GI1 Flashcards
how is the GI system regulated?
- innervation
- hormonal control
- immune control
- trophic effects
what is feeding?
the acquisition and ingestion of food
what species has the simplest GI system?
C. elegans
ezymatic digestion is the breakdown of what?
starches/sugars, proteins and fats
fermentative digestion involves what/
symbiotic microbes
bacteria in your gut can break down antioxidants in chocolate into what
anti-inflammatory compounds
what kind of digestion do carnivores have?
primarily enzymatic
what kind of digestion do omnivores have?
enzymatic and fermentative
______ ______ and ____ control are essential for GI functions
- intrinsic neural
- endocrine
what does motility do?
moves food
what does digestion do?
secretion of digestive substances
what does absorption do?
transports nutrients from the lumen to the blood
what is delivery?
circulation/distribution of absorbed substances
how is the GI protection?
- barrier function
- defense mechanism against pathogen invasion
what are the two parts of the extrinsic system?
- nerves (PS;S)
- extrinsic hormanal
what are the 4 parts to intrinsic systems?
- intrinsic hormonal
- immune control
- trophic effects
- nerves (ENS)
what does the “autonomy of the GI system” mean?
that the GI system is self-regulating
what intrinsically regulates the GI system ?
enteric nervous system
-neurogenic control of both secretion and GI motility
what are the three components to the ANS?
PS, S, ENS
how is the ENS modulated?
inputs from the extrinsic PS and S components
what is the submucosal plexus, what is the name of one, and where is it located?
-secretions and local blood flow
-Meissner’s plexus
located in the submucosal layer
what is the myenteric plexus, what is the name of one, and where is it located?
- muscle contraction and motility
- Auerbach;s plexus
- located between the circular and longitudinal muscles layers
what are two properties of the ENS neurons?
they have collaterals and varicosities
what is the input for chemoreceptors?
luminal chemical conditions
what is the input for mechanoreceptors
distension within muscle layers
what are the output targets for excitatory neurons (e.g ACh, Sustance P)
glands: secretion (or not)
what are the output targets for inhibitory neurons (e.g. NO, VIP)
Muscle layers: contraction/relaxation
what extrinsic components of the parasympathetic NS act on the GI?
- vagus n
- pelvic n
- pre-ganglionic
- stimulatory***
- ACh (cholinergic
what extrinsic components of the sympathetic NS act on the GI?
- splanchnic n
- primarily post-ganglionic
- inhibitory
- norepi (adrenergic)
what NT does the ENS use?
NO and VIP
parasympathetic neurons (stimulate/inhibit) motility?
stimulate
sympathetic neurons (stimulate/inhibit) motility?
inhibit
can the sympathetic NS override the PS influence on the GI tract?
YES
where do the PS fibers synapse?
on the ENS cell bodies
