The first thing that happens to most people is called high altitude pulmonary edema, a build up of fluid in the lungs that makes it hard for them to breathe. In very susceptible individuals this can happen at as low as 1500 meters above sea level (air pressure around 85 kPa).
At partial pressures of oxygen less than about 10 kPa, your lungs can no longer efficiently absorb oxygen from the air. If you're breathing normal air, this happens at an overall pressure of around 50 kPa, corresponding to a height of about 6 km above sea level.
Should the overall air pressure drop below around 10 kPa (normal atmospheric pressure is around 100 kPa and the pressure at the top of Mount Everest is around 30 kPa), water evaporation would become significant. By the time the pressure dropped to 6 kPa, all the moisture in your body would be evaporating so fast it would literally be boiling.
When you exhale, the pressure inside the thorax increases slightly due to the contraction of the diaphragm causing a decrease in thoracic volume. This increase in pressure helps to push air out of the lungs.
As the diver descends deeper into the water, the pressure increases. This causes the air molecules in the diver's lungs to compress, leading to a decrease in volume. In order to maintain equilibrium with the increasing pressure, the air molecules in the lungs will be forced into smaller spaces, potentially causing discomfort or injury if not managed properly through controlled breathing techniques.
During expiration, the diaphragm and intercostal muscles relax, causing the thoracic cavity to decrease in volume. This decrease in volume increases the pressure within the thorax, which pushes air out of the lungs. This process facilitates expiration by creating a pressure gradient that allows air to flow out of the lungs.
During inhalation, the diaphragm and rib muscles contract to expand the chest cavity, allowing air to flow into the lungs. During exhalation, these muscles relax, causing the chest cavity to decrease in size and air to be pushed out of the lungs. This process is driven by changes in air pressure within the lungs.
During the Valsalva maneuver, intrapulmonary pressure increases due to compressing the air inside the lungs while intrapleural pressure also increases due to the forced expiration against a closed glottis. This can lead to a decrease in venous return to the heart and a decrease in cardiac output.
An increase in intrapulmonary volume leads to a decrease in air pressure within the lungs. This decrease in pressure creates a pressure gradient, causing air to flow into the lungs during inhalation.
The act of inhaling is to create low pressure in the lungs, causing the air in the atmosphere to rush in as it is moving from a higher pressure (outside in the atmosphere) to the lower pressure (created in the lungs). However the fact that air does move into the lungs means that there is no net change in pressure.
When you inhale, the diaphragm and intercostal muscles contract, expanding the chest cavity. This expansion increases the volume of the lungs, causing a decrease in air pressure within them. Air moves from an area of higher pressure (outside the body) to an area of lower pressure (inside the lungs), resulting in inhalation.
When you exhale, the pressure inside the thorax increases slightly due to the contraction of the diaphragm causing a decrease in thoracic volume. This increase in pressure helps to push air out of the lungs.
Inspiration happens when the pressure inside the lungs is lower than the atmospheric pressure (outside) and air rushes into the lungs. Expiration is when the air inside the lungs is higher than the atmospheric pressure and the air rushes out of the lungs. If the intrapleural pressure (pressure within the pleura of the lungs) isn't maintained then the pressure in the lungs can't differentiate between inspiration and expiration and so the lung collapses.
As the diver descends deeper into the water, the pressure increases. This causes the air molecules in the diver's lungs to compress, leading to a decrease in volume. In order to maintain equilibrium with the increasing pressure, the air molecules in the lungs will be forced into smaller spaces, potentially causing discomfort or injury if not managed properly through controlled breathing techniques.
The diaphragm. (located beneath the lungs) When it contracts it moves down, thus expanding the volume of the lungs. This causes the pressure in the lungs to decrease and air to flow in to the lungs. (pressure is inversely proportional volume- Boyle's law) This is inhaling. When the diaphragm relaxes it moves back up, decreasing the volume of the lungs and increasing the pressure which forces the air out. This is exhalation.
The temperature and pressure rise.
When pressure inside the lungs is lower than outside, air flows into the lungs to equalize the pressure. This is known as inhalation, where the diaphragm contracts and the rib cage expands to create more space for air to enter the lungs.
When you inhale, the volume of your chest cavity increases. This expansion lowers the pressure inside your chest relative to the outside air, allowing air to rush in and fill your lungs. This process is driven by the contraction of the diaphragm and the expansion of the ribcage.
when air moves out of the lungs, the air pressure decreases
During expiration, the diaphragm and intercostal muscles relax, causing the thoracic cavity to decrease in volume. This decrease in volume increases the pressure within the thorax, which pushes air out of the lungs. This process facilitates expiration by creating a pressure gradient that allows air to flow out of the lungs.