Human respiratory system : Parts, Function, Disorder

The process of exchange of O2 from the atmosphere with CO2 produce by the cells is called Breathing. Commonly know as Respiration.


The Human respiratory system is the organ and tissue that help your breath. It include your airway, lungs and blood vessels. The muscles that power your lungs are also important for the Human respiratory system. These part work together to exchange of O2 from the atmosphere with CO2 produce by the cell is called breathing. Commonly know as respiration.

Human Respiratory System Diagram

Human respiratory system : Parts, Function, Disorder

Parts of Human Respiratory System

There are different part of Human respiratory system are as follows:


Human have a pair of external nostrils opening out above the upper lip. External nares open in vestibule region present in anterior part of nasal passage. Vestibule posteriorly connected with nasal chambers. Small hair’s follicle that cover the interior lining of nostrils act as the body’s first line to protect against unfamiliar microbes. Furthermore, they give extra moistness to breathed in.


Larynx is a cartilaginous box with helps in sound production and hence called the sound box. It is found in front of the neck and is responsible for vocal as well as aiding respiration. At the point when food is swallowed, a flap called epiglottis folds over the top of the windpipe and prevent food for going into the larynx.


The nasal chamber open up into a wide empty space called the pharynx. It is a common entry for air as well as food. At the time of swallowing of food, the Uvula lifts up and covers the internal-nares and so prevent the food from entering the nasal-passage. Near the glottis, a flat elastic cartilage called the Epiglottis is present. At the time of swallowing of food , this cartilaginous flap covers the glottis. During swallowing breathing stops. Pharynx is a common passage for food and air.


The trachea, commonly know as wind pipe. It is connect the larynx to the bronchi of lungs. In the trachea 16-20 ‘C’ shaped cartilaginous ring are present which prevent trachea from collapsing. These rings are incomplete on dorsal surface of trachea. The trachea extends further down into the breastbone and splits into two bronchi, one for each lungs.


The trachea inter each lung individually. It is divided into two branch secondary and tertiary bronchioles, and if further branches out into small air-sacs called the alveoli. The alveoli are single-celled sacs of air with thin walls. Exchange zone is the actual site of the diffusion of oxygen and carbon dioxide between blood and atmospheric air.


A pair of lungs are present in the thoracic-cavity of the chest. It is the primary organs of respiration in human and other vertebrates. Lungs are covered by a double-membrane which are called the Pleural-membrane. Outer membrane is the Parietal pleura and inner-membrane is the Visceral-pleura. Both these membranes are derived from the mesoderm.

The outer pleural membrane is in close contact with the thoracic where as the inner pleural membrane is in contact with the lung surface. In between both the membrane narrow cavity called Pleural-cavity is present. In this cavity a very thin layer of Pleural fluid is present. Pleural fluid reduced friction on the lung surface.

In human right lungs are made up of 3 lobes and left lungs are made up of 2 lobes.

Respiratory Tract

A passage by which air enter into lungs. Respiratory tract is made up of following part:

External nostrils – Nasal chamber – Internal nares – Pharynx – Larynx -Epiglottis – Trachea – Bronchi – Bronchioles – Alveoli – Lungs

External nostrils

The route for air entry into the Human respiratory system.

Nasal chamber

Air travel through these passages during breathing. The nasal passages filter and warm the air, and make it moist before it goes into the lungs.


It is a section behind the nasal chamber and the common passage for food and air.


Larynx is a cartilaginous box which helps in sound production and hence called the sound box.


A flat elastic cartilage structure that cover the glottis and prevent the entry of food into the windpipe.


It is a 10-12 cm long straight tube extending up to the mid thoracic cavity.


Trachea divided into left and right bronchi.


Every bronchus is additionally divided into finer channels know as bronchioles.


The bronchioles end in balloon-like structures know as the alveoli.


A pair of lungs are present in the thoracic-cavity, which are sac-like structures and covered by a double-membrane which are called the pleura.

Air is breathed with the help of of nostrils, and in the nasal cavity, the air is cleansed by the fine hair follicles present inside them. The cavity also has a group of blood vessels that worm the air. This air then passes to the pharynx, then to the larynx into the windpipe.

The windpipe and bronchi are covered with ciliated cells and goblet cells (secretory cells) with release mucus to moisten the air as it passes through respiratory tract. It also traps the fine pieces of dust or microorganism that escaped the hair in nasal opening. The motile cilia beat in an ascending motion, such that the mucus and other foreign particles are carried back to the buccal cavity where it my either be coughed out.

When the air reaches the bronchus, it moves into the bronchioles, and then into the alveoli.

Human Respiratory System Functions

The function of human respiratory system are :

Inhalation and Exhalation

Inhalation during which atmospheric air is drawn in the nose and moves through the pharynx, larynx, trachea and into the lungs. Exhalation by which the alveolar air is released out through the same pathway. Change in the volume and pressure in the lungs help in pulmonary ventilation.

Exchange of Gases between Lungs and Bloodstream

Alveoli are the primary sited of exchange of gases. Exchange of gases inside the lungs, the oxygen and carbon dioxide enter the exit individually through millions of microscopic sacs called alveoli. The breathed oxygen in oxygen diffused into the pulmonary capillaries, bind to hemoglobin and is pumped through the bloodstream. The carbon dioxide from the blood diffuses into the alveoli and is outside through exhalation.

Exchange of Gases between Bloodstream and Body Tissues

The exchange of gases between the blood and tissue cell in internal breath. The blood carries the oxygen from the lungs around the body and releases the oxygen when it reaches the capillaries. The oxygen is diffused through the capillary walls into the blood tissues. The carbon dioxide also diffuses into the blood and is carried back to the lungs for release. Gases exchange by passive activity. It is done by a simple diffusion.

The vibration of the Vocal Cords

The vocal cords produce sound when the come together and then vibrate as air passes through them during exhalation of air from the lungs. This vibration produce the sound wave for your voice.

Olfaction or Smelling

During inhalation breath, when the air inters the nasal cavities, few chemicals present in the air bind it and activate the receptors of the sensory organ on the cilia. The signals are sent to the olfactory bulbs via the brain.

Respiratory Disorder


Asthma is a difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles.


Bronchitis is a disorder of bronchi in which there is regular swelling and itching of bronchi and itching of bronchi and is characterised.


Emphysema is a chronic disorder in which alveolar walls are damaged due to which respiratory surface is decreased. One of the major causes of this is cigarette smoking.

Occupational Respiratory Disorder

In certain industries, especially those involving grinding or stone-breaking, so must dust produced that the defense mechanism of the body cannot fully cope with the situation. Long exposure can give to inflammation leading to fibrosis and thus causing serious lung damage. Workers in such industries should wear protective masks.

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