Q: Which of the following formulas is used to calculate alveolar ventilation rate (AVR)?

$$AVR = BF \times (TV - dead\ space)$$

Question 1

Which of the following best explains why intrapleural pressure (Pip) is always negative under normal conditions?

Accepted Answer

Because the opposing forces of lung recoil and chest wall expansion create a slight vacuum in the pleural cavity.

Question 2

A patient has a pneumothorax (collapsed lung) on the right side. Why does the left lung remain inflated?

Accepted Answer

Each lung is housed in a separate pleural cavity, so a collapse on one side does not affect the other.

Question 3

According to Boyle’s Law, what happens to the pressure inside the lungs if the volume of the thoracic cavity doubles, assuming the amount of gas remains constant?

Accepted Answer

The pressure is halved.

Question 4

Which equation correctly represents Boyle’s Law as it applies to pulmonary ventilation?

Accepted Answer

$$P_1V_1 = P_2V_2$$

Question 5

During inspiration, which of the following events occurs to allow air to flow into the lungs?

Accepted Answer

Thoracic volume increases, causing Ppul to drop below Patm.

Question 6

Which muscles are primarily responsible for increasing thoracic volume during quiet inspiration?

Accepted Answer

Diaphragm and external intercostals

Question 7

A person with asthma experiences bronchoconstriction. What effect does this have on airway resistance and gas flow, according to the equation $$F = \Delta P / R$$?

Accepted Answer

Airway resistance increases, and gas flow decreases.

Question 8

Which of the following best describes the role of surfactant in the alveoli?

Accepted Answer

It decreases alveolar surface tension, making the lungs easier to expand.

Question 9

A patient’s spirometry results show a reduced vital capacity. What does this most likely indicate?

Accepted Answer

The patient has a restrictive pulmonary disorder.

Question 10

Which of the following formulas is used to calculate alveolar ventilation rate (AVR)?

Accepted Answer

$$AVR = BF 	imes (TV - dead\ space)$$

Question 11

During forced expiration, which muscles are primarily involved?

Accepted Answer

Oblique and transverse abdominal muscles; internal intercostals

Question 12

If a patient’s dead space increases due to a pulmonary disorder, what is the effect on their alveolar ventilation rate (AVR), assuming tidal volume and breathing frequency remain constant?

Accepted Answer

AVR decreases.

Question 13

Which of the following is a direct result of fluid accumulation in the pleural cavity?

Accepted Answer

Intrapleural pressure (Pip) becomes positive, leading to lung collapse.

Question 14

Which of the following best explains why airway resistance is usually insignificant in healthy lungs?

Accepted Answer

The large diameter of conducting zone tubes and increased total cross-sectional area in smaller airways.

Question 15

A patient is exercising vigorously. Which of the following changes would you expect in their minute ventilation?

Accepted Answer

It increases up to 200–250 L/min.

Question 16

Which of the following scenarios would most likely result in a decrease in lung compliance?

Accepted Answer

Fibrosis (scarring) of lung tissue

Question 17

Which of the following best describes the effect of epinephrine on the bronchioles during an acute asthma attack?

Accepted Answer

It dilates the bronchioles, reducing airway resistance.

Question 18

If the pressure gradient ($$\Delta P) $$between the atmosphere and alveoli is 2 mmHg and airway resistance (R) is 1 mmHg/L/sec, what is the gas flow (F) according to the equation $$F = \Delta P / R$$?

Accepted Answer

$$F = 2\ L/sec$$

Question 19

Which of the following would most likely increase the effectiveness of alveolar ventilation?

Accepted Answer

Increasing tidal volume while keeping dead space constant

Respiratory Part 3 AP 2nd year Thoracic cavity spirometry

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