The different organs of the respiratory system such as nose, larynx, trachea, bronchi, etc. carry out the process of respiration/breathing. All these organs play an important role in supplying oxygen to the body and allowing its smooth functioning.
The rate at which human beings breathe is 12-18 breaths per minute. There are 1440 minutes in 24 hours, therefore, the average number of breaths drawn in by a human (at a rate of 12 breaths per minute) in a day’s time is 17,280.
The main function of respiratory system is to allow gas exchange (oxygen and carbon dioxide) with different parts of the body. The different organs of the respiratory system are nose, pharynx, epiglottis, larynx, trachea, bronchi and lungs. These organs carry out the process of respiration.
The process of respiration is classified as aerobic and anaerobic. Aerobic respiration takes place in the presence of oxygen while anaerobic respiration doesn’t require oxygen. The organs of the human respiratory system carry out aerobic respiration and fulfill the oxygen demands of our body.
Organs of the Respiratory System
A detailed study of the respiratory system should help us understand the process of respiration. Functions of different organs in the respiratory system are presented below.
It is a respiratory organ through which air is inhaled and exhaled. Nostrils (also known as external nares) are the parts of the nose which facilitate the process of inhalation and exhalation.
1. Vestibule is a part of nostrils which is lined with coarse hair. It filters and humidifies the air entering the nasal cavity.
2. The nasal septum divides the nasal cavity in two parts. Superior and lateral walls of the nasal cavity are formed of nasal, maxillary, ethmoid, frontal and sphenoid bones. The floor of nasal cavity is formed of hard and soft palates.
3. Cartilage is an external part of the nose which forms the tip. The bony shelves which project from lateral walls of the nose are referred to as inferior, middle and superior nasal conchae.
4. Meatuses are the spaces present between conchae.
Pharynx is a tubular part of the respiratory system which allows the passage of air into lungs. It is located behind the nasal and oral cavities. Pharynx is connected to the skull cavity by means of muscles and connective tissues.
The different parts of pharynx are as follows:
1. Nasopharynx: It connects the upper portion of the throat with the nasal cavity.
2. Oropharynx: It is located between the soft palate and upper part of epiglottis.
3. Laryngopharynx: This part of the pharynx is located below the epiglottis. It opens into the esophagus and larynx.
It is a flap-like structure (epiglottis) which prevents food or water from entering the trachea at the time of swallowing.
1. Epiglottis is composed of cartilaginous tissue. It is located at the opening of larynx (back of the tongue); the epiglottis is covered with mucous.
2. Since the epiglottis gets abraded easily (it lies in the digestive tract), its surface is covered with a layer of non-keratinized and stratified squamous epithelial cells.
It is a part of the respiratory system which connects the trachea with laryngopharynx. The larynx controls the flow of air at the time of breathing.
1. The larynx, also known as sound box, is formed of cartilages.
2. Epiglottis, thyroid and cricoid are the three important cartilages of larynx; other cartilages present inside the larynx are corniculate, arytenoid and cuneiform.
3. Corniculate cartilage facilitates the flap-like action of epiglottis.
The trachea, also known as windpipe, extends from larynx to bronchi. In fact, the trachea gets branched into bronchi. It facilitates the flow of air towards the bronchi.
1. Trachea lies to the anterior side of the esophagus; it is tubular in shape with a diameter of 1 inch. and length of 4.25 inch. Its length spans between the 6th cervical and 5th thoracic vertebrae.
2. The trachea is composed of 15-20 C-shaped pieces of hyaline cartilage. These pieces are held together by tracheal muscles.
Bronchus (singular of bronchi) is a passage which allows the flow of air into lungs. The bronchi extend from trachea to the lungs.
1. The tracheal tube, when divided into two at the caudal end, gives rise to the left and right bronchus.
2. The left bronchus is shorter than the right one; the left one is sub-divided into 2 lobar bronchi; right bronchus, on the other hand, is sub-divided into 3 lobar bronchi.
Human lungs are conical organs present inside the pleural cavities. They carry out the work of supplying the body with oxygen and removing carbon dioxide.
1. The left lung is divided into 2 lobes (superior and inferior) while the right lung into 3 (superior, inferior and middle).
2. Each lung possesses a triangular organ called hilum; blood vessels, nerves, lymphatics and bronchi pass through the hilum.
The alveoli are sac-shaped bodies present inside the lungs, at the tip of alveolar ducts. The alveoli function like an interface for the exchange of oxygen and carbon dioxide between lungs and capillaries.
1. Capillaries connect the alveoli with the rest of the body.
2. Alveoli are found in the lungs of mammals only.
Gas Exchange Process
The process of gas exchange in alveoli is characterized by inhalation of oxygen and exhalation of carbon dioxide.
1. Oxygen enters the blood cells by means of alveoli and a network of capillaries.
2. Oxygen is carried to the tissues of different parts of the body by means of blood.
3. Carbon dioxide is collected by the blood and carried to lungs.
4. Carbon dioxide diffuses from capillaries that surround the alveoli and is finally exhaled by lungs.
The diaphragm is formed of skeletal muscles. It creates a partition between the thoracic and abdominal cavity.
Contraction of muscles of the diaphragm leads to expansion of the thoracic cavity; contraction of diaphragm is important from the point of expansion of lungs at the time of inhalation.
Interesting Facts about Respiratory System
1. There are over 600 million alveoli in the lungs of an adult human being.
2. The right and left lungs of the human respiratory system do not have the same size. In fact, the left lung is a bit smaller than the right one.
3. The human body loses about 0.5 liters of water everyday through the process of breathing.
4. The process of respiration, apart from removing metabolic wastes, maintains the acid-base balance in our body.
In terms of animal physiology, respiration is defined as the process in which oxygen from environment enters the body and carbon dioxide from the body is released into the environment. The process of respiration takes place in four stages: ventilation, pulmonary gas exchange, gas transport and peripheral gas exchange.
1. In the ventilation stage, air moves in and out of the alveoli of lungs.
2. The gas exchange which takes place between pulmonary capillaries and alveoli is termed as pulmonary gas exchange.
3. Movement of gas within pulmonary capillaries, towards peripheral capillaries and back to lungs is referred to as gas transport.
4. The exchange of gases between tissues and tissue capillaries is referred to as peripheral gas exchange.
The facts presented in this article give us a rough idea of the anatomy and functioning of the respiratory system. The information about different organs in the respiratory system should allow you to understand their structure and functions in a better manner.