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94 Cards in this Set
- Front
- Back
Regarding constipation, what is colonoscopy useful for?
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Useful to identify lesions which narrow or occlude the bowel
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Regarding constipation, when is radiography useful (plain films of the abdomen or barium enema)?
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Useful to detect structural causes of constipation and fo rthe diagnosis of megacolon and megarectum
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Regarding constipation, when are colonic transit tests warranted?
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Useful in patients whose major complaint is infrequent defecation
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A patient presents with excessive straining, incomplete evacuation and occult bleeding. Is this primary or secondary constipation?
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Secondary
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A patient presents with a CC of constipation with abdominal pain and rectal bleeding. Is this primary or secondary constipation?
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Secondary
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A patient presents with changes in voice register, cold intolerance and constipation. The constipation is secondary to what disease?
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Hypothyroidism
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On rectal exam, you note a gaping and asymmetrical anal opening. What kind of secondary constipation disease does this suggest?
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Neurologic disorder impairing sphincter function
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Patient's over 50 with constipation should always get what?
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Colonoscopy for colon cancer; complete examination of the colon necessary to exclude a structural disease (colon cancer, colonic stricture) w/ recent change in bowel habits, blood in stool, or weight loss
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What kind of drugs are significantly associated with constipation?
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Opioids for chronic pain; diuretics, antidepressants,antihistamines, antispasmodics (calcium channels), anticonvulstants (calcium channels) and aluminum containing antacids
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A patient presents with a proximally enlarged bowel which is narrowed distally. What is occuring in this disease?
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Hirschsprung's disease; absence of ganglion cells in distal bowel results in overstimulation of nerves in affected region, resultin gin contraction (similar to achalasia)
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A patient who recently returned from Africa reports constipation. They note that a few weeks ago they had fever and malaise. What should you consider?
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Chaga's Disease; caused by Trypanosoma cruzi via insect vector
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A patient presents with prolonged and excessive straining before elimination. You decide a patient has defecatory or rectal evacuation disorders; what kind of primary constipation is this?
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Pelvic Floor Dysfunction
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A young female presents with less than 1 bowel movement a week. She notes a lack of urge to defecate, malaise, and fatigue. What kind of primary constipation is this?
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Slow - transit constipation;
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How can you measure colonic transit time?
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Pt swallows radiopague markers in gelatin capsule; abdominal x ray 120 hours after ingestion; retention in colon of radiopaque markers 5 days after ingestion = slow transit
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What kind of conservative treatment must be attempted before anorectal testing?
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Increased dietary fiber and liquids, elimination of medications with constipating side effects
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How long does it take to expel a 50ml water filled balloon normally?
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1 minute; abnormal expulsion indicates impaired evacuation
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What does pelvic floor dysfunction refer to?
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Inability to empty rectum effectively bc of incoordinated abdominal, rectoanal, and pelvic floor muscles; constipation is functional
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A patient presents with recurrent abdominal discomfort 3-5 days a month in the last 3 months associated with improvement with defecation, onset associated with a change in frequency and appearance of stool. What is the diagnostic of?
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Irritable Bowel Syndrome
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What are the four functions of the colon?
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1. absorption of water/electrolytes
2. absorptoin of short chain FA 3. storage and transport of undigested/waste material 4. elimination of undigested material/waste products |
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Endoscopy reveals a 'leaky' ileocecal valve. How would you expect this to affect transit time?
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Slows transit time bc when the ascending colon contracts it will push contents back through valve, increasing transit time
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Are there dominantly aerobic or anaerobic species in the colonic microflora?
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Anaerobic
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What essential things do microflora in our colon produce?
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K, B1, and B2 (vitamins)
also short chain fatty acids when these organisms die If bacteria were eliminated the intestines would atrophy |
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What is required for ileocecal sphincter emptying?
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The colon must be empty; if so, pressure and chemical irritation relax sphincter and excite peristalsis
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What is the large intestine transit time?
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48-72 hours; average is around 65 hours
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What effect does sympathetic stimulation have on GI valves?
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Closes them down; pyloric, ileocecal, anal (fight or flight)
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Describe the histology of the colon?
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FLAT, simple columnar epithelia, crypts with no villi, huge goblet cell density, lots of lymphocytes in lamina propria (purple dots when stained w/ H&E) - might see lymph nodules
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What do the colonic crypts secrete?
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Mainly secrete alkaline mucus; mucus secretion increased by parasympathetic stimulation
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What sympathetic nerve innervates the proximal colon?
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Vagus
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Which nerves innervate the distal colon, rectum and anus?
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Pelvic nerves (S2-S4)
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What is the sympathetic input to the rectum and anal canal?
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Hypogastric plexus
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What ganglion supplies the sympathetic input to the distal colon?
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Inferior Mesenteric Ganglion
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Which nerve ganglion supplies the proximal colon?
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Superior Mesenteric Ganglion
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Which nerves innervate the external anal sphincter?
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Pudenal nerves
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Why doesn't the myenteric plexus completely surrounding the large intestine?
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It is only under the tenae coli, which are three longitduinal muscle bands that contract to form the haustra
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What is the function of haustral contractions?
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To mix chyme; enhances fluid/electrolyte absorption
Propels fecal material (mass movements) |
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Describe the frequency of haustral contractions
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appear/disappear every 30-60s; require contraction of longitudinal and circular SM
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Distension of what two structures would cause mass movement in the colon?
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Gastrocolic reflex (distention of stomach) and duodenocolic reflex (distension of duodedenum)
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How long does it take food you eat to reach the large intestine?
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6-8 hours
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Which plexus carries the intrinsic defecation reflex (stretching of internal anal sphincter)?
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Myenteric plexus
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Describe the intrinsic defecation reflex
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Stretching of internal anal sphincter causes upstream muscularis to contract and internal sphincter to relax
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Describe the parasympathetic defecation reflex
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Stretching of rectum sends sensory signals to spinal cord, splachnic nerves return signals intensifying peristalsis
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Describe the sequence of events when you want to go to the bathroom
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Pudendal nerve activity to external anal sphincter is inhibited by input from higher brain centers -> external anal sphincter relaxes and higher centers stimulate pelvic floor muscle activity and other defectory actions -> defecation occurs
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Describe the sequence of events when you don't want to go to the bathroom
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Pudendal nerve activity is enhanced and the external anal sphincter contracts stronger -> defecation not allowed -> internal anal sphincter contracts and the urge to defecate subsides -> cycle repeats every 10-20 minutes
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What is the function of the pudendal nerves?
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External anal sphincter tone
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Where do fishbones always get stuck?
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epiglottic vallecula
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What is a characteristic morphological feature of the duodenal and jejunal lumen?
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Circular folds/valves of Kerckring
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Where is the ligament of treitz located?
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At the duodenojejunal flexure
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Which part of the biliary system has a spiral appearance?
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Cystic duct
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What do the hepatic and cystic duct join to form?
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Common bile duct
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Which arteries are along the greater curvature of the stomach?
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Gastroepiploic artery (left and right gastroomental)
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Which arteries run along the lesser curvature of the stomach?
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Gastric arteries (right and left)
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In an abdominal scan, where does the gas bubble in the stomach always migrate to?
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the highest point - if laying down it will migrate up toward the pylorus, if standing up it will migrate to the fundus
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Which aorta is always adjacent and to the left of the vertebra?
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Abdominal aorta
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Where does the tail of the pancreas point to?
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Spleen
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Where does the head of the pancreas connect?
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Duodenum
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what is the relation of the inferior vena cava to the abdominal aorta?
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the IVC is always to the left of the AA
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What is the input, output, and function of the insular cortex in relation to ANS?
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I: VMN of thalamus
O: Amygdala F: viscerosensory cotex for taste, visceral sensation and pain/temp |
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A patient presents with an inability to taste, feel visceral sensation or pain and temp. What autonomic CNS structure might be damaged?
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Insular Cortex
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What is the input, output, and function of the anterior cingulate gyrus in relation to ANS?
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I: PFC, amygdala
O: PFC, amygdala (reciprocal) F: Initiates motor/autonomic responses associated with emotional stimuli |
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What is the input, output, and function of the amygdala in relation to ANS?
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I: Brainstem, thalamus (pain/temp), cerebral cortex (processed sens. info)
O: hypothalamus, brainstem, spinal cord F: Coordinate autonomic, endocrine, and motor component of emotional response |
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What is the function of the periventricular hypothalamus?
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Circadian rhythms (suprachiasmatic nucleus SCN)
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A patient presents with messed up sleep cycles. What ANS related neural structure might be damaged?
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Periventricular area of the hypothalamus; coordinates circadian rhythms via suprachiasmatic nucleus (SCN)
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What is the function of the medial area of the hypothalamus?
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Response to stress via paraventiruclar nucleus PVN
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A patient presents with a diminished stress response. Which ANS related neural structure might be damaged?
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Medial area of hypothalamus; diminished stress response due to PVN damage
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What is the function of the lateral area of the hypothalamus?
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Arousal; sleepwake cycle; feeding/drinking
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A patient has a diminished desire to eat or drink. You suspect a neurological lesion where?
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Lateral hypothalamus
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Which tract conveys taste/visceral sensation from nucleus of solitary tract to hypothalamus?
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Dorsal Longitudinal Fasiculus
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Which tract originates from the PVN and lateral hypothalamic zone to the autonomic nuclei of the brainstem and spinal cord?
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Hypothalamospinal tract; main hypothalamic output
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How can you explain the phenomenon of referred pain?
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The proximity of visceral afferent fibers to the general somatic afferent fibers from the skin for pain produces this phenomenon
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Where are the preganglionic neurons of the sympathetic system located?
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IML cell column (T1-L3) of spinal cord
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What are the two destinations of the sympathetic nervous system neurons?
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Sympathetic trunk
Prevertebral ganglia (pass sympathetic trunk without synapse to enter splanchnic nerve) |
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What does the prevertebral ganglia give rise to?
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Splanchnic nerve
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What neurontransmitters are used by the sympathetic nervous system?
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Norepenephrine, and Ach/muscarinic cholinergic neurons
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A branch of CNVII, which ganglion innervates the lacrimal gland, mucosa of nose and palate?
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Pterogopalatine ganglion
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A branch of CNVII, which ganglion innervates the submandibular and lingual gland?
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Submandibular gland
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A nucleus of CNIII, what nucleus controls the sphincter papillae and ciliaris muscle?
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Edinger-Westphal nucleus
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Which parasympathetic division is involved with micturition, defecation, and sexual function?
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Sacral division, S2-S4
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Which four cranial nerves make up the parasympathetic cranial division?
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CN III, VII, IX, X
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What NT is used by postganglionic parasympathetic innervation?
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Ach/muscarinic cholinergic receptor
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Activation of CN V2 branches of the greater palatine nerve, lesser palatine nerve, and nasopalantine nerve all result in what?
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RUNNY NOSE
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If histamine in an allergic reaction activates the petrosal nerve pathway of CNVII what is the end result?
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LACRIMATION
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If the chorda tympani nerve pathway of CN VII is activated what is the end result?
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SALIVATION via submandibular/sublingual salivary glands
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If the CN IX pathway is activated what is the end result?
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Salivation via parotid gland
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Which cranial nerve supplies major nerve supply to GI tract?
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CN X; controls GI motility via myenteric plexus in the foregut and hindgut
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Activation of CN V2 branches of the greater palatine nerve, lesser palatine nerve, and nasopalantine nerve all result in what?
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RUNNY NOSE
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The sacral division of the ANS supplies nerve supply to what structure?
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Hindgut (last 1/3 of transverse colon, descending colon, sigmoid colon, rectum
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Describe the sympathetic and parasympathetic innervation of the foregut?
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S: Greater splanchnic nerve (T5-T9) > Celiac Ganglion > Target
PS: Vagus Nerve |
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If histamine in an allergic reaction activates the petrosal nerve pathway of CNVII what is the end result?
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LACRIMATION
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If the chorda tympani nerve pathway of CN VII is activated what is the end result?
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SALIVATION via submandibular/sublingual salivary glands
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Describe the sympathetic and parasympathetic innervation of the midgut?
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S: Lesser (T10-T11) and least (T12) splanchnic nerves > superior mesenteric ganglion > target
PS: Vagus nerve |
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If the CN IX pathway is activated what is the end result?
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Salivation via parotid gland
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Describe the sympathetic and parasympathetic innervation of the hindgut?
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S: Lumbar splanchnic nerves (L1-L3) > inferior mesenteric ganglion > target
PS: Pelvic splanchnic nerves (S2-S4) > pelvic plexus > target |
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Describe the sympathetic and parasympathetic innervation of the internal anal sphincter?
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S alpha-1 adrenergic receptor
PS: pelvic splanchnic nerves relaxation via VIP, NO or both |
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Which cranial nerve supplies major nerve supply to GI tract?
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CN X; controls GI motility via myenteric plexus in the foregut and hindgut
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