54- Normal Resp

what are the components of the resp system

1. nostrils, sinus, trachea, nasopharynx, etc

2. pulm vascular system

3. diaphragm, intercostal m

what is the function of the lung

facilitate o2 and co2 exchange

nostrils, nasal cav, paranasal sinuses, nasopharynx, larynx, trachea, and bronchi are part of what component

conducting

describe the conducting component histo

lined by pseudostratified, CILIATED columnar cells

lined by sensory olfactory epithelium

squamous epithelium

variable portion of goblet mucous cells

what is this image

conducting component

what serves as the transition zone bt conducting comp (ciliated) and air exchange (alveolar)?

bronchioles that branch off bronchi

describe the transition component cilia

the ciliar become scarce in the prox bronchiolar region until they disappear

what cells can be found in the trans component

club cells, neuroendocrine cells

NO goblet cells

what helps detox xenobiotics, repairs resp stem with stem cells, and contributes to the INNATE imm of lungs by secreting protective proteins and surfactant?

club cells of trans component

what is the air exchange component formed by

alveoli

what does the interstitium of the air exchange component support

alveolar epithelium and alveolar capillary endothelium

in the air exchange component, whats the blood air barrier formed from

vascular endothelium, basement mem, alveolar epithelium lining cells

whats a thin delicate network

alveolar walls

describe type I alveolar surface endothelial cells

membranous pneumocytes

cover majority of alvolar wall

func in gas exchange

describe type II alveolar surface endothelial cells

granular pneumocytes

larger cuboidal cells

produce surfactant

label the pneumocytes

purple- type 2

blue- type 1

whats the degree of lobulation determine?

the degree of air movement between lobules

collateral ventilation

movement of air between lobules and between adj alveoli

is collareral ventilation good in dogs or pigs

DOGS

pigs have thick CT of the interlobar septa seperating lung lobes

are these normal or pathological lungs

normal

what is pleura

single layer of mesothelial cells overlying mult layers of connective tissue

parietal pleura

lines thoracic walls, diaphragm, mediastinum

visceral pleura

lines lung surface

pleural space

between parietal and visceral pleura, sep by mediastinum

what animals have complete mediastinum

cattle goats and pigs

what animals have fenestrated mediastinum

horses and sheep

where is the resp system microbiota most abundant

nasal cavity, pharynx, larynx, trachea, bronchi, alveoli

what is complicated about mannheimia haemolytica in bovines

its part of their nasal flora. but can also cause pneumonia

aerogenous routes of entry

virus, bacteria, toxic gases, pneumotoxicants

hematogenous route of entry

virus, bacteria, fungi, parasites, emboli, IV inj, pneumotox

direct extension route of entry

penetrating wounds, migrating awns, bites, hardware

t or f: inflamm can extend locally regionally or systemically

t

what can laryngeal exudate from laryngitis cause

aspiration

what can a large vascular bed present in the lung lead to

sepsis and septic shock

why does hematogenous portal of entry occur commonly

bc pulm system is well vascularized

physical unidirectional movement and removal of deposited particles and gases disolved in the mucus

mucociliary clearance of the conducting/transitional component

what helps the main defense mechanism of the conducting component, mucociliary clearance

mucociliary escalator with mucus

why is cilia imp in the mucociliary clearance

the rapid movement of cilia causes synchronized waves that propels mucus and particles to the pharynx where its terminated and coughed up

what is the main defense mechanism of alveoli

phagocytosis by pulm alveolar macrophages

the # of macrophages in alveolar space is related to…

the # of inhaled particles reaching the lungs

describe the life span of alveolar macrophages

• few days long

• replaced by newly migrated monocytes

• migrate to bronchiolar region to mucocil elevator

• exits to pharynx

pneumoconiosis

lung dz caused by dust deposition

anthracosis

lung dz caused by carbon deposition

can can occur in animals living in pollution/smoking/fireplaces

anthracosis

whats the defense mech for the conducting and transitional components

mucociliary clearance

whats the defense mech for the air exchange component

phagocytosis from pulm alveolar macrophages

What are the portals of entry for injury into the lungs?

Inhalation

•Blood

•Direct extension

What are the portals of entry for injury into the thoracic cavity, mediastinum, or pleura?

•Hematogenous (common)
•Direct extension

Grossly, we see tiny black pinpoint foci on the lung that is associated with black pigment within macrophages on histology. What condition causes these lesions?

Alveolar phagocytosis when deposition of inhaled material/dust exceeds removal, leading to accumulation in the lung

what are these cells

pulm alveolar macrophages

Name the defense mechanisms against spec types of injury `

1. aerogenous

2. hematogenous

3. oxidants and free radicals

what is the underlying pathogenetic mechanism in many pulm diseases

abnormal retention of particles (aerogenous)

deposition

process of particles being trapped within resp sys

clearance

process which particles are destroyed from mucosal surface like sneezing, coughing, mucociliary transport, phagocytosis

if a particle is 10 um or greater…

lodges in nasal passage

if a particle is smaller than 10um,,,

progresses to tracheal and bronchial bifurcations

if a particle is 2um or smaller…

can progress to bronchiole and alveoli

what are intravascular macrophages responsible for in terms of hematogenous defense

removing circulating particles, bacteria, endotoxin

in systemic conditions like sepsis, ____________ by macrophages can cause acute lung injury

excessive release of cytokines

in terms of oxidant/free radical defense, scavengers can be found

in alveolar and bronchiolar epithelial cells and interstitium

what types of oxidant/free radicals cause damage

inhaled oxidant gases, xenobiotic toxin metabolites, free radicals released by phagocytic cells during inflamm (these can impair repair ability)

inhaled bacteria can colonize in bronchi can cause /…

infection leading to fatal pneumonia

what occurs 5-7 days after a viral infection

the phagocytic func of pulm alveolar macrophages and mucociliary clearance are impaired

what are known viruses to predispose to secondary BACTERIAL INFECTIONS

1. influenza in pigs and horses

2. BRSV in cattle

3. canine distemper

4. felid herpes and calicivirus

what are ex of immunodef that can increase susceptibility to resp conditions

SCID in arabian foals that succumb to adenoviral pneumonia and corticosteroids/chemo drugs

name some of the impairment defenses leading to pneumonia

stress, hypoxia, dehydration, anesthesia, starvation

what are 2 main conducting components

epithelium and bronchi

seq of events of injured pseudostratified ciliated epithelium

irreversible injury

1. ciliated cells swell

2. lose their attachment to BM

3. rapidly exfoliate (ulcerate)

viral infections replicate in ____. examples include:

resp epithelium

bovine herpes, felid herpes, canine adenovirus 2, canine parvovirus 2

if epithelial injury is chronic how does mucus production increase

goblet cell hyperplasia

what does chronic bronchial irritation cause

metaplasia of highly functional ciliated epithelium to nonfunctional squamous epithelium

bronchioles are part of the ___ component

transition

what is bronchiectasis

when an injury results in perm dilation of a bronchus with rupture of the bronchial wall as a result of obstruction or chronic inflammation

what does bronchiectasis form

prominent nodules from bronchi distention that contain exudate

describe alveolar injury

epithelial side lined w type 1 pneumocytes that are suseptible to noxious agents

when damaged, they detach and leads to edema and fibrin leakage

type 2 pneumocytes proliferate to compensate

describe bronchiolar injury

leads to goblet cell production turning the secretions more mucousy

this means the secretions arent removed as easily and can block airway

what happens with alveolar repair if BM stays intact?

cuboidal type II pneumocytes, club cells, and stem cells undergo mitosis and create large pool of new cells

what if alveolar injury persists

fibroblasts and myofibroblasts proliferate in alveolar walls and cause alveolar septal fibrosis

this alters lung function bc loss of type 1 pneumocytes = loss of gas exchange

what are the most numerous cells in pleural space and what do they do

mesothelial cells

capable of secreting pro and anti inflam mediators

can help repair and fibrosis

what occurs with chronic stimuation and mesothelial cells

mesothelial hyperplasia (plaque like proliferations diff to distinguish from neoplasia)

what is this

mesothelioma

what is this

mesothelial cell hyperplasia

What is shown in this histology?

Septal fibrosis and club cells that protruding into the alveolar space