The boundary between conducting zone and respiratory zone structures occurs at the terminal bronchiole/respiratory bronchiole junction. The major respiratory structures span the nasal cavity to the diaphragm. Functionally, the respiratory system can be divided into a conducting zone and a respiratory zone. The conducting zone of the respiratory system includes the organs and structures not directly involved in gas exchange. The gas exchange occurs in the respiratory zone.
I'm pretty sure it's Cells
The number of times per week that exercise is performed is known as frequency.
Exercise frequency answers the question how many times you workout per week total. This includes weight training workouts, cardio workouts.This is value that can vary depends on many factors specific to individual (age, weight, condition). Because of this, it’s impossible to say exactly how often(how many times) everyone should be working out per week total.
Probably through a electron microscope either TEM or SEM. or possibly a picture through the microscope. I hope that helped.
