Trans - Gastric Motility Flashcards by UPCM 2018

Which structure is mismatched with their description?

a. stomach - initial digestion of proteins
b. UES - Cricopharyngeus
c. LES - Circular Muscle thickening
d. Pylorus - Oblique Muscle thickening

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Which of the ff is not a function of the GI System?

a. facilitate speech
b regulate blood components
c. digest food and absorb nutrients
d. NOTA
b.

d. NOTA

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What layer is responsible for propulsion of bolus?

Muscularis Externa

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Which muscle layer is most affected by hypotension?

Mucosa

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Which layer is most susceptible to necrosis?

Mucosa; because it is farthest from vasculature

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Part of enteric nervous system found in submucosa?

Meissner’s plexus

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Part of enteric nervous system found between circular and longitudinal muscle layers

Auerbach’s plexus

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Parts of the GIT without serosa

Esophagus; most of the rectum

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3 Components of GI regulatory system

CNS, Enteric Nervous System; Enteroendocrine cells

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Differentiate short reflex and long reflex in the GIT

Short reflex: signals from chemoreceptors, osmoreceptors, mechanoreceptors reach nerve plexus and smooth muscle/glands producing a response; Long: signaling involves spinal cord and brain

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T/F smooth muscle lack cross- striations and thick an thin filaments

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Cellular components that helps in efficiency of contractions

dense bodies

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T/F GI smooth muscle act as one, are fast acting, hence more efficient

F; act as one, SLOW acting; more efficient

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what does contraction of the longitudinal muscle layer do? circular?

L: decrease length
C: decrease diameter

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Functions of UES

voluntary control of swallowing (e.g. option not to swallow spoiled food)
prevents:
entry of air into trachea; gas into esophagus

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T/F the LES is anatomically distinct

F; physiological only

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Which anal sphincter contributes the most to maintaining fecal continence?

Internal Anal Sphincter (70-80%)

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pacemaker of the GI

Interstitial Cells of Cajal

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The vagus nerve provides parasympathetic (stimulatory) innervation for the GIT. After Vagotomy, will GI motility cease?

No. as long as Interstitial cells of Cajal is intact, there will be GI Motility

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T/F No ICC no GI motility

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What cellular feature of the ICC make them act as one functional unit?

gap junctions

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T/F much of the neural and hormonal regulation of GI functions are intrinsic to the GIT

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Parasympathetic innervation of the GI from the esophagus to the ascending colon is via which nerves?

vagus nerves

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Parasympathetic innervation of the GI from the transverse colon to rectum is via which nerves?

Pelvic nerves

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Resting membrane potential of smooth muscle

-56mV

slow undulating changes in RMP

slow waves

True action potential that produces AP

<-40mV

T/F higher slow waves = less spike potential

T/F muscle contractions produced by spike potential is greater in force than contractions produced by slow waves

F; slow waves do not produce AP; therefore comparison can't be done

what stimulate spike potentials?

stretch, Ach

what does sympathetic innervation do to the membrane potential? what does this imply?

hyperpolarize from -56 to -70mV; inhibition - decrease muscle contraction

T/F contractile force increase with number of APs

T because of temporal summation

GIT segments in decreasing order of contraction rate

``` Stomach - 3/min Sphincter of Oddi - 4/min Colon - 6/min Ileum -9/min Jejunum -11/min Duodenum - 12/min ```

contraction is facilitates by _______ and _______; relaxation is facilitated by ___ and ___

Ach, tachykinins; VIP, NO

[analogy] Peristalsis:transit::Segmentation:______

mixing

Long sustained contraction that serve to limit flow

Tonic Contraction

what kind of movement are peristalsis ans segmentation?

phasic

which is more important? segmentation or peristalsis?

segmentation

causes of tonic contraction

repititive spike potentials, continuous depolarization of smooth muscle by hormones, continuous entry of Ca2+

The pylorus can only empty particles that <1mm in diameter. how are these removed?

MMC; specifically phase III

which MMC phase is absent in Diabetics?

Phase III; thus bezoar forms

what stimulates MMC?

motilin; erythromycin

Fed pattern vs MMC

fed pattern: contractions are longer but weaker | MMC: stronger contractions; shorter duration

T/F fed pattern lasts longer with fatty food

T; harder to digest

areas of the GIT without MMC

esophagus and colon

Segment with longest transit time; shortest? what are the implications of transit time?

longest: colon; more susceptible to CA shortest: esophagus; less susceptible to CA

What is the implication of a lower thoracic pressure compared to abdominal pressure?

chyme would tend to go up the esophagus from abdominal to thoracic part;

which has a greater resting pressure, UES or LES? what does the difference imply?

UES(50-150)>LES(15-50); UES can prevent reflux into respiratory tree

What controls UES tonic contraction?LES?

neural via vagus; hormonal(VIP, NO) and neural (Vagus)

after how many days of fasting will GI motility decrease to conserve energy?

3 phases of swallowing

oral pharyngeal esophageal

which esophageal peristalsis has no relation to food intake?

tertiary

condition characterized by not having enough nerves in distal esophagus

achalasia

parasympathetic and sympathetic innervation of stomach

vagus; celiac nerves

empty stomach fasting vol and resting pressure

>=50mL; 7-50mmHg

what is the trend of action potential as you go down the stomach

increase

what allows the stomach to accommodate large volumes with little increase in intragastric pressure

volume adaptation phenomenon

Which empties faster, liquid/solid?

liquid;

T/F if the first portion of the name of the reflex is anatomically more proximal than the second part, the reflex is inhibitory, otherwise excitatory

excitatory; inhibitory

where is the vomiting center located?

medulla; specifically obex

In retching, why is it that nothing comes out when one 'vomits'

because UES does not relax

what complication can result from severe retching?

tear of LES

Steps in vomiting

``` deep inspiration closure of glottis elevation of soft palate diaphragm contraction ab muscles contractiob LES UES relaxation Gastric contents into esophagus ```

describe the gastrocolic reflex

colon gets stimulated after eating due to distension of stomach(presence of food) and products of digestion in small intestine; mass movements are initiated reulting to urge to defecate

What is the only proximal-to-distally named reflex that is inhibitory?

Rectoanal reflex

What happens when there's a lot of accumulated feces in the rectum?

rectoanal reflex; inc pressure, dec in IAS pressure. feces can still be held due to EAS

Constipation vs. Obstipation

Constipation: defecation less than 3x a week Obstipation: no passage of stool/ flatus secondary to obstruction

What causes relaxation of Sphincter of Oddi?

CCK

What are the causes of gall bladder contraction?

Secretin; bile acids, vagal stimulation

[analogy] Proximal obstruction: extreme vomiting:: Low/Colon obstruction: ________

extreme constipatiob

[symptoms] obstruction in the esophagus

vomiting (non acidic)

[symptoms] obstruction in the pylorus

acidic vomitus

[symptoms] obstruction in the proximal and 2nd part of duodenum

neutral-basic vomitus

[symptoms] obstruction in the below duodenum before right colon

neutral-basic vomitus with bile stain

[symptoms] obstruction in the R colon

diarrhea

[symptoms] obstruction in the L colob

constipation

difficulty in swallowing

dysphagia

painful swallowing

Odynophagia