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Página creada con 'thumb|right|250px|Topografía del rumen (oveja) - Copyright RVC 2008 ==Introducción== The rumen is the first chamber of the ruminant stom...'
[[Image:Rumen Topography Sheep.jpg|thumb|right|250px|Topografía del rumen (oveja) - Copyright RVC 2008]]
==Introducción==
The rumen is the first chamber of the ruminant stomach. It is the largest chamber and has regular contractions to move food around for digestion, eliminate gases through [[Eructation - Anatomía & Fisiología|eructation]] and send food particles back to the mouth for [[Mastication|remastication]]. The rumen breaks down food particles through mechanical digestion and fermentation with the help of symbiotic microbes. [[Volatile Fatty Acids|Volatile fatty acids]] are the main product of ruminant digestion.
==Estructura==
[[Image:Rumen Anatomy Sheep.jpg|thumb|right|250px|Anatomía del rumen (oveja) - Copyright RVC 2008]]
Grooves correspond with thickened smooth muscle pillars on the inside of the rumen. '''Ruminal pillars''' divide the dorsal and ventral ruminal sacs. '''Coronary pillars''' divide the caudal blind sacs. The '''cranial pillar''' divides the dorsal and cranial sacs. It is covered by the greater omentum. The rumen is 38-40°C, anaerobic and has a pH of 6.7. It is buffered and has a large holding capacity. Water intake lowers the ruminal temperature so bacteria are tolerant to temperature changes towards the lower end of the scale. Objects are often lodged in the rumino-reticular fold. When the rumen contracts, the object can be pushed through the [[Reticulum - Anatomía & Fisiología|reticulum]] wall into the [[Heart Structure - Anatomía & Fisiología#Pericardium|pericardium]] and [[Heart - Anatomía & Fisiología|heart]].
The rumen is laterally compressed and extends from the cardia at the level of the 8th rib to the pelvic inlet. The serosa covers the entire rumen except dorsally where the rumen attaches to the abdominal roof allowing more freedom for ruminal movement and expansion. Ruminal contractions can be felt for in the left paralumbar fossa. 1-2 contractions should be felt per minute. The opening at the cardia into both the rumen and [[Reticulum - Anatomía & Fisiología|reticulum]] is called the reticular groove (see [[Oesophageal Groove|oesophageal groove]]).
==Función==
The rumen is involved in waste removal. Simpler products of digestion are assimilated directly, others continue down the digestive tract for further digestion. It mixes food and moves it forwards through the stomach chambers. Sensors in the rumen can determine the coarseness of the food. Coarse, tough feed needs stronger and more frequent ruminal contractions. The '''vagus nerve''' ([[Nervios Craneales - Anatomía & Fisiología|CN X]]) is needed for control of stomach movements. The reflex control is through sensory receptors in the medulla.
Ver [[Rumination - Anatomía & Fisiología|rumination]] and [[Eructation - Anatomía & Fisiología|eructation]].
==Ruminoreticular contraction==
[[Image:Contractions of the ruminoreticulum diagram.jpg|thumb|right|250px|Diagram of the contractions of the ruminoreticulum - Copyright RVC 2008]]
The contractions have to main functions:
:Primary contraction mixes food by a ruminoreticuluar mixing cycle. There are 2 contractions of the reticulum (2nd most powerful) which continue over the [[Rumen - Anatomía & Fisiología|rumen]]. Ingesta flows from the reticulum to cranial rumenal sac and then to reticulum (or ventral sac). It occurs every 60 seconds.
:The secondary contraction lets gas out (see [[Eructation - Anatomía & Fisiología|eructation]]). Ingesta flows from the ventral blind sac to the dorsal blind sac then to dorsal sac (eructation) and to the ventral sac.
==Vascularización==
The rumen receives blood from the '''cranial mesenteric artery''', '''celiac artery''' and '''right''' and '''left ruminal arteries'''.
==Inervación==
The rumen is innervated by the '''dorsal vagus''' nerve ([[Nervios Craneales - Anatomía & Fisiología|CN X]]) (most important) and '''ventral vagus''' ([[Nervios Craneales -Anatomía & Fisiología|CN X]]) nerve.
==Linfáticos==
The caudal '''mediastinal lymph node''' enlargement puts pressure on the dorsal vagus effecting ruminal contractions. There are numerous small lymph nodes scattered in the ruminal grooves. The lymph drains to larger atrial nodes between the cardia and the [[Omaso - Anatomía & Fisiología|omaso]], then to the cistera chyli.
==Microbios del Rumen==
The rumen has a variety of microbes that can utilise many substrates. The dominance of different bacterial species depends on pH. Ergo, microbial populations are not constant. Microbes digest cellulose and hemi-cellulose and provide a source of all amino acids. Microbes also synthesise vitamins (especially the B vitamins).
==Población Microbiana del Rumen==
'''Bacteria'''
There are over 2000 species, 99.5% are obligate anaerobes.
'''Protozoa'''
Large, unicellular organisms that prey on bacteria. Numbers are affected by diet.
'''Fungi'''
Digest fibre. Numbers present are usually low.
'''Common Rumen Microbes'''
{| style="width:75%; height:200px" border="1"
!'''Species'''
!'''Type'''
!'''pH'''
|-
| '''''Ruminococcus flavefauens'''''
| Fibre
| 6.15
|-
| '''''Fibrobacter succinogens'''''
| Fibre
| 6
|-
| '''''Megashpaera eisdeni'''''
| Lactate user
| 4.9
|-
| '''''Streptococcus bovis'''''
| Lactate producer
| 4.55
|}
==Histología==
[[Image:Rumen Histology Sheep.jpg|thumb|right|250px|Histología del rumen (oveja) - Copyright RVC 2008]]
The rumen has a '''keratinised stratified squamous epithelium'''. It is non-glandular and has no '''lamina muscularis'''.
There are two thick layers of '''tunica muscularis''', the inner circular and the outer longitudinal. The interior surface of the rumen forms numerous papillae. The papillae can be long and foliated or short and pointed. They are up to 6mm in length. Animals fed on rough grass or in the dry season have longer papillae, whereas animals fed on digestible feed or in the wet season have shorter papillae (1-2mm in length). There are fewer papillae present dorsally. They increase the surface area for [[Volatile Fatty Acids|volatile fatty acid]] absorption. The upper keratinised layer of papillae also protects the rumen against abrasion. The deeper layers of papillae metabolise the [[Volatile Fatty Acids|volatile fatty acids]].
==Diferencias Entre las Especies==
===Rumiantes Pequeños===
Sheep and goats have a larger ventral ruminal sac than dorsal ruminal sac. The cranial mesenteric artery and celiac artery come off the same root.
===Bóvidos===
The cranial mesenteric artery and celiac artery are close in the cow. Dairy cows have a rumen pH of 5.5 due to more digestible feed.
<br />
<br />
==Enlaces==
'''Haz "clic" aquí para información del [[Retículo - Anatomía & Fisiología|retículo - Anatomía & Fisiología]]'''
'''Haz "clic" aquí para información del [[Omaso - Anatomía & Fisiología|omaso - Anatomía & Fisiología]]'''
'''Haz "clic" aquí para información del [[Abomaso - Anatomía & Fisiología|abomaso - Anatomía & Fisiología]]'''
<br><br>
{{Learning
|videos = [http://stream2.rvc.ac.uk/Anatomy/bovine/Pot0052.mp4 Lateral view of the Abdomen of a young Ruminant]<br>[http://stream2.rvc.ac.uk/Anatomy/bovine/pot0175.mp4 Sections of the Ruminant Stomach]<br>[http://stream2.rvc.ac.uk/Frean/sheep/LeftSideTopography.mp4 Left sided topography of the Ovine Abdomen and Thorax]<br>[http://stream2.rvc.ac.uk/Frean/sheep/RightSideTopography.mp4 Right sided topography of the Ovine Abdomen]<br>[http://stream2.rvc.ac.uk/Frean/sheep/RuminantStomachStructure.mp4 Structure of the ruminant forestomachs]
}}
<br><br>
{{Translated
|por = 'Fanny Olsson'
|date = 16.07.2011
}}
[[Categoría:Estómago - Anatomía & Fisiología]]
==Introducción==
The rumen is the first chamber of the ruminant stomach. It is the largest chamber and has regular contractions to move food around for digestion, eliminate gases through [[Eructation - Anatomía & Fisiología|eructation]] and send food particles back to the mouth for [[Mastication|remastication]]. The rumen breaks down food particles through mechanical digestion and fermentation with the help of symbiotic microbes. [[Volatile Fatty Acids|Volatile fatty acids]] are the main product of ruminant digestion.
==Estructura==
[[Image:Rumen Anatomy Sheep.jpg|thumb|right|250px|Anatomía del rumen (oveja) - Copyright RVC 2008]]
Grooves correspond with thickened smooth muscle pillars on the inside of the rumen. '''Ruminal pillars''' divide the dorsal and ventral ruminal sacs. '''Coronary pillars''' divide the caudal blind sacs. The '''cranial pillar''' divides the dorsal and cranial sacs. It is covered by the greater omentum. The rumen is 38-40°C, anaerobic and has a pH of 6.7. It is buffered and has a large holding capacity. Water intake lowers the ruminal temperature so bacteria are tolerant to temperature changes towards the lower end of the scale. Objects are often lodged in the rumino-reticular fold. When the rumen contracts, the object can be pushed through the [[Reticulum - Anatomía & Fisiología|reticulum]] wall into the [[Heart Structure - Anatomía & Fisiología#Pericardium|pericardium]] and [[Heart - Anatomía & Fisiología|heart]].
The rumen is laterally compressed and extends from the cardia at the level of the 8th rib to the pelvic inlet. The serosa covers the entire rumen except dorsally where the rumen attaches to the abdominal roof allowing more freedom for ruminal movement and expansion. Ruminal contractions can be felt for in the left paralumbar fossa. 1-2 contractions should be felt per minute. The opening at the cardia into both the rumen and [[Reticulum - Anatomía & Fisiología|reticulum]] is called the reticular groove (see [[Oesophageal Groove|oesophageal groove]]).
==Función==
The rumen is involved in waste removal. Simpler products of digestion are assimilated directly, others continue down the digestive tract for further digestion. It mixes food and moves it forwards through the stomach chambers. Sensors in the rumen can determine the coarseness of the food. Coarse, tough feed needs stronger and more frequent ruminal contractions. The '''vagus nerve''' ([[Nervios Craneales - Anatomía & Fisiología|CN X]]) is needed for control of stomach movements. The reflex control is through sensory receptors in the medulla.
Ver [[Rumination - Anatomía & Fisiología|rumination]] and [[Eructation - Anatomía & Fisiología|eructation]].
==Ruminoreticular contraction==
[[Image:Contractions of the ruminoreticulum diagram.jpg|thumb|right|250px|Diagram of the contractions of the ruminoreticulum - Copyright RVC 2008]]
The contractions have to main functions:
:Primary contraction mixes food by a ruminoreticuluar mixing cycle. There are 2 contractions of the reticulum (2nd most powerful) which continue over the [[Rumen - Anatomía & Fisiología|rumen]]. Ingesta flows from the reticulum to cranial rumenal sac and then to reticulum (or ventral sac). It occurs every 60 seconds.
:The secondary contraction lets gas out (see [[Eructation - Anatomía & Fisiología|eructation]]). Ingesta flows from the ventral blind sac to the dorsal blind sac then to dorsal sac (eructation) and to the ventral sac.
==Vascularización==
The rumen receives blood from the '''cranial mesenteric artery''', '''celiac artery''' and '''right''' and '''left ruminal arteries'''.
==Inervación==
The rumen is innervated by the '''dorsal vagus''' nerve ([[Nervios Craneales - Anatomía & Fisiología|CN X]]) (most important) and '''ventral vagus''' ([[Nervios Craneales -Anatomía & Fisiología|CN X]]) nerve.
==Linfáticos==
The caudal '''mediastinal lymph node''' enlargement puts pressure on the dorsal vagus effecting ruminal contractions. There are numerous small lymph nodes scattered in the ruminal grooves. The lymph drains to larger atrial nodes between the cardia and the [[Omaso - Anatomía & Fisiología|omaso]], then to the cistera chyli.
==Microbios del Rumen==
The rumen has a variety of microbes that can utilise many substrates. The dominance of different bacterial species depends on pH. Ergo, microbial populations are not constant. Microbes digest cellulose and hemi-cellulose and provide a source of all amino acids. Microbes also synthesise vitamins (especially the B vitamins).
==Población Microbiana del Rumen==
'''Bacteria'''
There are over 2000 species, 99.5% are obligate anaerobes.
'''Protozoa'''
Large, unicellular organisms that prey on bacteria. Numbers are affected by diet.
'''Fungi'''
Digest fibre. Numbers present are usually low.
'''Common Rumen Microbes'''
{| style="width:75%; height:200px" border="1"
!'''Species'''
!'''Type'''
!'''pH'''
|-
| '''''Ruminococcus flavefauens'''''
| Fibre
| 6.15
|-
| '''''Fibrobacter succinogens'''''
| Fibre
| 6
|-
| '''''Megashpaera eisdeni'''''
| Lactate user
| 4.9
|-
| '''''Streptococcus bovis'''''
| Lactate producer
| 4.55
|}
==Histología==
[[Image:Rumen Histology Sheep.jpg|thumb|right|250px|Histología del rumen (oveja) - Copyright RVC 2008]]
The rumen has a '''keratinised stratified squamous epithelium'''. It is non-glandular and has no '''lamina muscularis'''.
There are two thick layers of '''tunica muscularis''', the inner circular and the outer longitudinal. The interior surface of the rumen forms numerous papillae. The papillae can be long and foliated or short and pointed. They are up to 6mm in length. Animals fed on rough grass or in the dry season have longer papillae, whereas animals fed on digestible feed or in the wet season have shorter papillae (1-2mm in length). There are fewer papillae present dorsally. They increase the surface area for [[Volatile Fatty Acids|volatile fatty acid]] absorption. The upper keratinised layer of papillae also protects the rumen against abrasion. The deeper layers of papillae metabolise the [[Volatile Fatty Acids|volatile fatty acids]].
==Diferencias Entre las Especies==
===Rumiantes Pequeños===
Sheep and goats have a larger ventral ruminal sac than dorsal ruminal sac. The cranial mesenteric artery and celiac artery come off the same root.
===Bóvidos===
The cranial mesenteric artery and celiac artery are close in the cow. Dairy cows have a rumen pH of 5.5 due to more digestible feed.
<br />
<br />
==Enlaces==
'''Haz "clic" aquí para información del [[Retículo - Anatomía & Fisiología|retículo - Anatomía & Fisiología]]'''
'''Haz "clic" aquí para información del [[Omaso - Anatomía & Fisiología|omaso - Anatomía & Fisiología]]'''
'''Haz "clic" aquí para información del [[Abomaso - Anatomía & Fisiología|abomaso - Anatomía & Fisiología]]'''
<br><br>
{{Learning
|videos = [http://stream2.rvc.ac.uk/Anatomy/bovine/Pot0052.mp4 Lateral view of the Abdomen of a young Ruminant]<br>[http://stream2.rvc.ac.uk/Anatomy/bovine/pot0175.mp4 Sections of the Ruminant Stomach]<br>[http://stream2.rvc.ac.uk/Frean/sheep/LeftSideTopography.mp4 Left sided topography of the Ovine Abdomen and Thorax]<br>[http://stream2.rvc.ac.uk/Frean/sheep/RightSideTopography.mp4 Right sided topography of the Ovine Abdomen]<br>[http://stream2.rvc.ac.uk/Frean/sheep/RuminantStomachStructure.mp4 Structure of the ruminant forestomachs]
}}
<br><br>
{{Translated
|por = 'Fanny Olsson'
|date = 16.07.2011
}}
[[Categoría:Estómago - Anatomía & Fisiología]]