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| − | <big><center>[[Alimentary - Anatomy & Physiology|'''BACK TO ALIMENTARY - ANATOMY & PHYSIOLOGY''']]</center></big>
| + | #REDIRECT[[:Category:Large Intestine - Anatomy & Physiology]] |
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| − | ==Introduction==
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| − | The large intestine extends from the [[Ileum - Anatomy & Physiology|ileum]] of the [[Small Intestine - Anatomy & Physiology|small intestine]] to the anus. Water is absorbed from the ingesta and faeces are stored prior to defeacation. Every species has a large microbial population living in the large intestine, which is of particular importance to the [[Hindgut Fermenters - Anatomy & Physiology|hindgut fermenters]]. For this reason, hindgut fermenters have a more complex large intestine with highly specialised regions for fermentation.
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| − | The large intestine can be divided into:
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| − | *[[Caecum - Anatomy & Physiology|Caecum]]
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| − | *[[Colon - Anatomy & Physiology|Colon]]
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| − | *[[Rectum - Anatomy & Physiology|Rectum]]
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| − | *[[Anus - Anatomy & Physiology|Anus]]
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| − | ==Structure==
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| − | ==Function==
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| − | ==Vasculature==
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| − | *The '''cranial mesenteric artery''' supplies the caecum, ascending and part of the transverse colon.
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| − | *The '''caudal mersenteric artery''' supplies the rest of the transverse colon, the descending colon and the rectum.
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| − | ==Innervation==
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| − | *Like the [[Small Intestine - Anatomy & Physiology|small intestine]], the large intestine recieves sympathetic and parasympathetic innervation.
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| − | *Neurones interact with the myenteric plexus to affect contractility, and with the submucosal plexus to affect secretions.
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| − | **The '''sympathetic '''have coeliac, cranial mesenteric and caudal mesenteric ganglia.
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| − | **As the sympathetic fibres leave the ganglia, they surround their respective artery.
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| − | **'''Parasympathetic''' innervation stimulates peristalsis.
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| − | ==Lymphatics==
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| − | ==Histology==
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| − | [[Image:mucosal layer of colon.jpg|thumb|right|150px|Mucosal Layer of Colon (Fox) - Copywright RVC 2008]]
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| − | *The mucosa of the large intestine is smooth; there are '''no villi'''.
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| − | *Mucosal glands are much longer and straighter.
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| − | *The number of goblet cells in the mucosa is increased compared to the small intestine.
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| − | **Mucus is very important for lubrication of the ingesta as it passes through the intestine, particularly as more water is absorbed from the lumen making it drier.
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| − | *There are numerous scattered lymph nodules.
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| − | **The number of lymph nodules increases compared to the small intestine.
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| − | *'''Taenia''' may be present.
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| − | **These are concentrations of the longitudinal muscle layer into long bands.
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| − | **When the taenia contract, they cause shortening of the large intestine, which produces saccualtions, or '''haustra'''.
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| − | *Many glands are present in the mucosa and skin of the anal region.
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| − | ==Species Differences==
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| − | ===Carnivore===
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| − | *The dog and cat posses two '''anal sacs'''. In the dog, these are the size of a hazlenut.
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| − | **They are located ventrolaterally between the internal and external anal sphincters.
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| − | **The fundus of the sac secretes a potent smelling fluid that drains through a single duct to an opening near the anocutaneous juncntion.
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| − | **The anal sacs get compressed during defecation, which causes the fluid to be expressed. The scent of the fluid is thought to act as a territorial marker.
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| − | ===Ruminant===
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| − | ===[[Hindgut Fermenters - Horse - Anatomy & Physiology|Horse]]===
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| − | ===Pig===
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| − | *Taenia present
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| − | ==Links==
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| − | [[The Small and Large Intestines|Pathology of the Small and Large Intestine]]
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