phys quiz 4/10

Most pancreatic enzymes are produced as inactive precursors called

zymogens

when do most zymogens become active

SI

What activates trypsinogen?

enterokinase

what does trypsinogen make

trypsin

what does trypsin do

digest proteins

what does trypsin activate

other enzymes

what regulates the digestive system

neural and endocrine control mechanisms

what does the neural and endocrine control mechanisms do

modify GI tract fucntioning

what primes the digestive tract for food

sight, smell, taste, or though of food

what does the sight, smell, taste, or though of food stimulate

digestive salivation and gastric secretions

in the neural and endocrine control mechanisms, stimulation goes from brain to organ via what

vagus nerve

when stimulation goes from brain to organ via the vagus nerve, what kind of reflex is it

conditioned

what is a short reflex of the regulations of digestive

enteric nervous system

what can the enteric nervous system do

function independently of the brain

what does the GI tract produce

hormones that can target GI tract

Where is gastrin and gherlin secreted by

stomach

what does gastrin do

stimulates parietal cells to secrete HCL and chief cells to secrete pepsinogen

what secreted secretin

SI

what does secretin do

stimulates water and bicarbonate secretion in pancreatic juice
potentiates actions of cholecystokinin on pancreas

what is cholecystokinin released by

SI

what does cholecystokinin do

stimulates contraction of the gallbladder
stimulates secretion of pancreatic secretion of enzymes
inhibits gastric motility and secretion
maintains structure of exocrine pancreas

where is gastric inhibitory peptide or glucose dependent insulinoptrpic peptide (GIP) PPY (polypeptide YY) secreted

SI

what does the gastric inhibitory peptide or glucose dependent insulinoptrpic peptide (GIP) PPY (polypeptide YY) secreted do

inhibits gastric motility and secretion
stimulates secretion of insulin from pancreatic islet
decreases hunger and food intake

where is glucagon-like peptide I secreted

ileum and colon

what does the glucagon-like peptide I do

inhibits gastric motility and secretion
stimulated secretion of insulin from pancreatic islets

where is guanylin secreted

ileum and colon

what does guanylin do

stimulates intestinal secretion of Cl- causing elimination of NaCl and water in the feces

motility and secretion of gastric functions are somewhat

automatic

pacesetter cells in gastric functions

greater curvature of stomach stimulate contraction (intrinsic regulation)

in regulation of gastric function, what happens when proteins enter stomach

stimulate secretion of HCL and pepsinogen

G cells

secrete gastrin

D cells secrete

somatostatin

ECL cells secrete

histamine

what are the phases of extrinsic gastric regulation

cephalic, gastric, and intestinal

what is the cephalic phase controlled by

brain via vagus nerves

what starts the cephalic phase

sight, smell, thought, or taste of food

what does the cephalic phase stimulate

ECL (major response), chief cells, and parietal cells

When does the cephalic phase last

30 minutes after meal

what is the gastric phase triggered by

arrival of food into the stomach

during the gastric phase, what is gastric secretion stimulated by

stomach dispersion, and chemical natural of chyme

during the gastric phase, as more proteins are broken down, what happens

more secretions are released to break them down

what inhibits gastric secretion

fat

during the gastric phase, pH drops due to

more HCL

during the gastric phase as pH drops, what happens

somatostatin is released

during the gastric phase, what does somatostin do

inhibits gastric secretion

during the gastric phase, large amount of proteins and polypeptides do what

buffer pH

during the gastric phase, why do large amounts of proteins and polypeptides buffer pH

so secretion matches protein concentration

what does the intestinal phase do

inhibits gastric activity when chyme enters the SI

what does the intestinal phase do to the movement of chyme into duodenum

slows it down

why does the intestinal phase slow down the movement of chyme

allow enough time for digestion and absorption

during the intestinal phase, what happens when food enters the duodenum

stretches to stimulate a neural reflex

during the intestinal phase, when it stretches to stimulate a unreal reflex, why does it do this

to inhibit gastric stimulation via the vagus nerve

during the intestinal phase, what does the presence of fats do

stimulate duodenum t make enterogastrone

what does enterogastrone do during the intestinal phase

inhibit gastric function

what are the enterogastric hormones

GIP, somatostatin, CCK, GLP-1

what does GIP do

-Stimulates insulin secretion
-Inhibits gastric acid secretion

where is CCK secreted

secreted by the duodenum in response to chyme

what is GLP-1 secreted by

secreted by the ileum-insulin stimulator

what regulates the intestinal function

enteric nervous system

what does the enteric nervous system include

myenteric plexus and submucosal plexus

the enteric nervous system acts independently from

CNS

the enteric nervous system uses some feedback to CNS via

vagus nerve

what is the enteric nervous system involved in

regulation by ANS

what does the enteric nervous system innervate

intersisla cells of cajal and smooth muscle

why the enteric nervous system innervate intersisla cells of cajal and smooth muscle

intrinsically regulate peristalsis

what cells are involved in the paracrine regulation of the intestinal function

enterchromaffin-like cells

what do the enterchromaffin-like cells secrete

serotonin and motilin

during paracrine regulation, what do the enterchromaffin-like cells secrete serotonin and motilin in response to

baroreceptors and chemorecptors- stimulate muscle contractions

during the paracrine regulations, what does guanylin secrete from

ileum and colon

during paracrine regulations, what does guanylin secrete

water and CL-

during paracrine regulation, what does guanylin inhibit

NA+ absorption

how does guanylin act

activating guanylate cyclase to produce second messenger cGMP

what are the intestinal reflexes

gastroileal reflex
ileogastric reflex
intestino-intestinal reflex

what does the gastroileal reflex do

increase gastric and ileum activity and movement of food through the ileocecal valve

What does the ileogastric reflex do?

distension of ileum causes a decrease in gastric motility

what does the intestino-intestinal reflex do

over dissension of one portion of the intestine causes relation of other portions

during the regulation of pancreatic juice and bile salts, what does the entry of chyme stimulate the release of

secretin and cholecytsoinin

during the regulation of pancreatic juice and bile salts, what is secretin released

in réponse to decreases pH

during the regulation of pancreatic juice and bile salts, what does secretin stimulate

release of pancreatic juice rich i enzymes and alkalinic pancreatic juice

what doe secretin use as a second messenger

cAMP

during the regulation of pancreatic juice and bile salts, cholecystokinin released in the response of

proteins and fats in chyme

during the regulation of pancreatic juice and bile salts, what does cholecystokinin do

stimulates the release of pancreatic juice rich in enzymes

What does cholecystokinin use as a second messenger

Ca2+

liver produces bile

continuously

what does the arrival of food into the duodenum do

stimulates increased bile production

bile acids are returned to the liver when

after intestinal abosprtion

what does intestinal absorption occur via

enterohepatic circulation

what does secretin and CCK stimulate

increases bicarbonate secretion into bile

what does CCK do

stimulate Gallbladder contractions

during carb digestion in mouth, what are polysaccharides broken down into

shorter chains

Do carbs digest in the stomach?

no, acidic pH inactivates amylase

protein digestion continues in

inestines with pancreatic amylase

what are short chains broken down into the the intestines with pancreatic amylase

disacrahides with maltose

what finishes breaking down disacharides into simple sugars of glucose

brush border enzymes

in the absorption of carbs, where are monosaccharides absorbed

across epithelium via a number of processes

what are the processes that aid in the digestion of monosaccharides

secondary active transport with sodium (cL- follows)
facilitated diffusion through GLUT carriers into interetsial fluid and then to capillary blood of villus
water flows the NaCl through a paracellular route and is absorbed with glucose and NaCl

what aids in digestion of proteins in stomach

pepsin and hydrochloric acid to produce shorter chain polypeptides

where does protein digestion finish

duodenum and jejunum

what aids in protein digestion in duodenum and jejunum

pancreatic trypsin, chymotrypsin, elastase, and carboxypeptidase, and brush border enzyme amino peptidase

what is the final product of protein digestion

amino acids, some dipeptides and tripeptides