Define the Concept of Partial Pressure of a Gas and Explain the Different Partial Pressures of Oxygen and Carbon Dioxide Found in Atmospheric Air, Alveolar Air, Blood and Tissues

in contact with water, what happens to gas molecules

In contact with water, gas molecules will dissolve - more will dissolve if the partial pressure of the gas increases.

what is reached when the number of molecules of a given gas entering and leaving solution is equal

When the number of molecules of a given gas entering and leaving solution during a given unit of time is equal, this is a dynamic equilibrium.

At this point, the partial pressure of the gas molecules in solution can be said to be equal that of the molecules in the gas phase.

what does hyperventilation lead to

Hyperventilation will cause excess loss of CO2 leading to a drop in PaCO2 = hypocapnia.

what does hypoventilation lead to

Hypoventilation will cause reduced PAO2 and increased PACO2.

In turn, this leads to reduced PaO2 (hypoxia) and increased PaCO2 (hypercapnia).

dead space

Dead space → areas which are ventilated but don't participate in gas exchange.

examples of dead space

Airways = anatomical dead space

Unperfused alveoli = functional dead space

what happens to dead space during inspiration

During inspiration, dead space gas fills alveoli before fresh air gets there - shallow breathing exacerbates this (panting).

Equipment that we use for anaesthesia for example can also be dead space

Equipment that we use for anaesthesia for example can also be dead space:

* Circuits
* ET tubes