GI Mod 1 Flashcards
accessory organs of digestive system
liver, gallbladder, exocrine
4 layers of the GI tract
- mucosea
- submucosa
- muscularis
- adventitious (serosa)
3 parts of the mucosa layer of the GI tract
- mucosa epithelium
- lamina propria
- muscularis mucosae
what is the submucosa made up of in the GI tract
glands and associated ducts
what is the muscularis layer of the GI tract made up of
- circular layer
2. longitudinal layer
what is the adventitious (Serosa) layer of GI tract made up of
connective tissue
the enteric nervous system is considered part of which nervous system
ANS
the enteric nervous system functions ________ and influenced extrinsically via what nervous systems
- autonomously
- parasympathetic/sympathetic nervous systems
3 enteric plexuses
- submucosal plexus (Meissner plexus)
- located in submucosa - myenteric plexus (Auerbach plexus)
- located bw circular and longitudinal layers of muscularis - subserosal plexus
three general functional components of enteric plexuses
- sensory neurons monitor: distension and the chemical status of GI tract
- motor neurons control: motility of the gut wall, smooth muscle of GI vasculature, secretions of the mucosa/submucosa
- interneurons communication bw sensory and motor
definition of appetite
hunger
definition of satiety
sensation of fullness/satisfied
two centers that control appetite and satiety
lateral center and medial center
where are the two centers that control appetite and satiety located
hypothalamus
function of lateral center
(appetite center)
stimulate appetite
excitatory to hunger contractions in stomach
stimulus of lateral center
- smell (CN 1), visual, taste (CN 7&9), hearing (CN8)
- physiological depletion of nutrient/energy stores
- memory/fantasy - limbic/insular lobes
- gastric hormones
what gastric hormone stimulates appetite
ghrelin - hunger hormone - released from stomach
what is the function of the medial center
(satiety center)
suppress appetite
inhibitory to hunger contractions in stomach
stimuli of medial center
hormones:
- GI hormones - released during food ingestion (CCK,GLP) - short term
- Letpin - released by fat cells and chief cells
- PYY - released by SI after meal
- INsulin - released by pancreas after increase in blood glucose after meal
extrinsic regulation of the GI tract
sympathetic regulation and parasympathetic regulation
sympathetic regulation of the GI tract
- pathway
- function
pathway - nerves of sympathetic tract in thoracic and upper lumbar regions function - inhibitory to GI tract - decrease peristalsis and secretions, inhibit blood flow to GI tract
parasympathetic regulation of GI tract
pathway - vagus nerve (esophagus to transverse colon) and pelvic nerves of sacral plexus function - excitatory to GI tract - increase peristalsis and secretions, relax involuntary sphincters of GI tract, facilitate blood flow to GI tract
peristalsis require what two movements? how does the vagus nerve play into it?
requires contraction and relaxation
-vagus nerve has dual role on the smooth muscle of GI
structures of the GI tract
mouth, esophagus, stomach, SI, LI, rectum, anus