Question

Cluster of air sacs in lungs are called ___

• A. Bronchi
• B. Alveoli
• C. Bronchioles
• D. Air spaces

Hint:

Lung Anatomy. Airways: Trachea $\rightarrow$ Bronchi $\rightarrow$ Bronchioles $\rightarrow$ Alveolar ducts $\rightarrow$ Alveoli (Air sacs, site of gas exchange).

Answer 1

The Correct Option is B

The respiratory system involves a branching network of airways. Trachea branches into bronchi, which further branch into smaller bronchioles. The bronchioles terminate in clusters of tiny, thin-walled air sacs called alveoli (singular: alveolus). These alveoli are the primary sites of gas exchange (oxygen and carbon dioxide) between the air in the lungs and the blood in the surrounding capillaries. "Air spaces" is a general term. Bronchi and bronchioles are conducting airways. The functional units for gas exchange, which appear as clusters of sacs, are the alveoli.

Answer 2

The lungs are essential organs of the respiratory system responsible for the vital process of gas exchange, which sustains life by providing oxygen to the body and removing carbon dioxide.
The functional units within the lungs that make this gas exchange possible are called alveoli.
These alveoli are tiny, sac-like structures clustered together at the ends of the smallest air passages known as bronchioles.
Their unique shape and microscopic size allow for an immense surface area — roughly 70 square meters in total in an average adult human — which is crucial for efficient gas exchange.

Each alveolus is surrounded by a dense network of capillaries, where oxygen diffuses from the thin walls of the alveoli into the blood, and carbon dioxide moves in the opposite direction to be expelled from the body during exhalation.
The walls of alveoli are incredibly thin — only one cell thick — facilitating rapid diffusion of gases.
Moreover, the alveoli are coated with a special substance called surfactant, which reduces surface tension and prevents the alveolar sacs from collapsing, thereby maintaining their shape and functionality.

The clustering of alveoli allows for maximum exposure of inhaled air to the blood supply, ensuring that oxygen delivery meets the metabolic demands of the body's tissues and organs.
Damage to alveoli, such as in conditions like emphysema or pulmonary fibrosis, severely compromises lung function and the body's ability to oxygenate blood, illustrating the critical importance of these structures.
In summary, alveoli are not just simple air sacs; they are complex, highly specialized structures vital for breathing, oxygen transport, and overall survival.