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==Introduction==

==Introduction==

Eructation is the release of gases from the stomach through the [[Oesophagus - Anatomy & Physiology|oesophagus]]. Carbon dioxide, methane, hydrogen and other volatile products are produced in the [[The Rumen - Anatomy & Physiology|rumen]] through the fermentaion of food by microorganisms and most of these gases are then released through eructation.  

Eructation is the release of gases from the stomach through the [[Oesophagus - Anatomy & Physiology|oesophagus]]. Carbon dioxide, methane, hydrogen and other volatile products are produced in the [[Rumen - Anatomy & Physiology|rumen]] through the fermentation of food by microorganisms and most of these gases are then released through eructation.  

Not all the carbon dioxide produced in the [[The Rumen - Anatomy & Physiology|rumen]] is released through eructation. Some of the gas is absorbed directly over the [[The Rumen - Anatomy & Physiology|rumen]] wall.

Not all of the carbon dioxide produced in the [[Rumen - Anatomy & Physiology|rumen]] is released through eructation. Some of the gas is absorbed directly over the [[Rumen - Anatomy & Physiology|rumen]] wall. If gas release does not occur, or gas elimination does not equal gas production, a condition called [[Bloat|bloat]] will arise.

 

If gas release does not occur, or gas elimination does not equal gas production a condition called [[Bloat|bloat]] will arise.

==Process==

==Process==

[[Image:Diagram of eructation.jpg|thumb|right|150px|Diagram of Eructation - Copyright RVC 2008]]

[[Image:Diagram of eructation.jpg|thumb|right|250px|Diagram of Eructation - Copyright RVC 2008]]

*[[The Rumen - Anatomy & Physiology#Ruminoreticular contraction|Ruminal contractions]] (no reticular contribution)

The process of eructation includes [[Rumen - Anatomy & Physiology#Ruminoreticular contraction|ruminal contractions]] (no reticular contribution). Before eructation can occur the cardia must be cleared of liquid ingesta, as the cardia is reflexly closed on contact with the liquid [[Rumen - Anatomy & Physiology|rumen]] contents. Contractions start in the ventral sac and spread to the dorsal sac. Contractions spread caudally to cranially over the [[Rumen - Anatomy & Physiology|rumen]]. Ruminal gas is forced towards the cranial cardiac area where it is aspirated into the [[Oesophagus - Anatomy & Physiology|oesophagus]]. The gases are moved orally by an antiperistaltic wave passing through the relaxed '''pharyngoesophageal sphincter''' into the [[Pharynx - Anatomy & Physiology|pharynx]]. Some of the eructated gas passes to the lungs, whilst the rest is released from the [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]].

*Contractions start in the ventral sac and spread to the dorsal sac

In the dairy cow, 0.5-1 L of gas is produced per minute in the '''ruminoreticulum'''. The exact amount of gas absorbed into the blood and lymph is unknown, but the majority is eliminated by eructation.

 

*Contractions spread caudally to cranially over the [[The Rumen - Anatomy & Physiology|rumen]]

 

*Ruminal gas is forced towards the cranial cardiac area where it is aspirated into the [[Oesophagus - Anatomy & Physiology|oesophagus]]

 

*The gases are moved orally by an antiperistaltic wave passing through the relaxed pharyngoesophageal sphincter into the [[Pharynx - Anatomy & Physiology|pharynx]]

 

*Some of the eructated gas passes to the lungs, whilst the rest is released from the [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]]