GI secretions

Question 1

Secretin

Answer 1

nature’s antacid
released from duodenal mucosa by HCl causes pH falls below 4.5

stimulates pancreatic and liver bicarb, stimulates pancreatic growth, inhibit gastric emptying, inhibits gastrin

Question 2

Gastrin

Answer 2

released from G cells in gastric mucosa, duo, pancreas in response to proteins, distention, nerves, Ca, decaf coffee, wine

stimulates HCl from stomach via Hist (indirect) or can stimulate the Parietal cells directly

aids in gastric motility, stim GI mucosal growth
inhibited by acid, secretin, glucagon

Question 3

CCK

Answer 3

released from mucosal cells of the SI and the duodenum by proteins and fat
stimulates GB contractions to release bile
sim pancreatic bicarb
stimulates pancreatic growth

Question 4

GIP

Answer 4

released from intestinal mucosa in response to Glu, fat and protein
inhibits gastric secretions and stimulates insulin release

Question 5

motilin

Answer 5

released cyclically (/90min) from the SI under neural control during periods of fasting or in presence of acid or fat in duo

stimulates gastric motility, GI motility via the interdigestive migrating myoelectric complex

Question 6

Enteroglucagon

Answer 6

formed in the pancreatic a cells
stimulated by fat
causes insulin release, inhibits gastric secretion, delays gastric emptying

Question 7

Pancreatic polypeptide

Answer 7

isolated from insulin
stimulated by protein, fat, glucose
inhibits pancreatic bircarb and enzyme secretion

Question 8

Substance P

Answer 8

stimulates intestinal motility and GB contraction

Question 9

VIP

Answer 9

mediates relaxation of intestinal smooth muscle and vascular smooth muscle (VD) via NO

stim pancreatic and intestinal secretion
inhibits gastric secretion
n

Question 10

Somatostatin

Answer 10

from gastric, duodenal mucosa and pancreas
inhibits gastrin release and gastric acid secretion
paracrine

Question 11

Histamine

Answer 11

produced in ECL cells 
stimulated by gastrin 
stimulates acid secretion from parietal cells, increases gastrin and ACh activity 
basis for H2 R blockers 
paracrine

Question 12

salivary bicarb

Answer 12

minimizes tooth decay***

neutralizes refluxed gastric acid (heart burn)

Question 13

Neuronal regulation of salivary glands

Answer 13

ANS regulate the flow
SNS stim secretion: alpha and beta receptors
PSNS stim secretion (dominant) M3R

Question 14

Hormonal control of salivary glands

Answer 14

ADH and ald modify composition of saliva by decreasing its Na conc and increasing K conc

Kallikrein—>bradykinin–>VD—>increases blood flow—>increased salivary secretion

Question 15

what inhibits saliva secretion

Answer 15

sleep, fear, antidepressants, dehydration, fatigue

Question 16

Xerostomia

Answer 16

dry mouth due to absence of saliva production (drugs, radiation AI DISEASE)
Buccal infection
dry mouth ONLY

Question 17

Sjogren syndrome

Answer 17

AI process targets salivary AND LACRIMAL GLANDS

difficulty chewing, swallowing, and speech, poor dentition

Question 18

digitoxin therapy

Answer 18

increases Ca and K in saliva

Question 19

Parietal cells (oxyntic)

Answer 19

body and fundus

secrete HCl and IF (needed for B12 abs)

Question 20

Chief (Peptic) cells

Answer 20

secrete pepsinogen, zymogens—>converted into pepsin

Question 21

Mucous cells

Answer 21

secrete mucous (thick and thin) (highest up)
located in the body as well as the antrum an pyloric regions

Question 22

G cells

Answer 22

secrete gastrin—>stimulates parietal cells—>HCl and pepsinogen
located in the antrum and pyloric regions

Question 23

alkaline tide

Answer 23

the release of H+ by parietal cells is balanced by their release of HCO3- into the blood, making the venous blood leaving the gut highly alkaline

Question 24

Causes of Gastric Ulcer formation

Answer 24

Occurs in the gastric mucosa
from increased acid secretion
**gastrinoma or Zolliner-Ellison syndrome—>inc gastrin
Pepsin remains active for too long
failure of mucosal defense (NSAIDS, H. Pylori)

Question 25

Duodenal Ulcer

Answer 25

occurs in the duodenum more common from increased acid secretion in the gastric region pepsin remains active for too long decreased bicarb secretion from pancreas (pancreatitis)

Question 26

Gastrinoma or zollinger-ellison syndrome

Answer 26

pancreatic islet cell adenoma--->increased gastrin--->increased gastric acid secretion--->gastric and or duodenal ulcer due to increased acid and pepsin activity no change in acid after gastrin challenge (acid already maxed out)

Question 27

Pernicious anemia

Answer 27

AI condition in which antibodies act against parietal cells and/or IF--->decreased H+ and somatostatin---> decreased inhibition of gastrin, but still no H+ lack of IF= no B12 reabs =no RBC formation Acid output is always 0 even after gastrin challenge

Question 28

Pentagastrin

Answer 28

used to evaluate gastric function under normal conditions you see a large increase in acid output after giving it -people with duodenal ulcers will also have a large increase in acid output no change in pt with gastric ulcer (gastrinoma) or pernicious anemia)

Question 29

H. pylori activity

Answer 29

colonizes mucus layer releases urase which damages epithelial cells causes inflammation, mucosal degradation and cell death

Question 30

PPI's and s/e

Answer 30

inhibit the H/K+ exchanger decrease H+ release--->increased gastric pH s/e are Pneumonia (due to increased pH, which is better for bacteria growth) C. Diff growth in gut Osteoporosis Duodenal ulcer

Question 31

Steatorrhea

Answer 31

fat in stool early sign of pancreatic dysfunction indicates reduced pancreatic enzyme and bicarb secretion

Question 32

alcoholism and pancreatitis

Answer 32

ETOH damages the liver causing TGs and Ca to enter the blood which damage pancreatic tissue (activation of pancreatic enzymes which start to autodigest) chronic condition

Question 33

Cephalic phase of gastric acid secretion

Answer 33

30% of total gastric acid secretion conditioned reflexes ACh acts on parietal cells and ECL

Question 34

Gastric phase of gastric acid secretion

Answer 34

``` food distends gastric mucosa 50-60% vagus and ENS reflexes activated increases acid and pepsinogen secretion increased gastrin release ```

Question 35

Intestinal phase of gastric acid secretion

Answer 35

peptide in duo stimulate gastrin acidic chyme inhibits impulses from the MO and decrease vagal stimulation, decrease acid secretion release of Secretin, GIP and CCK activation of pancreatic enzymes: highest rate of release at this point in time inhibits release of food from the stomach so that you can take care of the food already in the duodenum