Physiology Flashcards
Which salivary gland secrets 70% of all secreted saliva
Sub Mandibular Gland
The facial nerve carries parasympathetic innervation For which gland
Sub Mandibular and sublingual
the glossopharyngeal nerve carries parasympathetic innervation to which bland
parotid
Describe the ionic movement of anciner cells As isotonic saliva Is moving through the duct cells
Efflux of chloride and sodium ion; Influx of potassium and bicarbonate ions; net result is hypotonic saliva relative to the plasma
the nucleii salvatorii are located in which region of the CNS?
Medulla oblongata
is the nucleii salvatorii carry parasympathetic innervation of the salivatory glands. Where are the ganglia & cell bodies for the sympathetic innervation located
cell bodies reside in the Superior cervical ganglion located in vertebral levels T1 to T3
What constitutional symptoms inhibit the action of n theucleii salvatorii?
sleep; fatigue; dehydration
Salivary glands secrete this glycoprotein To protect this vitamin From acid degradation in the stomach
transcobalamin protects vit. B12
sjorgren syndrome Is an autoimmune disease that most often affects women around 50 to 60 years of age. what GI symptoms Are associated with this disorder?
no saliva production increases risk of gum infections and reduces dental protection from cavities
Which cranial nerves carry sensory information to the medulla oblongata regarding swallowing
CN V & IX
Which cranial nerves carry motor innovation To carry out the act of deglutition?
CN V, IX, X, & XII
Relaxation of the lower esophageal spinchner Is regulated by what Endogenous hormone?
Vasoactive intestinal peptide (VIP) & NO
In the absence of deglutition, Both esophageal spinchers stay contracted. This ensures that the following pressure gradient is maintained For proper movement of bullets through the esophagus.
Pp > Pues; Pe > Ples
Which muscle Is primarily responsible for preventing bolus from entering the trachea And error from the esophagus during Inspiration
upper esophageal spinch tur
Which neurotransmitters are involved in contraction of the lower esophageal spinach?
Ach & substance P
Which layer of the gi canal Is missing in Zenker’s diverticulum
muscularis layer
What is the pathogenesis of scleroderma
Excess production of collagen
How would Excessive collagen production affect Mastication & deglutition
Epithelial thickening will make it harder to contract muscles and therefore reduce the amplitude of contraction
mastication is not affected
degluition however is affected
Which cranial nerve Innervates autonomics of both esophageal spinach
Vagus
How would chewing and swallowing be impacted if the lower esophageal spinchter Stays contracted
Bolus will stay in the esophagus Because pressure of the LES will exceed that of the esophagus
AKA: achalasia
What happens when there is an increase in the amplitude of esophageal contractions Which is the case for diffuse esophageal spasm
bolus Will still be able To move through the esophagus into the stomach but at a much faster rate than normal
How will mastication and deglutition be impacted if the pharynx is paralysed
Mastication and swallowing mechanisms will be impaired
What dysfunction is occurring For gastroesophageal reflux disease
Dysfunctional LES
What neuronal pathway Regulates secretion of gastric acid
M3
Which cells regulate the hormonal pathway of gastric acid secretion
gastrin cells
which cells are involved in the regulation of the paracrine pathway of gastric acid secretion
ECL & D cells
What hormone is the primary inhibitor of gastric acid production
somatostatin
secretin is secreted by which cells?
S cells
What is the primary function of gastric secretin?
inhibition Of gastric Acid secretion (not production)
somatostatin is secreted by what cells?
D cells
Which cells can be stimulated by histamine
parietal cells
What effect does histamine have on the regulation of gastric acid secretion
Stimulates parietal cells to secrete acid
What are the primary stimulators of gastric acid secretion
histamine; gastrin; acetylcholine
what are the main inhibitors of gastric acid secretion
Somatostatin; Secretin
sight, smell, taste, & thoughts of food stimulate vagus action on the stomach; what cells are activated during this 1st step: cephalic phase
Mucus cells; chief cells; parietal cells; g cells
What new players are introduced During the gastric phase (step 2) of gastric secretion
Short reflex: Submucosal and Myanteric Plexissors
Long Reflex: Vaso-vagal
Step three or the intestinal phase of gastric secretion Introduces what new players into the action
Secretin; duodenal stretch and chemoreceptors, CCK & GIP
What are the net metabolic effects of the gastric phase
Lower ph; distension; protein metabolites
what are the net metabolic effects of the intestinal phase
hyper osmolarity; acidic chyme; fats
CCK & GIP also inhibit HCl secretion but to a much lesser extent than secretin & somatostatin. Which cells secrete the former and the latter
K cells secret GIP
I cells to create CCK
cell bodies of sympathetic innervation to the stomach are located where
celiac ganglion
what is the primary role of the meissner plexus?
control of local gi secretion and nutrient absorption
What is the primary role of the auerbach plexus?
Intrinsic myogenic control of the GI tract
what is the primary function of motilin?
produced by Mo cells; activated during fasted state; clears the stomach of any residue remaining from the previous meal
Describe the process of receptive relaxation
Allows the stomach to accommodate large amounts of food and fluid; this is mediated by the vaso-vagal reflex and VIP
gastrin stimulates parietal cells to release what and ECL cells to release what
HCL & histamine
How does alcohol affect gastric motility
Stimulates gastric emptying
how does gastrin affect gastric emptying
inhibits gastric emptying by increasing tone of the pyloric sphincter
What is the primary function of GIP
contraction of the pyloric spinchter
What are the primary roles of the enterogastric reflex
Increased tone of pyloric spinchter; Decreased rate of pyloric pump contractions; Inhibition of gastric emptying
What is the primary role of cck in regulation of gastric motility
inhibition of pyloric pump; increased tone of the pyloric spinchter
How does depression affect gastric emptying
Decreases gastric emptying
How do anger and stress affect gastric emptying
Increases gastric ending
How is bile acid from the gallbladder released into the bile duct
CCK facilitates contraction of gallbladder smooth muscle to release bile into the duct
how Is bile In the bile duct released into the duedenum
CCK stimulates relaxation of the spinchter of Oddi
How does CCK act as a neurotransmitter in addition to a hormone
CKK Also stimulates vagal afferents to initiate a positive feedback loop that further enhances acid secretion
whatt Neurotransmitters and pathways are involved in vagus induced biliary secretion
vagal afferents stimulate the dorsal vagal complex to send vagal efferents down to the gallbladder to enhance biliary secretion
Vagal efferents:
AcH: gallbladder contraction
NO & VIP: relaxation of sphincter of Oddi
what biomolecules in the duodenum lumen stimulate secretion of CCK
lipids & fatty acids
Pancreatic & gallbladder inflammation is likely to precipitate what kind of gall stones?
brown pigment stones
Abnormal cholesterol metabolism is likely to promote the formation of what kind of stones
All cholesterol stones (most common) are derived from the gallbladder but can travel to the bile or cystic ducks
What kind of stones would you expect to find in the gallbladder of a patient With a hemalytic disease
black stones (most commonly arise from the GB)
What are primary bile acids
bile acids that are produced directly in the liver
colic acid
chenodeoxycholic acid
what are secondary bile acids
These are primary bile acids With a removed hydroxyl group By the gut flora:
deoxycholic acid
lithocholic acid
What amino acids are Used in the conjugation process of bile acids
glycine and taurine
What’s the difference between a bile acid and a bile salt
Bile salts are the product of bile acid conjugation
Why Is bile acid conjugated to bile salt
Bile salts are more soluble in the duodenum
What is the name of the detergent property of bile salts
amphipathic: both hydrophilic & lipophilic
Describe the process of emulsification
Takes place in the small intestine
Lipids are consumed by bile salts to form micelles when exposed to water
What is the primary function of bile
Digestion and absorption of lipids and fat soluble vitamins Which include vitamin A, D, E, K
What are other functions of bile
buffers pancreatic and duodenal content because bile content also contains bicarbonate ions
Almost 100 percent of all dietary lipids are what type
triglycerides
In what vessels does the distribution of chylomicrons take place
lacteal lymphatic vessels situated in The intestinal interstitum
Where does the assembly of micells take place
in the lumen Of the small intestine
Where does the breakdown of lipids to fatty acids and monoglycerides take place
lumen of the small intestine
What happens after the fatty acids and monoglycerides passively diffuse into the epithelium of the small intestine
they are reformed into triglycerides And packaged into lipoproteins called Chylomicrons
chylomicrons are exocytosed into the lacteal and enter what duct
Thoracic duct
and then to liver
conjugated bile acids are reabsorbed in which section of the small intestine
terminal ilium
How are bile salts transported into enterohepatic circulation
Passive diffusion (unconjugated bile acids) And via active transportation through sodium bile salt co-transporters (conjugated bile acids)
Which two co activators Are required for activation of fxr transcription
Retinoic and bile acids
FXR inhibits what metabolic pathways
Gluconeogenesis; lipogenesis; Cholesterol Conversion to bile acid; BA reabsorption in the intestine
FXR Promotes the release of what factor to inhibit the conversion of cholesterol to bile acids
FGF 19
What role does FXR play in the conjugation process of BA
It reduces ba toxicity by increasing the expression of BA modifying enzymes
How does FXR decrease BA reabsorption in the small intestine
It down regulates expression of the sodium dependent BA transporter On the apical side of the intestinal epithelium
This promotes absorption of BA into enterohepatic circulation to be recycled
Fxr Up regulates expression of this protein in fatty liver disease
ceramide
How does FXR have an anti inflammatory effect
Promotes differentiation to the macrophage M2 phenotype And up regulates secretion of IL-10 both of which are anti inflammatory mediators
where are Pancreatic juices produced
the pancreatic acinus
In what cells are zymogen granules stored
acinar cells
Pancreatic duct cells secret
bicarbonate
the Endocrine component of the pancreas involves what hormones
Cck and secretin
The neurocrine Component of the pancreas involves what substances
substance P; Ach; grp; VIP
What second messengers Are involved in receptor mediated exocytosis of pancreatic juices
Calcium and cyclic amp
What pancreatic cells secrete CCK
I cells
What key zymogen Is secreted by the pancreas To activate all other pancreatic proteases once they enter the duodenum
Tripsynogen
What duodenal enzyme Converts trypsinogen to trypsin
Enterokinases Located on the Brush border of duodenal enterocytes
What pancreatic enzymes Break peptide bonds to form peptide fragments
Tripsyn, elastase, chymotrypsin
What pancreatic enzyme cleaves the terminal carboxyl Segment of peptides into amino acid monomers
carboxypeptidase
Amino acids are absorbed into enterocytes via what co-transporter ion
sodium
What role does secretin have in the pancreatic duct cells
biCarbonate & water secretion
VIP & GRP specifically act on pancreatic acinar cells to stimulate what?
Secretion of digestive enzymes
How is water transported Into the pancreatic lumen
via an Osmotic gradient
What drives Sodium ion transportation into the pancreatic lumen
Electrical gradient
+charged BLM to the -charged AM
What condition stimulates pancreatic s cells to secrete secretin
low pH in the duodenal lumen
What effect does secretin have on ductal cells in the pancreas to promote secretion of bicarbonate into the pancreatic duct lumen
It increases intracellular cyclic amp which is a second messenger that enhances the activity of CFTR
How is bicarbonate secreted into the lumen of the pancreatic duct on the apical side
facilitated via CFTR: Exchanges bicarbonate For chloride
What effect do acetylcholine and CCK have in pancreatic S cells
Potentiation of cyclic amp
What is the primary role of Secretin in the pancreas
facilitation of bicarbonate secretion in the gi canal
what is the primary role of pancreatic CCK
Digestion of fats and protein
What effect Do vagal efferents have on pancreatic duct cells
Potentiation of bicarbonate secretion
What effect do vagal efferents have on pancreatic aciner cells
Stimulates release of zymogens
What substances can stimulate the vago-vagal reflex?
CCK & monomers of macro-biomolecules
