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96 Cards in this Set

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Is the muscle in the oropharynx and upper 1/3 of esophagus smooth muscle or striated muscle?
Striated
Is the muscle is the lower 1/3 of the gut striated muscle or smooth muscle? What's the one exception?
-Smooth muscle
-External anal sphincter is striated!
What surface of the gut faces the lumen?
Mucosa
What are the 2 components of the extrinsic nervous system in the gut?
Sympathetic and parasympathetic
What is the 1 component of the intrinsic nervous system in the gut?
Enteric nervous system
What is the neurotransmitter that is used for the parasympathetic and sympathetic preganglionic fibers? What receptor?
-Acetylcholine
-Nicitinic receptors
What is the neurotransmitter that is used for the parasympathetic and sympathetic postganglionic fibers? What receptors?
-Parasympathetic - acetylcholine in muscarinic receptors
-Sympathetic - norepinephrine in adrenergic receptors
What are the 2 nerve plexi that make up the enteric nervous system? Where are they?
-Myenteric in between the inner circular and outer longitudinal muscles of muscularis externae
-Submucosal is just deep to the submucosal layer (in between submucosal and inner circular muscle layer)
Describe the vagovagal reflex.
-Vagal afferent neurons
-DMX and Solitary Nucleus
-Vagal efferent neurons release Ach at nicotinic synapses.
(Eg stomach relaxes in response to distension in the esophagus)
Is there digestion of carbs in the stomach?
NO
What is the rate limiting step of carbohydrate digestion?
Transport into the enterocytes. ONLY monosaccarides.
Where in the GI tract is most of the water absorbed?
Duodenum and jejunum!
Where is iron absorbed?
Mostly in the small intestine. Through active transport via a specialized transporter
Inhibitory or excitatory in the GI tract:
Substance P
Excitatory
Inhibitory or excitatory in the GI tract:
Neurokinin A
Excitatory
Inhibitory or excitatory in the GI tract:
Nitric oxide
Inhibitory
Inhibitory or excitatory in the GI tract:
Vasoactive intestinal polypeptide (VIP)
Inhibitory
What type of cell releases serotonin in response to stroking or stretch of the mucosa?
Enterochromaffin cells
Name the hormone:
"released in response to distension of the stomach or the presence of amino acids in the antrum (near the duodenum."
Gastrin (from G cells in the stomah)
Name the hormone:
"released in response to duodenal acidity, causes increased becarbonate secretion from pancreatic duct cells"
Secretin (from S cells in the duodenum)
Name the hormone:
"Released in response to fat and protein digestion products in the duodenum. Contracts gall bladder, increases exzyme secretion from pancreatic acinar cells"
CCK aka cholecystokinin (from I cells in the duodunem)
Name the hormone:
"Primes insulin release in response to antiipation of the nutrient absorption"
GIP aka Glucose-dependent insulotropic peptide
Name the hormone:
"involved in fasting contractions in the stomach and intestine"
Motilin (from M cells in the lower stomach)
Name the hormone:
increases bicoarbonate secretion from pancreatic duct cells". Increases intestinal secretion and inhibits smooth muscle contractility.
VIP aka vasoactive intestinal polypeptide
Name the hormone:
"released from cells in the ileum in responses to fat; slows motility (ileal brake)"
Neurotensin and Polypeptide Y (PPY)
Name the hormone:
"present in vagal terminals that innervate G cells (that secrete gastrin); increases gastrin release (stomach stretch, presence of aa's)
GRP gastrin releasing peptide
Serous or mucus secretion?
Parotid glands
Serous
Serous or mucus secretion?
Submandibular glands
Both serous and mucus
Serous or mucus secretion?
Sublingual glands
Both serous and mucus
Serous or mucus secretion?
Buccal glands
Mucus
Where does the ionic content of saliva get altered?
In the salivay sucts AFTER being secreted by the acini
Is salivation controlled by sympathetic pathways or parasympathetic?
Parasympathetic
How many primary teeth are there? How many secondary teeth are there?
-20
-32
Can you tell what blood type a person is by their saliva?
YES!!!
What is digested and/or absorbed in the esophagus?
Nothing, the esophagus just passes food stuffs to the stomach
What is the innervation of the esophagus? Consider both smooth and skeletal muscle.
-Skeletal - vagus nerve directly to motor end plates
-Smooth - autonomics
What stage of swallowing:
"Food pushed to posterior part of mouth; tongue forces food bolus into pharnx by pushing backward and upward against palate"
Voluntary
What stage of swallowing:
"Food stimulates swallowing receptor area; impulses sent to swallowing center in the brain stem"
Pharyngeal stage (involuntary)
Name 6 processes that occur during the pharyngeal stage of swallowing.
-Soft palate pulled forward (closes posterior nares)
-Palatopharyngeal folds pulled medially (won't permit too-large bolus)
-Vocal cords close (protect airway
-Larynx pulled up and forward by muscles attached to hyoid (opens esophagus)
-UES relaxes and opens via chricopharyngeus
-Superior constrictor muscles of pharynx contract (starts peristaltic wave)
What is the difference between primary peristalsis and secondary peristalsis during the esophageal stage of swallowing?
-Primary - begins in pharynx and is initiated by a swallow. One wave for one swallow.
-Secondary - begins in the esophagus and is initiated by distention in the esophagus. Will continue until esophagus is empty
What is described below:
"non-peristaltic (non-progressive), localized, segmental contractions of the esophagus"
Tertiary contractions (ABNORMAL)
What is the effect of rapid swallows on peristalsis in the esophagus?
Delays peristalsis until swallowing is complete. "Clearing wave" after completion of swallowing
What is it called when the LES relaxes with swallowing?
"Receptive relaxation"
-Precedes peristaltic wave
-Maintained until peristaltic wave passes
What effect does a hiatal hernia on reflux?
-Reflux mostly related to a competent LES
-Reflux can be worsened by hiatal hernia in the setting of a hiatal hernia.
Is the tonic contraction of the lower esophageal due to intrinsic muscle activity or to neural stimulation?
Intrinsic muscle activity
Is the relaxation of the lower esophageal sphincter due to an intrinsic property of the muscles or neural control?
Neural stimulation of vagus nerve.
-Unknown neurotransmitter (NANC, possibly NO or VIP)
Does a vagotomy affect the resting pressure of the lower esophageal sphincter?
NO, tonic contraction is due to intrinsic muscle property.
Does tetrodotoxini affect the resting tone of the lower esophageal sphincter or relaxation of the LES or both?
Just relaxation (neurally controlled)
Does these hormones increase or decrease LES pressure?
-Gastrin
-Motilin
-Substance P
-Pancreatic polypeptide
-Pitressin
-Angiotensin II
Increased pressure
Do the following substances increase or decrease LES pressure?
-Secretic
-Cholecystokinin
-Glucagon
-Gastric inhibitory polypeptide
-Vasoactive intestinal polypeptide
-Progesterone
Decreased pressure
What foods might decrease LES pressure?
Fats
Alcohol
Chocolate
What phase of swallowing?
"mastication and bolus formation"
Oral preparatory phase
What phase of swallowing?
"transport bolus to the posterior area of the oral cavity"
Oral phase
What is the most effective mechanism to prevent aspiration during swallowing?
Adduction of the true vocal cords
What with dysphagia would you use thin fluids? Thick fluids?
Thin fluids - poor clearance but no aspiration
Thick fluids - aspiration
What cell type is described:
"May contribute to cell defense; has lysozymes stored in granules; can also phagocytose"
Paneth cell
What cells secrete HCl?
Parietal cells
Where in the stomach are parietal cells (oxyntic) located?
Cardia, fundus, corpus
What cells secrete intrinsic factor?
Parietal cells
What is the function of intrinsic factor?
Necessary for the absorption of Vit B12 in the ileum
What are 3 examples of enteroendocrine cells?
-G cells secrete gastrin
-S cells secrete secretin
-M cells secrete motilin
What is the function of somatostatin?
Inhibits the release of gastrointestinal hormones
What are SGLT's and why are they important?
-Sodium-dependent glucose transporters
-These proteins use the energy from a downhill sodium gradient to transport glucose across the apical membrane against an uphill glucose gradient.
What two cell populations are found in the myenteric plexus?
-Post-ganglionic parasympathetics
-Neurons of enteric nervous system
Is there a basal electrical rhythm in the esophagus?
NO, not in the esophagus, the proximal stomach, or the sphincters
Is there a basal electricla rhythm in the colon?
Yes, in the colon, the small intestines, and the distal stomach
Can action potentials occur in the gut without any extracellular Ca2+?
No
Do the following factors increase or decrease excitability in the bowels:
"stretch, ACh, parasympathetics, GI hormones, Substance P"
Increase excitability (move towards depolarization)
Do the following factors increase or decrease excitability in the bowels:
"Norepinephrine, Epinephrine, NO, Vasoactive intestinal polypeptide, sympathetics"
Decrease excitability (move towards hyperpolarization)
What do the pelvic splanchnics innervate in the GI tract?
Parasympathetic innervation to the hindgut
What does the vagus innervate in the GI tract?
Parasympathetic innervation to the esophagus, stomach, pancreas, intestine
What are the 2 excitatory ENS neurotransmitters?
Ach and Substance P
What are the 2 inhibitory ENS neurotransmitters?
VIP and NO
What is the function of the interstitial cells of Cajal?
Pacemaker cells of the GI tract
What is an example of a short reflex in the gut?
The control of peristalsis and mixing in the gut. Requires the coordination of the inner circular muscle and the outer longitudinal muscle coordinated by the ENS.
What is an example of a long reflex in the gut (but not including the CNS)?
The gastrocolic reflex
What is an example of the longest reflex in the gut (involving the CNS)?
The vagovagal reflex involving receptive relaxation of the stomach in response to the swallowing of food.
Is there MMC (migrating motor complex) in the colon?
No, only in the stomach and small intestine
What is gastroparesis?
Delayed gastric emptying
What ions come in to depolarize the smooth muscle in the gut when action potentials are generated?
Ca2+ and Na+
Is the enterogastric reflex a short, long, or longest reflex?
Long
What effect does eating have on the MMC (Migrating motor complex)?
Stops it!
What do chief cells of the stomach do? Where are they found?
-Releases pepsinogen
-Mostly in the fundus of the stomach
Is the vagus N primarily afferent or efferent in dealing with the gut?
Primarily afferent
What vagus nucleus controls striated muscle of the esophagus?
Nucleus ambiguous
What vagus nucleus controls smooth muscle of the esophagus?
Dorsal motor nucleus (DMX)
What is the enterogastric reflex?
It delays gastric emptying
Where are Paneth cells found?
Small intestine- they are thought to be part of the host defense system
Where do you find lacteals?
In the lamina propria of villi in the small intestine
What is the function of Brunner's glands?
-Secrete mucus in response to vagal stimulation and tactile stimulation
-Protects the duodenum from acid coming from the stomach.
What is the basic process of digestion of carbs, proteins, and fats?
Hydrolysis! Accomplished by different enzymes for different food stuffs.
What are the 3 basic monosaccarides that an enterocyte can absorb? Where does this occur?
-Glucose, fructore, galactose
-Throughout small intestine primarily JEJUNUM
What's special about the absorption of Vit B12? Where does absorption occur?
-Requires intrinsic factor secreted by the parietal cells in the stomach.
-Absorbed in the ileum
Is the parotid gland serous or mucus secretions? Is the pancreas serous or mucus secretions?
Both are ONLY serous.
BUT:
-parotid gland has fat cells
-pancreas has centroacinar cells
What effect does fat in the ileum have on gut motility?
Decreases gut motility (ileal brake)
Does exercise, NG tubes, or laxitives help resolve an ileus?
NO!