How do we inhale and exhale? Which muscle contract when? What does that do to th
ID: 3480429 • Letter: H
Question
How do we inhale and exhale? Which muscle contract when? What does that do to the lungs? Why does air move the direction it does? What differences exist between passive breathing (aka at rest) and active breathing (aka during exercise)? How do we inhale and exhale? Which muscle contract when? What does that do to the lungs? Why does air move the direction it does? What differences exist between passive breathing (aka at rest) and active breathing (aka during exercise)? Which muscle contract when? What does that do to the lungs? Why does air move the direction it does? What differences exist between passive breathing (aka at rest) and active breathing (aka during exercise)?Explanation / Answer
Inhalation
When we inhale, diaphragm contracts and moves down. The volume of the thoracic cavity increases and the lungs expand. The intercostal muscles contract to pull the rib outward and upward to increase the chest cavity when we inhale.
When the thoracic cavity expands, a negative pressure is created which is proportional to the force of Contraction. This cause the air to suck in through our nose which passes windpipe, lungs, bronchial tubes and alveoli. Air is transferred from alveoli to the capillaries around them. Hemoglobin will carry the oxygen to the heart through pulmonary vein. The aerated blood is pumped to all parts/organs/tissues.
Exhalation
The de oxygenated blood from other parts reach the heart through pulmonary artery and are carried to the lungs. When we breathe out, the diaphragm and intercostal muscles relax but the abdominal muscles contract. This creates a positive pressure and decreases the thoracic cavity. The carbon dioxide from the capillaries are transferred to alveoli. The high pressure will push the air out.
Air direction
Air moves from high to low pressure. When we inhale pressure is low in lungs and the air comes in. When we exhale air moves out since pressure is high in lungs. The pressure is created by the volume of thoracic cavity.
Difference
The above mechanism is for passive breathing.
During active breathing, the abdominal muscle contracts and push the diaphragm more against the lungs than the passive Exhalation. Hence there is rapid Exhalation. The same increase in the force of Contraction makes the Inhalation rapid.
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