How does the exchange of air take place???  -Health Knowledge on -Human Lungs.The air that
we inhale through our mouth nose goes down our windpipe.On the way,tiny hairs called cilia
filter out the mucus and dirt.Passing through the series of bronchi and bronchioles,the inhaled
air finally ends up the alveoli where oxygen from the air is observed in to the blood in the tiny
capillaries............How does the exchange of air take place???  -Health Knowledge on -Human Lungs.







What are the lungs?


The lungs are the organs of respiration in a human body.Each human has two lungs.The lungs
are covered by a thin tissue layer called the pleura.The same kind of thin tissues lines the inside
of the chest cavity-also called pleura.A thin layer of fluid acts as a lubricant allowing the lungs
to slip smoothly as they expand and contract with each breath. The lungs are protected by the rib 
cage and important vital organ of respiration in a human body.

Where in the body are the lungs located?


The lungs are located with in our chest cavity inside the rib cage on either side of the heart.The two
lungs are separated  by a structure called the mediastinum .The mediastinum contains the heart ,trac-
hea, esophagus, and blood vessels.


What is the size of human lungs?


Each lungs is between 10 and 12 inches long.The lung in the left is a bit smaller than the lung on
the right ,because it has to make room for the heart to fit in the chest.Each lungs weights 1.1 kilo
grams (KGs)  therefore making the entire organ about 2.3 kilograms.




What the lungs do?

Since the lungs process air, they are the only internal organs that are constantly exposed to the 
external environment.The air that we breath contains several gases , including oxygen that is 
important for keeping us alive, because body cells need oxygen for energy and growth.With each
breath our lungs add fresh oxygen to our blood, which then carries it to our cells.The lungs also
enable our body to get rid of carbon dioxide when the air is breathed out.

What is the respiration?


Respiration is the set of events that results in the exchange of oxygen from the atmosphere and carbon dioxide from the body"s cells. The process of taking air into lungs is inspiration, or inhalation
,and the process of breathing out it is expiration, or exhalation.Lungs breathe in between 2100 and 
2400 gallons of air each day.

What is the external structure of the lungs?


Occupying most of the space within the thoracic cavity, the lungs extend laterally from the heart
to the ribs on  both sides of the chest and continue posteriorly towards the spine.Each soft, spongy
lungs is roughly cone-shaped.The base of the lungs is concave to follow the contour of the diaphragm.The left lung is slightly smaller than the right lung because 2/3 of the heart is located 
on the left side of the chest.Each lung consist of several distinct lobes.The right lung has 3 lobes 
while the smaller left lung only has 2 lobes.


What is the internal structure of the lungs?


At the bottom of the trachea, or windpipe , there are two large tubes called the main stem bronchi
. One of them heads into the left lung, while the other heads into the right lung.Inside each lung, the
bronchus divides into smaller and still smaller tubes, like branches of a big tree.The tiniest tubes,called bronchioles ,eventually end in clusters of microscopic air sacs called alveoli .Each
alvelous has a mesh like covering of very small blood vessels called capillaries.


How does the exchange of air take place?


The air that
 we inhale through our mouth nose goes down our windpipe.On the way,tiny hairs called cilia
filter out the mucus and dirt.Passing through the series of bronchi and bronchioles,the inhaled
air finally ends up the alveoli where oxygen from the air is observed in to the blood in the tiny
capillaries .From here the oxygen hitches a ride on  red blood cells and travels through layers
of blood vessels to the heart. The heart then sends the oxygenated blood  out to all the cells in the
body .Carbon dioxide , a waste product of metabolism , travels from the blood to the alveoli, from
where it travels in the reverse order -through the bronchioles,out the bronchi, out the trachea,and finally out through  our mouth and nose.