Glossary of AVP Respiratory

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What are the 4 defences of the respiratory system?
1. Coughing/sneezing
2. Mucoiliary escalator
3. Phagocytosis
4. Immune mediated - IgA URT, IgG LRT
What are the divisions of the respiratory system?
URT = nasal cavity, paranasal sinuses, nasopharynx
LRT = larynx, trachea, bronchi, bronchioles, alveoli
Describe the histology of the respiratory tract
Begins with pseudostratified columnar ciliated epithelium. Goblet cells are intersperced, trachea ++ but not in bronchioles. Goes into transition zone with simple cuboidal non ciliated. BALT - secretory IgA
What are causes of irritation to the URT?
Physical (dust,heat)
What changes occur as a result of irritation to URT?
- Reduced number cilia
Increased number and activity of goblet cells
- acute inflammation of lamina propria
- Get abnormal mucous flow patterns
What happens with continued irritation of respiratory tract?
With continued irritation get metaplasia = columnated cells become more cuboidal and less cilia
- Increased adhesiveness of mucous
- Ciliostasis
What are the 5 causes of problems in the larynx?
1. Anomalies (brachycephalic syndrome, equine DDSP, subepiglottic cysts)
2. Inflamatory
3. Neoplasia
4. Circulatory (latyngeal oedema)
5. Degenerative (equine laryngeal hemiplegia)
What are the 5 causes of problems to the trachea?
1. Anomalies (tracheal collapse, tracheal hypoplasia, tracheo-oesophageal fistula, ciliary dyskinesia)
2. Inflammatory (necrotic laryngitis, kennel cough, herpes)
3. Neoplasia
4. Circulatory (tracheal oedema)
5. Parasitic (filaroised oseleri in dogs)
Describe VA
What affects/changes VA?
VA inversely proprtional to PaCO2.
- Decreased pH of CSF = increased VA
- Increased PaCO2 = increased VA
What are the VA control centers?
1. Central control - medullary respiratory center responds to changes in CSF pH
2. Peripheral contro - chemoreceptors on aortic and carotid bodies respond to fall in blood pH and increased PaCO2
What are the major clinical signs of respiratory failure?
1. Changes in rate and depth of respiratoin
2. Cyanosis
What is respiratory failure defined as?
1. PaO2 falls from 90-100mm Hg to 60-70 mm Hg
2. PaCO2 rises from 40mm Hg to 50 mm Hg
What are the two types of respiratory failure?
1. Restrictive = a pulmonary or thoracic process restricting inflation of the lungs
2. Obstructive - a pulmonary process obstructing the airways of reducing elastic recoil
What are the clinical signs of restrictive respiratory failure?
Inspiratory dyspnoea
Rapid shallow breaths
What are the 2 types of restrictive respiratory failure?
1. Intrapulmonary
- Predominantly affects the inerstital tissues (alveolar and interlobar septa)
2. Extrapulmonary
- In pleural cavity, mediastinum, thorcic wall
What are examples of the 2 types of restrictive respiratory failure?
1. Intrapulmonary
- pulmonary oedema
- Pneumonia
- Alveolar fibrosis
2. Extrapulmonary
- haemothorax
-deformities of thoracic wall
Describe what happens with Inrapulmonary restrictive respiratory failure
The septa are thickened by accumulation of fluid, inflammatory cells or fibrous tissue. There is type II hyperplasia where type II cells predominate. This causes reduced compliance and thicker diffusion barrier.
What are the types of obstructive respiratory failure?
1. Airway obstruction
- bronchitis, bronchiolitis
2. Reduced elasticity
- Emphysema
What are the clinical signs of obstructive respiratory failure?
- Inspiratory and expiratory dyspnoea
- hypoxia
- rapid deep breaths
- eucapnia/hypocapnia
What are the 3 types of pulmonary oedema?
1. Hydrostatic
- happens with increased pulmonary venous pressure
- common in L heart failure
-Fluid overload
2. Permeability oedema
- Inflammation
-bacterial enotoxins
3. Lymphatic oedema
- obstruction of lymphatic drainage i.e. neoplasm
What are the events in pulmonary edema?
1. Fluid accumulates in interstitium around bronchi and larger vessels
2. Extends to septa adjacent to thick sectors of capillary wall - this restricts lung expansion as reduced compliance alveolar walls
3. Fluid accumulates in alveoli = rapid, late, abrupt - get obstructive failure
What are the clinical signs of pulmonary oedema?
- Incaresed rate and depth breathing
- soft moist cough
- may have foam at nares
What is alectasis? What type of respiratory failure is it?
Atelectasis is collapse or incomplete inflation of the lung. It is restrictive intrapulmonary respiratory failure.
What are the 3 types of atelectasis?
1. Aquired compressive - where contents such as air, fluid, intestinal contenst are introduced into the pleural cavity.
2. Aquired obstructive - obstruction of bronchi or bronchioles - lung distal to obstruction fills with fluid and then collapses
3. Congential
What is the end result of atelctasis?
End up with a VA/Q mismatch so that blood going through the lungs is not properly perfused so blood shunted from R) to L) of the heart.
What is emphysema? What type of respiratory failure?
Part or all of the lung is overdistended with air. Usually co-exists with bronchitis or bronchiolitis. It is obstructive respiratory failure.
What are the 3 types of emphysema?
1. Interstitial
- air forced from overdistended alveoli into interstitial CT. Caused by bronchiolar inflammation - enzymatic lysis of elastin fibers in alveolar walls
2. Vesicular
- Overdistention confined to alveoli and alveolar ducts - get stretching of CT and loss of elsatic recoil.
3. Blubous
-large scale rupture of alveoli produce air filled cavities w/i lung or beneath pleura
What are the clinical signs of emphysema?
Forced expiration
Soft breath sounds
Expiratory wheeze
What are the 2 types of pneumonia?
1. Exudative
- Usually infectious and aerogenous in origin
- Alveolar lumen is filled with fluid and inflammatory cells
2. Proliferative
- Alveolar lumen remains relatively clear
-alveolar walls are thickened by hyperplatic epithelial cells and inflammatory cells
What are the 2 patterns of exudative pneumonia?
1. Bronchopneumonia
- subacute to chronic
- usually bacterial
- inflammatoin from bronchioles spreads down to involve alveolar ducts and alveoli
- lesions spread in defined lobular pattern
2. Lobular pneumonia
(fibrinous pneumonia)
- acute-peracute
- rapid spread of inflammation
- extensive vascular damage - haemorrhage
- may also get abscess formation
What is proliferative pneumonia?
Inflammatory process centered on alveolar septa. Also called interstitial pneumonitis, alveolistis
What are the clinical signs of proliferative pneumonia?
- Restricyive
- exercise intolerance
- incaresed respiratory effort
- Increased breath sounds
- late inspiratory crackles
What are the causes of proliferative pneumonia?
- bacterial (mycoplasma ovipnemonidae)
- Toxic - paraquat, pyrrolizidine alkaloids
- Allergic - mouldy hay
What types of neoplasm are there?
1. Primary
2. Secondary

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