How do we breathe?


          The body needs continual supplies of oxygen. This invisible gas makes up about one-fifth of the air around us. It is needed for chemical processes inside the body’s cells that release energy from food. Breathing draws air into the body so that oxygen can be absorbed.



RESPIRATORY SYSTEM



          The respiratory system draws fresh air into the body, absorbs the vital oxygen from it into the blood, and then passes the stale air out again. The main parts of the system where oxygen is absorbed are the lungs. Breathing muscles stretch the lungs to make them larger and suck in air. These muscles are the diaphragm below the lungs, and the intercostal muscles between the ribs. Fresh air passes in through the nose and mouth, down the pharynx (throat) and trachea (windpipe), into the lungs. The lung airways, called bronchi, divide many times and become thinner, ending in terminal bronchioles, narrower than human hairs.



          Each terminal bronchiole ends in a cluster of microscopic air bubbles, called alveoli. There are about 300 million alveoli in each lung, giving the whole lung a spongy texture. Besides fresh air, the lungs also receive low-oxygen blood from the heart along the pulmonary arteries. These divide and form networks of microscopic blood vessels (capillaries) around the alveoli. Oxygen from the air inside the alveoli passes easily through the thin walls of the alveoli and capillaries into the blood. This high-oxygen blood returns along pulmonary veins to the heart.



CLEANING THE LUNGS



          The lungs are delicate and easily damaged. Hairs in the nose filter bits of floating dust and other particles from air as it is breathed in. The airways are lined by sticky mucus which traps dirt and dust. Microscopic hairs, called cilia, line the smaller airways. They sweep mucus and trapped dirt into the throat, where it can be swallowed.



SPEECH



          Air emerging from the lungs not only carries waste carbon dioxide. It has another use—speech. At the top of the trachea is the larynx (voice box). This has a shelf-like fold of cartilage projecting from each side, known as the vocal cords. To speak, muscles pull the vocal cords together so that there is only a very narrow slit between them. Air rushing through the slit makes the cords shake or vibrate, which produces sounds. These sounds are shaped into clear words by movements of the mouth, cheeks, teeth, tongue and lips.



 





BREATHING RATE



          As oxygen passes from the air in the alveoli into the blood, the waste substance carbon dioxide passes the opposite way, from the blood into the air. This stale air is then pushed out of the lungs when the breathing muscles relax and the stretched lungs spring back to their smaller size. At rest, an adult person breathes in and out about 12 times each minute. Each breath is around half a litre of air. After running a race, a person may breathe 60 times each minute and take in more than two litres of air each time, to obtain extra oxygen for the active muscles.



Picture Credit : Google



 


 



 


Trackbacks

Trackback specific URI for this entry

Comments

Display comments as Linear | Threaded

No comments

Add Comment

Enclosing asterisks marks text as bold (*word*), underscore are made via _word_.
Standard emoticons like :-) and ;-) are converted to images.
E-Mail addresses will not be displayed and will only be used for E-Mail notifications.
To leave a comment you must approve it via e-mail, which will be sent to your address after submission.