnea, tachycardia, cyanosis, hypotension
Respiratory viral infection followed by a bacterial
infection
Viral Particles
QUESTION
For which viruses is a 2-year-old most at risk?
a. Rhinoviruses
b. Parainfluenza viruses
c. Respiratory syncytial virus (RSV)
d. All of the above
e. b and c
ANSWER
d. b and c
Rationale: Slightly older children (> 5 y) are at
risk for rhinoviral infections. Children under the
age of 3 are at risk of infection from both
parainfluenza viruses and RSV.
MECHANISM OF VIRAL INFECTION AND
TREATMENT
amantadine,
rimantadine
zanamivir,
oseltamivir
PNEUMONIA—INFLAMMATION OF ALVEOLI AND
BRONCHIOLES

Typical: bacteria in the alveoli
 Lobar:
affect an entire lobe of the lung
 Bronchopneumonia: patchy distribution
over more than one lobe

Atypical
 Viral
and mycoplasma infections of alveolar
septum or interstitium
Pneumonia
Typical Pneumonia inhaled and
cultured particles in the alveoli
Atypical when virons invade and
colonize in the alveolar septum
Type of pneumonia is further
identified by lung or bronchial
location.
ONSET OF PNEUMONIA

Infection
Signs of systemic
inflammation
 Malaise
 Chills and fever
Inflammation
Serous exudate
Congestion,
productive
cough
serous exudate


Blood-tinged sputum
Pleuritic pain
fibrous exudate:
RED
HEPATINIZATION
WBCs denature
hemoglobin:
GRAY
HEPATINIZATION
consolidation
Hepatinization – Tissue
that takes on the
appearance of Liver
IF WBCS OVERCOME THE INFECTION
WBCs denature
hemoglobin:
GRAY
HEPATINIZATION
WBCs destroy fibrous
proteins and liquefy
exudate: it is reabsorbed
into the circulation
resolution
QUESTION
Tell whether the following statement is true or
false.
In the progression of pneumonia, serous exudate
develops before fibrous exudate.
ANSWER
True
Rationale: Serous exudate develops (just after
inflammation) before fibrous exudate, and is
characterized by a congested, productive
cough. If the pneumonia does not resolve at
this stage, fibrous exudate develops, and the
patient will experience pleuritic pain (worse
when taking a deep breath or coughing) and
may expectorate blood-tinged sputum.
TUBERCULOSIS

World’s foremost cause of death from a single
infectious agent

Causes 26% of avoidable deaths in developing
countries

Drug-resistant forms

Mycobacterium tuberculosis hominis
 Aerobic
 Protective
 Can
waxy capsule
stay alive in “suspended animation” for years
INITIAL TB INFECTION

Macrophages begin a
cell-mediated immune
response

Takes 3–6 weeks to
develop positive TB test

Results in a
granulomatous lesion
or Ghon focus containing



Macrophages
T cells
Inactive TB bacteria
GHON COMPLEX




Nodules in lung tissue
and lymph nodes
Caseous necrosis
inside nodules
Calcium may deposit
in the fatty area of
necrosis
Visible on x-rays
CASEOUS NECROSIS GHON FOCUS
CAVITARY TUBERCULOSIS
CAVITARY TUBERCULOSIS & BRONCIIAL PNEUMONIA
DISCUSSION
If someone in your class has a positive TB test.
Question:
 What does this mean?
 Are you at risk of infection?
PRIMARY TB
usually
isolated in
Ghon foci
bacteria
are
inactive
not
contagious
primary
TB
if immune response is
inadequate, bacteria
multiply in the lungs
progressive primary TB
MILIARY TB
Miliary TB
lesions look like
grains of millet
in the tissues
 Meat inspection
was introduced
to keep them
out of the food
supply
 Pasteurization
of milk was
introduced to
keep TB out of
the milk supply

progressive primary TB
signs of
pneumonia
bacteria in
sputum and
exhaled
droplets
bacteria may
erode blood
vessels and
spread through
the body
MILIARY
TB
SECONDARY TB
Reinfection from inhaled droplet nuclei
 Reactivation of a previously healed primary
lesion
 Immediate cell-mediated response walls off
infection in airways
 Bacteria damage tissues in the airways,
creating cavities
 Signs of chronic pneumonia: gradual
destruction of lung tissue
 “Consumption”: eventually fatal if untreated

QUESTION
Which type of TB may be reactivated if the patient
becomes immunocompromised?
a. Primary
b. Latent
c. Miliary
d. Secondary
ANSWER
Secondary
Rationale: Secondary TB, often referred to as
reactivation or reinfection TB, may occur if
patients are reexposed to TB bacilli (after a
primary infection) or if they become
immunocompromised (they are unable to
contain the infection).
d.
CAVITARY TUBERCULOSIS
LUNG CANCER

Bronchogenic carcinoma
 Arises
from epithelial cells lining the lungs
 Small-cell
lung cancer
 Non–small-cell
lung cancer
º
Large-cell carcinoma
º
Squamous cell
º
Adenocarcinoma
ADENOCARCINOMA OF THE LUNG
Large Cell
Carcinoma
MANIFESTATIONS OF LUNG CANCER

Changes in organ function (organ damage,
inflammation, and failure)

Local effects of tumors (e.g., compression of nerves
or veins, gastrointestinal obstruction)

Ectopic hormones secreted by tumor cells
(paraneoplastic disorders)

Nonspecific signs of tissue breakdown (e.g., protein
wasting, bone breakdown)
RESPIRATORY DISTRESS SYNDROME



Lack of surfactant; infants
are not strong enough to
inflate their alveoli
Protein-rich fluid leaks into
the alveoli and further blocks
oxygen uptake
Treatment with mechanical
ventilation may cause
bronchopulmonary dysplasia
and chronic respiratory
insufficiency
RESPIRATORY DISTRESS SYNDROME

Lack of
surfactant;
infants are not
strong enough to
inflate their
alveoli
QUESTION
Tell whether the following statement is true or
false.
Premature infants are at greater risk of
developing respiratory distress syndrome (RDS)
than term infants.
ANSWER
True
Rationale: RDS occurs due to a lack of surfactant
in the alveoli (the surfactant is produced by
alveolar cells, and keeps them inflated).
Surfactant is typically produced from week 28
(gestational age) through term (40–42 weeks).
The more premature the infant/neonate, the
greater the likelihood that there will be
insufficient surfactant to sustain ventilation.
RESPIRATORY OBSTRUCTION IN CHILDREN

Increased airway resistance
 Extrathoracic
º
º
Prolonged inspiration; inspirational stridor
Inspiratory retractions as ribs are moved
outward and body wall does not expand with
rib cage
 Intrathoracic
º
º
airways (upper airways)
airways (lower airways)
Prolonged expiration with wheezing
Rib cage retractions as ribs are pulled inward,
but air does not leave lungs
OBSTRUCTIVE DISORDERS

Upper airway
 Croup
 Epiglottitis

Lower airway
 Acute
bronchiolitis
QUESTION
Tell whether the following statement is true or
false.
Epiglottitis causes stridor.
ANSWER
True
Rationale: Epiglottitis affects the upper airway
(inflammation causes the lumen of the upper
airway to become more narrow). When the child
inspires, it is difficult to pass air through the
narrowed airway. This causes noisy
inspiration/stridor.