We explain what the respiratory system is, what its organs and functions are. In addition, its characteristics and possible diseases.

What is the respiratory system?

The respiratory system is the set of organs that intervene in respiration. This system is responsible for the distribution of oxygen in the body. It is responsible for capturing oxygen and removing carbon dioxide from the body.

The organs of the respiratory system are not found in all living beings in the same way. Some animals have a type of respiration in which the cells do not carry oxygen to the rest of the body. Rather, their breathing is cutaneous. Examples of these animals are sponges or coelenterates.

Some beings have a respiratory system made up of gills. Others, meanwhile, have lungs. Evolutionarily speaking, branchial respiration is said to be more primitive than pulmonary respiration.

As for the respiratory system of human beings, it has lungs and takes 26,000 daily breaths while a baby breathes up to 51,000 times a day.

Organs of the respiratory system

The respiratory system is made up of different organs: nasal passages, nasal cavity, oral cavity, pharynx (which is also part of the digestive system ), larynx (here are the vocal cords), epiglottis (it is in charge of closing the trachea while the person is eating), trachea (cartilaginous tubes that retain dust particles), bronchi, bronchioles, pulmonary alveoli, and lung.

Functions of the respiratory system

Functions of the respiratory system

The main functions of the respiratory system are:

  • Provide the oxygen necessary for the body to live. When inhaling the person inhales oxygen. It is the respiratory system that is responsible for transporting it to the blood to provide oxygen to the different organs of the body.
  • Eliminate carbon dioxide from it, by exhaling the air.
  • Warm the air that is inspired.
  • Filter and clean the oxygen itself.


For its study, it is classified into 2 zones.

  • Driving zone. This includes all the anatomical zones that oxygen passes through before reaching the next zone (respiratory zone).
  • Respiratory zone. It is the area where gas exchange happens.

Types of alveolar cells

Types of alveolar cells

In the respiratory system there are two types of cells that fulfill different functions:

  • Type I pneumocytes. These cover between 95% and 97% of the total surface area of the lungs.
  • Type II pneumocytes. These cells are found in less quantity (only between 3% and 5%). They secrete a substance called lung surfactant. This substance prevents tension within the alveoli. In this way, they prevent them from collapsing. This surfactant is made up of phospholipids and proteins.

Properties of the lungs

Properties of the lungs

  • Adaptability. In other words, the lungs exchange air. This causes some expansion or dilation of the lungs.
  • Elasticity. Although they have the particularity of dilating, they contract thanks to this elasticity they have and which is necessary thanks to the fact that they have elastin proteins.
  • Surface tension. It refers to the tension that occurs within the alveoli.

Muscles that act on the respiratory system

Although the muscles do not belong to this respiratory system, they act and intervene in respiration.

  • The muscles involved in inspiration :

    • Sternocleidomastoid
    • Scalenes
    • External intercostals
    • Para-sternal intercostals
    • Diaphragm

  • The muscles involved in expiration :

    • Internal intercostals
    • External oblique of the abdomen
    • Internal oblique of the abdomen
    • Transverse abdomen
    • Rectus abdominis

Pulmonary ventilation

Pulmonary ventilation

It is a process that allows both the movement of air into the lungs (inspiration) and out (expiration). Although only two moments appear here, there is certainly another moment that little is taken into account: the moment without expiration or inspiration. That is to say, the moment of rest.

Lung capacity

There are different volumes of oxygen that enter the lungs. This is how they differ between:

  • Tidal volume. It is the normal or usual volume that enters the lungs.
  • Inspiratory reserve volume. It is called the type of oxygen that enters the lungs through excess and does so in a forced way.
  • Expiratory reserve volume. It is the amount of air that is forced out of the body and excessively.
  • Vital capacity. It refers to the amount of air that can be exhaled after a forced inspiration.
  • Residual rate volume. It is the amount of air that remains inside the lungs permanently. In the case of adult humans, this amount can be up to 1.5 liters.
  • Total lung capacity. It is the maximum amount that the lungs can hold.

Unusual breathing functions

Unusual breathing functions

  • Cough. It is a reflex action that can come from the nervous, respiratory or digestive systems.
  • The hiccups. It is an involuntary contraction of the diaphragm.
  • The sneeze. Which occurs as a response to irritation from dust particles or odors.
  • Yawning. Related to the nervous system and associated with physical and mental fatigue and with the person's sleep levels. This is also a way to increase the blood supply to the brain.
  • The sigh. It is a way to level the volume of air that enters the brain.
  • Laughter. From the point of view of the respiratory system, laughter comprises a series of actions that release air from the body in a short, weak, and intermittent manner.

Diseases of the respiratory system

Diseases of the respiratory system

Some specific diseases or pathologies that affect the respiratory system:

    • Bronchial asthma
    • Pulmonary edema
    • Lung infarction
    • Respiratory insufficiency
    • Viral or bacterial infectious diseases.
    • Cancer of the lung, larynx, trachea, pharynx, etc.

Take your General Knowledge to the next level

The above content published at Collaborative Research Group is for informational and educational purposes only and has been developed by referring to reliable sources and recommendations from technology experts. We do not have any contact with official entities nor do we intend to replace the information that they emit.


MA student of the TransAtlantic Masters program at UNC-Chapel Hill. Political Science with a focus on European Studies. Expressed ideas are open to revision. He not only covers Technical articles but also has skills in the fields of SEO, graphics, web development and coding. .

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