GI Flashcards
What are the two enteric plexuses that innervate the GI
Submucosal (Meissner Plexus) and the Myenteric (Auerbach Plexus)
Myenteric plexus is responsible for:
GI movement/motility- increased tonicity, intensity, rate, velocity, and local blood flow
Inhibits sphincter tone (pylorus & ileocecal valve)
what does the meissner (submucosal) plexus do
GI secretion & local blood flow
-very small segments of GI wall, lead to various degrees of unfolding wall
what does the ptyalin secrete
salivary amylase, digest starch
parietal cells of the oxyntic gland in the mucosal layer of the stomach secrete:
HCL & intrinsic factor
What do chief cells secrete
pepsinogen
How does pepsinogen become activated?
HCl splits it into an active form of pepsin
D cells secrete:
somatostatin (inhibits gastric juices)
G cell
secrete gastrin increasing gastric juice
ECL cells in the Oxyntic gland secrete
histamine (stimulates gastric acid juice)
Where is the swallowing center located
medulla and pons
Splanchnic flow describes::
nutrients from the gut, spleen, and pancreas travel via portal vein to liver
Describe rhythmic slow waves
smooth muscle that shows undulating changes in resting membrane potential but don’t cause contraction
What causes contaction of GI
Channels open allow for Ca++ along with Na+ to enter and cause long AP, contraction
What occurs in liver
removes bacteria/particles
what are the accessory organs of digestion
liver, gallbladder, and pancreas
what is saliva made up
water, mucus, amylase, bicarbonate, K+, and lingual lipase
Where and why would you see a apthous ulcer
“cold sore” disruption in mucousal surface from trauma infection, or inflammation
What two things occur in order to move the bolus from mouth into esophagus
pharynx muscles raise soft palate closing entry to nasopharynx, and epiglottis slides back to close off larynx & trachea
whats the main function of the UES
prevent air into esophagus during respiration
whats the main function of LES
prevents backflow from stomach
How do both Esophageal Sphincters perform there function
maintaining tonicity
Describe the muscularis propria in the esophagus
Proximal 1/3 smooth
middle 1/3 skeletal, smooth
Distal 1/3 smooth
what is achalasia
LES fails to relax preventing food from entering stomach
how would u tx achalasia
antispasmodics, balloon placement
Esophageal strictures are caused by
scar tissue, sometimes from GERD
Describe the gastroileal reflex
it increases ileal motility (emptying ileum, preparing for more chyme)
describe gastroenteric reflex
distension of the stomach triggers peristalsis
how do rugae help aid digestion
allow for increased volume without change in pressure, and increase surface area
Describe retropulsion in the stomach
as the pyloris contracts sending chyme to duodenum, the remaining gets propelled back away from sphincter for further mixing
what cells mediate the pace of peristalsis in stomach
Cajal cells
What two structures of the GI are retroperitoneal
esophagus and duodenum
what structures are intraperitoneal
jejunum, ileum, liver and stomach
What do the Brunner’s Glands do in the duodenum
secrete alkaline mucus for protection via neutralizing acid
why does a patient become constipated with an inflamed appendix?
irritates the cecum (close in location) hence, sphincter spasms cause partial paralysis of ileum
what does the Crypt of Leiberkuhn do to contribute to the health of the SI
contains undifferentiated cells to replace the epithelial layer, secretes some digestive juices
how do gastrin, insulin, motilin, and serotonin act on peristalsis
increase
what acts to delay emptying of the stomach?
distension, irritation, acidity, CCK, GIP, & Secretin
Cholecystokinin CCK functions to:
stimulate release of bile & pancreatic juices to break down lipids & aa
Inhibits: gastric emptying & parietal cells secretion HCL
these two enzymes are secreted from the pancreas to aid with digestion of proteins
trypsinogen and chymotrypsin
why aren’t trypsinogen and chymotrypsin able to act immediately on digestion
they are inactive forms to prevent them from destructing the pancreas… must be modified.
How are fats aided in digestion?
bile salts from the liver and lipase from the pancreas both facilitate fat breakdown.
what is the route of bile once it is ejected from the gallbladder to the SI
to cystic duct, common bile duct, and to the Sphincter of Oddi at the Ampulla of Vater at junction of the duodenum
what carries bile from hepatocytes to the bile ducts
bile canalculi
What does the liver store
fat, glycogen iron, copper, Vitamin B12, A, D, and E
what does the liver synthesize
fat, phospholipids, cholesterol, plasma proteins, non-essential aa, serum enzymes (AST, ALT, LDH, and alk phosp)
where is calcium primarily absorbed
ileum
how is calcium absorbed
via passive, active, and carrier proteins
what enhances calcium absorption
bile salts, which also enhances vitamin D
What does vitamin B12 bind to
intrinsic factor making it resistant to digestion
where does most absorption of vitB12 occur
ileum terminally
Whats vitamin B12 necessary for
erythrocyte maturation
why does a deficiency of vitB12 cause pernicious anemia
without B12, one wouldn’t have RBC formatioin
what is pernicious anemia caused from
lack of B12 in order to have erythrocyte maturation
Secretin is stimulated to be secreted by what
low pH
GIP does what
secretes insulin, it also inhibits parietal/chief/paralysis
Iron and calcium have a special regulation in the body
amount absorbed dependent on amount needed
iron absorption is facilitated by
vitamin C
Describe the ileogastric reflex
when ileum is distended, it inhibits gastric motility
describe gastrocolic
distended gastric promotes propulsion through colon
What do the I cells in Small Intestine secrete
Cholecystokinin- responsible for ejecting bile (inhibits gastrin motility)
