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Reticulum - Anatomy & Physiology (view source)

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==Introduction==
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The reticulum is the second chamber of the ruminant stomach. It has regular contractions which precede the biphasic ruminal contraction for digestion of food particles.
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Mechanical digestion and microbial fermentation occur to breakdown food particles for absorption. [[Volatile Fatty Acids - Anatomy & Physioogy|Volatile fatty acids]] are the major product of ruminant digestion.
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==Structure==
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[[Image:Reticulum Anatomy Sheep.jpg|thumb|right|150px|Reticulum Anatomy (Sheep) - Copyright RVC 2008]]
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*Covered by greater omentum
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*The rumino-reticular fold often gets object lodged. When the [[The Rumen - Anatomy & Physiology|rumen]] contracts, the object can be pushed through the reticulum wall into the [[Structure of the Heart - Anatomy & Physiology#Pericardium|pericardium]] and [[Heart - Anatomy & Physiology|heart]].
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*Opening at the cardia into both the reticulum and the [[The Rumen - Anatomy & Physiology|rumen]] is called the reticuluar groove (see [[Oesophageal groove|oseophageal groove]]). The reticular groove also opens into the [[The Omasum|omasum]].
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*Cranial to the [[The Rumen - Anatomy & Physiology|rumen]]
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*Ribs 6-8
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*From cardia to the diaphragm
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*Lies above the xiphoid process of the sternum
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*Serosa covers the surface
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==Function==
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*Waste removal
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*Movement
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*Simpler products of digestion are assilimated directly, others continue down the digestive tract for further digestion
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*See [[Rumination - Anatomy & Physiology|rumination]]
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*See [[Eructation - Anatomy & Physiology|eructation]]
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==Ruminoreticular contraction==
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[[Image:Contractions of the ruminoreticulum diagram.jpg|thumb|right|150px|Diagram of the contractions of the ruminoreticulum - Copyright RVC 2008]]
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*Primary mixes food
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**Mixing cycle of ruminoreticulum
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**2 contractions of the reticulum (2nd most powerful) which continues over the [[The Rumen - Anatomy & Physiology|rumen]]
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**Ingesta flows from the reticulum to cranial ruminal sac to reticulum (or ventral sac)
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**Every 60 seconds
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*Secondary lets gas out
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**See [[Eructation - Anatomy & Physiology|eructation]]
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**Ingesta flows from ventral blind sac to dorsal blind sac to dorsal sac ([[Eructation - Anatomy & Physiology|eructation]]) to ventral sac
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==Vasculature==
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*Cranial mesenteric artery
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*Celiac artery
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*Right and left ruminal arteries
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==Innervation==
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*Dorsal vagus ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]]) (most important)
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*Ventral vagus ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]])
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==Lymphatics==
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*Numerous small lymph nodes are scattered in the grooves
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*The lymph drains to larger atrial nodes between the cardia and [[The Omasum|omasum]], then to the cistera chyli
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==Histology==
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[[Image:Reticulum Histology Sheep.jpg|thumb|right|150px|Reticulum Histology (Sheep) - Copyright RVC 2008]]
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*Keratinised stratified squamous epithelium
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*No glands
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*Honeycomb appearance of short and tall folds
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*Mucosal layer thrown into folds
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*The folds gradually merge into papillae where the reticulum meets the rumen
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*Lamina muscularis present as discrete bands of smooth muscle (not continuous)
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*[[Oral Cavity - Tongue - Anatomy & Physiology#Types of Papillae|Conical papillae]], also called secondary papillae, on folds providing a rough surface to increase food breakdown
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*2 thick layers of tunica muscularis- inner circular and outer longitudinal
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*The upper keratinised layer protects against abrasion
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*The deeper layers metabolise [[Volatile Fatty Acids - Anatomy & Physioogy|volatile fatty acids]]
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==Species Differences==
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===Small Ruminants===
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*Larger reticulum compared to cattle
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*In sheep and goats the ridges of the reticular cells are lower and have more prominant serrated edges than in cattle
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*The papillated ruminal mucosa expands over a greater proportion of the reticulum
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==Links==
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[[The Rumen - Anatomy & Physiology|The Rumen - Anatomy & Physiology]]
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[[The Omasum|The Omasum - Anatomy & Physiology]]
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[[The Abomasum|The Abomasum- Anatomy & Physiology]]
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[[The Stomachs of the Ruminant - Anatomy & Physiology - Flashcards#The Reticulum|The Reticulum Flashcards]]
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'''Video'''
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[http://stream2.rvc.ac.uk/Anatomy/bovine/Pot0052.mp4 Pot 52 Lateral view of the Abdomen of a young Ruminant]
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[http://stream2.rvc.ac.uk/Anatomy/bovine/pot0175.mp4 Pot 175 Sections of the Ruminant Stomach]
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[http://stream2.rvc.ac.uk/Frean/sheep/LeftSideTopography.mp4 Left sided topography of the Ovine Abdomen and Thorax]
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[http://stream2.rvc.ac.uk/Frean/sheep/RightSideTopography.mp4 Right sided topography of the Ovine Abdomen]
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[http://stream2.rvc.ac.uk/Frean/sheep/RuminantStomachStructure.mp4 Structure of the ruminant forestomachs]
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