An important part of the Respiratory system Alveoli  facilitates exchange oxygen and carbon dioxide molecules to and from the bloodstream. They are the Smallest balloon shaped passage way in the respiratory system. The alveoli allows easy passage of oxygen(O2) and carbon dioxide (CO2) between the alveoli and blood capillaries.

Around 170 alveoli. / cmm of Lung tissue., On an average 600 millions Alveoli within the human lungs .

There are different types of PNEUMOCYTES present in Alveoli

Macrophages (immune cells) in the alveoli,  which acts as “garbage trucks” of the immune system, and phagocytize or “eat” debris they come across suchas  dead bacteria,Viruses

Because the concentration of oxygen is lower in the capillaries diffusion of O2 from the alveoli to capillaries occur.,               Similarly, where the concentration of carbon dioxide is lower in Alveoli CO2 diffuses from the capillaries to the alveoli

Negative pressure in the chest is created by contraction of the diaphragm leads to expansion of Alveoli leads to O2 inhalation.            The alveoli recoil (spring back) as the diaphragm relaxes during exhalation of CO2

Acute Respiratory Distress Syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) is a condition of Respiratory system that prevents oxygen transport to the lungs because of fluid accumaltion in the alveoli (Pulmonary Edema). Patients affected with viral infections such as  COVID-19 Pandemic suffer ARDS which leads to Respiratory failure .


Persistent exposeure to Nicotine and other toxic fumes Alveolar damage occur to the molecular level and leads to irreparable and irreversible leading to permanent Lung damage and HYPOXIA.

A Word From indofrench

One of the most important functions our body is The Alveoli function which facilitates Oxygen enters our bloodstream and every cell for Energy production (ATP) and  expulsion of the waste products of metabolism (carbon dioxide) from the body.

Viral infections such as COVID-19 affect the alveoli can result in reduced oxygen being delivered to the tissues of our body, and finally to a situation is known as HYPOXIA  which could be fatal.