Pathology

Respiratory tract

What do you need to know about the pleural cavity

* Maintained at negative pressure
* Lined by mesothelial cells
* Site of pleural effusions
* Parietal pleura has pain receptors

What is the flow of the inverted tree-like airway structure?

Trachea→ Main Bronchi(L, R) → Lobar bronchi (2L, 3R) → Segmented bronchi(9L, 10R) → Many conducting airways → Terminal bronchiole

Describe a single terminal bronchiole

Supplies air to one lung lobule which is also known as an acinus

Where does gas exchange occur and what is it composed of?

Gas exchange occurs in the lung lobule and it is composed of Respiratory bronchioles, alveolar ducts and alveolar sacs

What is heavily vascularized

The alveoli

Respiratory epithelium is also called

Pseudostratified columnar epithelium which is also a simple columnar epithelium

What does a ciliated columnar cell do?

Rhythmic movement of cilia clears airways

What does Goblet cells do?

produces mucus

What does Club cells(Clara cells)

secretes multiple factors that protect the epithelium

What does the neuroendocrine cells do?

they direct neural connection and secret several hormone

What does the basal(stem) cells do?

They divide the cells that replenish the epithelium

Describe what the mucosa involves

The epithelium + basement membrane + lamina Propria

(connective tissues, blood vessels, bronchial lymphoid tissue)

Describe what the submucosa involves

The smooth muscle layer + Secretory glands

Describe the cartilage and are cartilages in bronchioles

The cartilage rings in large airways, discontinuous cartilage in medium to small bronchi

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Theres no cartilage in bronchioles

What are the alveolar cell types

* Type I Pneumocytes
* Type II Pneumocytes
* Alveolar Macrophages
* Leukocytes

Describe Type I Pneumocytes

They are thin squamous cells covering most of the alveolar surfaces, permits efficient gas exchange

DescribeType II Pneumocytes

They are large cells that synthesize and secrete surfactant and several immune proteins. These cells can regenerate damaged alveoli.

Describe Alveolar Macrophages

Specialized macrophages that operate in a high oxygen environment

Describe the Leukocytes

Few in a healthy person but neutrophils and/or lymphocytes can be found in large numbers depending on the type of infection

Smokers have a large number of neutrophils in the alveoli

In dual blood supply what are the two circulations

Pulmonary and Bronchial circulations

Describe pulmonary circulation

Blood vessels directly connect to the heart and are used for gas exchange

Describe Bronchial circulation

The bronchial arteries branches off the aorta and supplies the lung parenchyma

Gas exchange in the lungs

* The lungs have a very large surface area
* Ventilation(V, air flow) and Perfusion(Q, blood flow) must be matched for optimal gas exchange(O2 in, CO2 out)

Gas exchange: V/Q mismatches result in what?

Results in decreased O2 in blood(hypoxemia)

Describe the acid-Base balance in the lungs

the removal of CO2 is essential for systemic acid-base balance, too much CO2 in the blood (hypercapnia) leads to acidosis

Breathing: Apnea

Breathing has stopped for 10 seconds or longer

Breathing: dyspnea

Shortness of breath

Breathing: Tachypnea and what are the normal ranges

Rapid breathing, more than 24 breaths per minutes( normal 12-20)

Inflammation: Alveolitis

inflammation of the air spaces (alveoli)

Inflammation: Bronchiolitis

Inflammation of the small airways (bronchioles)

Inflammation: Pneumonitis

inflammation of the lungs interstitium (stroma surrounding alveoli)

Inflammation: pleuritis

Inflammation of the pleura

Inflammation: Empyema

Pus in the pleural cavity

Lung collapse: What is Atelectasis and it is caused by?

collapsed lungs and it is caused by air or fluid(blood, edema) entering the pleural space and collapsing(air) or compressing(fluid) the lungs

Lung collapse: Hydrothorax

Fluid in the pleural or subpleural space, compresses the lungs

Lung collapse: Pneumothorax

Air in the pleural space, can cause atelectasis

What is primary spontaneous Pneumothorax

This occurs in the absence of lung disease(primary) and not caused by an injury(spontaneous)

Primary spontaneous Pneumothorax caused by the rupture of what?

What should you not confuse it with?

It is caused by the rupture of Blebs and don’t confuse it with Bullae (large cysts in emphysema)

What happens when a Blebs ruptures?

The air escapes into the pleural cavity causing a pneumothorax.

Describe an injury-induced Pneumothorax

This occurs with traumatic injury or with extreme changes in pressure

Warning sings of lung disease

* Coughing up blood(Hemoptysis)
* Shortness of breath (dyspnea)
* Chronic cough
* Chronic mucus production (sputum)
* Chronic wheezing
* Chronic chest pain (pleuritic pain)

Describe pulmonary hypertension

What is the result?

Increased pressure in the low-pressure pulmonary circulation caused by many diseases that block blood flow in the lungs(fibrosis)

Results: compensatory hypertrophy of the pulmonary blood vessels

Describe Cor pulmonale

The right sided heart failure due to lung disease. Which causes pulmonary hypertension which stresses the right side of the heart and results in cor pulmonale

Describe systemic hypoxia

Results from V/Q mismatches that produces hypoxemia(causes cyanosis). It affects all organs and causes multiple symptoms and the most severe results is sudden cardiac arrest.

What are the six test for lung function/ disorders

* Pulse oximetry
* Arterial blood gases
* Pulmonary function test(PFTs)
* Imaging
* Bronchoscopy
* Autopsy

Describe the pulmonary function test (PFTs)

spirometry measures lung volumes, detects obstructive and restrictive lung diseases

Congenital Abnormalities: what is the most common defect

Agenesis (hypoplasia) of both lungs, one lung or single lobe

Congenital Abnormalities: Atresia

Failure to develop

Congenital Abnormalities: Stenosis

Narrowing that impairs function

Congenital Abnormalities: Fistula

An abnormal connection to another cavity (esophagus)

What is cystic fibrosis

Most common genetic defect in the US. Defect in the CFTR gene which is critical for the cell membranes chloride transport channel

Neonatal Respiratory distress syndrome

Also known hyaline membrane disease. Immature lungs lack surfactant and results in collapse of alveoli and hypoxia.

Neonates on ventilators can develop

Neonates on ventilators can develop what disease

Bronchopulmonary dysplasia(BPD)

CFTR defect causes what?

Causes mucus secretion to be very thick, obstructing airways resulting in recurrent bacterial infections

Cystic fibrosis: Chronic infection can cause

Dilation of the bronchi (bronchiectasis) with fibrosis of teh lung parenchyma

What are the three types of pulmonary edema

* Cardiogenic pulmonary edema
* Non-cardiogenic pulmonary edema
* Adult respiratory distress syndrome

Describe Cardiogenic pulmonary edema

Heart failure increases pressure in the pulmonary circulation that causes congestion of the pulmonary vessels resulting in edema(transudate)

Describe Non-cardiogenic pulmonary edema

caused by acute inhalation of toxic gases/particulates that directly injures the lungs producing edema (inflammatory exudate)

Describe Adult respiratory distress syndrome(ARDS)

Acute lung injury with multiple causes such as sepsis

Alveolar filling disorders: Pneumonias

What is the general rule in clinical medicine

* Any obstruction will predispose to an infection

Alveolar filling disorders: Pneumonias

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What does the defense mechanism do?

It normally keeps the respiratory tract sterile below the level of the larynx

Alveolar filling disorders: Pneumonias

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Pneumonias can be cause by what?

Viral bacterial, fungal infections and most clinically-significant pneumonias(exudate fills alveoli) are caused by bacteria

Alveolar filling disorders: Pneumonias

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What is a consolidation

airspace that are uniformly filled with anything but air, seen in both pulmonary edema and pneumonias

Alveolar filling disorders: Basic patterns of pneumonia

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What are the three basic patterns of pneumonias

* Bronchopneumonia(most common)
* Lobar Pneumonia
* Interstitial Pneumonia

Describe Bronchopneumonia(most common)

* What is the most common
* List the two bacterias
* What does it affects
* where is it acquires
* Who gets it and what age group

Cause by almost any microbe. Staphylococcus is very common

* Pneumocystis jiroveci and P.aeurginosa are opportunistic infections
* Affects lower lobes and usually in both lungs with patchy distribution
* Nosocomial infections in elderly and immunocompromised

Describe Lobar Pneumonia

* What is it known for?
* Explain it?
* What bacteria causes
* how is it acquires

Major cause of death in pre-antibiotic era

* Complete, uniform distribution of entire lobe (consolidations) usually only in one lung(often the lower lobes), often with pleural involvement
* S.pneumoniae, L.Pneumophilia, K.pneumoniae
* Community acquired infections

Descrive interstitial pneumonia

* What does it affect
* What is it also called
* What is it caused by
* how is it acquires

Affects interstitial space NOT air space

* AKA infectious pneumonitis
* Caused by viruses or mycoplasma. M. pneumonia=primary atypical pneumonia
* Community acquired infections

Pneumonia patterns: how the three looks like

* Bronchopneumonia: patchy distributions in both lungs, usually lower lobes
* Lobar Pneumonia: consolidation usually in one lung, often in lower lobes, may involve pleura
* interstitial pneumonia: lungs interstitum involved, NOT air spaces

Aspiration Pneumonia is caused by what?

It is caused by inhaling injurious substances into the lungs(usually food or gastric content)

Aspiration Pneumonia are most often occur in?

* Persons with impaired swallowing
* Elderly on medications that may impair cognitions and/or motor skills
* Individuals under general anesthesia who ate a meal before surgery
* Alcohol intoxication to the point of “falling down drunk”
* READ MORE ON SLIDE 29 for more information if reviewing

Complications of Pneumonia can cause what to the lungs?

it can cause extensive lung damage depending on the type and severity of the infection

Most pneumonias resolve… this means what?

The normal tissue architecture and functions is restored

Complications of Pneumonias include:

* Damage of lung parenchyma
* Necrosis and Abscess formation
* Pleural involvement
* Bacteremia

Complications of Pneumonias:

Explain the Damage of lung parenchyma

After the injury the lungs becomes solid and inelastic due to over-growth of tissue with scarring called Organization/ carnification(meat-like)

Complications of Pneumonias: Necrosis and Abscess formation

Extensive necrosis of lung tissue(caused by a massive neutrophil infiltration) can produce a hole in the tissue known as Abscess. Necrotic content(pus) are usually coughed up leaving an empty space

Complications of Pneumonias: Pleural involvement

Often occurs with lobar pneumonia and can produce pain, and fibrinous exudate( pleurisy) or purulent exudate(edema)

Complications of Pneumonias: Bacteremia

Systemic spread of the lung infection into the blood, potentially causing infections in other organs

Describe Respiratory syncytial virus (RSV)

Causes an acute viral infection of the bronchioles(bronchiolitis) but doesn’t NOT extend to alveoli

Describe Parainfluenza virus

causes an acute viral infection of the larynx, usually in children called the croup with a distinct barking cough.

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Can be life-threating if laryngeal swelling(edema) obstructs the trachea

Describe Haemophilus influenzae

Causes an acute bacterial infec tion of the larynx, particularly epiglottis

Describe Fungal infections

* They produce what type of infection affecting who?
* Lis the three most common fungi

They produce opportunistic lung infections in immunocompromised persons

The most commons are candida, Aspergillus and Cryptococcus

Fungal Infections: What is Dimorphic fungi?

* Where are they endemic and how can someone be infected?

They endemic in the soil in certain parts of the US and can produce a lung infection in healthy persons who inhale fungal spores

Fungal Infections: Dimorphic fungi

* Individuals taking medications and the immunocompromised are particularly susceptible:
* List them, where they are found, common or uncommon, how severe or not severe

* Histoplasma (central US): most common fungal infections and usually resolves without treatment
* Coccidiodes(Southwest US): AKA valley fever, usually resolves without treatment
* Blastomyces(Southeast US): not common, lung infection can be more severe and may spread to the skin and form ulcerative lesions

Medications and Lung infections: Blocking cytokines can do what?

Blocking cytokines can impair macrophages anti-microbial functions, resulting in increased risk of fungal infections and TB

Tuberculosis (TB):

* Chronic or Acute?
* Caused by?
* Who does it affect?
* How does someone get it?

Chronic bacterial infection caused by M.tuberculosis and causes diseases in all age groups which is linked with poor nutrition and sanitation

Tuberculosis (TB):

* Is the infection active or latent
* What is the end-stage of active TB called

It can be either active or latent(dormant, with no signs or symptoms).

The end stage of active TB is called consumptions

Describe the stain for M.tuberculosis?

M.tuberculosis has a thick waxy outer coat that stains red with special stain

How is the Mantoux skin test conducted and what are the results?

inject TB purified protein derivative(PPD) into skin(forearm) and wait 48-72hrs. A raised, hard lesion is positive for prior TB exposure. Positive test requires chest X-ray

Acid-fast bacillus is positive diagnostic for what

M.tuberculosis

Explain Bacille Calmette Guerin(BCG)

An attenuated strain of M.bovis which is used globally except the US as a vaccine for TB because it will result in a positive Mantoux skin test even though person was never infected with TB

TB: primary infection

* Explain Caseating Granuloma
* Hilar lymph nodes
* Ghon complex

The initial infection in persons not previously exposed, majority are asymptomatic

* Caseating Granuloma(caseous necrosis) in the lung parenchyma at the site of infection is a hallmark of TB
* Hilar lymph nodes are enlarged with granulomas
* Infected persons become positive for PPD skin test
* Ghon complex: lung granuloma and enlarged lymph nodes visible by X-ray

TB: Complications of Primary Infcetion

* Usually in what group of people
* List the 4 complication

Usually in immunocompromised persons

* Pneumonic spread
* Military TB
* TB meningitis
* Pott’s disease

TB: Complications of Primary Infection

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Explain:Pneumonic spread

Massive infection throughout the lungs

TB: Complications of Primary infcetion

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Explain:Military TB

blood-born TB spread TB “seeds” the lung with multiple small granulomas that resemble millet seed(bird seeds)

TB: Complications of Primary infection

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Explain: TB meningitis

systemic TB infects the covering of brains and spinal cord

TB: Complications of Primary infection

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Explain: Pott’s Disease

TB can infect bone, often the vertebral bodies of the spine and destroys the bone causing a hunchback posture.

TB: Complications of Post-Primary(secondary) Infection

* Apical cavitation?
* Can TB spread? If yes where and it causes what?

* Reactivation of dormant TB
* More severe and destructive disease than primary TB
* Apical Cavitation: large cavity in the upper lobes of the lung, often both lungs
* TB can spread to other organs and cause cavitation

Describe restrictive lung disease

The class of diseases where the lung that can’t expand(inflate) consequently the person can’t inhale properly

List the three restrictive lung disease

* Chest wall immobility
* Pleural Disease
* Lung parenchymal disease

Restrictive lung disease: Explain chest wall immobility

The bellows function of the lung is not working, usually due to muscle paralysis