Ruminant anatomy and physiology Flashcards
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What are the four chambers of the ruminant stomach and which are non-glandular and which are glandular?
- reticulum
- rumen
- omasum
= non-glandular - abomasum
= glandular
What are foregut fermenters?
- digestive process in which plant material is fermented in a specialized combination of stomach compartments
What is rumination?
- animal regurgitates previously consumed food and chews it further and re-swallows
What is eructation?
- release of gas produced by fermentation from the stomach or oesophagus through the mouth
What are pseudo-ruminants?
- like ruminants use foregut fermentation but have 3 compartments instead of 4
- camels and hippos
What do the three compartments of the pseudo-ruminant stomach do?
- C1 - essentially a fermentation vat
- C2 - some nutrient absorption occurs
- rhythmic contractions then eructation and regurgitation
- C3 - true stomach - distal part secretes HCL
Where does the reticulum lie?
- lies cranial to the rumen under the 6th-8th ribs
- lies up against the diaphragm
What distinct feature does the reticulum have?
- distinct honey comb structure covered in short papillae
The rumen and reticulum are often together - what is their joint term?
- reticulorumen
What lines the reticulum?
- non-glandular mucosa lined by stratified squamous epithelium
What lines the rumen?
- non-glandular mucosa
- keratinised stratified squamous epithelium
What in the rumen increases the surface area 7-fold?
- papilla present formations of the lamina propria and submucosa
What layer is not present in the rumen?
- muscularis mucosa is absent
Where are papillae not present in the rumen?
- not present over the centre of the roof or the free margins of the pillars
Where does the omasum lie?
- lies within the intrathoracic part of the abdomen to the right of the reticulorumen
How are short papillae formed in the omasum?
- internal parallel laminae - thick muscular sheets covered with non- glandular mucosa forms papillae
Where does the muscularis mucosa extend into in the omasum?
- extends into the laminae
What is the abomasum?
- the true stomach with glandular mucosa containing gastric glands and pyloric glands
What covers the abomasum?
- simple columnar epithelium
What increases the mucosal surface area if the abomasum?
- mucosal surface area increased by large folds which do not disappear when the stomach distends
The muscularis externa (found in the abomasum) is comprised of what?
- inner circular layers
- outer longitudinal layers of smooth muscle
In calves what prevents milk from entering the rumen (which isn’t fully developed)?
- oesophageal groove = muscular folds of the reticulorumen
What are new-born calves described as?
- pre-ruminants
What is the transition phase in calves?
- from pre-ruminant to ruminant