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158 Cards in this Set

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Digestive system is supplied by 2
different plexuses (parasympathetic):
1- ?
2- ?
1- Submucosal plexus of Meissner
2- Myenteric plexus of Auerbach
Parasympathetic preganglionic fibers synapse in the
_______ and _______ plexuses
-Myenteric

-submucosal
Carries information to the lower
parts of the large intestine and
pelvic organs.
Pelvic splanchnic nerve (S2-4)
sends information to the esophagus, stomach, pancreas, intestine down to the upper parts of the large intestine.
Vagus (CNX)
Postganglionic adrenergic fibers
leave the prevertebral ganglia
and synapse in the ______
and _______ plexuses.
myenteric and submucosal plexuses.
All of the GI muscle is smooth muscle except?
pharynx, upper 1/3 of the esophagus, and the external anal sphincter, all of which are striated muscle.
are found in esophagus, gastric antrum, and small intestine which contract and relax periodically.
Phasic contraction
are found in lower esophageal sphincter, the orad stomach, and the ileocecal and internal anal sphincters
Tonic contraction
slow waves originate in the _________, which serve as the pacemaker for GI smooth muscle
-interstitial cells of Cajal
Are slow waves action potentials?
no
Slow depolarization is by _____ and slow repolarization is by _____
Ca++

K+
are slow waves influenced by neural or hormonal input?
nope
Frequency of slow waves is highest in ______ and lowest in ______
highest = duodenum

slowest = stomach
Spike potentials are triggered at ____mV. Resting membrane potential floats between -50 to -60 mV
(negative)-40 mv
Factors that accelerate the spike wave are stimulation by parasympathetic NS
Stretching
Acetylcholine
Parasympathetic stimulation
Specific gastrointestinal hormones
Factors that inhibit the spike wave and cause hyperpolarization?
Norepinephrine/epinephrine
Sympathetic stimulation
Calcium ions act through ______ as the calcium regulator to coordinate the myosin/actin filament binding
calmodulin
Cholecystokinin?
from mucosa of jejunum in response to fats, increases contractility of gallbladder to release bile and concomittantly decreases stomach contractilty (hold fats still for digestion)
Secretin?
from mucosa of duodenum in response to acid, has a mildly inhibitory effect on GI motility to moderate acid load to small intestine
Gastric inhibitory peptide?
from mucosa of upper small intestine in response to fats (lesser to carbs) to decrease motor function (peristalsis) when the upper small intestine is already full!
Defects in Meissner’s plexus lead to ?
malabsorption
The swallowing reflex is coordinated in the medulla by?
by CNIX and CNX
where does peristalsis begin?

What relaxes?
-the pharynx

-upper esophageal sphincter relaxes
esophagus passes through esophageal hiatus of diaphragm at the level of ?
T10
where esophagus enters the stomach
Cardia
Because the esophagus is located in the thorax, intraesophageal pressure equals ________, which is ________ atmospheric pressure
-thoracic pressure

-lower than
receptive relaxation of the ________ of the stomach to allow the food bolus into the stomach.
orad region
Gastric reflux may occur if the tone of the _________ is decreased and gastric contents reflux into the esophagus.
lower esophageal sphincter
retrosternal pain, neuromotor disorder of the lower esophageal sphincter (LES). Decreased cells in the myentric plexus (analogous to Hirschsprung’s disease), dysphagia for solid and liquid. Dilated proximal esophagus and aperistalsis, increased LES pressure.
Achalasia (cardiospasm)
Achalasia (cardiospasm)? analogous to?
retrosternal pain, neuromotor disorder of the lower esophageal sphincter (LES). Decreased cells in the myentric plexus (analogous to Hirschsprung’s disease), dysphagia for solid and liquid. Dilated proximal esophagus and aperistalsis, increased LES pressure.
Esophageal atresia?
when distal end of the esophagus is closed.
Tracheoesophageal fistula?
when there is a hole
(connection) between esophagus and the trachea.
Milk from the newborn esophagus finds its way into the
respiratory tract causing severe respiratory problems.
Malignancy is frequently at transition between ______.
epithelia
Sliding hiatus hernia (A)?
when abdominal part of the esophagus and cardia and even
part of the fundus slide up through the esophageal hiatus.
Main symptom of Sliding hiatus hernia (A)?
*Regurgitation and heart burn
Paraesophageal hiatus hernia (B)?
Cardia doesn’t move but part of the fundus and peritoneum passes through the esophageal hiatus.
Main symptom of Paraesophageal hiatus hernia (B)?
Usually no regurgitation
In most cases, the operation performed to correct gastroesophageal reflux is a procedure called ?
fundoplication.
fundoplication?
The upper portion of the stomach (the fundus) is wrapped (plicated)
around the lower portion of the esophagus and anchored securely below the diaphragm.
Orad region?

Caudad region?
orad = top half

caudad = bottom half
Chief cells?
in body/fundus, produce pepsinogen
Parietal cells ?
in body/fundus, produce HCl and the intrinsic factor for VitB12 absorption in the ileum.
Vit B12 is absorbed using IF in the?
ileum
*Gastrin
is produced by G cells mainly in pyloric antrum
stimulate acid secretion and growth of parietal cells
*Secretin
via duodenum inhibits HCl secretion
pepsinogen
is a protein-splitting enzyme activated by HCl of the stomach into pepsin to break the food.
*Endocrine cells of mucous membrane (1.2% of all) ?
mainly in antrum, produce: histamine, somatostatin,
gastrin, serotonin.
**Zollinger-Ellison syndrome?
gastrin secretion by non-beta cells of the pancreas (multiple ulcers in stomach)
Secretion of gastric juice: 2 phases?
Nervous and Gastric phase
Nervous secretion?
by vagus nerve, activated by
taste, smell and sight (even if stomach is empty).
Gastric (digestive) phase secretion?
stimulated by food ingestion.
Enterochromaffin-like (ECL) cells are found in ?
the stomach and intestine
Enterochromaffin-like (ECL) cells function?
secrete histamine and 5-hydrooxytryptamine (serotonin) as paracrine regulators of the GI tract
G cells?
secrete the hormone gastrin into the blood
D cells?
secrete the hormone somatostatin
_____ mediates receptive relaxation
CCK
________ are contractions that occur at 90-minute intervals
to clear the stomach of residual food (even during fasting).
Migrating myoelectric complex
______ mediates Migrating myoelectric complex Contractions.
Motilin
The rate of gastric emptying is fastest when the stomach contents are ?
isotonic
____ inhibits gastric emptying (increases gastric emptying time) by release of _____.
Fat inhibits gastric emptying (increases gastric emptying time) by release of CCK.
H+ in the duodenum________ gastric emptying via direct neural reflexes
inhibits
Parasympathetic innervation of the stomach:
are the ant and post vagus trunks, giving the anterior and posterior gastric (Latarget) nerves
Sympathetic innervation mostly come from __________ nerves
which synapse in the ______
ganglion. Postganglionic fibers
innervate the stomach.
-splanchnic nerves (also from upper lumbar)

-Celiac
Sympathetic nerves inhibit peristalsis and gastric secretion and cause pyloric ______. They also convey pain.
contraction
The GI paracrines are ?
somatostatin and histamine.
Somatostatin?
-Is secreted by cells throughout the GI tract in response to H+ in the lumen.
-Inhibits the release of all GI hormones.
-Inhibits gastric H+ secretion.
Somatostatin secretion is ________ by vagal stimulation.
inhibited
histamine?
Is secreted by mast cells of the gastric mucosa.
Increases gastric H+ secretion directly and by potentiating vagal stimulation and effect of gastrin
gastrin?
1- increased H+ secretion by the gastric parietal cells.
2- stimulates growth of gastric mucosa by stimulating the synthesis of RNA and new protein. Patients with gastrin-secreting tumors have hypertrophy and hyperplasia of the gastric mucosa.
Stimuli for gastrin?
amino acids
distention of the stomach
vagal stimulation
the most potent stimuli for gastrin secretion are ?
phenylalanin and tryptophan
_______ in the lumen of the stomach inhibits gastrin release
H+ in the lumen of the stomach inhibits gastrin release
Zollinger- Ellison syndrome (gastrinoma)
Occurs when gastrin is secreted by non-β- cell tumors of the pancreas.
CCK is homologous to?
gastrin
5 actions of CCK
1- stimulates contraction of gallbladder and simultaneously causes relaxation of the sphincter of Oddi for secretion of bile.
2- stimulates pancreatic enzyme secretion.
3- potentiates secretin-induced stimulation of pancreatic HCO3- secretion.
4- stimulates growth of the exocrine pancreas.
5- Inhibits gastric emptying. Thus, meals containing fat stimulate the secretion of CCK, which slows gastric emptying to allow more time for intestinal digestion and absorption.
What secretes CCK?
I cells
CCK is released from the I cells of the duodenal and jejunal mucosa by?
a- small peptides and amino acids
b- fatty acids and monoglycerides.
Do triglycerides stimulate the release of CCK
Triglycerides do not stimulate the release of CCK because they cannot cross intestinal cell membranes.
Secretin is homologous to ?
Secretin is homologous to glucagon, fourteen of the twenty-seven amino acids in secretin are the same as those in glucagon.
Actions of Secretin?
1- stimulates pancreatic HCO3- secretion and increases growth of exocrine pancreas.
2- stimulates HCO3- and H2O secretion by the liver, and increases bile production.
3- inhibits H+ secretion by gastric parietal cells.
Secretin is released by?
S-cells of the duodenum
Stimuli for secretin release
a- H+ in the lumen of the duodenum
b- Fatty acids in the lumen of the duodenum
Gastric Inhibitory Peptide (GIP) is homologous to?
secretin and glucogon
Actions of GIP?
1- stimulates insulin release.

2- inhibits H+ secretion by gastric parietal cells
_____ glucose is more effective than _______ glucose in causing insulin release and, therefore, glucose utilization.
oral glucose is more effective than intravenous glucose
GIP is released by ?
duodenum and jejunum.
GIP is the only GI hormone that is released in response to ?
fat, protein, and carbohydrate.
Salivary glands?
Parotid gland, Submandibular gland, and Sublingual gland
Salivary glands receive parasympathetic innervation from superior and inferior salivatory nuclei, through CN __ and CN ___.
CN VII and CN IX.

aka facial and glossopharangeal
Inflammation of the parotid gland is notably caused by ?
Mumps virus (myxovirus).
What does mumps surpress?
Sex hormones = infertility
initial triglyceride digestion is by ________.
lingual lipase
Saliva has high?

Saliva has low?

tonicity?
-high K+ and HCO3- concentration

-low Na+ and Cl- concentration

-hypotonicity
At low saliva flow rate composition?
Everything's concentration is "low" except K+ is high
At high saliva flow rate?
the composition of saliva is closest to that of plasma.
Cholinergic receptors on acinar and ductal cells of salivary gland are _________
muscarinic
The second messengers for salivary glans are ?
-IP3 and Ca2+

inositol 1,4,5-triphosphate (IP3) and increased intracellular [Ca++].
Atropine effect on salivary glands?
inhibit the production of saliva and cause dry mouth
Effect of sympathetic on salivary glands?

Second messenger?
-increases growth of gland

-B2 receptor with cAMP
another name for parietal cells?
Oxyntic glands
In parietal cells, H+ is secreted into the lumen of the stomach by the ?
H+/K+ pump (H+/K+-ATPase)
vomiting causes?
no acid in stomach = HCO3- stays in blood and isn't secreted by pancreas to neutralize stomach acid = metabolic acidosis
IF is a co-secretion product with HCl, so destruction of parietal cells (e.g., gastritis) leads to ____ and ____
achlorhydria and pernicious anemia
Direct pathway of H+?

Indirect Pathway?
-vagas nerve innervates parietal cells

-vagas nerve innvervates g-cells which release GRP and cause H+ secretion
Which pathway does atropine block? So is acid secretion ever blocked completely?
direct

no
How do you block both pathways?
vagotomy
The 2nd messenger for histamine is ______

H2 receptor-blocking drug?
-cAMP

-cimetidine
cimetidine also blocks?
also blocks histamine’s potentiation of Ach effects
What inhibits gastric H+ secretion?

The hormonal mediators are ?
-pH < 3 and chyme in the duodenum

-GIP (released by fatty acids in the duodenum) and secretin (released by H+ in the duodenum)
Helicobacter pylori has high ______ activity and converts urea to NH4+, which damages the gastric mucosa.
urease
In gastric ulcers, H+ secretion is ________

Gastrin levels are __________
-H+ is decreased

-Gastrin is increased
Duodenal ulcers are ______ common than gastric ulcers
more common
Effect of duodenal ulcers?
everything is increased
Menetrier’s disease?

hypertrophic or atrophic?
Hypertrophic gastritis giant rugal folds simulating cancer.

Atrophic = protein loss
The duodenum secretes the hormone ____________, that inhibits stomach peristalsis
enterogastrone
enterogastrone?
secreted by duodenum - t inhibits stomach peristalsis
__________ of the duodenum has a common opening for the common bile duct (CBD)
and the main pancreatic duct in its postero-medial wall, called?
-2nd or descending

-major duodenal papill
The common opening is dilated and forms the hepatopancreatic ampulla of ____ which is surrounded by the ampullary ___________
-ampulla of Vater

-sphincter of Oddi
Gastroileal reflex is mediated by ?
-the ANS and by Gastrin
Presence of food in the stomach triggers increased peristalsis in the
ileum and relaxation of the ileocecal sphincter. Known as?
Gastroileal reflex
Functions of the Ileocecal Valve?
Prevent backflow of fecal contents
Illocecal valve function in appendicitis?
may culminate in additional abdominal pain over the RUQ inflammation and reflux and vomiting
Peristaltic rush
the normally weak peristalsis action become more powerful and rapid.
Is the migrating motor complex (MMC)
no
most colonic water absorption occurs in the ?
proximal colon
Composition and characteristics of pancreatic secretion:

Na and K?
- high volume

- same Na+ and K+ concentrations as plasma
Composition and characteristics of pancreatic secretion:

HCO3?
- much higher HCO3- concentrations than plasma
Composition and characteristics of pancreatic secretion:

tonicity?
isotonic
At low flow rates: the pancreas secrets an isotonic fluid that is composed mainly of ?
Na+ and Cl-
At high flow rates: the pancreas secrets an isotonic fluid that is composed mainly of ?
Na+ and HCO3-
Produce a small volume of initial pancreatic secretion, which is mainly Na+ and Cl-
Acinar cells
modify the initial pancreatic secretion by secreting HCO3- and absorbing Cl- via a Cl-_HCO3- exchange mechanism in the luminal membrane.
Ductal cells
CCK acts on pancreatic _____ cells to increase enzyme secretion (amylase, lipases, and proteases).
acinar
Ach is released in response to ______ _______ and ______ in the duodenal lumen.
H+, small peptides, amino acids, and fatty acids
Ach causes?
Stimulates enzyme secretion by the acinar cells and, like CCK, potentiates the effect of secretin on HCO3- secretion.
CCK effect on the galbladder
Causes contraction of the gallbladder and relaxation of the sphincter of Oddi
Ach effect on the galbladder
Causes contraction of the gallbladder
Bilirubin is generated when rbc dies, lyses hemoglobin which is phagocytosed and processed by tissue macrophages collectively known as the ?
reticuloendothelial system
Heme ring is “opened” to release iron -> binds _______

The remaining straight chain (four pyrrole nuclei) _______ becomes bilirubin in a couple of steps
-transferrin

-biliverdin
__________ excreted by the kidneys gets oxidizes in the air after it is micturated as urine and is reduced to _______ which is yellowish
-Urobilinogen

-urobilin
Stercobilin = ?
brownish fecal color
Hemolytic jaundice?

Obstructive jaundice?
Hemolytic jaundice – increased rbc lysis

Obstructive jaundice – blockage of the bile duct or liver damage prevents bilirubin excretion to GI
Prehepatic Jaundice
Due to hemolytic – destruction of RBC/Hgb
Hepatic Jaundice
Due to obstruction of bile trees in common bile duct/cycstic duct -> bile has bilirubin
Destruction of hepatocytes -> ie hepatitis -> cirrhosis – tissue becomes fibrosis/tough
Post hepatic jaundice
Mostly due to obstruction of the cystic duct ie Gal stones
hemolytic jaundice results in?
darker/yellower foamy urine.
obstructive jaundice results in?
increased plasma levels of conjugated bilirubin
Pain, nausea and vomiting and involuntary muscle guarding, Painful splinting of respiration during deep inspiration in the palpation of right upper quadrant
Murphy’s sign
Blood flow into the liver:

Portal vein - __ ml/min
Hepatic artery - ___ ml/min
Portal vein - 1100 ml/min
Hepatic artery - 350 ml/min
The _______ are specialized macrophage type cells that ingest bacteria in 1/100th of a second so the liver can effectively screen >99% of the bacterial load in the blood transit time through the liver.
Kupffer cells
What vitamins does the liver store? What cofactor?
-A, D, B12

-iron
Excess plasma Ca++ is excreted via ?
bile
Hemochromatosis?
a hereditary disease causing the accumulation of iron in the body, eventually leading to liver damage.
Wilson's disease?
a hereditary disease which causes the body to retain copper.
pigment stones
Stones made from too much bilirubin in the bile
Medical conditions that cause the liver to make too much bilirubin, such as chronic hemolytic anemia, including ________
sickle cell anemia
pigmented stones are caused by
Liver cirrhosis and biliary tract infections
Clay-colored stools notably
gallstones