Respiratory system: Overview

Functions of the respiratory system
Upper and lower respiratory tract.
~ 3 min

The respiratory system (systema respiratorium) is comprised of various organs that work together to facilitate gas exchange in the human body.

Respiratory system (systema respiratorium)
Respiratory system (systema respiratorium)

Gas exchange refers to the process of inhaling oxygen from the air and transferring it to the bloodstream, while simultaneously releasing carbon dioxide from the bloodstream into the exhaled air.

The respiratory system is divided into two main parts:

  1. Airways (or the upper respiratory tract), which serve to conduct air, warm it, humidify, and purify it.
  2. Respiratory part (or the lower respiratory tract), which is the site of gas exchange.

The vocal cords are the border between the upper and lower respiratory tract.

Vocal cords (plicae vocales)
Vocal cords (plicae vocales)
Vocal cords (plicae vocales)
Vocal cords (plicae vocales)

Let’s take a closer look at the parts of the respiratory system and the process of gas exchange.

The respiratory tract originates from the nasal region, which includes the external nose and the nasal cavity.

External nose (nasus externus)
External nose (nasus externus)
External nose (nasus externus)
External nose (nasus externus)

The nasal cavity, in turn, is divided into respiratory and olfactory regions. The respiratory region consists of nasal meatuses, which conduct air.

Then the air passes into the larynx, where it passes further and creates sound for the voice. This is the function of the vocal ligaments.

Larynx (larynx)
Larynx (larynx)
Vocal cords (plicae vocales)
Vocal cords (plicae vocales)

The larynx continues into the trachea. The trachea is virtually a hollow tube, which freely passes air further into the right and left main bronchi.

Trachea (trachea)
Trachea (trachea)

The main bronchi are divided into lobar bronchi, which in turn are divided into segmental, subsegmental, and interlobular bronchi.

Right main bronchus (bronchus principalis dexter)
Right main bronchus (bronchus principalis dexter)
Left main bronchus (bronchus principalis sinister)
Left main bronchus (bronchus principalis sinister)
Segmental and interlobular bronchi
Segmental and interlobular bronchi

Then the diameter of the bronchi becomes so small that they turn into bronchioles. Terminal bronchioles are further divided into primary, secondary, and tertiary respiratory bronchioles.

Terminal bronchiole
Terminal bronchiole
Respiratory bronchiole
Respiratory bronchiole

The smallest bronchioles pass into the alveolar ducts, which end in alveolar sacs and alveoli.

Alveolar ducts (ductuli aveolares)
Alveolar ducts (ductuli aveolares)

The bronchoalveolar system corresponds to the structure of the lung itself.

Alveolar sacs (sacculi alveolares)
Alveolar sacs (sacculi alveolares)
Alveoli (alveoli)
Alveoli (alveoli)

The right lung contains three lobes, and the left one contains two lobes. Each lobe consists of several segments.

Segments of the left lung
Segments of the left lung
Segments of the right lung
Segments of the right lung

The respiratory system does not work independently. The thoracic cage participates in breathing. The movements of the diaphragm contract and expand the thoracic cavity, and the intercostal muscles additionally expand it in the anteroposterior direction. Forced respiration involves the muscles of the abdomen.

When the air has completely passed all the airways, it enters the respiratory part, and there, in the final structure of the lung called the acinus, it overcomes the air-blood barrier.

Capillary network of ronchioles
Capillary network of ronchioles

Here, oxygen molecules penetrate through the membrane formed by the wall of the alveolus and capillary and linger on red blood cells. And carbon dioxide goes through an exact opposite process.

Dictionary

Respiratory system: Overview

Respiratory system
systema respiratorium
Vocal cords
plicae vocales
External nose
nasus externus
Nasal cavity
cavitas nasi
Larynx
larynx
Trachea
trachea
Right main bronchus
bronchus principalis dexter
Left main bronchus
bronchus principalis sinister
Alveolar ducts
ductuli aveolares
Alveolar sacs
sacculi alveolares
Alveoli
alveoli
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