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GI of carnivores, ruminants, hind-gut fermenters - Coggle Diagram

- - - - one big tube
      - mucosa - inner most lining of GI tract; epithelium and loose connective tissue
      - submcosa
        
        dense connective tissue
        
        may contain glands
      - muscle layer - outside submucosa
      - serosa
        
        outermost layer
        
        thin tough connective tissue
  - - - duodenum - first short segment leaving the stomach
        
        pancreas secretes bicarbonate into duodenum to neutralise HCl
        
        gallbladder secretes bile for fat emulsification
      - jejunum - longest portion
      - ileum - separated from colon by ileocecal sphincter
        
        regulated movement of materials from the small intestine into the colon or the cecum
      - within the mucosa - many villi and subsequent microvilli (ciliated brush border cells) that increases surface area
      - mesentery - network of connective tissue suspending the gastrointestinal system keeping it well organised and secure
        
        fat
        
        arteries
        
        veins
        
        lymph vessels
        
        general suspensory ligament sheets
      - omentum - suspends stomach to dorsal wall of abdomen
    - - a portion of the intestine falls into itself
      - typically if an animal is struggling to regulate motility
      - severe diahhorea eg. from heavy parasite burden
    - - string is particularly bad in cats
    - - components - species variation in structure, poorly developed in carnivores
        
        cecum - blind sac at ileocecal junction
        
        colon - some microbial digestion, absorption of water and electrolytes
        
        rectum
  - - - es enters stom on angle in cardia region surrounded by cardiac sphincter mscle
      - as stomach expands, fold of stomach against soph closes the lower end of esoph
        
        reduces risk for reflux
        
        in some species closure is strong enough to prevent vomiting permanently eg. horse rabbit rat
        
        vomiting is an active reflux - involved abdominal muscles, stom muscles, esoph muscles
        
        regurgitation is passive - minimal reverse peristalsis
      - gastric motility
        
        visceral smooth muscle in stomach wall responds to hormones peptides nervous system controls
        
        parasympathetic stimulation causes fundus to relax and increases contractions in antrum)
        
        sympathetic stumalation can cause a decrease in motility - gastric atony (delayed gastric emptying)
      - stomach made up of numerous layers
        
        generous folds aka rugae - increase surface area
      - gastric dilatation volvulus
        
        clinical symptoms
        
        big dog with barrel chest and tucked abdomen - trying to vomit but cannot
        
        stomach has swollen - food, water, gas - has taken on a pendulous motion within lower thoracic region and has flipped on itself
        
        SEVERE EMERGENCY
  - - - mastication - chewing, physically break down food into smaller pieces
      - ruminants have no upper incisors
        
        dental pad - flat thick connective tissue structure ob the maxilla opposite the lower incisors and canine teeth
    - - produce saliva, usually three pairs with ducts that carry the saliva to the oral cavity
        
        parotid salivary glands - ventral to the ear canals
        
        mandibular salivary glands - ventral to the parotid glands at the caudal angle of the mandible
        
        lingual salivary glands - medial to the shafts of the mandible just under the base of the tongue
        
        cats and dogs also have zygomatic salivary glands
    - - prehend food
      - mechanical digestion
      - chemical digestion
      - prepare food for swallowing
  - - - mouth
      - pharynx
      - cranial part of esophagus
      - external anal sphincter
      - allows processes of chewing, mixing saliva with food, initiation of swallowing
    - - wall of the majority of the oesophagus, stomach, small intestine, large intestine, internal anal sphincter
      - primarily arranged in circular and longitudinal layers
- - - - fundus
      - body
      - pyloric antrum
  - - - most digestion occurs here
      - sodium bicarbonate received from pancreas
      - bile from liver emulsifies fats
    - - some digestion and some absorption
    - - mostly absorption
  - - - bacteria create vitamin K - essential for clotting factors
    - - almost non functional in mono gastric systems
    - - bacterial activitiy
      - water absoprtion
      - waste storage
    - - waste storage
  - - - internal sphincter - autonomic control
      - external sphincter - voluntary control
- - - - fundus
      - body
      - pyloric antrum
  - - - most digestion occurs here
      - sodium bicarbonate received from pancreaus
      - fat emulsified by bile from gallbladder
    - - soem digestion and some absorption
    - - mostly absorption
  - - - create vitamin k
    - - fermentation of carbohydrates
      - secretes bicarbonate to buffer acidic contents
    - - broken down into
        
        ventral colon
        
        dorsal colo
        
        small. colon
      - water and electrolyte absoption
      - waste storage
    - - waste storage
  - - - internal sphincter - autonomic control
      - external sphincter - voluntary control (less than foreguts as constantly eating)
- - - - mechanical
      - smalles most cranial
      - separated from rumen by ruminoreticular fold
      - lining is honeycomb arrangement of fold
      - works with rumen
    - - mechanical and bacterial (fermentative)
      - series of muscular sacs partially separated by long muscular folds of rumen wall called pillars - aid in mixing and stirring oof contents
      - reticuloruminal contractions allow partially digested plant food to be regurgitated
        
        allow built up co2 or methane gas to be expelled from rumen
      - bloat
        
        huge excessive bloating - some bloating can be normal on left side but this is pronounced and excessive, won't go away
        
        sometimes fixed by a plug or antibloat agents
        
        could be caused by dietary or nutritional issues
    - - mechanical
      - absorbs VFAs
      - removes bicarbonate ions and some water
      - reticulorumne contractions move ingest into omasum
        
        msucular organs with many folds, breaks down food further etc
    - - true stomach
      - mechanical and chemical breakdown of carbs and proteins
      - functions the same as a monogastric stomach fundamentally
      - displaced absomasum
        
        majority of cases occur soon after calving
        
        uterus displaces abomasum so much it can cause chronic displacement
        
        if abomasum stop functioning will accumulate gas and move dorsocranially up abdomen
  - - - most digestion occurs here
      - sodium bicarb received form pancreas
      - fat emulsified by bile from gallbladder
    - - some digestion and some absoption
    - - mostly absorption
  - - - almost non functional in monogastric systems
    - - bacterial activity, water absorption, waste storage
    - - terminal porto=n of large intestjne
      - nervos systen control of motility similar to colon
      - numerous mucus secreting glands lubricate and aid passage
      - sensory receptors detect stretching and stimulate defecation response
  - - - internal sphincter - autonomic
      - external sphincter - voluntary
- - - - bile acids
      - chlesterol
      - bilirubin
      - secreted into bile ducts, onto hepatic duct, to gallbladder for starage
        
        stimulation by CCK causes gallbladder contraction
        
        forces bile down the common bile duct into the duodenum