This week in our organ system section we are going to continue you on with the respiratory system and delve into the anatomy of breathing.
Breathing, as you know, is extremely important. It provides vital oxygen for tissues and removes carbon dioxide from the body.
When breathing in – inspiration is activated by the contraction of muscles, such as the diaphragm and the intercostal muscles. The diaphragm flattens to extend part of the thoracic cavity. The intercostal muscles elevate the ribs and sternum. The action of these muscles increases the volume of the thoracic cavity. This allows the lungs to take in more oxygen and for the lungs to increase their volume capacity. With an increase in volume in the lungs, there is a decrease in pressure. The pressure of the environment external to the lungs is now greater than the environment within the lungs, meaning air moves into the lungs down the pressure gradient.
When we breathe out and expire, the muscles we used for inspiration relax. The diaphragm returns to its normal position as do the intercostal muscles, lowering the rib cage and sternum. This reduces the volume of the thoracic cavity. The lungs spring back to their normal shape and size due to the elasticity present. This time around, the pressure in the lungs is now greater than its external environment meaning air moves out of the lungs down the power gradient.
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