GI Physiology 1 Flashcards
(43 cards)
GI tract is a…
Tube! mouth to anus
Systems needed for food acquisition and ingestion
Sensory!
tactile, visual, olfactory, memory
and of course mechanical ingestion
Pre-gastric mechanical functions
prehension - seizing food in mouth
mastication
deglutition- swallowing
3 stages: mouth (voluntary), pharynx, esophagus (both reflex)
What is segmentation
back and forth mixing due to intermittent contraction of circular smooth muscle
(promotes digestion and absorption!)
What is peristalsis?
unidirectional waves of contraction towards the anus
(propulsive in nature)
Motility in the gut wall (3 types)
propulsive - moving aboral
retentive - material is retained longer
mixing - material within lumen is churned
timing of material from one area to another is called…
transit time
transit time ___ between species and diet
VARIES
minutes in small birds eating high energy dense food (rapid absorption)
30+ hours in ruminants - time needed for roughages and microbial environment
altering transit times?
increasing retention and reducing propulsive motility are the basis of treatments for diarrhea
digestion vs absorption
digestion = reduction in size
- reduce food to molecules to be absorbed
- physical, chemical, enzymatic breakdown
absorption = transport of nutrient particles into vascular system
- must follow digestion
chemical and enzymatic digestion
chem: hydrolysis of chemical bonds, by HCl
enzyme: hydrolysis of chemical bonds via enzymes
Saliva function and what species its greatest in?
aids mastication and deglutition
volume varies but is greatest in herbivores!
Ruminant saliva
buffering solution - support rumen microbes and buffer acid produced in fermentation process
antifoaming
continuous flow
80% of water in ruminant stomach is from salivary secretions
In all species the major digestive enzyme produced by the salivary glands is?
Amylase
maldigestive diseases share clinical signs with______ diseases
malabsorptive
etiologies are treated differently
(bad teeth = maldigestive, vs parvo pet where absorptive lining has been destroyed)
What is detoxification?
liver is integral in detoxifying substances
for bacterial housing; all species MUST (4)?
• Prevent bacteria from leaving the gut and entering the bloodstream
• Maintain the ‘correct’ types of bacteria for that species.
• Keep colonic bacteria out of small intestine
• Provide a good environment (be a good host) for fermentative bacteria.
2 systems control GI Function
extrinsic and intrinsic
both controlled by nerves and endocrine secretions
Intrinsic neuronal control in the enteric nervous system
autonomic system
-regulation of digestion
ENS controls GI functions independent of central nervous system
Intrinsic gut hormones
gastrin, gastric inhibitory peptide (GIP), cholecystokinin (CCK), secretin, and motilin.
not responsible for digesting
hormones made by_______ tract have both local and systemic influences because…
alimentary
they are secreted by the organ into systemic circulation
APUD cells are?
group of endocrine cells that (some) secrete hormones with GI function
Amine Precursor Uptake Decarboxylase
APUD cells in the GI are distributed______ and secrete different hormones based on ….
throughout!
where they are in the GI
Extrinsic nervous control is via the … (4 nerves)
Vagus nerve!! (parasympathetic)
pelvic nerve (parasympathetic)
Splanchnic nerve (sympathetic)
Hypogastric nerve (sympathetic)
