JNTU B.Pharmacy I Year HUMAN ANATOMY AND PHYSIOLOGY - II Previous Question Paper (June - 2022 - R17)

Lung volumes and capacities are measurements of the amount of air moved during breathing, which are recorded using a spirometer. The graphical representation of these volumes over time is called a spirogram.

Lung Volumes:

• Tidal Volume (TV): The volume of air inspired or expired during a normal, quiet breath, approximately 500 mL.
• Inspiratory Reserve Volume (IRV): The extra volume of air that can be forcibly inspired after a normal tidal inspiration, approximately 3000 mL.
• Expiratory Reserve Volume (ERV): The extra volume of air that can be forcibly expired after a normal tidal expiration, approximately 1100 mL.
• Residual Volume (RV): The volume of air remaining in the lungs after a maximal forced expiration, approximately 1200 mL; this cannot be measured by simple spirometry.

Lung Capacities:

• Inspiratory Capacity (IC): TV + IRV (approx. 3500 mL).
• Functional Residual Capacity (FRC): ERV + RV (approx. 2300 mL).
• Vital Capacity (VC): IRV + TV + ERV (approx. 4600 mL); the maximum amount of air exhaled after maximal inhalation.
• Total Lung Capacity (TLC): VC + RV (approx. 5800 mL).

Spirometer Diagram Description: A basic wet spirometer consists of an inverted bell suspended in a water-filled tank. A mouthpiece is connected via a tube to the air space inside the bell. As the subject breathes into the mouthpiece, the bell rises and falls. A pen attached to a counterweight records these movements on a rotating drum (kymograph), creating the spirogram tracing. The apparatus includes a soda lime container to absorb exhaled carbon dioxide and a valve system to allow fresh oxygen intake.