Diaphragm contraction

This is very much like your lungs, by the way. As your diaphragm contracts, it reduces the pressure in the thoracic cavity to about 600 Pa below atmospheric pressure, and about 500 mL of air is drawn into your lungs. Note that we have used an idealized object (a frictionless piston) in this example. While such an object does not exist, it is frequently useful to incorporate such idealizations into working models to help us understand more complicated systems. Now, back to our frictionless piston with 2.5 L of air. How much work is done when the piston slides to a new volume of 3.0 L, assuming the pressure remains constant ... 

A When you breathe in, the diaphragm contracts and flattens. The glottis and epiglottis open, and air rushes in. 

The diaphragm contracts, and the chest expands, causing the lungs to expand. The increased volume decreases the pressure in the lungs to below the external pressure, causing air to move into the lungs faster than it moves out. 

The major muscles involved in inspiration and expiration include the diaphragm and the intercostal muscles. During inspiration, the diaphragm contracts, pulling the inferior lung surface (via the pleural... 

Breathing consists of the cyclic action of the lungs to inspire and expire atmospheric gases. Inspiration occurs when the diaphragm and intercostal muscles contract, generating a negative pressure in the pleura surrounding... 

Elimination of one tubesheet reduces initial cost. Tube bundle is removable for inspection and cleaning. Full tube bundle minimizes shell-side bypassing. U-bends permit each tube to expand and contract individually. Tube bundle expansion is independent of shell no expansion diaphragm is required. 

Retching A process that follows nausea and consists of diaphragm, abdominal wall, and chest wall contractions and spasmodic breathing against a closed glottis. 

Assisting the diaphragm with inspiration are the external intercostal muscles, which connect adjacent ribs. When the external intercostal muscles contract, the ribs are lifted upward and outward (much like a handle on a bucket). Therefore, contraction of these muscles causes an increase in the horizontal dimension of the thoracic cavity and a further increase in thoracic volume. The external intercostal muscles are supplied by the intercostal nerves. 

Deeper inspirations are achieved by more forceful contraction of the diaphragm and external intercostal muscles. Furthermore, accessory inspiratory muscles, including the scalenus and sternocleidomastoid muscles, contribute to this process. Located mainly in the neck, these muscles raise the sternum and elevate the first two ribs. As a result, the upper portion of the thoracic cavity is enlarged. 

During exercise or voluntary hyperventilation, expiration becomes an active process. Under these conditions, a larger volume of air must be exhaled more rapidly. Therefore, two muscle groups are recruited to facilitate this process. The most important muscles of expiration are the muscles of the abdominal wall. Contraction of these muscles pushes inward on the abdominal contents and increases abdominal pressure. As a result, the diaphragm is pushed upward more rapidly and more forcefully toward its preinspiration... 

Botulinus toxin comes from Clostridium botulmum, an organism that causes food poisoning. Botulinus toxin prevents the release of ACh from nerve endings by mechanisms that are not clear. Death occurs from respiratory failure caused by the inability of diaphragm muscles to contract. 

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