Human respiratory system MCQ - Practice Questions & Answers

Quick Facts

Respiratory System in Humans

The human respiratory system is divisible into two portions:
- Conducting Portion:
  - Nose
  - Pharynx
  - Larynx
  - Trachea
  - Bronchi
  - Lobular and terminal bronchioles
- Respiratory Portion:
  - Respiratory bronchioles
  - Alveolar ducts
  - Alveolar sacs and alveoli
There is a pair of external nostrils opening out above the upper lips. It leads to a nasal chamber through the nasal passage.
The nasal chamber opens into the pharynx.
The pharynx opens through the larynx region into the trachea.
The larynx is a cartilaginous box which helps in sound production and hence called the soundbox.Larynx is made up of 9 cartilages out of which three are paired and three are unpaired
During swallowing, glottis can be covered by a thin elastic cartilaginous flap called the epiglottis to prevent the entry of food into the larynx.
The trachea is a straight tube extending up to the mid-thoracic cavity, which divides at the level of 5th thoracic vertebra into a right and left primary bronchi.
Each bronchus undergoes repeated divisions to form the secondary and tertiary bronchi and bronchioles ending up in very thin terminal bronchioles.
The tracheae, primary, secondary and tertiary bronchi, and initial bronchioles are supported by incomplete cartilaginous rings.
Each terminal bronchiole gives rise to a number of very thin, irregular-walled and vascularised bag-like structures called alveoli.
The branching network of bronchi, bronchioles and alveoli comprise the lungs.