The Human Respiratory System

 

It is a system that is related with respiration and consists of all the respiratory organs.

What is respiration?

Respiration is the process of liberating energy by the process of food oxidation the system gets oxygen for breathing from the environment and also removes carbon dioxide gas in turn.

Respiratory organs

The human respiratory system typically includes the following organs that help in the exchange of gases.

• nose
• pharynx
• larynx
• trachea
• bronchi
• bronchioles
• alveoli
• lungs

Nose consists of two nostrils. Each has got the tiny hairs (cilia), mucus membrane, blood capillaries. It not only serves as a sense organ for smelling things but also acts as a passage of air. The tiny hairs filter the air while mucus sticks any solid particle like dust or any other substance however blood capillaries help in warming up the air that is entering inside the other respiratory organs.

Pharynx is a part of the throat and serves as a passage for both air and food. There is a flap on the glottis which is known as epiglottis, it closes to provide the smooth passage for the food to pass through the food pipe, however, it remains opened so that the air can pass smoothly through it. 

Larynx is a cartilaginous structure and contains vocal cords. When the air passes through it, vocal cords vibrate and produce sound, it also allows the air to pass through the trachea.

Trachea is commonly known as windpipe that is lined with mucus membrane and cilia. It also serves as the passage of air and keeps the air moist and clean before it reaches the lungs.

Bronchi are the two tubular structures that are formed by the division of trachea and have the same composition as that of trachea. They enter the lungs of their own side and allow the air to enter the lungs smoothly under optimum pressure.

Bronchioles are the fine branches of bronchi that provide fresh air (oxygen rich) to alveoli that are located at their ends.

Alveoli are the microscopic air sacs that give lungs a spongy look and are the chief sites of gaseous exchange. They are having blood capillaries in the surrounding hence allow the gaseous exchange possible from and to the blood.

Lungs are the main organs of respiration and located in the thoracic cavity. Externally, they are surrounded by double membrane called pleura having pleural cavity in between them which is filled with pleural fluid that serves as a lubricant and avoids friction when the lungs are expanding or contracting during the breathing process. Lungs are protected with the ribs because they are very delicate and vital organs hence need firm support and protection from the skeletal system.

Important respiratory muscles

• Intercostal muscles
• Diaphragm

Intercostal muscles are attached to the ribs and allow them to move appropriately during mechanical movement of ribs. There are two types of them i.e. internal and external intercostals.

Diaphragm on the other hand is the muscular and membranous structure that separates the thoracic and abdominal cavities and shows specific movement during breathing.

Mechanism of respiration

It consists of two main steps

Step 1: Breathing

Step 2: Cellular respiration

Breathing is simply the exchange of gases. It involves two steps.

• Inhalation- When we inhale, our diaphragm contracts hence air finds it way to the lungs. On the other hand, internal intercostals relax while external intercostals contract and rib cage moves outwards and as lungs expand, they get filled up with the air.

• Exhalation- During exhaling air, mechanism is reversed. Diaphragm relaxes and comes back to its original doom shape. The internal intercostals contract and external intercostals relax so that the lungs shrink and rib cage also moves inward hence releases the air outside in the surrounding.

Cellular respiration involves oxidation of glucose which not only produces carbon dioxide gas that is removed outside the body but also serves as an energy releasing process that liberates 2827 kJ/mol of glucose.