L7 Respiratory Physiology Pathology and Lung Volumes Flashcards
Mucus linings help trap inhaled particles in the upper and lower respiratory tracts. How are particles that reach the alveoli cleared?
Macrophages
What is ‘mucociliary transport’ and how does it aid body defense?
Cilia of mucosa beat in a rhythmic and coordinated way and carry trapped particles towards the pharynx and the digestive tract.
In the digestive tract, acid and pepsin break down swallowed particles.
What lymphatic tissues are present in the upper respiratory tract to aid the body’s defences?
Tonsils and adenoids - fixed and wandering macrophages ingest particles and function as antigen-presenting cells and so activate the immune system.
How fast can air be expelled via a cough?
75-100km/hr
True or false: when cyanosis occurs as a result of respiratory disease, it is because the ventilation rate exceeds blood supply.
False.
Cyanosis can be caused by respiratory disorders resulting in blood supply exceeding ventilation rate.
This results in higher concentration of reduced haemoglobin, thus an increased physiological shunt
At what concentration of deoxygenated Hb does cyanosis become evident?
5g/dL in arterial blood
What is the general term for respiratory tract diseases involving a narrowing of the air passages?
Obstructive lung disease
What is the general term for respiratory diseases involving a loss of lung compliance?
Restrictive lung disease
True or false: Otitis media is an infection of the upper respiratory tract
True
Specifically, otitis media is an infection of the inner ear.
True or false: Pharyngitis is an infection of the upper respiratory tract
True
What is the most common cause of pneumonia?
Streptococcus pneumoniae
TB causes the lungs to become caseous. What does this mean?
Caseous = like swiss cheese
True or false: Asthma, bronchitis and emphysema are examples of restrictive lung disease.
False
These are all common examples of obstructive lung disease
Generally, what effect do obstructive lung diseases have on vital capacity?
Generally, no significant effect on vital capacity.
Generally, what effect do obstructive lung diseases have on airflow during expiration?
Generally, significantly reduce airflow during expiration
What is ‘status asthmaticus’?
Severe acute asthma - a medical emergency
What disease is characterised by recurrent, reversible airway obstruction, caused by bronchial hyper-responsiveness leading to bronchospasm?
Asthma
True or false: Emphysema is caused by the loss of elastin in the lungs and is an obstructive lung disease.
True
How does smoking cause COPD?
Smoking allows the inhalation of nicotine, which accumulates in the pulmonary epithelial cells.
Nicotine can act directly on alveolar macrophages and neutrophils, inducing them to increase the secretion of the enzyme elastase and oxygen radicals.
Elastase degrades elastin. Oxygen radicals inhibit antitrypsin, which is the antagonist of elastase (less antitrypsin = more elastase = less elastin).
What is elastase?
A serine protease that targets elastin.
It is produced by neutrophils and macrophages.
Which of the following is the normal genotype for antitrypsin?
a) SS
b) MZ
c) SZ
d) MM
e) ZZ
d) MM
95% have the normal MM genotype
Which antitrypsin genotype(s) is/are related to having susceptibility to obstructive lung disease?
a) ZZ
b) SZ
c) MZ
d) both a and b
e) both a and c
d) both a and b
ZZ = 10-15% normal antitrypsin activity
SZ = 30-35% normal antitrypsin activity
SS and MZ = 50-60% normal antitrypsin activity (does not cause disease)
Pulmonary fibrosis is usually a characteristic of which type of respiratory disease?
a) Obstructive
b) Restrictive
b) Restrictive
Which of the following is NOT generally true of restrictive lung disease?
a) Lung compliance decreases
b) Vital capacity drops
c) Peak flow rate decreases
d) Typically caused by asbestos, silica and coal dust
c) Peak flow rate decreases
In restrictive lung disease, lung compliance decreases, vital capacity drops, but peak flow rate remains high.
It is typically caused by asbestos, silica, and coal dust.
What are the three effects of aging on the respiratory system?
Decreased lung compliance and vital capacity as elastic tissues deteriorate.
Arthritis restricts chest movements and limits respiratory minute volume.
Emphysema may result in individuals over 50yo, depending on their exposure to irritants (cigarette smoke etc).
In what two ways can the respiratory system adapt to changing oxygen demands?
Varying the number of breaths per minute (respiratory rate)
Varying the volume of air moved per breath (tidal volume)
How do you calculate the respiratory minute volume?
Respiratory rate x Tidal volume
What is the respiratory minute volume in ‘normal, healthy individuals’?
About 6L
What is ‘alveolar ventilation’?
The amount of air reaching the alveoli each minute
(tidal volume - anatomical dead space) x respiratory rate
What is ‘residual volume’?
The volume of air that remains in the lungs and cannot be exhaled.
Why is ‘residual volume’ so important?
Prevents alveolar collapse and maintains pH
What is ‘tidal volume’?
The volume of air moved during normal breathing
What is ‘vital capacity’?
The total volume of air that can be moved in and out of the lungs under forced conditions.
Accounts for the total lung capacity minus residual volume.
What is a normal tidal volume?
500ml
What is a normal inspiratory reserve volume?
3100ml
What is a normal inspiratory capacity?
3600ml (inspiratory reserve volume + tidal volume)
What is a normal expiratory reserve volume?
1200ml
What is a normal residual volume?
1200ml
What is a normal functional residual capacity?
2400ml (expiratory reserve volume + residual volume)
What is a normal total lung capacity?
6000ml
What is FEV1?
Forced expiratory volume in 1 second
What is FVC?
Forced vital capacity
How can FEV1 and FVC be helpful in diagnostics?
In obstructive lung disease, FEV1 is reduced due to an obstruction of air escaping the lungs - thus the FEV1:FVC ratio will be reduced.
In restrictive lung disease, FEV1 and FVC are equally reduced due to fibrosis or other restrictive pathology. Thus the FEV1:FVC ratio should be approximately normal.
Obstructive lung disease, restrictive lung disease, or no lung disease?
FEV1 is 87% of predicted normal
FVC is 81% of predicted normal
FEV1/FVC ratio is 0.8
No lung disease
Abnormality would be indicated by:
FEV1 <80% predicted normal
FVC <80% predicted normal
FEV1/FVC ratio reduced (<0.7)
Obstructive lung disease, restrictive lung disease, or no lung disease?
FEV1 is 73% of predicted normal
FVC is 85% of predicted normal
FEV1/FVC ratio is 0.65
Obstructive lung disease
FEV1 reduced (<80%)
FVC usually reduced, but to a lesser extent than FEV1
FEV1/FVC ratio reduced (<0.7)
Obstructive lung disease, restrictive lung disease, or no lung disease?
FEV1 is 52% of predicted normal
FVC is 56% of predicted normal
FEV1/FVC ratio 0.9
Restrictive lung disease
FEV1 AND FVC reduced (<80%)
FEV1/FVC ratio normal (>0.7)
Why might somebody with emphysema or a similar obstructive pulmonary disease have a low blood pH?
Their disease means they are unable to ventilate their lungs to clear the CO2, which builds up and lowers the blood pH, resulting in acidosis.
