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Anatomy > digestive system pt 2/ ruminants > Flashcards

digestive system pt 2/ ruminants Flashcards

1
Q

what is a ruminant

A
  • cub chewing animals (swallow their food then bring it back up to chew again later)
  • Ruminants have a four chambered stomach
  • all ruminants are herbivores but not all herbivores are ruminants
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2
Q

what are come common ruminant species and some pseudo-ruminants

A
  • bovine, ovine, caprine, deer, moose, elk
  • pseudo- ruminants - camelids (camels, lama, alpaca) and hippos
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3
Q

what are the four compartments of the ruminant stomach

A
  1. rumen
  2. reticulum
  3. omasum
  4. abomasum
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4
Q

where in general is the ruminant stomach located

A
  • caudal to the diaphragm
  • caudo-lateral to the liver
  • more towards the left side of the abdomen
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5
Q

how big is the ruminant stomach

A
  • occupies roughly 3/4 of the stomach
  • 220L in cow
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6
Q

describe the rumen

A
  • AKA paunch or fermentation vat
  • largest capacity 80% by volume
  • extends from the cranial abdomen , near the liver and diaphragm
  • ends near the pelvic inlet
  • most of the left side of the abdominal cavity
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7
Q

what is the rumen structure

A
  • external grooves and internal vertical and horizontal pillars
  • incompletely divide the rumen into a dorsal and ventral sac
  • each sac is further subdivided into cranial sac and caudal blind end sac
  • 4 sacs total
  • internal surface covered in many papillae of varying lengths (gives appearance of a shag carpet)
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8
Q

what is the rumen function

A
  1. mixes and churns and softens injected food
  2. initiates rumination and eructation
  3. site of fermentation
    - primarily mechanical digestion
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9
Q

define fermentation

A
  • breakdown of cellulose and other plant structures by microorganisms
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10
Q

what is the ideal environment for fermentation to occure

A
  • proper pH, temperature, bacteria and anaerobic conditions
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11
Q

describe the reticulum

A
  • AKA honeycomb or hardware compartment
  • most cranial compartment towards the left
  • closest to the liver and diaphragm
  • not completely separate from the rumen
  • at junction of esophagus and rumen
  • 5% of ruminant stomach volume
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12
Q

reticulum function

A
  1. acts as a passageway for food
  2. initiates mixing waves for the rumen (paces the contractions of the rumen)
  3. traps heavy objects
    - mechanical digestion
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13
Q

reticulum structure

A

honeycomb like appearance on inner surface

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14
Q

describe omasum

A
  • AKA book stomach
  • round to oval bowling ball sized
  • on the right of the abdomen, between reticulum and abomasum
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15
Q

omasum structure

A
  • internally layers of laminae resemble pages or hangs from a roof
  • covered in short blunt papillae
  • 8% of stomach volume
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16
Q

omasum function

A
  1. grinds food
  2. absorbs bicarbonate
  3. resorbs water
    - mechanical digestion and absorption
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17
Q

describe abomasum

A

AKA true stomach
- glandular stomach
- caudo ventral to the omasum
- extends along right side fo the rumen
7% by volume

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18
Q

abomasum structure

A
  • consists of 12-15 internal, spiral, lengthwise folds
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19
Q

abomasum function

A
  1. chemical digestion (acid and enzymes)
  2. mucus production
  3. mixing
    - will then pass the digesta through the pylorus into the small intestine (duodenum)
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20
Q

what is the flow of digesta in the ruminant stomach (if u dont know this by now give up)

A

rumen–> reticulum–> omasum–> abomasum
- contents of the rumen and reticulum enter and exit freely, not a strict order between the two

21
Q

what is the esophageal groove

A
  • two thick muscular folds from esophagus to omasum
  • folds form a continuous tube when a young ruminant nurses
  • allows milk to bypass the rumen and reticulum because fermentation of milk would negatively alter rumen pH
  • reflex initiated by suckling
  • pail-fed calves may not initiate reflex, results in pot bellied cows
22
Q

describe the process of rumination

A
  • chewing the cud
  • eat quickly with little initial chewing
  • ingests moves back up into the oral cavity from the rumen where additional saliva and chewing further breaks down plant matter before reswallowing
  • in cows approx. 8h.day
  • not vomiting
23
Q

what are the four basic steps to rumination

A
  1. regurgitation
  2. reinsalivation (more saliva added to ingesta
  3. remastication (rechewind, approx 35 min/period)
  4. deglutination (reswallowing)
24
Q

how regurgitation works

A
  • scratch reflex in dorsal sac determines coarseness of the feed
  • rumen contraction in a cranial direction moves feed to the esophageal sphincter
  • animal inspires against a closed glottis
  • effect is to decrease the pressure in the chest (creates negative pressure in the chest)
  • causes espohagus to dilate and esophageal sphincter to relax
  • pressure in the rumen is now greater than in the esophagus
  • bolus is sucked into the esophagus
  • reverse peristaltic wave moves up the esophagus
25
Q

eructation

A
  • AKA belching or burping
  • similar process to rumination
  • removes gasses produced in fermentation - methane, CO2
  • occurs about once every minute
26
Q

describe how eructation works

A
  • pressure receptor in dorsal sac measure increasing pressure
  • registered by reflex centers in the medulla
  • motor nerve impulses sent to the rumen
  • rest is similar to rumination (neg pressure, gas moved up esophagus)
27
Q

what happens if eructation fails

A
  • bloat
  • unable to ride of gas
  • obstruction, high grain diets (excessive fermentation and gas production)
  • excessive legumes (excessive foam produced that blocks the escape of gas)
  • hardware disease
28
Q

describe the small intestine

A
  • long tube extending from pylorys of the stomach to the start of large intestines
  • has three regions
  • has specialized structures to increase surface area for absoprtion
29
Q

what is the SI the primary site of

A

digestion and absorption

30
Q

explain SI how it works (enzymes responsible for digestion)

A
  • produces multiple digestive encymes
  • secretes mucus from goblet cells
  • secretes cholecytoskinin into the blood in the presence of fats and proteins
  • CCK stimulates intestinal motility and gallbladder contraction
  • moves ingesta via peristalsis and segmentation
31
Q

what are the specialized structures increasing the surface area of SI

A
  1. circular folds - deep mucosal folds
  2. intestinal vili - long slender projections
  3. microvilli - on columnar epithelial cells
32
Q

explain villi

A
  • blood and lymph vessels in the center of each villus
  • absorb nutrients through simple columnar epithelial cells
  • villus cells constantly renew
  • diseases like parvovirus attack these cells, greatly reducing ability to digest and absorb nutrients
33
Q

more about microvilli

A
  • on columnar epithelial cells
  • micro villi layer is called the brush border
  • brush boarder cells have many carrier molecules and digestive enzymes in their cell membranes
  • all help digestion and absorption of nutrients, minerals and vitamins
34
Q

what are the three regions of the SI (just list)

A
  1. duodenum
  2. jejunum
  3. ileum
35
Q

what is the duodenum

A
  • represents 5% of the length of the small intestines
  • receives secretions from liver and pancreas
  • produces enxymes
36
Q

what are the 3 enzymes the duodenum produce and their functions

A

proteases (break down starches)
amylases (break down starches)
lipase (break down fat)

37
Q

what is jejunum

A
  • represents 90% of the length of the small intestines
  • absorption, mixing
38
Q

what is the ileum

A
  • 5% of length of small intestine
  • protection
  • highest concentration of Peyer’s patches (lymphoid tissues)
39
Q

small intestine vs large

A
  • large is shorter
  • large has larger diameter and lumen
  • large doesnt secrete any enzymes
  • large has 4 parts not 3
40
Q

what are the divisions of the large intestine (4 parts)

A
  1. cecum
  2. colon (ascending, transverse, descending)
  3. rectum
  4. anus
41
Q

describe the cecum

A
  • found at the ileocecocolic junction
  • blind-end sac/pouch
  • well developed in all herbivorous animals that dont ruminate (site of fermentation for non ruminant herbivores)
  • both rabbits and horses have large sacculated ceca
42
Q

what is the cecum function

A
  • bacterial fermentation
  • aids in the breakdown of cellulose
  • absorption of volatile free fatty acids (VFA)
  • protection (lymphoid tissue in walls)
43
Q

what is the colon divided into (list)

A
  • ascending
  • transverse
  • descending
44
Q

describe ascending colon

A
  • from junction with ileium and or cecum, along right side of body wall, extends cranially
45
Q

describe transverse colon

A
  • from right to left side of the abdomen
46
Q

descending colon

A
  • from transverse colon to where sigmoid curve joins cranial rectum
  • extends mostly along left side of the body wall and enters the pelvic canal
47
Q

colon function

A
  1. mucus secretion (goblet cells help lubricate lining)
  2. vitamins B and K production and absorption
  3. mineral absorption
  4. primary site of fluid and electrolyte recovery and absorption
  5. propels waste towards rectum (segmentation and mass movement)
48
Q

describe rectum

A
  • end portion of the large intestine
  • located in the pelvic cavity
  • secretes mucus
  • many stretch receptors (initiate defecatio reflex when fecal material present, causing contraction f rectum and colon)
49
Q

describe anus

A
  • terminal end of GIT
  • opening to exterior
  • has two spincter muscles (one internal involuntary and one external voluntary)
    sphincters relax with defecation reflex

Anatomy (8 decks)

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