Human Respiratory System

Respiratory System is an anatomical system that helps in the exchange of gases.

We need energy for doing external activities and for carrying out the functions of the internal organs. Energy is released with the help of oxygen present in the air, oxygen reacts with the food and releases energy by a process known as “oxidation”. During the oxidation of the food carbon dioxide is released which is a harmful gas and it has to be sent out.

The above function is performed by the respiratory system. The taking in of oxygen and release of carbon dioxide is known as “respiration”. The organs which carry out respiration are called respiratory organs and the system is called the respiratory system.

Parts of the Human Respiratory System:

The respiratory system consists of

• Nose
• Pharynx
• Larynx
• Trachea
• Bronchi
• Lungs

Nose:

The nose is in the shape of a pyramid and consists of a cavity known as the nasal cavity. The nasal septum divides the nasal cavity into two nasal passages which are lined internally by a moist mucous membrane. This mucous membrane makes the air moist and warm as the air passes through it and protects the lungs from the ill effects of dry and cold air. Fine hairs are present in the nasal passages whose function is to filter the dust particles that enter along with the air and are trapped in the mucous membrane. The nose opens outside through a pair of external nostrils. Internally it opens at the upper end of the pharynx through a pair of internal nostrils.

Pharynx:

Pharynx is a junction for the food and air passages. Near the pharynx, there are a pair of tonsils and adenoids that are used for the filtration of microbes, etc.

Larynx:

Larynx is called the “voice box“. Larynx is found just below the pharynx. At the top of the larynx, a flap-like structure known as epiglottis is present and is made of cartilage. The function of the epiglottis is to prevent food and fluid from entering into the larynx. Larynx consists of a pair of cords known as vocal cords that produce sounds when the air comes out of the lungs.

The larynx of a man is larger than that of a woman and consists of long vocal cords, so the voice of a man is deep-pitched. The larynx then opens into the trachea.

Trachea:

Trachea is also known as the “windpipe” and it is a long tube-like structure. It travels through the neck and enters the chest cavity or thoracic cavity. The wall of the trachea consists of “C” shaped cartilaginous rings. The C-shaped rings may range from 16 to 20 rings, which are useful for regulating air pressure. Trachea is also lined internally by the mucous membrane and it consists of millions of cilia, that sweep away the tiny dust particles that enter along with the air.

Bronchi and bronchioles:

Trachea in the chest cavity gets divided into the right and left branches. These branches again divide into smaller branches called bronchi. The bronchi in each lung divide into a number of very small tubes known as bronchioles. These bronchioles end in air sacs or alveoli.

Alveoli are the basic structural units of the lungs. They are very minute and consist of a very thin wall. They are also called air sacs. In an adult human being there are about 600,000,000 alveoli. The walls of the alveoli consist of an extensive network of very small blood vessels called a capillary network. During the entry of air into the lungs, the oxygen present in it diffuses into the blood of these minute blood vessels and carbon dioxide goes out from these vessels.

Lungs:

There are a pair of lungs in the chest cavity, one on either side of the heart. The lungs are covered by the pleural membranes that protect the lungs.

The lungs are slate colored and elastic in nature. Lungs are made up of a mass of spongy tissue with minute passages for air. Lungs are protected from external injury by the sternum or breast bone in the front, a vertebral column on the back, and ribs on the sides which altogether form a bony box and protect the lungs.

Entry into and Exit of air from lungs:

Air –> External Nostrils –> Nasal Passages –> Internal Nostrils –> Pharynx –> Larynx –> Trachea –> Bronchi –> Bronchiloes –> Air Sacs (Alveoli) of Lungs.

The above sequence is the entry of air into the lungs. The exit is from the air sacs to the external nostrils.

  organ systems, Respiratory System