Flashcards in Physiology Deck (57):
How do the lungs adhere to the thoracic wall?
Intrapleural fluid cohesiveness
Negative intracellular pressure
What happens during inspiration?
Diaphragm contracts and flattens
External intercostals contact and increase ant-post diameter
Ribs moved up and out
Increased in lung size reduces intra-alveolar pressure
Air enters down pressure gradient
Why do the lungs and chest wall recoil?
Due to elasticity
What is the role of surfactant?
Reduces alveolar surface tension to prevent collapse
What cells produce surfactant?
Type ii alveoli
What causes respiratory distress of the newborn?
Preterm births result in babies with lack of surfactant so high surface tension
What is the theory behind alveolar interdependence?
If an alveoli starts to collapse...
- Stretches surrounding alveoli
- They recoil -> Expansive
- Re-opens closed alveoli
What is the tidal volume?
Volume entering/leaving lungs in a single breath (~500ml)
What is the inspiratory reserve volume?
Extra air that can be expired over resting TV (~3000ml)
What is the inspiratory capacity?
Max volume of air inspired at the end of quiet expiration (~3500ml)
IC = IRV + TV
What is the expiratory reserve volume?
Extra air that can be expired after quiet expiration (~1000ml)
What is the residual volume?
Minimum lung volume after max expiration (~1200ml)
What is the functional residual capacity?
Volume of air in lungs after normal quiet expiration (~2200ml)
FRC = ERV + RV
What is the vital capacity?
Max volume of air that can be exhaled following max inspiration (~4500ml)
What is the total lung capacity?
TLC = VC + RV
If pulmonary compliance decreases, what effects will be noted?
Increased inflation work
Shortness of breath
What can cause decreased Po compliance?
What occurs in emphysema?
Elastic recoil lost
Increased exhalatory work
Which is greater and why, alveolar or pulmonary ventilation?
Anatomical dead space
Is it better to increase tidal volume or RR to increase ventilation?
What factors affect gas exchange in alveoli?
Partial pressure gradient of gasses
Diffusion coefficient for gasses
What would a big gradient between PAO2 and PaO2 suggest?
Right-left shunt in the heart
Beginning at the trachea, describe the respiratory "tree"
What causes a right shift in the Hb saturation curve?
Where is myoglobin found?
In skeletal and cardiac muscle
When myoglobin is present in the blood what does this indicate?
How is carbon dioxide transported in the blood?
Carbamino compounds (30%)
What is the equation for bicarbonate formation?
CO2 + H2O H2CO3 H+ + HCO3-
What enzyme catalyses the production of carbonic acid?
What are the driving forces behind bicarbonate formation?
Venous [Cl-] > Arterial [Cl-]
Arterial [HCO3-] > Venous [HCO3-]
Which respiratory group neurones result in inspiration?
What results in passive expiration (neuronal)?
The dorsal resp. group stops firing
What neuronal controls result in active expiration?
Increased dorsal firing results in ventral firing
Where are the dorsal and ventral respiratory groups located?
In the medulla
What is the role of the pneumotaxic centre?
Stimulated when dorsal group fires
What happens if the pneumotaxic centre is inhibited?
Prolonged inspiratory gasps - apneusis
What is the role of the apneustic centre?
Excites dorsal area
Inhibits pneumotaxic area
Where are the pneumotaxic and apneustic areas located?
In the pons
What structures stimulate the respiratory centres in the brain?
Higher brain centres
What is the Hering-Breuer Reflex?
A stretch response inhibiting inspiration and preventing hyperinflation
What factors increase ventilation?
Increased body temp
What are some symptoms of altitude sickness?
What are the chronic adaptions to high altitude hypoxia?
Increased 2,3-Bisphosphoglycerate production
Increased number of capillaries
A 67 year old man who smokes since his teens has got COPD. What is his FEV1/FVC:
Which of the followings is correct in a patient with emphysema? Select ONE BEST OPTION
A. Gas exchange is unaffected
B. The work of breathing is decreased
C. The pulmonary compliance is increased
D. The total lung volume is decreased
E. The FEV1/FVC ratio is increased
Pulmonary compliance is increased
Which of the followings is correct in a patient with COPD? Select ONE BEST OPTION
A. Inspiration will be more difficult than expiration
B. Dynamic airway compression is likely to occur during active expiration
C. The presence of emphysema will help alleviate dynamic airway compression
D. Oxygen saturation should be maintained near 100% if the patient is retaining CO2
E. Dynamic airway compression is likely to occur during inspiration
Dynamic airway compression is more likely to occur during active expiration
From the list below select the ONE MOST RELEVANT option which describes the mechanisms involved in the causation of shortness of breath in this patient
A 21‐year‐old woman sees her GP about intermittent breathlessness. She often feels breathless when she’s in a crowded room. When she feels breathless, she also notices numbness and tingling around her mouth. A full blood count requested by the GP showed haemoglobin of 10.5 grams/dl.
A. Increased work of breathing due to reversible airways obstruction
B. Increased central and autonomic arousal
C. Reduced oxygen carrying capacity of the blood
D. Stimulation of peripheral chemoreceptors
E. Reduced surface area for gas exchange
Increased central and autonomic arousal
Q5) From the list below select the ONE MOST RELEVANT option which describes the mechanisms involved in the causation of shortness of breath in this patient
A 52‐year‐old man complains of gradually increasing shortness of breath on exertion and a dry cough. He has smoked 10 cigarettes a day since he was 14. On examination of his chest there are dry crackles at both bases.
A. Reduced pulmonary compliance and impaired gas diffusion
B. Increased work of breathing caused by reversible airway obstruction
C. Increased alveolar surface tension
D. Fixed airway obstruction and decreased surface area for gas exchange
E. Metabolic acidosis
Reduced pulmonary compliance and impaired gas diffusion
In a patient with pulmonary fibrosis, the FEV1/FVC% is likely to be Select ONE OPTION
A. 35% B. 40% C. 80% D. 60% E. 20%
Q7) From the list below select the ONE MOST RELEVANT option which describes the mechanisms involved in the causation of shortness of breath in this patient
A 72‐year‐old woman has had two myocardial infarctions in the past, and a recent echocardiogram has shown moderately impaired left ventricular function. She complains to her GP of shortness of breath, which is worse at night.
A. Increased alveolar surface tension
B. Increased work of breathing due to reversible airways obstruction
C. Reduced oxygen carrying capacity of the blood
D. Reduced pulmonary compliance and impaired gas diffusion
E. Stimulation of central chemoreceptors
Reduced pulmonary compliance and impair gas diffusion
Q8) From the list below select the ONE CORRECT ANSWER
A previously fit 22 old man has been unwell for 2 days. He presents with cough productive of greenish septum, fever, and shortness of breath. His PO2 is 8.2 kPa. What is his saturation likely to be?
Q9) A 52‐year‐old man with shortness of breath on exertion was diagnosed with diffuse pulmonary fibrosis. His arterial blood gas results under resting conditions showed a PO2 of 10.2 kPa, %saturation of 97%, and PCO2of 4.9 kPa. His haemoglobin is 10.5 grams/dl
Which of the followings sets of results would be expected for him during climbing stairs? – Select one answer: Normal values
PCO2 4.7‐6.1, PO2 12.0‐14.7
A. %Saturation: 90%, PO2: 8.3, and PCO2: 4.8
B. %Saturation: 97%, PO2: 11.3, and PCO2: 5.9
C. %Saturation: 98%, PO2: 12.6, and PCO2: 3.4
D. %Saturation: 90%, PO2: 9.4, and PCO2: 6.7
E. %Saturation: 95%, PO2: 8.3, and PCO2: 7.1
Q10) From the list below select the ONE MOST LIKELY set of arterial blood gases in this patient
A 32‐year‐old woman with type 1 diabetes that is usually well‐controlled. She is admitted with a 2 day history of dysuria, urinary frequency and vomiting. On arrival, she is comatose, with deep, ‘sighing’ respiration, and a temperature of 38.2oC.Normal values
pH 7.36‐7.44, PCO2 4.7‐6.1, HCO3‐ 24‐30, PO2 12.0‐14.7
A. pH 7.26 PCO2 3.2 HCO3‐ 8 PO2 12
B. pH 7.08 PCO2 5.2 HCO3‐ 8 PO2 11.8
C. pH 7.1 PCO2 7.1 HCO3‐ 26 PO2 10.2
pH 7.26, pCO2 3.2, HCO3- 8, pO2 12
Q11) Which of the followings is correct about Functional Residual Capacity? Select ONE BEST OPTION
A. Is usually increased in obese subjects
B. Is measured by spirometry
C. Is decreased in COPD
D. Is normally about 20% of total lung capacity
E. Is approximately about 2.2 litres in a young adult man
Q12) Which of the followings is correct about normal lungs? Select ONE BEST OPTION
A. A low PO2 causes pulmonary vasoconstriction
B. Larger airways are supplied by pulmonary circulation
C. Beta 1 agonists causes bronchodilation
D. Parasympathetic stimulation causes bronchodilation
E. The surface area for gas exchange remains constant in the absence of disease
Low pO2 causes pulmonary vasoconstriction
Which of the following is true in a tension pneumothorax
A. The intra‐pleural pressure becomes more negative
B. The trachea may deviate to the same side
C. Patient is likely to be hypotensive
D. Breath sounds are increased
E. Chest pain is not a symptom
Patient is likely to be hypertensive