Respiratory Flashcards
Left lobe
All domestic species have two lobes - cranial and caudal
Cranial clearly divided into two parts both supplied by some bronchus
- Cranial and caudal parts of left cranial lobe
- Not in horse
Accessory lobe
Ventral midline between caudal lobes of left and right lung
Own pleura - mediastinal recess
Right lobe
Four lobes - cranial, middle, caudal, accessory
Not horse
Ruminants:
- Look as though 5 lobes but two most cranial are supplied by the same lobar bronchus
- Cranial and caudal parts of cranial lobe
Ruminant and pig: cranial lobe supplied by tracheal bronchus
Visceral (pulmonary) pleura
Attached to surface of lung including fissures - contains abundant elastic fibres
Parietal pleura
Derived from the somatic mesoderm and it lines the wall of the pleural cavity
3 compartments:
- Costal pleura: lines inside of lateral wall of ribcage
- Mediastinal pleura: lines the mediastinal
- Diaphragmatic pleura: lines the cranial surface of the diaphragm
Mediastinum
Parturition between left and right pleural sacs
Contains: heart in pericardiac sac, thoracic trachea, thoracic oesophagus, thymus, mediastinal LN, great vessels, nerves
Does not contain: lungs, caudal, vena cava, right prenic nerve
Pharynx
Connect orals cavity with oesophagus and nasal cavity with larynx
Soft palate seperates rostral part of pharynx into dorsal and ventral portion: nasopharynx and oropharynx
Larynx
Bilaterally symmetrical tube-shaped musculocartiligenous organ connects pharynx and trachea Protects trachea from aspiration Increases intra-abdominal pressure Important for vocalisation Richly innervated by vagus nerves
Caudal laryngeal nerve
Paralysis of left recurrent laryngeal nerve - stertorous sounds produced at inspiration (roaring) - air flow passively vibrating a lax adducted vocal fold
Pores of Kohn
Gaps in the alveolar septa to enable more efficient movement of inspired air between alveoli
Infant respiratory distress syndrome
Stiff lungs with low compliance
Alveolar collapse
Alveoli filled with transudate
Treat with synthetic surfactant
Exercise induced pulmonary haemorrhage (EIPH)
Small blood vessels in lung burst under high pressure and bleed into airway
Epistaxis in small proportion of EIPH cases
Racehorses
Pulmonary embolism
Obstruction to a branch of pulmonary artery
May be fatal if both pulmonary trunk or both pulmonary arteries are blocked
Enlargement of bronchial arteries by dilation
Angiogenesis: new bronchopulmonary arterial anastomoses - can bypass obstructed PA
Fick’s law
Rate of transfer through a sheet of tissue is proportional to the tissue area and the difference in partial pressure between the two sides and inversely proportional to the the tissue thickness
Area of the respiratory surface
Thickness of the respiratory surface
PO2 difference between alveolus and capillary
Pulmonary oedema
Guttural pouch
Air filled pouch
When infected, carotid artery bleed into nasal cavity and out of nose
Brachycephalic respiratory issues - anatomy
Larynx and nasal cavities - greatest resistance to airflow
Brachycephalics have:
- Narrow nasal passages
- Shorter jaw and misaligned teeth
- Wider optical cavity
- Longer nasal cavity
More resistance to airflow - increase respiratory effect
Longer soft palate - more effort, inflammation, less space - positive feedback
Narrow trachea, laryngeal collapse can occur
Tracheal collapse
Common in some breeds of dog e.g. Yorkshire terrier
Reduced exercise capacity
Not ventilating properly
Apply tracheal stent - good for younger dog
Pulmonary surfactant
Oppose surface tension
Polar phospholipid secreted from type II alveolar cells (pneumocytes)
Increases compliance, promotes alveoli stability, keeps alveoli dry
Alveoli emphysema
Sometimes die to ischaemia of alveolar wall due to obstruction of bronchial arterial supply or alveolar capillaries
Hormonal control of airway diameter
Presence of many beta2 adrenergic receptors:
- Highly sensitive to adrenaline
Cytokine production by inflammatory cells:
- Mostly bronchoconstrictors (histamine, prostaglandin D2, F2alpha etc.)
- Prostaglandin E2 and prostacyclin are bronchodilators
Haemoglobin
O2 binds loosely and reversibly with the heme portion of Hb
High PO2 - O2 binds to Hb
Low PO2 - O2 released from Hb
Bohr effect
Shift of oxygen-haemoglobin dissociation curve to the right due to increased CO2 concentration
Shift to the right enhances O2 unloading in the tissues and increasing oxygenation of blood in the lungs
The Haldane effect
Binding of O2 with Hb tends to displace from the blood
When O2 binds Hb in the lungs, the Hb becomes a stronger acid
Causes displacement of CO2 from blood to alveoli
Avian air sacs
1 interclavicular sac 2 cervical sacs 2 anterior thoracic sacs 2 posterior thoracic sacs 2 abdominal sacs
Act as bellows to ventilate the lungs