• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/48

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

48 Cards in this Set

  • Front
  • Back
Major functions of GI system (5)
Motility
Secretion -synthesis and release of products
Digestion - dietary constituents into molecules
Absorption
Elimination
GI role in immunity
protect against microbial pathogen and permits immunologic tolerance of diet and helpful enteric microbes
Enterogastric NS plexuses (2)
Myenteric and Submucosal - execute gut motor activity in response to sensory input
Enteric motor neuronal innervation
Smooth muscle - exhitatory or inhibitory
Blood vessels - vasodilation
Epithelial cells - H20, electrolyte secretion
Glandular cells - secretion
Endocrine cells - hormone secretion
Enteric reflex circuits - produced stereotyped responses when?
Both fasting and fed states
What 3 types of receptors are included in enteric sensory neurons?
Mechanoreceptors
Chemoreceptors
Thermoreceptors
What is the effect of ACh on enteric NS?
Smooth musc cx, salivary gland, stomach, and pancreatic secretion
What is effect of NE on enteric NS?
Inhibits sm m cx, stimulate salivary secretions, cx of some sphincters
Effect of VIP (vasoactive intestinal peptide) on ENS?
Inhibits sm. m cx, stimulates pancreas/intestinal secretions
Effect of GRH (Gastrin releasing hormone) on ENS?
Stimulates G cells of stomach to release Gastrin
What is the effect of enkephalins (endorphins) on ENS?
Sm m cx but not peristalsis, inhibit intestinal secretion
Effect of neuropeptide Y on ENS?
Inhibitory, decreased secretion of water and electrolytes, decreased sm m cx
Substance P
Stim sm m cx
Serotonin
Excitatory in neuro-neuronal tx
Gastrin, from G cells of stomach, does what?
Stimulates gastric mobility but inhibits emptying, increases HCl secretion, stimulates mucosal growth
CCK, from the I cells of duodenum, does what?
Inhibits gastric emptying, stim gb cx, stim pancreatic enzyme secretion/growth of pancreas, potentiates secretin
Secretin, from the S cells of duodenum, does what?
Inhibits gastric emptying and HCl secretion, stim pancreastic/liver secretion of HCO3-, potentiates CCK
GIP (gastric inhibitory peptide), from the duodenum/jejunum, does what?
stim insulin secretion, inhibits gastric emptying and HCl secretion
Motilin, from D&J, does what?
In fasting state -> interdigestive migrating motor complex
Intersitital cells of Cajal
where are they found
what do they do
Found primarily in myenteric plexus
Act as pacemaker, smooth waves hypopolarize sm m
Autonomic components of enteric NS?
Sympathetic
Parasympathetic
Nanadrenergic, noncholinergic
Vagovagal pathway - stimulus and effects
Gastric distention induces receptive relaxation of fundus, increased HCl and gastrin secretion,
Gastroileal pathway - stimulus and effects
Gastric distention induces ileum motility and ileocecal sphincter relaxation
Gastrocolic pathway - stimulus and effects
Gastric distention induces colic motility
Enterogastric reflex - stimulus and effects
Acid, fat, or protein in duodenum inhibits gastric emptying
Ileogastric reflex - stimulus and effects
Distention of ileum inhibits gastric emptying
Intestinointestinal reflex - stimulus and effects
Distention of intestines inhibits motility below site of distention
Why do we chew our food?
Reduce food size, facilitate mixing of saliva with food to begin digestion, enhance sense of taste
5 stages of oropharyngeal swallowing
Elevation of tongue
Closure of nasopharynx
Relaxation of UES
Closure of glottis
Pharyngeal peristalsis
How do primary and secondary peristalsis differ?
Primary peristalsis occurs after pharyngeal cx when LES is relaxed
Secondary peristalsis occurs in response to esophageal distention
Lower esophageal sphincter innervation
PNS - ACh binds M3 -> cx
Sympathetic - NE binds alpha, triggering Ach release and increased tone
Heartburn and LES tone
Decreased LES tone causes GERD
Achalasia and LES tone
Inability of LES to relax causes achalasia
Describe receptive relaxation of the stomach
Occurs with every swallow
Vagovagal reflex
Describe accommodation of stomach
Prevents increased gastric pressure
Vagovagal refex
Longterm (fundal cx are independent of gastric slow waves)
Describe characteristics of gastric slow waves
Initiated by ICC in body of stomach, triphasic
Strength and duration of cx depends on amplitude of slow waves
Why is retropulsive flow necessary?
Caused by contractile wave hitting closed antrum and bouncing back, sheering reduces food particle size
What is the relationship of osmolarity to emptying of stomach?
Hyper/hypoosmotic fluids slow emptying
Acid in duodenum and emptying of stomach
Enterogastric reflex - slows emptying of stomach
Calories and gastric emptying
More calories, slower emptying
Particle size and gastric emptying
Particles > 1 mm not emptied. Large particle size inhibits empyting
What are brush cells and where are they found?
Chemosensory cells in the duodenum that mediate responses to stimuli
Consequences of delayed gastric emptying
Nausea, vomiting, bloating, epigastric pain, heartburn, wt loss
Consequences of rapid gastric emptying
anxiety, dizziness, tachycardia, sweating
Fasting MMC complexes
Phase I
Quiescent period 45-60 min
Fasting MMC complexes
Phase II
30-45 min, intermittent contractions
Fasting MMC complex
Phase III
5-10 min, cx with each slow wave, concentration of motilin increases prior to this phase
Absence of MMC poses what risks?
bacterial overgrowth in antrum and small intestine