exam 2 Flashcards
intrinsic control of the GIT
enteric nervous system
GI hormones
extrinsic control of the GIT
vagus n.
splanchnic n.
non-GI hormones
where is the enteric nervous system located
in the GI wall
located b/w the submucosa and circular m.
regulates mucus secretion and food absorption
plexus submucosus
located in the muscularis externa b/w the muscle layers
controls of tone and contraction rhythm
plexus myentericus
the muscle bundles of the enteric nervous system connect with one another through
gap junctions
enteric neurons secrete neurotransmitters from
varicosities
which type of sensory nerve cell recognizes stretching of the intestinal wall or volume changes
mechanosensitive cells
which type of sensory nerve cell detects the presence of nutrients in the GI lumen, changes in osmolarity and changes in the pH
chemosensitive cells
where do the axons of sensory nerve cells travel to
enteric nerve cells and CNS
interneurons send signals to ___
motor neurons
muscle motor neurons are located in the ____
plexus myentericus
secretory motor neurons are located in the ___
plexus submucosus
____ motor neurons are located in both plexuses; they regulate the tone of blood vessels
vaso motor neurons
non-noradrenergic, non-cholinergic (NANC) neurotransmitters include
NO
VIP
substance P
ATP
NANC inhibitory; reduces GIT motility
NO
NANC inhibitory; relaxes sm. m sphincters
possibly stimulatory to secretory glands
VIP
NANC excitatory; inc secretion and GIT motility
substance P
which SNS neurotransmitter inhibits GI activity
norepinephrine
which PSNS neurotransmitter excites GI activity
acetylcholine
visceral afferents are stimulated by:
irritation of gut mucosa
excessive gut distention
presence of specific chemical substances in the gut
____ fibers of the PSNS become integrated with fibers of the ENS
pre-ganglionic
PSNS post-ganglionic neurotransmitters are
acetylcholine
VIP
NO
SNS post-ganglionic neurotransmitter
noradrenaline
the frequency of slow waves determines
rhythm of GI contractions
AP of the GIT; occur when the RMP of the GI sm. m. becomes more positive than -40mV
spike potentials
slow waves originate in specialized smooth muscle cells called _____; “electrical pacemaker” for smooth muscle cells
interstitial cells of cajal (ICC)
stimuli for depolarization in the GIT
stretching
Ach release
GI hormones
stimulus for hyperpolarization in the GIT
NEPI and EPI
which reflexes are integrated entirely within the gut wall
control of GI secretion
peristalsis
formation of mixing contractions
local inhibitory effects
reflexes from the gut to the prevertebral sympathetic ganglia
gastrocolic reflex
enterogastric reflex
colonoileal reflex
signals from the stomach that cause evacuation of the colon
gastrocolic reflex
signals from the colon and small intestine to inhibit stomach motility and stomach secretion
enterogastric reflex
signals from the colon that inhibit emptying of ileal contents into the colon
colonoileal reflex
reflexes that travel from the gut to the spinal cord or brainstem
gastric motor and secretory activity
pain reflexes
defecation reflex
during peristalsis, how are the muscles behind the site of distension
longitudinal relaxed
circular contracts
during peristalsis, how are the muscles distal to the site of distension
longitudinal contracts
circular relaxed
during peristalsis, contraction of which muscle moves the chyme
circular
contraction of muscles during peristalsis occurs when motor neurons release
Ach and substance P
relaxation of muscles during peristalsis occurs when motor neurons release
NO
VIP
ATP
reflex that controls motility of the GI muscle layers in response to distention by chyme; ex. receptive relaxation of the stomach in response to mastication and deglutition
vagovagal reflex
which region of the stomach is the gastric reservoir
proximal
which region of the stomach is the gastric pump
distal
true or false: there is no change in intraluminal pressure of the stomach when it enlarges
true
sequence of inflow into the gastric pump
- tonic contraction of fundus
- strong peristaltic wave in the corpus
- passage into grinder and then pylorus
- emptying into duodenum
what happens if a piece of food is still too big to go through the pylorus
pyloric sphincter closes so it can go through another mixing cycle
during feedback relaxation of the stomach, what is released when nutrients reach the duodenum
CCK
two patterns of movement in the small intestine during the digestive period
propulsive pattern
non-propulsive pattern
type of contraction during the propulsive pattern
peristaltic
type of contraction during non-propulsive pattern
segmentation, localized contractions of circular muscle
fx of non-propulsive pattern
splits the chyme for better digestion
time between meals when the stomach and sm. intestine are empty
interdigestive period
motility pattern during interdigestive period
migrating motoric complex (MMC)