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Med 1: GI > Goal 1: Gastro Intro > Flashcards

Goal 1: Gastro Intro Flashcards

1
Q

Steps of what happens when you eat a meal?

A
  • Distention of GI tract wall—stretch receptors activated—sensory input sent to CNS—-CNS increases parasymp to increase motility—-goes to pancreas to tell it to release insulin
  • GI lumen senses carbs—-tells endocrine cells of small intestine—-GLP-1 and GIP activated—-goes to pancreas to tell it to release insulin
  • nutrients digested and absorbed—-plasma amino acids and glucose increase—- pancreas releases insulin
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2
Q

What’s Amylin for? How is it similar to Incretins?

A
  • released from pancreatic beta cells
  • DOES NOT CAUSE INSULIN SECRETION
  • does other stuff to prevent big sugar spikes after a meal like slow gastric emptying
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3
Q

What are the two Incretins? What do they do? What organ releases them?

A
  • GLP 1
  • GIP
  • stimulate insulin secretion after eating
  • from pancreatic beta cells of Islets of Langerhans
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4
Q

What do Ghrelin and Leptin do? What are their different pathways?

A

-Ghrelin: hunger hormone made by gastric mucosal cells, increases appetite just before meals
Fasting—-Ghrelin released—-hypothalamus told—-stimulates orexiogenic and inhibits anorexiogenic—-appetite increases

-Leptin: made by adipose cells, decrease appetite to decrease fast stores
During meal—Leptin released—-hypothalamus told—-stimulate anorexiogenic and inhibit orexiogenic—decrease appetite and increases energy losing

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5
Q

Leptin ve Ghrelin: ways of how they are adversaries?

A
  • gastric bypass: lost Ghrelin activity so that’s why bypass is so effective since Leptin may be inhibiting it
  • in obesity: thought that Leptin is inhibited by ghrelin
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6
Q

What are all the GI hormones?

A
  • Gastrin
  • Cholecystokinin
  • Secretin
  • Motilin
  • Gastric Inhibitory Peptide
  • Glucagon-Like Peptide-1
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7
Q

What stimulates Gastrin to be released? What cells does it come from? What does it do? What inhibits it?

A
  • peptides and amino acids
  • G Cells
  • stimulates gastric acid secretion and mucosal growth
  • Somatostatin inhibits it
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8
Q

What stimulates Cholecystokinin to be released? What cell is it released from? What is it’s target organs? What does it do?

A
  • fatty acids
  • I Cells
  • gallbladder, pancreas, stomach
  • stimulate gallbladder contraction and pancreatic enzyme secretion, inhibits gastric emptying, promotes satiety
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9
Q

What stimulates the release of Secretin? What cells do they come from? What organs do they target? What do they do?

A
  • acid in small intestines
  • S Cells
  • pancreas and stomach
  • stimulates HCO3 secretion, inhibits gastric emptying
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10
Q

What stimulates Motilin to be released? How often is it released? What cells do they come from? What organs are their target? What do they do? What inhibits it?

A
  • fasting
  • every 1.5-2hrs
  • endo M Cells
  • gastric and intestinal smooth muscle
  • stimulates migrating motor complex
  • eating a meal inhibits it
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11
Q

What stimulates GIP release? What cells do they come from? What organ is their target? What do they do?

A
  • glucose, FA, and amino acids in small intestine
  • K cells
  • target beta cells of pancreas
  • stimulates INSULIN release, inhibits gastric emptying
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12
Q

What stimulates GLP-1 release? What cells do they come from? What organ is their target? What do they do?

A
  • mixed meals with carbohydrates or fats
  • from L Cells
  • endocrine pancreas is the target
  • STIMULATES INSULIN RELEASE and INHIBITS GLUCAGON RELEASE, inhibits gastric emptying, promotes the feeling of fullness
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13
Q

What’s the difference between short and long reflexes of the GI system?

A
  • short: stimulus sensed by GI tract receptors and that’s processed ALL INSIDE THE ENTERIC NS
  • long: signals sent to CNS from receptors INSIDE OR OUTSIDE the GI tract
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14
Q

What are the steps of the Relaxation Pathway within the GI tract?

A
  • stimulus: sight, smell, thought of food, food in GI tract
  • sensory receptors: inside (eg chemoreceptors) or outside (eg photoreceptors) GI tract
  • input signal: AP sent via afferent neurons
  • integrating center: sent to CNS or enteric nervous system
  • output signal: AP sent via efferent neurons (para or sym or enteric)
  • target: effector cells of GI tract target exocrine or endocrine muscle cells
  • response: change secretion and motility of GI tract
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15
Q

What neurotransmitters contract smooth muscles?

A
  • Ach
  • Enkephalins
  • Substance P
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16
Q

What neurotransmitters relax smooth muscles?

A
  • Norepinephrine
  • Vasoactive Intestinal Peptide (VIP)
  • nitric oxide (NO)
  • Neuropeptide Y
17
Q

What neurotransmitters increase salivary secretion?

A
  • Ach
  • Norepinephrine
  • Substance P
18
Q

What neurotransmitters decrease intestinal secretion?

A
  • Enkephalins (opiates)

- Neuropeptide Y

19
Q

What neurotransmitters increase pancreatic secretion?

A
  • Ach

- VIP

20
Q

What neurotransmitters increase gastric secretion?

A
  • Gastric-Releasing Peptide (GRP) aka Bombesin

- Ach

21
Q

Which neurotransmitter comes from cholinergic neurons? Adrenergic neurons? Vagal neurons?

A
  • cholinergic: Ach
  • adrenergic: norepinephrine
  • Vagal: GRP
22
Q

What neurotransmitter relax sphincters? Which contracts?

A
  • relax: Ach

- contract: norepinephrine

23
Q

What activates Myosin light chain kinase (MLCK)?

A

Ca2-Camodulin

24
Q

What are the 5 steps of smooth muscle contraction and relaxation?

A
  • 1: intracellular Ca2 increase when Ca2 enters cell and is released from SR
  • 2: Ca2 binds to calmodulin
  • 3: now Ca2-calmodulin activated MLCK
  • 4: MLCK phosphorylates light chain myosin heads and increase myosin ATPase activity
  • 5: active myosin cross bridges slide along actin and create muscle tension
25
Q

What causes the spikes in Spike Potentials?

A

-Ca ions enter fibers and cause CONTRACTION

26
Q

What 3 things cause depolarization (spikes) in Spike Potentials?

A
  • stretch
  • Ach
  • parasympathetics
27
Q

What two things stimulate hyperpolarization (relaxation) Spike Potentials?

A
  • norepinephrine

- sympathetics

28
Q

What causes Slow Waves? How does it happen? What type of junctions do slow waves go through?

A
  • Intersitial cells of Cajal
  • back to back depolarizations (influx of Ca) and repolarizations (efflux of K)
  • gap junctions
29
Q

What two ions control the resting membrane potential of the GI smooth muscle?

A
  • Ca: depolarization

- k: repolarization

30
Q

What are the two types of contractions? What areas of the body does it happen?

A
  • Tonic: constant contraction or tone without relaxation—upper region of stomach; in lower esophageal, ileocecal, and internal anal sphincter
  • physic: periodic contractions followed by relaxation—esophagus, gastric antrum, small intestines
31
Q

What will happen if no constant contraction to LES?

A
  • Heartburn

- stomach acid contents will back up without that tightness at that sphincter keeping it down

32
Q

What happens if tonic contractions don’t happen at the ileocecal sphincter?

A

-stool backs up into the ileum, bacteria increases so does the chance of infection

33
Q

What are the two ways to categorize smooth muscles?

A
  • Communication: single unit and multi unit

- contraction: tonic and phasic

34
Q

What is the difference between single unit and multiunit smooth muscle cells? Where do you see them?

A
  • single: connected by gap junctions, contract individually—walls of most hollow organs like bile duct, ureters, uterus, blood vessels
  • multi: no gap junctions, and each cell must be stimulated independently—iris and ciliary body of eye, piloerector muscles
35
Q

Describe the structure of a smooth muscle cell.

A
  • non-striated
  • dense bodies with actin attached to it
  • regulated by myosin-thick filament regulated
  • spindle shaped
  • Side polar cross bridge arrangement
  • no troponin complex
36
Q

What are the 4 layers of GI tract? What are in each?

A
  • mucosa: layer of epithelial cells, lamina propria, Muscularis mucosae
  • Submucosa: submucosal plexus
  • Muscularis externa: longitudinal layer of smooth muscles, myenteric plexus, circular layer of smooth muscles
  • serosa
37
Q

What type of cells do the myenteric plexus have?

A

Interstitial cells of Cajal

38
Q

Where are Peyer’s Patches located? What does it contain and what are their function?

A
  • small intestine mucosa
  • have lymphoid follicles
  • helps with immune system
39
Q

What are the functions for the liver? The pancreas?

A
  • liver: glucose and fat metabolism, protein synthesis, bile production, hormone production, urea production, detoxification, storage
  • pancreas: exocrine-make digestive enzymes, endocrine-make hormones like insulin

Med 1: GI (15 decks)

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