Questions for Respiratory Quiz Flashcards
4 important functions of the airway epithelium
Physical barrier
Antimicrobial defense
Pro-inflammatory function
Regulatory function
How is the airway epithelium a:
Physical barrier
First ling of defence against bacteria, viruses, allergens, dust particles, and air pollution
No molecule can easily pass through the epithelium
Cilia are present to sweep these particles away
How is the airway epithelium an:
Antimicrobial defence
Secretes mucus, immunoglobulins, lysozyme, lactoferrin, and mucous proteinase inhibitors to attack foreign particles
How is the airway epithelium a:
Pro-inflammatory function
Produces arachidonic acid metabolites and inflammatory cytokines
Good to recruit cells of the immune system, but can be damaging in excess
How is the airway epithelium a:
Regulatory function
Secretes neuropeptide degrading enzymes, endothelin, nitric oxide, TGF-beta
Regulates cell growth, blood vessel constriction and dilation, and the concentration of neuropeptides
3 important functions of the ASL
Airway hydration
Antimicrobial defence
Innate immunity
How does the ASL act in:
Airway hydration
Provides a layer of fluid on top of the respiratory epithelium that hydrates the cells and brings them nutrients
The composition and pH of the pericilia layer is important to enable MC clearance
How does the ASL act in:
Antimicrobial defence
Secretes a lot of proteins and molecules (lactoferrin, defensins, lysozyme, IgA, antimicrobial surfactant proteins, etc) that destroy or target foreign particles for destruction
How does the ASL act in:
Innate immunity
Innate immunity is the non-specific immune system
The ASL can prevent infection and damage from a wide array of particles
What effects do changes in ASL composition have?
All from defective CFTR
Decreased bicarbonate absorption leads to decreased ASL pH and decreased MC clearance
More Na absorption and O2 consumption can decrease the ASL O2 and allow for colonization of P aeurginosa
More Na absorption can lead to decreased ASL volume and decreased bacterial clearance
Decrease in gland fluid secretion/altered protein and ion content can increase the viscosity leading to decreased bacterial clearance and decreased antimicrobial secretion
Explain the function and regulation of the submucosal glands
Have both serous (watery secretions, most of the CFTR), and mucus (mucins) glands that produce the ASL
Innervated by the parasympathetic NS
Housekeeping and emergency secretion
Housekeeping secretion
Regulated by VIP and CFTR dependent
Controlled by the intrinsic neural network (local neurons)
Low flow rate but constant production
If CF patients get a lung transplant this function will be preserved
Emergency secretion
Regulated by ACh and CFTR independent
Controlled by the vagus and central neuronal network
High rate of gland secretion - triggered by coughing - increases the amount of mucus made from the submucosal glands
5 elements of lung defence that are affected in CF
Mucociliary clearance and mucus production Cough Decreased bacterial killing Decreased bacterial clearance Decreased secretion of VIP
How is MC clearance and mucus production affected in CF?
Abnormal CTFR results in an increased viscosity of mucus because of the dehydration (doesn’t pump out Cl, Na comes in, water enters cell too)
Decrease in volume of the pericilia layer, so together with increased amounts of mucus the cilia collapse and mucociliary clearance is no longer functional
Increase in inflammation and amount of material in the lungs also stimulates the lungs to produce more mucus, which is not productive (the lung cannot distinguish between mucus layers and foreign particles, so it only knows to secrete more mucus – causes inflammatory response (apoptosis, degradation, denudation)
How is cough affected in CF?
Because of the increased obstructions in the airways, a persistent cough develops
It is often non-productive due to the fact that the mucus is so thick (why you need chest physiotherapy and aerosol treatments)
Chronic inflammation and chronic cough can also cause damage in the lung, making the cough even less productive over time
Cough is stimulated by inhalation of particles, irritants, food, pathogens, inflammation and accumulated secretions
How is decreased bacterial clearance a result from CF
You get mucus plugging, decreased ciliary motility and increased adherence from increased inflammation which reduce clearance
From lung damage and bacterial infections
How is decreased bacterial killing a result from CF
You get decreased pathogen uptake and altered ASL as well as impaired innate immune factors from increased inflammation
How is VIP secretion affected in CF
There is a decreased secretion
VIP normally suppresses airway inflammation and airway hyper-reactivity
It has many important roles in healthy lung function and lung defense
What are the different parameters that can be measured during a pulmonary function test?
Measures how much air you can breathe out and how fast
Vital capacity, FVC, IV, EV, tidal volume, etc
What cannot be measured during pulmonary function test?
Reserve/residual volume (the amount of air left in your lungs after VC released)
So also not FRC or TLC
What are the different lung volumes (values and description)
Tidal volume (500 mL) – normal amount you breathe in and out
Inspiratory reserve volume (3 L) – the total amount of air you can breathe in after a normal breath in
Expiratory reserve volume 1.2 L) – from the end of a normal breath to the very last amount you can blow out
Residual volume (1.2 L) – the amount of air always present in your lungs – cannot measure vs spirometry
Total lung volume (6 L)
Inspiratory capacity (500 mL + 3L) – total amount of air you can breath in from a normal exhalation
Vital capacity (3 L + 500 mL + 1.2 L) – from lowest exhale to highest inhalation
Forced vital capacity (5 L) – total amount of air you can breathe out
Forced vital capacity in 1 s (4 L) – amount of air you can breathe out in 1s
Main differences between an obstructive and restrictive lung disease
Obstructive: something is blocking the air flow (airflow limitation), normal or increased compliance, decreased FVC and decreased FEV1/FVC ratio (due to poor airflow), increased lung volume, air trapping
Restrictive: something is hindering the intake of air (reduced lung volume), decreased compliance (increased lung stiffness), decreased FVC and FEV1 but better or normal FEV1/FVC ratio
What drug is given to some patients before measuring lung function? explain why and the expected results
Bronchodilators (like a beta-2 agonist – gives effects rapidly but doesn’t last for a very long time – cause an inhibition of the release of pro-inflammatory mediators from mast cells, and bronchial smooth muscle relaxation in bronchiole walls – results in a dilation of the airways = decrease resistance to airflow and increase ventilation)
Do this to see if the drugs will change or improve the test results
You expect to see an increase in the FVC and the FEV1/FVC ratio as opening the airways starts to get the lung function back to normal
What is the partial pressure of oxygen in the atmospheric air, into the lungs, in the alveolar space and in the arterial blood?
Atmospheric air: 160mmHg (0.21 x760)
Into the lungs: 150mmHg ((760-47) x 0.21)
Alveolar space: 105 mmHg
Arterial blood: 100 mmHg
How is oxygen transported?
2% dissolved in the blood plasma
98% bound to hemoglobin – Hb has 4 subunits each with 1 ferric ion (so 1 molecule of Hb can transport 4 oxygen molecules)
Hb saturation is affected by PO2, blood pH, temperature, RBC metabolism (and PCO2)
What factors affect the diffusion of oxygen?
Differences in partial pressure are the most important driving force to get gases to diffuse) - Partial pressure of O2 and CO2
Distance the gases have to travel (because they only move via simple diffusion – big problem in fibrosis)
Diffusion coefficient of the gas (why CO2 moves so much faster than O2 – depends on molecular weight and gas liposolubility)
Surface area of contact needs to be large
Blood flow and airflow need to be coordinated (the amount of time they are in contact for has to be enough so that the gases can diffuse properly)
What factors affect the transport of oxygen?
Temperature
pH
2,3-DPG
ppCO2
Hypoxic hypoxia
Not enough oxygen in the arterial blood (arterial PO2 is reduced)
Usually due to problems with the lungs (not getting enough oxygen from the air, pulmonary problems, lack of VQ coupling)
Anemic Hypoxia
Total blood O2 content is reduced due to an inadequate number of RBCs, deficient or abnormal Hb, or competition for Hb by CO
Ischemic hypoxia
Not enough oxygen is getting to the tissues because of a lack of blood flow
Ex from obstruction of a blood vessel
Histotoxic hypoxia
Oxygen is getting to the tissues but cannot be taken into the cell because of interference with cell’s metabolic apparatus
Ex: cyanide poisoning
Describe a situation where oxygen delivery to tissue is facilitated
Right shift
Exercising (increase temperature, increase ppCO2, decrease pH, increase 2,3-DPG causes a right shift which makes it easier to unload the oxygen from the HB and deliver it to the tissues)
Describe a situation where oxygen delivery to tissue is reduced
Left shift
Hyperventilation (decreased temperature, decreased ppCO2, decreased 2,3-DPG, increased pH – rapid breathing is delivering too much O2 and getting rid of too much CO2, so right shift happens which makes it easy to load the amount of oxygen but difficult to unload it to the tissues)
