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The diaphragm contracts, causing the lungs to expand. This creates a 'pressure difference' and air fills the lungs. When the diaphragm relaxes, it 'squeezes'[ the lungs, forcing the unabsorbed air (and waste gasses) back out again.

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Q: How do pressure changes within the chest cavity cause inspiration and expiration?
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What makes move into and out of the lungs?

Pulmonary ventilation or breathing has two phases. Inspiration or inhalation moves air into the lungs and expiration or exhalation moves air out of the lungs. The lungs are enclosed within the thoracic cavity. Thus changes in the shape and size of the thoracic cavity result in changes in the air pressure within that cavity and in the lungs. This difference in air pressure causes the movement of air into the lungs. Air moves from an area where pressure is high to an area where pressure is low. Respiratory muscles are responsible for the changes in the shape of the thoracic cavity that cause the air movements involved in breathing.The abdominal diaphragm is (or should be) the major muscle driving respiration.Source(s):Structure and function of the body


What makes air moves into and out the lungs?

Pulmonary ventilation or breathing has two phases. Inspiration or inhalation moves air into the lungs and expiration or exhalation moves air out of the lungs. The lungs are enclosed within the thoracic cavity. Thus changes in the shape and size of the thoracic cavity result in changes in the air pressure within that cavity and in the lungs. This difference in air pressure causes the movement of air into the lungs. Air moves from an area where pressure is high to an area where pressure is low. Respiratory muscles are responsible for the changes in the shape of the thoracic cavity that cause the air movements involved in breathing.The abdominal diaphragm is (or should be) the major muscle driving respiration.Source(s):Structure and function of the body


The diaphragm contracts and the pressure in the chest cavity decreases during?

Inspiration


When dogs pant they inhale through the nose and exhale through the mouth how does this provide a cooling mechanism?

Through the nasal cavity a major a mount of vapor is released during inspiration and expiration as well. This vapor is warm and during expiration its released into the environment. During inspiration fresh air gets into the nasopharyngeal cavity and cools down the animal. This "used" air gets warm and leaves the nasal cavity via expiration


Why pause between inspiration and expiration in bronchial breathing?

inspiration is an active process that takes place by creation of negative intrathoracic pressure, in normal states where breathing is vesicular, even at a low negative pressure air keep on flowing into alveoli but in bronchial breathing as alveoli are either filled with secretions as in consolidation or a cavity is already filled with air and other contents, no movement of air takes place at the end inspiration despite of negative intrathoracic pressure thereby causing a pause between inspiration and expiration- now pay me thousand dollar!


What is the result of inspiration and expiration?

This occurs within the respiratory system. During inpiration, the intercostal muscles contract, the diaphragm descends, and the rib cage rises. The thoracic cavity volume increases, stretching the lungs, and the intrapulmonary volume increases. This causes the intrapulmonary pressure to drop. Air flows into the lungs until the intrapulmonary pressure equals the atmospheric pressure. During expiration the intercostal muscles relax, the diaphragm rises, and the rib cage descends. The thoracic cavity volume decreases, causing the the lungs to recoil, and the intrapulmonary volume decreases. This causes the intrapulmonary pressure to rise, and the air flows out of the lungs until the intrapulmonary pressure equals the atmospheric pressure.


Why do you think the rib cage is not solid sheet like the skull?

If the ribcage were a solid sheet like the skull, it would be difficult for the thoracic cavity to expand and contract with inspiration and expiration.


What is the breathing process?

Breathing consists of two phases, inspiration and expiration.During inspiration, the diaphragm and the intercostal muscles contract. The diaphragm moves downwards increasing the volume of the thoracic (chest) cavity, and the intercostal muscles pull the ribs up expanding the rib cage and further increasing this volume. This increase of volume lowers the air pressure in the alveoli to below atmospheric pressure. Because air always flows from a region of high pressure to a region of lower pressure, it rushes in through the respiratory tract and into the alveoli. This is called negative pressure breathing, changing the pressure inside the lungs relative to the pressure of the outside atmosphere.In contrast to inspiration, during expiration the diaphragm and intercostal muscles relax. This returns the thoracic cavity to it's original volume, increasing the air pressure in the lungs, and forcing the air out.


What is the dome-shaped muscle under the thoracic cavity and what are its functions?

The dome-shaped muscle under the thoracic cavity is the diaphragm. Its function is to contract to increase the volume of the thoracic cavity, thereby decreasing pressure in the lungs and causing inspiration.


What is the pressure difference between the external air and the pleural cavity when inhalation just begins?

In inspiration, intrapulmonary pressure drops 3mm/Hg below atmospheric pressure and air flows into the lungs.


What caueses Movement of air into the lungs?

Passive inspiration is accomplished solely by the diaphragm muscle. During passive inspiration, contraction of the diaphragm increases the vertical length of the thoracic cavity thereby greatly increasing its volume. In accordance with boyle's law, an increase in volume under constant temperature results in a decreased pressure which in this case falls below atmospheric pressure. As the thoracic pressure is now lower, air rushes into the thoracic cavity filling it up resulting in passive inspiration.


What causes a pressure chage in the chest cavity during breathing?

The movement of the rib cage changes the air pressure in the chest cavity depending on the physical activity the person is performing. If they are running, the air pressure will be constantly increasing and decreasing, leading to stress on the rib cage.