The respiratory system is one of the favorites of our production team. Creation of pulmonary alveoli medical animation was an excellent opportunity to show their masterpiece. We hope you enjoy this fragment.

Pulmonary alveoli medical animation

Functions of the pulmonary alveoli

Pulmonary alveoli are an essential part of our respiratory system whose primary purpose is to exchange oxygen (O2) and carbon dioxide (CO2) molecules to and from the bloodstream by the process of diffusion. They are tiny, balloon-shaped air sacs sitting at the very end of the respiratory tree and arranged in clusters throughout the lungs. During inhalation, the air travels down the pharynx, larynx, and trachea into the bronchi, entering the lungs through the bronchioles to reach the alveoli. When the inhaled air reaches the alveoli, the oxygen passes into the blood due to a low partial pressure of oxygen in them.

On the other hand, carbon dioxide moves into a low CO2 pressure region in the alveoli from a high CO2 pressure region in the capillaries. The type-2 alveolar cells present in the alveoli, produce surfactant, a fluid that lines each alveolus. It helps to maintain their shape and surface tension, keeping them from collapsing during the process of breathing.

How does a pulmonary alveolus look like?

A pulmonary alveolus has a shape of a hollow cavity located in the parenchyma of the lung. It is the functional unit of lungs and the basic unit of ventilation. A capillary network covers about 70% of the area of each alveolus. An alveolus of an adult human has an average size of two hundred micrometers in diameter, which increases during inhalation.

Pulmonary alveolus microanatomy

It consists of an epithelial layer and an extracellular matrix surrounded by capillaries. In some alveolar walls, there are pores between the alveoli called Pores of Kohn. The alveoli also contain collagen fibers and elastic fibers. The elastic fibres allow the alveoli to stretch and expand when filled with air during inhalation and spring back during exhalation to expel the carbon dioxide-rich air. The alveolar wall consists of three major types of cell – two types of alveolar cells (also known as pneumocytes) and a large phagocyte known as an alveolar macrophage.

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