Respiratory System & Lungs: Basic Information

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Respiratory System & Lungs: Basic Information
Respiratory System & Lungs: Basic Information

Video: Respiratory System & Lungs: Basic Information

Video: Respiratory System & Lungs: Basic Information
Video: Respiratory System, Part 1: Crash Course A&P #31 2023, September

Respiratory system & lungs: basic information

Breathing is an involuntary process - it does not require conscious control. The chest or stomach rises and falls. Only when breathing is disturbed (e.g. by sudden shortness of breath) or when we concentrate on it, do we draw our attention to it. Breathing enables the supply of vital oxygen. A healthy adult breathes in and out about twelve to fifteen times per minute.


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  • Breathing - vital gas exchange
  • Control center brain
  • Airways as "gatekeeper"
  • Respiratory system lungs and its functions

Breathing - vital gas exchange

A distinction is generally made between “internal” and “external” breathing. A chemical process takes place in “internal” respiration - cell respiration. Organic compounds are changed (oxidized) under the influence of oxygen so that the cells can gain energy. The gas exchange between the lungs and blood is referred to as "external respiration": Oxygen enters the body while carbon dioxide is removed. The inhaled air penetrates through branched and increasingly smaller airways (bronchi) into the alveoli, where the gas exchange takes place. The breathing muscles enable inhalation and exhalation through their pumping action. While we calmly inhale and exhale about five liters of air per minute,this amount increases twenty-fold with physical exertion.

Control center brain

The brain controls the involuntary breathing activity: the breathing center is located in the elongated spinal cord and the cervical spinal cord. Nerve fibers then run from the cervical and thoracic spinal cord to the respiratory muscles and activate them.

The respiratory center continuously receives feedback from the body's own measuring stations (e.g. in arteries, in the lungs and in the chest) about the current breathing status. The oxygen saturation of the blood, the proportion of carbon dioxide and the pH value in the blood and liquor (fluid in the central nervous system) are the important data for the rhythm generator.

Airways as "gatekeeper"

Graphic representation of airways and lungs © snapgalleria

Before the oxygen reaches the lungs, the air must first pass through the airways. They perform a number of important respiratory roles. The airways include:

  • nose
  • mouth
  • Nasopharynx
  • Larynx
  • windpipe
  • Bronchi and bronchioles

The nose, mouth, nasopharynx and larynx are part of the upper airways - the trachea, bronchi and bronchioles are part of the lower airways. The air is warmed or cooled in the respiratory tract when inhaled, so that the temperature in the nasopharynx is constant. In addition, small particles (soot, dust, pollen etc.) and pathogens (e.g. bacteria, fungal spores or viruses) are "filtered" or fall victim to a self-cleaning process. The mucous membrane of the respiratory tract is normally well moistened. Microscopic cilia (cilia) transport unwanted substances towards the nose and mouth in regular wave movements. The secretion is removed from the body or swallowed by clearing the throat or coughing. If the cilia are damaged or destroyed (e.g.smoking or COPD) leads to irritation of the throat and reduced self-cleaning of the airways.

Respiratory system lungs and its functions

The lungs (called pulmo in Latin) are located in the chest above the diaphragm. The space between the two lungs is called the mediastinum: the mediastinum accommodates the heart, large blood vessels, thymus, esophagus and lymph nodes. The term "one lung with two lobes" is widely used. In anatomical jargon, however, a distinction is made between two lungs: the right and left lungs. These differ somewhat in shape and size as the heart reduces the space for the left lung. However, the left lung can expand more downward - due to the contour of the diaphragm. The average volume of air in a lung is two liters.

The lungs in detail

You can visualize the lungs when you think of a tree upside down. The trachea forms the trunk. On the right and left are the two lungs (colloquially the lungs). In each of the two lungs there is a main branch of the bronchi, which branches off from the trachea. The bronchi branch out more and more and become increasingly smaller in diameter. This is followed by the smallest bronchi (bronchioles), which split up like twigs. At the end of the bronchioles are the alveoli. Humans have around 300 million alveoli.

Oxygen in - carbon dioxide out

Gas exchange with human blood takes place in the alveoli. The alveoli are surrounded by a dense network of tiny pulmonary vessels (capillaries). Oxygen is exchanged for carbon dioxide, which is produced in the body, and is exhaled through the lungs. Only the air that penetrates into the alveoli takes part in the gas exchange. The remaining volume in the airways is called dead space. After oxygen has been absorbed from the alveoli into the blood vessels, the oxygen travels with the red blood cells as a transporter to all regions of the body. Since the exchange of carbon dioxide and oxygen only works in the alveoli, it is important for the supply of the body that the air you breathe can flow there unhindered. But this is only possibleif the way to the alveoli is permeable.

Other functions of the lungs

In addition to its main task of breathing, the lungs also fulfill other functions. The main tasks for them are:

  • Acid-base balance: The lungs play an essential role in the acid-base balance. The pH value in the blood is constant on average 7.40. To keep this value in balance, breathing can be increased or decreased to a certain extent. If more carbon dioxide is exhaled, the blood becomes more basic (ie the pH value rises). If you breathe less, more carbonic acid builds up in the blood and the blood becomes more acidic (ie the pH value drops).
  • Conversion of hormones: e.g. angiotensin I into angiotensin II. Angiotensin is essential for regulating blood pressure.
  • Removal of substances from the bloodstream: e.g. serotonin.
  • Regulation of blood volume: the pulmonary circulation serves as a collection container for blood.
  • Filters for small blood clots: The lungs catch the clots before they can cause damage to the heart or brain, for example.