Question

Dead space air in man is
A.Five hundred mL
B.One hundred and fifty mL
C.Two hundred and fifty mL
D.One and a half liter

Answer 1

The dead space is the volume of air that is inhaled that does not take part in the gas exchange, because it either remains in the conducting airways or reaches the alveoli that are not perfused or poorly perfused.

Complete answer: An atomic dead space is the total volume of the conducting airways from the nose or mouth down to the level of the terminal bronchioles and is about one hundred and fifty ml on average in humans.
The anatomic dead space fills with inspired air at the end of each inspiration, but this air is exhaled as unchanged.
Therefore, the correct answer in option B.

Additional information:
There are two different ways to define the dead space an atomic and the physiologic.
Anatomic dead space is the total volume of the conducting airways from the nose or from the mouth down to the level of the terminal bronchioles and is about one hundred and fifty ml on average in humans.
Physiologic dead space includes the dead space of the upper airways but also accommodates for the dead space in the alveoli that do not take part in the gas exchange for a number of reasons.

Note: The dead space ventilation that is VD is then calculated by multiplying VDphys by the respiratory rate that is RR.
Total ventilation that is VE is, therefore, the sum of the alveolar ventilation that is Valv and the VD.
The Enghoff's equation compiles these variables, tidal volume that is TV.