Changes

 

==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 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 rumen is released through eructation. Some of the gas is absorbed directly over the 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 [[Forestomach - Nutritional Pathology#Bloat/ Tympany|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]]

*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]].

 

 

 

*The gases are moved orally by an antiperistaltic wave passing through the relaxed pharyngoesophageal sphincter into the pharynx

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.

 

*Some of the eructated gas passes to the lungs, whilst the rest is released from the oral cavity