human respiratory system and mechanics of breathing

 Every breath we take allows us to move , talk and live , we take oxygen through our respiratory system naturally , and we do so without even thinking about it . 


Where the respiratory system is an important organ , to maintain human health .


human respiratory system function

The main function of the respiratory system includes moving air in , and out of the lungs .  And protect the body from harmful particles that are inhaled .


Its most important function is the exchange of oxygen , and carbon dioxide .


It transports oxygen to the lungs and then to the rest of the body , and at the same time it transfers carbon dioxide , from different parts of the body to the lungs and then outside the body.


It supplies cells with oxygen necessary for activities , and removes carbon dioxide .


The respiratory system provides oxygen to the human body , which is important for the life of cells , tissues , and is also used to remove toxic gases from the body ; Which is eliminated by breathing ” inhale and exhale ” .


As it consists of small branching tubes , these branches contain very small chambers . 


The gas exchange takes place on the wall , as the respiratory system is made up of a group of organs that work together , to make the system function normally .


Now we will review , the main components of the respiratory system :

respiratory system

Respiratory system components

 1) – nose :


  • Nose is the passage for breathing in air, and it is also responsible for the sense of smell . 


  • The nose has the primary function of moistening the air entering the lungs , and preventing fine particles from passing through , by sticking to the mucous membrane of the nasal cavity .


  • At the beginning of the airway, the nasal cavity is separated from the mouth by the soft, hard pad .  The nasal cavity is divided into two parts (the left and right part) by the herniated septum. 


  • The inner cavity is lined with a membrane covered with mucous cells , which moisturizes and helps warm the inhaled air .  The nasal cavity also contains the sensory end , to the olfactory nerve .


2) – paranasal sinuses :

  • They are airways connected directly to the oral cavity , which are the “maxillary sinus , frontal sinus , lacrimal sinus, palatine sinus , and sphenoid sinus” .


3) – Pharynx :


  • pharynx is part of the digestive as well as the respiratory system, and it connects the airways to the larynx and esophagus. 


  • Because food and air pass together, it is a muscular tube about 12 cm long .  Above the throat is a small cartilage called “cartilage”.


  • When air or water enters, the air separates from the food.  This cartilage seals the windpipe so that neither food nor water can enter it and cause suffocation .


  • But when air enters , the cartilage remains open , allowing air to pass through the windpipe and then into the lungs .


4) – Larynx “throat” :

  • It is the tube of cartilage responsible for expressing the tones , so it is called the voice box. 


  • The epiglottis is located at the upper end of the throat .  The glottis is the active muscle between the esophagus and the opening of the windpipe . 


  • The glottis blocks the esophagus when breathing in , and the windpipe opens when swallowed to prevent food from entering the lungs .


5) – Trachea:

  • It is an incomplete cartilaginous ring, “Crescent C,” in which the tracheal wall is made of a lot of cartilage .  But this cartilage only covers the front part of the windpipe, while the posterior part of the wall is made up of muscles instead of cartilage. 


  • This structure makes the trachea strong , and open to allow air to circulate , while also making it flexible , allowing the muscles in the tracheal wall to contract .


  • trachea is the main channel for air to enter and exit the lungs .  The inner wall of the trachea is covered by a refined mucous membrane , which cleans the respiratory tract dust and foreign bodies , which are usually associated with the inhaled air .


6) – Bronchial :

  • The bronchi are similar in structure to the muscle and cartilage structure of the trachea.  


  • trachea branches into two main “bronchi” branches.  At its ends, one branch connects to the right lung, while the other branch connects to the left lung. 


  • The bronchi branch into small secondary branches , and terminate in the alveoli that form the lung lobes .


7) – Alveoli :

  • In the lungs there are about 300 million alveoli .  These vesicles are surrounded by a very fine capillary network ‘capillaries’. 


  • The interference and coordination between the oxygen-carrying air in the outside air , and the carbon-dioxide-carrying blood from the heart leads to the transport of oxygen from the alveoli, then to the capillaries . 


  • thus transfer it to all parts of the body, and removes carbon dioxide at the same time from the body .


lungs main function

 8) – lungs :

  • lungs are located in the thoracic cavity , and are surrounded by visceral crystal membranes.


  • in the cavities of the rib wall , sternum , and spine , and are supported by the diaphragm .


  • They are resonant, spongiform organs, which include the bronchial tree made up of alveoli . 


  • The lumen of each vesicle is divided into many bulges , and these bulges are alveoli that increase the volume of the inner surface of the air .


  • The alveoli converge to form the alveoli , and the alveoli converge to form cone-shaped masses called lung lobes.


  • The three lung lobes converge in the right lung, while there are only two in the left lung.


Perhaps the question now is why are three on the right side, and why two on the left? 


Because there is a small cut in the lungs, and it is called a cardiac fissure, because our heart is sitting a little to the left, and we need to make room for the heart.


So there is a little less lung on the left side, and thus there is less space for the lobes, so there are only two lobes on this side.


9) – Pleura :

  • Each lung is surrounded by two lobes called the pleura, and each membrane consists of two sheets. 


  • The inner leaf is attached to the lungs , and the outer leaf is attached to the inner surface of the rib cage and separates them .


10) – Pulmonary vascular :

  • The pulmonary artery flows from the right ventricle and divides into two parts , each part entering the lungs and extending parallel to the windpipe.


  • It branches like branches until it ends at the periphery of the pulmonary alveolus , forming abundant capillary networks around it. 


  • The meeting of capillaries results in venous branches that converge to form two veins in each lung . and the four pulmonary veins exit and pour into the heart into the left atrium. 


  • Since the walls of the pulmonary alveoli are very thin , the blood in them and the air of the alveoli are in direct contact with a very wide surface , and then there is a “pulmonary gas exchange” .


 mechanics of breathing

  • Respiration is a complex process carried out by the respiratory system . 


  • First, air must enter and leave the lungs, then gas exchange between the air and blood and between blood and cells . 


  • The respiratory system strictly controls these substances.


 mechanics of breathing

 The purpose of the respiratory system is to exchange oxygen and carbon dioxide, between the tiny alveoli and the blood.  Air enters through the nose or mouth, then reaches the trachea through the larynx.


  The trachea divides into the left and right bronchi and reaches the lungs. The lungs expand and contract with the movement of the rib cage and diaphragm.


 Inhalation refers to the process of air entering the lungs. When inhalation occurs, the diaphragm muscles that separate between the chest and abdomen contract, so the diaphragm moves downward, and the intercostal muscles move between the ribs to the outside. 


This leads to an increase in the chest cavity and a decrease in air pressure in the lungs.  This creates a difference between the air pressure and the air pressure in the lungs.  Thus it pushes air from the nasal passage into the lungs to equalize the pressure.


 But during exhalation, the diaphragm muscles relax, the chest cavity decreases, and the air pressure in the lungs increases.  This leads to the flow of air from the lungs into the atmosphere.


 Gas exchange

 The bronchi branch into a tree-like shape, and the tiniest branches are called bronchioles.  At the end of the bronchi are many tiny air sacs called alveoli, in which air and gases exchange with the blood through the alveolar walls.


 Gas exchange occurs between the alveoli and the capillaries that surround them.  The alveoli are filled with air rich in oxygen and low in carbon dioxide. 



While the blood in the capillaries is rich in carbon dioxide and the percentage of oxygen in it is low, so the oxygen is transferred from the alveoli to the blood in the capillaries by simple diffusion, and the oxygen-rich blood moves to the heart to be distributed to the various parts of the body.  


A similar exchange takes place between the capillaries surrounding the cells and the tissues. Oxygen moves from the capillaries to the cells, and carbon dioxide moves from the cells into the blood, which carries it through the veins to the heart.


 The lungs are in direct and continuous contact with the external environment, in addition to increasing the number of potentially dangerous particles and gases. 


The lungs are also exposed to many infectious organisms.  However, the lungs have defense mechanisms, and in most cases, these mechanisms can successfully protect them from negative external influences.


 The moisture of all the breathing passages from the nose to the end of the bronchi is maintained by a layer of mucus, covering the entire surface. 


In addition to keeping the surface moist, mucus can also trap a small amount of air and prevent most of it from reaching the socket. 


Then the mucus is removed from the respiratory tract through cilia, which are small hair-like structures on the surface of the respiratory tract.


 Cilia are constantly moving and mucus moves slowly out of the lungs.  Then the mucus and particles on it are swallowed or coughed up.  This is called mucociliary clearance, and the respiratory system is protected by the immune system.


 Some notes on the breathing process

  •  1- The amount of air entering the lungs during inhalation is 3 liters.


  •  2- In adults, the number of breaths at rest is 12-16 breaths per minute.


  •  3- The amount of air that enters and leaves the lungs is about 6 liters per minute, and this amount can increase up to 10 times during strenuous exercises.


  •  4- The number of alveoli in the lungs is about 300 million.


  •  5- The amount of air in the lungs of an adult is about 6 liters for men, and about 5 liters for women.  As a person gets taller, the amount of air in the lungs increases, as does the height of a person.


  •  6- A person can live with one lung, if this lung performs its function properly.


 Maintaining and improving respiratory health

 1- It is extremely important to maintain a healthy weight exercise, and to avoid excess weight.  As the extra weight puts pressure on your lungs, it causes all of the respiratory muscles to work harder and less efficiently.


 Drinking lots of water. Dehydration can thicken the mucous lining, become sticky and make you more vulnerable to disease.


 Avoid smoking: due to smoking in oxidative stress inflammation, it causes cell death.  It can cause a whole host of diseases, including chronic bronchitis and lung cancer.


 One of the things you can do to improve your respiratory health is to boost your respiratory capacity.  



that by breathing through difficult exercises such as breathing through a straw can help improve the capacity of your lungs, by blocking the nose with a finger and breathing through a straw for one minute, like the racing team, especially if you suffer from chronic bronchitis.


 Learn to breathe yoga, learn how to breathe deeply to help your lungs function better over time, as it can increase your lung capacity.


 Eat foods rich in vitamins, especially folate, vitamin B12, minerals and antioxidants, such as vegetables, fruits and nuts, that can help reduce inflammation and fight oxidative damage. 



Foods rich in folate include dark leafy greens, rock beans, and lentils.  Seafood foods that contain vitamin B12 include oysters, beef, cheese, eggs and yogurt.


 Reducing exposure to common allergens such as dust mites, pollen, and animal dander.


 Maintain good hygiene, as viruses are transmitted due to poor hygiene and poor hand washing.


 Regular aerobic activity can help the respiratory system more health, as it helps in improving air quality, and has a great impact on overall health. Remember that people are happy when they are in good health, so stay healthy.