Flashcards in GI - Large Intestine Deck (14):
1
colon fxns
absorption: Na, SCFAs, water
secretion: K, mucous
2
colon motility
mix: haustrations - like segmentation but less frequent
propulsion: mass mvmts - propel distances, gastrocolic reflex
3
colon and diarrhea
K deficits can happen w/ severe diarrhea since colon secretes K
4
colon and aldosterone
aldosterone ups # Na channels
activates basolateral Na/K ATPase pumps --> K secretion
5
defecation: reflex/voluntary
mass movement
rectum fills -->
reflex relaxation of IAS
voluntary relaxation or constriction of EAS
if defecation postponed - sphincters regain normal tone
urge temporarily subsides
6
anatomical age changes to SI/LI
down:
- digestive enzyme secretion
- elasticity of rectal wall
- IAS tone
- mucous secretion
atrophy of muscle/mucosa
thinning of villi, epi
7
physiological age changes to SI/LI
may down absorption of vit B12
slower/dull neural impulses to sense urge to defecate
--> potential incontinence, incomplete emptying, constipation
8
Hirschspring's disease aka
aka congenital megacolon
9
Hirschspring mech
enteric neurons are congenitally absent from part of colon (usually by IAS)
reflex rxn doesn't occur w/ rectum filling
fxn obstruction and dilation of colon above obstruction
10
types of diarrhea
osmotic
secretory
inflammatory/infectious
deranged motility
11
osmotic diarrhea
ingestion of poorly absorbed substrate
ex: lactose, some antacids
12
deranged motility diarrhea
hypermotility of intestine
ex: diabetic neuropathy (down symp inhibition); hyperthyroidism
13
parietal cells ion mvmt
extract:
- Cl
- CO2
- H2O
add
- HCO3
14