Question

Give 3 examples of biomedical or biological time constants. Estimate the duration of time over which each system changes.

Answer 1

Q) GIVE THREE EXAMPLE OF BIOMEDICAL OR BIOLOGICAL TIME CONSTANT. ESTIMATE THE DURATION OF TIME OVER WHICH EACH SYSTEM CHANGES.

ANS) Time constant
That part of a circuit that determines the time interval over which the rate of electrical events will be averaged; in pulmonary physiology, the factors determining rate of flow in the airways.

For a volatile anesthetic agent, the time constant (τ) is volume divided by flow. From the standpoint of the anesthesia circuit, the time constant is the volume of the circuit divided by the fresh gas flow rate (units of L divided by L/min results in min). From the standpoint of the lungs, the time constant is the volume of the lungs (FRC) divided by the minute ventilation. It takes three time constants for 95% of a concentration change to be achieved.

Time Constant (τ)

• Definition (circuit): volume of the circuit divided by the fresh gas flow rate
• Definition (lungs): volume of the lungs (FRC) divided by minute ventilation
• Meaning: it takes three time constants for 95% of a concentration change to be achieved