15 Must-Know Respiratory Flashcards for NEET PG 2026

Flashcard 1

Simple Pneumothorax

• In case of an injury to the chest wall causing an opening on the chest wall.
• The opening causes the air to enter the pleural space because the intrapleural pressure is lower. Air in this space is called Pneumothorax.
• Air will continue to enter the intrapleural space unless equilibrium is reached, which is 760 mmHg, the same as the atmospheric pressure. The entry of air will then stop. i.e., it creates an intrapleural pressure that is equal to the atmospheric pressure, which is 0 mmHg.
• Since the pressure becomes neutral, the alveoli or the lung will collapse.
• In case there is a full collapse of the lung, the minimum volume of air that will remain inside the collapsed lung is known as the minimal lung volume.
• The minimal lung volume is equal to 500 ml. This happens because the bronchioles collapse earlier than the full collapse of the alveoli.
• The minimal lung volume is lesser than the residual volume.

Flashcard 2

Intra-alveolar Pressure Graph

The X-axis represents the time, and the Y-axis represents the pressure. The time duration between the first two curves is the inspiratory phase of respiration, and the duration between the second and the third line is the expiratory duration. Before the start of the inspiration, in the resting condition, intra-alveolar pressure is 0 mmHg.

During inspiration the intra-alveolar pressure will be negative. At the end of inspiration, the intra-alveolar pressure will again become 0 mmHg. During expiration, the alveolar pressure will be increased due to the alveoli being compressed. At the end of expiration, the alveolar pressure will be zero. The maximum positive pressure is +1 mm Hg and the minimum pressure reached is –1 mmHg. This is typical of intra-alveolar pressure.

Flashcard 3

Forceful inspiration or Expiration 

Valsalva Maneuver

Forceful expiration against a closed glottis. Intrapleural pressure will become more and more positive and can rise to +100 mmHg. This is severe positive pressure in the intrapleural space.

Because this is done against the closed glottis, the alveoli will not collapse.

Muller's Maneuver

Forced inspiration against a closed glottis. The intrapleural pressure will be negative up to –80 mmHg.

Flashcard 4

Ventilation 

Ventilation is the amount of airflow occurring inside the lungs.

Types of ventilation

Pulmonary Ventilation (Minute Ventilation): It is the amount of air entering the lungs in a minute. Tidal Volume (TV) 500ml x Respiratory Rate (RR) 12 = approximately 6L/minute.

Alveolar Ventilation: It is the volume of air that reaches the alveolar zone for gas exchange. (TV - Dead Space) x RR, (500 - 150) x 12 = approximately 4.2 L/minute.

Flashcard 5

Graphical Representation of the V/Q ratio

• X-axis - PO Y-axis - PCO 2; 2.
• The normal V/Q ratio is 0.8 and P O is 100, and P CO is 40. A 2 A 2
• When the V/Q ratio is infinite, P O is 150, and P CO is 0. A 2 A 2
• If the V/Q ratio is zero, the P O is 40 and P CO is 46. A 2 A 2
• If all the points are connected, the V/Q curve is smooth.

Flashcard 6

Zones of the Lungs

Zone 1: Alveolar pressure > pulmonary artery pressure > pulmonary venous pressure. This results in the complete occlusion of capillaries, and hence there is no blood flow. It is not present in healthy lungs.

Zone 2: Pulmonary arterial pressure > Alveolar pressure > Pulmonary venous pressure. So, in this zone, the blood flow is intermittent.

Zone 3: It is found at the base of the lungs. Pulmonary arterial pressure > Pulmonary venous pressure > Alveolar pressure. Here, the blood flow is continuous.

Flashcard 7

Q. The tidal volume of a person is 600 mL. Upon inspiration, their intrapleural pressure changes from –4 cm of H2 O to –8 cm of H2 O. Calculate the compliance of this person. 

Ans:

• The total volume change inside the lungs is equal to the tidal volume (TV) of 600mL.
• The change in pressure is 4 cm of H2 O 2
• ΔV = 600 mL; ΔP = 4 cm of H2 O 2
• Therefore, the compliance will be 600/4 = 150 mL/cm H O

Flashcard 8

Compliance of Emphysema, Asthma, and Bronchitis

In the case of emphysema, due to excessive expansion, the alveoli and their surrounding elastic tissue rupture. The opposing forces decrease, and thus higher compliance is seen. In the case of asthma, compliance is also a little higher. In the case of bronchitis, compliance is almost normal. The compliance is also high in the case of old age lungs because of the destruction of the elastic tissue. Whenever the surfactant amount increases in the lungs, surface tension decreases and compliance increases.

Flashcard 9

Static and Dynamic lung volumes and capacities

Lung volumes and capacities are divided into static and dynamic lung volumes and capacities

Aspect	Static Lung Volumes andCapacities	Dynamic Lung Volumes andCapacities
Measurement Focus	Lung volume without the recordingof time	Lung volume with respect to timeis recorded
Units of Measurement	Measured in milliliters (ml) orliters	Measured in milliliters persecond (ml/second)

Flashcard 10

Lung capacities

• Lung capacity is the combination of multiple lung volumes.
• TV+IRV is known as Inspiratory capacity (IC).
• TV+IRV+ ERV is known as vital capacity (VC).
• RV+ERV is known as functional residual capacity (FRC).
• TV+IRV+ERV+RV is known as total lung capacity (TLC).

Flashcard 11

Guyton and Hall's textbook states that the dorsal respiratory group of neurons (DRG) is the main center for respiration. However, recent concepts state that the main center for respiration is located at the ventral respiratory group of neurons (VRG).

Flashcard 12

Relationship between Ventilation and Hypoxia

• A graph is drawn, the x-axis - PO2 , and the y-axis - ventilation. 
• The curve here will not be linear like the CO curve but will be very different from it. ( ) 2 IBQ
• When the PO2 is 160 mm of Hg, no hypoxia is seen. The resting ventilation is low but is still there. 
• When the PO2 has reduced to 100 mm Hg, there is still no hypoxia, and ventilation rises very little. If the PO2 is decreasing to 60 mm Hg, the ventilation is not rising to a very high level. 
• From 60-100 mm Hg, there is hypoxia, but it is not stimulating the ventilation to high levels, but after 60 mmHg, there is a sudden increase of ventilation.

Flashcard 13

J-Receptor Reflex 

• It is also known as the C-fibre receptor reflex.
• In neuronal classification, there are A, B and C fibres. C fibre is the unmyelinated nerve fibre.
• The afferent from the J-receptor is also the vagus, but it is the unmyelinated fibre of the vagus, which is the C fibre. Hence it is also known as the C-fibre receptor reflex. J stands for juxta capillary receptors.

Flashcard 14

Response on J-Receptor Activation

• Hyperventilation
• Apnoea (Rapid shallow breathing)
• Bronchoconstriction
• Increased mucous secretion
• Decreased blood pressure and Heart rate
• All these conditions ultimately leading to Dyspnoea

Flashcard 15

Anaemic Hypoxia

In anaemic hypoxia there is a decrease in quality or quantity of hemoglobin. The P 2O is normal. Since haemoglobin is the main source of transport of O2 to the blood and when this haemoglobin is at fault. This type of hypoxia is called anaemic hypoxia.

Also read: Exam-Oriented Neoplasia Questions and Answers

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