VMED 02610: Pathobiology II Systemic Pathology – Respiratory System Lecture 3

What are the epithelium of the bronchi

 Ciliated pseudostratified epithelium with goblet cells

 Submucosal glands

What kind of muscles do you see in the bronchi

 Cartilage plates & smooth muscle

What is the epithelium of Bronchioles (Transitional)

 Ciliated simple columnar to cuboidal epithelium

 No goblet cells

 No cartilage or submucosal glands

What are the club cells made of in the bronchioles

secrete proteins, components of surfactant, progenitor cells

What are the chronic outcomes in bronchi

 Gobet cell hyperplasia

 Bronchiectasis

What are the chronic outcomes in bronchioles

 Goblet cell metaplasia

 Bronchiolitis obliterans

Airway obstruction can lead to

emphysema and/or atelectasis

How does inflammation occur in the bronchi/bronchioles

infectious agents, inhaled toxins, and allergens

What are Gross lesion of chronic bronchitis/bronchiolitis (WHAT WE CAN SEE)

1. Excessive mucus or mucopurulent exudate

2. Thickened mucosa

3. Polyps extending into the lumen

4. Lymphoid nodules

What does acute Bronchi and Bronchioles look grossly (talking about inflammation)

Hyperemic mucosa; exudate in lumens on cut surface

What does acute Bronchi and Bronchioles look microscopic (talking about inflammation)

Necrosis, exfoliation, denuded BM, neutrophils/fibrin

What does CHRONIC Bronchi and Bronchioles look grossly (talking about inflammation)

Excess mucus; thickened walls; secondary atelectasis or emphysema

What does CHRONIC Bronchi and Bronchioles look microscopic (talking about inflammation)

Goblet cell hyperplasia/metaplasia, squamous metaplasia, gland hyperplasi

What do bronchioles look like when there is inflammation

Rarely visible; inferred from atelectasis/emphysema

What do bronchioles look like microscopically when there is inflammation

Mucus plugs, BALT hyperplasia, polyps (obliterans

Bronchiectasis are they fixed dilation of bronchi/bronchioles?

yes: Fixed dilation of bronchi/bronchioles

In Bronchiectasis does the airway reduce in diamter during expiration?

Airways do not reduce in diameter during expiration

Bronchiectasis commonly affects what animal

Cattle most commonly affected

What is the mechanism for Bronchiectasis

mechanism involves inflammatory destruction of wall and luminal occlusion by exudate

What organ is affected by Bronchiectasis

Cranioventral lung is most commonly affecte

What does Bronchiectasis look grossly

dilated airways can appear nodular on lung surface and are filled with exudate on cut section

Bronchiectasis can lead to what

lead to abscess formation

What are the Bronchiectasis microscopic features:

 Lumen filled with neutrophils, mucus, and necrotic cellular debris

 Epithelium is hyperplastic, attenuated, or destroyed

 Leukocytes and granulation tissue in walls

Bronchiolitis Obliterans is organized how

Organized exudate forming fibrovascular polyps within the bronchiolar lumen

Granulation tissue polyp cover by what

bronchiolar epithelium attached to the wall

Why do horses get equine asthma

Disease of horses with an allergic basis

What is the major lesion of the equine asthma

Major lesion is mucoid bronchiolitis, which can be detected grossly

Why does equine asthma occur

Recurrent airway obstruction

Type I pneumocytes cover the

cover the majority of the alveolar walls

What are the functions Type II pneumocytes

1. Repair of damaged type I cells

2. Production of surfactant

3. Detoxification of chemical

What are the mechanisms for maintainign patency

 Smooth muscle action in walls of bronchi/bronchioles

 Ciliary action

 Coughing

 Collateral ventilation

What is emphysema

 Increased amount of air within airways

 More significant in humans than animals

What is Alveolar emphysema

 Increased amount of air within alveolar spaces

 Reversible or irreversible with alveolar wall damage

What is the mechanism of Alveolar emphysema

• Expiratory obstruction

• Air enter at inspiration but cannot exit with expiration

We mentioned the mechanism of alveolar emphysema is Expiratory Obstruction, what animal can it affect

Especially in cattle

Which animals are affected by Interstitial emphysema

In species with septated lungs (cattle, sheep, and pigs)

What is Interstitial emphysema

Air accumulates in interlobular septa, in the subpleural space, and around blood vessels and bronchi

Interstitial emphysema is commonly found

Common agonal change in cattle

What is affected by Pulmonary emphysema sequelae:

 Pulmonary hypertension and right-sided heart failure (cor pulmonale)

 Respiratory acidosis

What is Atelectasis

Incomplete expansion of lung parenchyma or collapse of previously expanded parenchyma

What are the types of Atelectasis

1. Acquired

a. Obstructive

b. Compressive

2. Congenital

What is the most common Atelectasis

Obstructive Atelectasis

Which area does Obstructive Atelectasis affect what

Cranioventral areas most susceptible

What kind of exudate is Obstructive Atelectasis

Exudate blocks airways completely, gas escapes, and alveoli collapse

From the order of greatest to least sucetiple for Obstructive Atelectasis

Cattle and sheep > pigs > horses > dogs and cats

What does Obstructive Atelectasis look like grossly

Sunken, dark red, slightly denser lungs

Compressive Atelectasis is caused by

Caused by pressure from intrathoracic or intrapulmonary space-occupying lesions

What does Congenital Atelectasis look like grossly

Lungs are diffusely affected, dark red, and do not float

Congenital Atelectasis occurs when ?

In Stillborn animals

What is the function for surfactant

Functions to decrease surface tension

In surfactant phospholipidsd secreted by what

type II pneumocytes

When does lung surfactant become deficient

rematurely born animals and humans

Pulmonary Hypoplasia does what to body

• Reduced lung size

• May accompany other congenital defects, including generalize edema (anasarca) in calves