Mechanics of Respiration

How are the lungs kept open?

• Effect of individual's height

• Dimension of thoracic cavity

• Pressure difference between lung and pleura

• Volume of air entered lung

[MCQ] Which of the following is directly involved in ventilation?

• Intrapleural pressure

• Partial pressure of oxygen

• Acidity of expired air

• Intra-alveolar pressure

In spontaneous pneumothorax, the lung collapsed due to

• Elastic recoil of lung

• Higher resistance in airway

• Reduced lung stability

• Increased intra-alveolar pressure

During inspiration, which combination best describes the pressure changes in lung.

• Palv = PIP

• Palv<Patm

• Palv>Patm

• PIP>Palv

In patients with below neck paralysis, will they have breathing difficulty?

• Yes

• No

Shahril slept late last night. Now, he felt tired and yawn with his mouth wide open during physiology lecture. When he yawn, he felt more air entered his chest. Which of the following BEST describes the cause of increase in air flow into the lungs.

• Reduced airway resistance

• Increased in lung volume

• Increased sympathetic stimulation

• Increased force of external intercoastal muscle contraction

Sharlene has an allergy to pollen. She went to meet her friend, Amir where he gave her some flowers to hold. Within 5 minutes, Sharleen started to sneeze. Which muscles were involved in sneezing?

• Contraction of diaphragm

• Relaxation of epiglottis

• Contraction of external oblique muscle

• Relaxation of pectoralis minor

When sneezing, Sharleen’s intrapleural pressure exceeded the atmospheric pressure. Sharlene’s experienced sudden onset of breathlessness. Amir, who happened to be a doctor thinks that Sharleen’s alveolar has collapsed. Under normal conditions, which of the following statements protects Sharleen from alveolar collapse?

• The atmospheric pressure is always positive.

• The diaphragm activity controls the lung pressures.

• The alveolar surfactant reduces the intrapleural pressure.

• The intra-alveolar pressure increased with intrapleural fluid contraction.

A COPD patient presented to the outpatient clinic for follow up appointment. He appears short of breath and reported having more difficulty in expiring than inspiration. Which option best describe the mechanism of difficulty in expiration?

• Dynamic airway compression

• Increased airway resistance

• Destruction of airway cartilage

• Expiratory muscle fatigability