GI - Large Intestine

Question 1

colon fxns

Answer 1

absorption: Na, SCFAs, water
secretion: K, mucous

Question 2

colon motility

Answer 2

mix: haustrations - like segmentation but less frequent
propulsion: mass mvmts - propel distances, gastrocolic reflex

Question 3

colon and diarrhea

Answer 3

K deficits can happen w/ severe diarrhea since colon secretes K

Question 4

colon and aldosterone

Answer 4

aldosterone ups # Na channels

activates basolateral Na/K ATPase pumps –> K secretion

Question 5

defecation: reflex/voluntary

Answer 5

mass movement
rectum fills –>
reflex relaxation of IAS
voluntary relaxation or constriction of EAS
if defecation postponed - sphincters regain normal tone
urge temporarily subsides

Question 6

anatomical age changes to SI/LI

Answer 6

down:
- digestive enzyme secretion
- elasticity of rectal wall
- IAS tone
- mucous secretion
atrophy of muscle/mucosa
thinning of villi, epi

Question 7

physiological age changes to SI/LI

Answer 7

may down absorption of vit B12
slower/dull neural impulses to sense urge to defecate
–> potential incontinence, incomplete emptying, constipation

Question 8

Hirschspring’s disease aka

Answer 8

aka congenital megacolon

Question 9

Hirschspring mech

Answer 9

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

Question 10

types of diarrhea

Answer 10

osmotic
secretory
inflammatory/infectious
deranged motility

Question 11

osmotic diarrhea

Answer 11

ingestion of poorly absorbed substrate

ex: lactose, some antacids

Question 12

deranged motility diarrhea

Answer 12

hypermotility of intestine

ex: diabetic neuropathy (down symp inhibition); hyperthyroidism

Question 13

parietal cells ion mvmt

Answer 13

extract:
- Cl
- CO2
- H2O
add
- HCO3

Question 14

pancreatic duct cells ion mvmt

Answer 14

extract:

• HCO3
• Na