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Flashcards in Drug Targets - GIT Deck (15):
1

Drugs which imitate ANS on SI smooth muscle contraction

epinephrine - symp - inhibits contraction
acetylcholine - parasymp - promotes

2

sympathetic receptors - via noradrenaline

a1 + B2

3

parasympathetic receptors - via acetylcholine

M1 + M2 muscarinic

4

motility summary

gut muscle shows spontaneous slow wave activity
slow wave amp gives likelihood of AP in muscle, whilst freq gives when AP firing can occur
amp and rate of slow waves may be changed with hormones + paracrine mediators
autonomic nervous system also affects motility - symp inhibits, para stimulates
sphincter tone generally controlled inversely

5

types of movement

swallowing
stomach contractions
peristalsis + segmented in SI
peristalsis + haustration in colon
reverse change

6

pro - kinetic drugs

mimic parasympathetic nervous system
metochlopramide - increase Ach release by dopamine antagonism
carbachol + more are M1 agonists

7

defaecation

complex reflex - 2 parts
increase activity in distal colon
distension of rectum
reflex contraction of rectum
relaxation of internal + external anal sphincters

8

constipation - define

hard faeces due to increased h2o absorption

9

constipation - treatment

lubricate - liquid paraffin
bulk forming - absorb water e.g wheat bran
osmotic - water drawn to LI causes distension e.g lactulose, mg sulfate, na sulphate, enema
stimulant - direct irritant effect e.g senna, bisacodyl

10

vomiting

chemoreceptor trigger zone (CTZ) responsive to emetic signials in the blood + from vestibular centre to start vomiting reflex
forceful ejection of stomach +/- duodenum by contracting enteric muscle + some surrounding skeletal muscle - esp diaphragm

11

emetics - effects

remove non-corrosive poisons
stimulate vomiting centre or CTZ e.g apomorphine (dopamine agonist)
irritate gastric mucosa e.g epsom salts (MGSO4) -emergency other salts can be used

12

anti-emetics

for motion sickness + other causes of emesis
dopamine antagonists e.g phenothiazines like ACP - may inhibit M1, H1 and a receptors
M1 + H1 antagonists e.g hyoscine

13

5 main GI peptide hormones

gastrin
cholecystokinin (CCK)
secretin
gastric inhibitory peptide (GIP)
motilin

14

3 phases of gastric secretion

cephalic - reflex, gastrin + histamine secreted. increase stomach motility, HCL + pepsinogen secreted
gastric - chemo + mechano receptors. gastrin + histamine
intestinal - inhibits acid secretion + motility by secreting secretin, GIP + CCK

15

gastro-protective + ulcer-healing drugs

antacids - NaHCO3, MgCO3, AL(OH)3, CaCO3
histamine H2 antagonists e.g cimentidine
proton pump inhibitors e.g omeprazole
mucosal binding agents e.g sucralfate - coats mucosa/ulcer
prostaglandin analogues (inhibit H+ production) e.g misoprostol