Ruminant & Hind-gut Fermentors Flashcards
what are the 4 tunics of the GI tract?
- Mucosa
- Submucosa
- Muscularis
- Serosa or adventitia
what are the three parts of the mucosa?
- Epithelium
- Lamina propria
- Muscularis mucosa
what muscle type is found in the GI tract?
smooth
what are the two layers of the tunica muscularis (in the typical gut section)?
- The inner circular muscle layer forms sphincters
- The outer longitudinal muscle layer may form
longitudinal bands (tenia)
what is the difference between an adventitia and serosa
- Tunica adventitia:
o ill-defined layer of connective tissue blending with surrounding connective tissue - Tunica serosa:
o thin connective tissue layer covered by mesothelium
o (a simple squamous epithelium) aka the visceral peritoneum
what type of epithelium found in the mouth, esophagus, tongue, stomach (different sections), small intestine, large intestine, and rectum.
Mouth: stratified squamous epithelium
Esophagus: thick stratified squamous epithelium
Tongue: stratified squamous epithelium
Stomach: simple columnar epithelium
Small intestine: simple columnar epithelium
Large intestine: simple columnar epithelium
Rectum: stratified squamous non-keratinized epithelium
what are the four stomachs in the ruminant?
- Rumen
- Reticulum
- Abomasum
- omasum
Which are the forestomachs? Which is the true stomach?
- The rumen, reticulum, and omasum are the forestomachs
- The abomasum is the true stomach
Is the rumen on the right or left side?
left
is the abomasum on the left or the right side?
right
what are the physical features of the rumen, reticulum, and omasum
Rumen:
- Luminal surface is covered with small, paddle-shaped papillae
- Does NOT have a muscularis mucosa
Reticulum:
- Tripe
- Important for mechanical digestion
- Most cranial compartment of the 4 stomachs
- Located on the median plane against the diaphragm
- Surface folds form honeycomb-like network of ridges with muscularis mucosa in the free edge only
- Small secondary papillae extend from the folds
Omasum:
- Heavy & hard
- Absorption of water (60%)
- Called the “butcher’s bible” or “book) because the muscular laminae look like the pages of the book
which has numerous paddle-shaped papillae?
rumen
which does not have a muscularis mucosa?
rumen
which is found along the median plane against the diaphragm?
rumen
which has honey-combed folds?
reticulum
Which is known as the butcher’s bible?
omasum
Rumination
- Ruminants chew cud
- Rumination involves:
o Bolus of previously eaten food carried back into
the mouth by reverse peristalsis
o Fluid in bolus is squeezed out with the tongue and
swallowed
o Bolus is rechewed and reswallowed - Rumination may occupy ~1/3 of the ruminant’s day
Eructation
- Fermentation of food in the rumen generates large quantities of gas
- Belching is how ruminants get rid of fermentation gases
Sigmoid flexure
- Region of the descending colon with a long mesocolon hanging down into the abdomen
- Allows great movement during rectal palpation
what is the purpose of the reticular groove?
a channel from the esophagus to the omasum (bypasses the rumen)
Know the structure of the spiral colon of the ruminant
what branch of the abdominal aorta supplies the ruminant forestomach?
celiac artery
do horses have gall bladders?
NO
what are the three parts of the equine cecum? Is it on the left or right side of the body?
- cecal base
- cecal body
- cecal apex
RIGHT SIDE
what are the four parts of the equine ascending colon?
- Ascending colon (~12 feet long)
o Right ventral colon (sternal flexure)
o Left ventral colon (pelvic flexure)
o Left dorsal colon (diaphragmatic flexure)
o Right dorsal colon
Ampulla coli is the expanded terminal portion
of the right dorsal colon
what is the direction does the transverse colon travel? Left to right or right to left?
travel from right to left
what is the order of structures that digesta travels from the cecum to the rectum in the horse (including the names of the different flexures).
- Small intestines are ~70’ long
- Small intestine empties into the cecum via the ileocecal
orifice (1) - Ingesta passes from the cecum to the colon via the
cecocolic orifice (2) - Cecum is large, and it takes feed ~3-4 days to pass into
the colon - Allows for slow fermentation of fiber
what is number of tenia located on the right dorsal colon, the left dorsal colon, the right ventral colon, and the left ventral colon
- Tenia (bands)
- Right dorsal colon: one band in mesocolon and 2 free
- Left dorsal colon: one band in the mesocolon
- Right & left ventral colon: 2 bands in the mesocolon and 2 free
