explain the mechanism of breathing in human beings
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Breathing is simply defined as the physical process in which oxygen is taken into the body and carbon dioxide is forced out from the body.
Breathing is brought about by two sets of muscles-
i. Internal intercoastal muscles
ii. External intercoastal muscles
Besides these muscles, diaphragm and abdominal muscles help in breathing.
The process of breathing involves two phases:
Inspiration/ InhalationExpiration/ Exhalation
1. Inspiration
It is the inhalation of air into lung and is brought about by chest expanding.
It takes place when the volume of thoracic cavity increases and the air pressure decreases.
Enlargement of thoracic cavity involves the following events which occurs simultaneously:
During inspiration, the external intercostal muscles contract and the internal one relax.Due to contraction of external intercostal muscles, the ribs are pulled upward and outward.The muscle of diaphragm contract which lowers the diaphragm.As a result the size of thoracic cavity increases as well as the lungs expand simultaneously.As the lungs expand, the air pressure inside the lungs decreases.In order to balance the air pressure, air rushes from atmosphere into the lungs through air passage.
The process of inspiration is active, as it needs energy for muscle contraction. At rest, it lasts about 2 sec.
Breathing is brought about by two sets of muscles-
i. Internal intercoastal muscles
ii. External intercoastal muscles
Besides these muscles, diaphragm and abdominal muscles help in breathing.
The process of breathing involves two phases:
Inspiration/ InhalationExpiration/ Exhalation
1. Inspiration
It is the inhalation of air into lung and is brought about by chest expanding.
It takes place when the volume of thoracic cavity increases and the air pressure decreases.
Enlargement of thoracic cavity involves the following events which occurs simultaneously:
During inspiration, the external intercostal muscles contract and the internal one relax.Due to contraction of external intercostal muscles, the ribs are pulled upward and outward.The muscle of diaphragm contract which lowers the diaphragm.As a result the size of thoracic cavity increases as well as the lungs expand simultaneously.As the lungs expand, the air pressure inside the lungs decreases.In order to balance the air pressure, air rushes from atmosphere into the lungs through air passage.
The process of inspiration is active, as it needs energy for muscle contraction. At rest, it lasts about 2 sec.
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When we inhale air,it passes through our nostrils into the nasal cavity. from the nasal cavity,the air reaches our lungs through the wind pipe. Lungs are present in the chest cavity. This cavity is surrounded by ribs . A large muscular sheet called diaphragm forms the floor of the chest cavity .Breathing involves the movement of the diaphragm and the rib cage. During inhalation,ribs moves up and outwards and diaphragm moves down . This movement increases space in our chest cavity and air rushes into the lungs . The lungs get filled with air .During exhalation,ribs move down and inwards while diaphragm moves up to its former position. This reduces the size of the chest cavity and air is pushed out of the lungs.
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