Difference between revisions of "Hindgut Fermenters - Anatomy & Physiology"

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<big><center>[[Alimentary - Anatomy & Physiology|'''BACK TO ALIMENTARY - ANATOMY & PHYSIOLOGY''']]</center></big>
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<big><center>[[Large Intestine - Anatomy & Physiology|'''BACK TO LARGE INTESTINE - ANATOMY & PHYSIOLOGY''']]</center></big>
  
 
==Introduction==
 
==Introduction==
  
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Hindgut fermenters are evolved to eat a herbivorous diet. Such a diet includes large quantities of insoluble plant carbohydrates, such as cellulose. Mammals cannot digest these insoluble carbohydrates as they lack the essential enzymes, such as cellulase. However it is important that they do digest these carbohydrates as there is insufficient quantity of soluble carbohydrates in plant material. Some microbes do have the enzymes to digest these insoluble carbohydrates and so hindgut fermenters hold a symbiotic relationship with these microbes. Hindgut fermenters have anatomical adaptations to allow for an expanded microbial population. The products of fermentation are [[Volatile Fatty Acids|volatile fatty acids]]. It is important to supply a source of fibre in their diet as it stimulates peristalsis in the gut and prevents a build up of gas.
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==Caecum==
  
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==Cellulose Structure==
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*On the right side of the abdomen.
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*Very large, roughly 1m in length with a 30L capacity.
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*Consists of a base, body and apex (blind ending).
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*The base lies in the right dorsal part of the abdomen in contact with the abdominal roof.
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*Apex lies on the ventral abdominal wall, and terminates at the level of the xiphoid cartilage.
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*Exists at the junction with the ileum and colon.
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**The '''caecocolic orifice''' is where the caecum opens into the ascending colon. This exists as a transverse slit formed by a constriction of the ascending colon.
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**The ileum opens into the caecum at the '''ileal papilla'''. This is a small projection into the caecum housing the ileal sphincter and venous plexus that, together, control the ileal orifice.
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*Taenia are present.
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**Taenia are formed by concentration of the ''longitudinal'' muscle layer.
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**Between the taenia are sacculations, or haustra.
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**Haustra appear as folds on the interior surface.
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***There are '''four''' taenia over the caecum: -dorsal - ventral - lateral -medial.
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***The ''dorsal'' taenia provides the attachment site for the ileocaecal fold, which joins the caecum to the ileum.
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***The ''lateral'' taenia provides the attachment site for the caecocolic fold, which joins the caecum to the ascending colon.
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***The ''ventral'' taenia is free.
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***The ''medial'' and ''lateral'' taenia are where the caecal vessels and lymph nodes are located.
  
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[[Image:cellulose.jpg|thumb|right|250px|Cellulose - © RVC 2008]]
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In the horse, the caecum is responsible for the digestion of complex carbohydrates such as cellulose. Ingesta is regularly transported from the ileum to the caecum, this movement can be heard upon auscultation of the right dorsal quadrant of the caudal abdomen. Ausculatation of this area is carried out in assesment of colic.
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Cellulose exists in the cell walls of plants. Mammals are unable to digest cellulose due it's structure. Cellulose is a polymer of glucose where each glucose monomer is joined to the next by a '''β-1,4 glycosidic bond'''. Mammalian enzymes only have the capability to break '''α-1,4 glycosidic bonds''', which are seen in starch and glycogen.
 
  
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==Comparison with [[Ruminant Stomach - Anatomy & Physiology|foregut fermenters]]==
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==Colon==
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Hindgut fermenters have an enlarged hindgut as opposed to foregut, as the [[Ruminant Stomach - Anatomy & Physiology|ruminants]] do, for microbial fermentation to take place. Hindgut fermentation provides advantages and disadvantages.
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*Taenia present.
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'''Advantages:'''
 
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Soluble carbohydrates, such as glycogen, are available to the animal before they are available to the microbes. Therefore the brain, which can only utilise glucose, receives a good, constant supply with relatively less time and energy utilised than in the ruminant. [[Ruminant Stomach - Anatomy & Physiology|Foregut fermenters]] receive nearly all of their energy in the form of [[Volatile Fatty Acids|VFAs]], which have to be converted to glucose by gluconeogenesis in the liver to be able to be used by the brain.
 
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'''Disadvantages:'''   
 
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Microbes in the foregut can convert non-proteinaceous sources of nitrogen, like ammonia and urea to all of the amino acids. Microbial protein is available to the ruminant when the microbes die and pass down into the [[Abomasum - Anatomy & Physiology|abomasum]] and [[Small Intestine Overview - Anatomy & Physiology|small intestine]]. Therefore ruminants can survive on a poor quality source of of nitrogen. Microbial protein is not available to hindgut fermenters because when the microbes in the [[Large Intestine - Anatomy & Physiology|large intestine]] die, they get excreted as there is no further opportunity for their digestion. Microbes in the foregut synthesise vitamins, which are also available to the animal further on in the digestive tract. Again, they are not available to the hindgut fermenter. Microbes in the foregut can detoxify some poisonous compounds. Poisonous compounds can be digested and absorbed before they reach the microbes in the hindgut.
 
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==Links==
 
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'''Click here for more information on the [[Alimentary System  - Horse Anatomy|horse]], [[Rabbit Alimentary System|rabbit]] and [[Elephant Alimentary System - Anatomy & Physiology|elephant]]'''.
 
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{{Template:Learning
 
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|flashcards = [[Hindgut Fermenters - Anatomy & Physiology - Flashcards|Hindgut Fermenters]]
 
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}}
 
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==Webinars==
 
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<rss max="10" highlight="none">https://www.thewebinarvet.com/gastroenterology-and-nutrition/webinars/feed</rss>
 
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[[Category:Large Intestine - Anatomy & Physiology]]
 
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[[Category:A&P Done]]
 

Revision as of 10:29, 12 July 2008

BACK TO ALIMENTARY - ANATOMY & PHYSIOLOGY
BACK TO LARGE INTESTINE - ANATOMY & PHYSIOLOGY

Introduction

Caecum

  • On the right side of the abdomen.
  • Very large, roughly 1m in length with a 30L capacity.
  • Consists of a base, body and apex (blind ending).
  • The base lies in the right dorsal part of the abdomen in contact with the abdominal roof.
  • Apex lies on the ventral abdominal wall, and terminates at the level of the xiphoid cartilage.
  • Exists at the junction with the ileum and colon.
    • The caecocolic orifice is where the caecum opens into the ascending colon. This exists as a transverse slit formed by a constriction of the ascending colon.
    • The ileum opens into the caecum at the ileal papilla. This is a small projection into the caecum housing the ileal sphincter and venous plexus that, together, control the ileal orifice.
  • Taenia are present.
    • Taenia are formed by concentration of the longitudinal muscle layer.
    • Between the taenia are sacculations, or haustra.
    • Haustra appear as folds on the interior surface.
      • There are four taenia over the caecum: -dorsal - ventral - lateral -medial.
      • The dorsal taenia provides the attachment site for the ileocaecal fold, which joins the caecum to the ileum.
      • The lateral taenia provides the attachment site for the caecocolic fold, which joins the caecum to the ascending colon.
      • The ventral taenia is free.
      • The medial and lateral taenia are where the caecal vessels and lymph nodes are located.

In the horse, the caecum is responsible for the digestion of complex carbohydrates such as cellulose. Ingesta is regularly transported from the ileum to the caecum, this movement can be heard upon auscultation of the right dorsal quadrant of the caudal abdomen. Ausculatation of this area is carried out in assesment of colic.

Colon

  • Taenia present.
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