Question

air from the outside environment first enters the respiratory system through the
nasal cavities
nostrils

Answer 1

Corrected sentence:
- Air from the outside first enters the respiratory system through the nostrils (external nares) into the nasal cavities.

Quick clarification and context:
- Nostrils (external nares) are the external openings; the nasal cavities are the internal spaces behind them.
- In the nasal cavities the air is warmed, humidified, filtered (nasal hairs, mucus, cilia) and guided by the nasal conchae/turbinates.

Usual airway pathway after the nasal cavities:
- Nasal cavities → pharynx (nasopharynx) → oropharynx → laryngopharynx → larynx → trachea → primary bronchi → branching bronchi/bronchioles → alveoli.

Note: Air can also enter through the mouth (oral cavity), especially during heavy breathing.