CVR: Respiratory Flashcards
What two areas of the brain, not in the medulla oblongata, are involved in the control of breathing?
Pneumotaxic and apneustic centres in the pons.
What two areas of the brain, not in the pons, are involved in the control of breathing?
Dorsal respiratory group and ventral respiratory group, both in the medulla oblongata.
Which area of the medulla oblongata is predominantly active during inspiration?
The dorsal respiratory group (DRG).
What provides background ventilatory drive?
A neural network in the brainstem (central pattern generator).
Concentration of which gas predominantly influences breathing?
CO2
What do the central chemoreceptors in the brainstem detect to monitor breathing?
Hydrogen ion concentration.
How does an increase of PaCO2 cause the central chemoreceptors in the brainstem to detect increase in hydrogen ion concentration via the bicarbonate buffer system?
- CO2 crosses blood brain barrier.
- CO2 + H2O (catalysed by carbonic anhydrase) = H2CO3 (carbonic acid)
- H2CO3 dissociates = H+ + HCO3-
Where are the peripheral chemoreceptors?
Carotid bodies and aortic arch.
What do the peripheral chemoreceptors in the carotid bodies and aortic arch measure to monitor breathing?
Measure PaCO2 predominantly, but also measure PaO2 and pH.
What are the three types of mechanoreceptors in the lungs that send afferent information to the respiratory control centres via the vagus nerve?
JIS!
J receptors (juxtacapillary AKA pulmonary C-fiber receptors), irritant, and stretch.
Where are the receptors which prevent respiratory activity during swallowing?
The pharynx.
Why can x-rays be dangerous?
They are a form of ionising radiation, which can damage tissue, cells, and DNA (mutagen).
What colour are more dense structures on an x-ray? Give an example.
White. E.g. bones.
On a chest x-ray, why is the diaphragm higher on the right?
Due to the presence of the liver.
What anatomical landmark on a chest x-ray can be used to assess symmetry?
The clavicles.
Why aren’t the anterior aspects of the ribs easily visible on a chest x-ray?
They are cartilaginous.
Which view is most ideal for a chest x-ray and why; AP (anterior-posterior) or PA (posterior-anterior)?
PA (posterior-anterior); patient facing the detector, standing up.
This is because there will be a crisper image and accurate size of the heart than in AP view, and the scapulae can be protracted.
Which causes more ionising radiation for a patient, chest x-ray or abdominal x-ray?
Abdominal x-ray.
Where should you look to check for cyanosis?
Under the tongue at glossal artery.
Both Type 1 and Type 2 respiratory failure are characterised by hypoxaemia (low PaO2) due to an inability to maintain normal blood gases. What is the difference between Type 1 and Type 2 respiratory failure?
Type 1 = hypocapnia/normal PaCO2
Type 2 = hypercapnia (high PaCO2)
What causes Type 1 respiratory failure?
Many different causes, including infectious, congenital, and neoplasmic (tumour) causes.
What causes Type 2 respiratory failure?
Hypoventilation leading to hypercapnia. For example, in COPD.
Why might someone with anaemia not be cyanotic when severely hypoxic?
Cyanosis is caused by large amount of deoxygenated haemoglobin. Anaemic patient might not have enough haemoglobin to be cyanotic.
In chronic hypercapnia, such as in COPD, chemoreceptors are thought to reset. Breathing is no longer driven by increase in PaCO2 and instead driven by decrease in PaO2.
Why might giving supplementary O2 to a patient with COPD cause Type 2 respiratory failure?
If give supplementary O2 and raise PaO2, the patient might lose their ventilatory drive and hypoventilate, causing CO2 retention and hence Type 2 respiratory failure.
At the level of what rib is the optimal VQ ratio seen?
Rib 3
The total lung capacity is found by adding what two lung volumes?
Residual volume and vital capacity.
Laplace’s law states P = 2T / r
where P = pressure, T = tension, r = radius.
In relation to Laplace’s law, why do premature babies, who haven’t developed surfactant yet, struggle to inflate their lungs?
Surfactant reduces surface tension of alveoli, reducing the pressure needed to overcome to inflate alveoli.
Does the alveolar epithelium have a role other than gas exchange?
Yes! Also has a host defence function; can be triggered to produce certain defence proteins (e.g. anti-viral) when a pathogen is present.
Mucus and cilia in the respiratory epithelium are an important intrinsic (non-immunity) host defence mechanism. Why?
Mucus and cilia together form the mucociliary escalator (AKA mucociliary clearance); trapping pathogens and particles and wafting them up out of the respiratory tract.
What is airway mucus?
A viscoelastic gel produced by goblet cells and submucosal glands. Contains water, carbohydrates, proteins, and lipids.
Why is mucus important in the respiratory tract?
Protects the epithelium from foreign material/pathogens and reduces fluid loss.
What reflexes are an important part of intrinsic/non-immune host defence mechanisms?
Sneezing and coughing.
Name the four afferent nerves involved in the cough reflex.
Trigeminal, glossopharyngeal, superior laryngeal, vagus.
What two efferent nerves are involved in the cough reflex?
Recurrent laryngeal and spinal nerves.
Where are the sensory neurons which trigger the sneeze relfex?
In the nasal cavity.
Do motor neurons for sneeze or cough reflex trigger more effectors?
Sneeze.
Name the four steps involved in respiratory epithelium repair/regeneration following insult/injury.
- Spreading and de-differentiation (stop being cuboidal and ciliated).
- Cell migration.
- Cell proliferation (from basal cells).
- Re-differentiation (become ciliated epithelial cells again).
What feature of respiratory epithelium allows it to effect a complete repair?
Functional plasticity; they can change their phenotype.
What airway abnormality are most chronic pulmonary diseases associated with?
Respiratory epithelial abnormalities.
Poor mucociliary clearance function can cause potentially fatal obstructive mucus plugs. How do mucus plugs form?
Proteins in mucus polymerise to form large plugs.