Final answer:
The pressure measurable within the mouth during breathing is known as intra-alveolar or intrapulmonary pressure, which always equalizes with the atmospheric pressure.
Step-by-step explanation:
The pressure that can be measured within the mouth is known as intra-alveolar pressure or intrapulmonary pressure. This is the pressure of the air within the alveoli of the lungs, and it changes during the different phases of breathing. The intra-alveolar pressure always equalizes with the atmospheric pressure as the alveoli are connected to the atmosphere through the airways.
Measuring various pressures within the body, such as blood pressure or intraocular pressure, provides important medical indicators. For example, the shape of the eye is maintained by the intraocular fluid pressure, while blood pressure measurements are routine health checkups to assess cardiovascular health.