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PHYSIOLOGY III > L18: intro to GI function > Flashcards

L18: intro to GI function Flashcards

1
Q

what are the 3 sphincteres of the GI tract

A
  • lower esophageal sphincter
  • pylorus
  • ileo-cecal sphincter
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2
Q

what has failed to fuse in cleft palate

A

the opening between the oral and nasal cavity

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3
Q

stenosis and atresia of the intestine is a _______ malformation; caused by what during embryonic development

A

congenital
inadquate blood supply - leads to atrophy of affected portion

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4
Q

what layers make up the mucosa of the wall of the GI tract

A

epithelium
lamina propria
muscularis mucosa

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5
Q

what are the muscle layers that are in the wall of the GI tract

A

inner circular muscle
outer longitudinal

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6
Q

what plexuses make up the enteric NS of th GI tract

A

submucosal plexus + myenteric plexus

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7
Q

what type of epithelium is in the esophagus

A

multilayered stratified squamous

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8
Q

what type of epithelium is in the stomach, small and large intestine

A

columnar single layer

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9
Q

the small and large intestine epithelium is arranged in what way and for what purpose

A

LI: crypts
SI: crypts + villi
arrangement is for surface amplification

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10
Q

where do stem cells originate

A

neck area of crypts

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11
Q

what is the benefit to the constant renewal of the GI tracts epithelial layer

A

helps prevent accumulation of defects

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12
Q

neurons of the intrinsic nervous system (ENS) are located where

A

between an inner circular and outer longitudinal layer of muscularis externa (myenteric, Auerbach’s plexus) and within the submucosa (submucosal, Meissner’s plexus)

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13
Q

what do the neurons within the Myenteric plexus innervate

A

the longitudinal and circular smooth muscle layers; primarily - control of gut movement

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14
Q

what do the neurons of the submucosal plexus innervate

A
  • glandular epithelium
  • intestinal endocrine cells
  • submucosal blood vessels
    primarily - control of intestinal secretion
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15
Q

NTs of the enteric nervous system are released from ?

A

structures of the axons and axon collaterals called varicosites

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16
Q

what is the advantage of varicosites in the ENS

A

they are able to innervate a larger area

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17
Q

what are the excitatory NTs of the ENS

A

ACh and substance P

18
Q

what are the inhibitory NTs of the ENS

A

Nitric oxide
Vasoactive intestinal peptide (VIP)

19
Q

what is the function of the motor neurons on the ENS

A

innervate muscles and sphincters and cause contraction and or relaxation

20
Q

what do the sensory neurons of the ENS detect

A

detect luminal pH, temperature and pressure

21
Q

what are interstitial cells of Cajal (ICC)

A

specialized smooth muscle cells
- act as pacemakers to modulate contractile activity
- they have long processes that for gap junction with the longitudinal and circular sm cells
- self generating depolarizing rhythm that generate regular oscillations in the membrane potentia = slow waves

22
Q

what is resposible for generating the slow waves of the GI tract

A

Interstitial cells of Cajal

23
Q

what nerve is associated with the SNS of the GI

A

splanchnic

24
Q

what nerve is associated w/ the PNS of the GI

A

vagus

25
Q

what molecules are associated with sympathetics of the ENS and what effects do they have

A

NO and VIP
they decrease motility and secretions and increase sphincters

26
Q

what molecules are associated with parasympathetics of the ENS and what effects do they have

A

Ach and substance P
they increase motility and secretions and decrease sphincters

27
Q

what is the effect of NE on motility and secretions

A

decrease

28
Q

what is the effect of Ach on motility secretions and gut blood flow

A

increases

29
Q

what is a vagotomy

A

one of more branches of the vagus nerve are cut to reduce the rate of gastric secretions nad motility

30
Q

enteroendocrine cells release what from their basal side into circulation or interstitium

A
  • hormones
  • neuroactive substances
  • paracrine
  • autocrines
31
Q

what does the apical side of enteroendocrine cells do

A

sense gut content

32
Q

endocrine secretions reach their target tissue via?

A

blood

33
Q

paracrine secretions reach their target tissue via?

A

diffusion through the interstitial space

34
Q

autocrine secretions of the paracrine cell modify the functions of ..?

A

the same cell
hence auto

35
Q

enteric neurons secrete contents via _______ from _______

A

vesicles
varicosites

36
Q

what hormones are produced by enteroendocrine cells

A

gastrin, secretin, CCK, GIP and motilin

37
Q

where are intrinsic endocrine neuroactive substances (NO, substance P, VIP, enkephalines) released

A

near afferent nerve terminals into the underlying lamina propria

38
Q

what does aldosterone do

A

stimulates water and sodium reabsorption in the colon by increases the amount of ENaC sodium channels

also increases reabsorption in salivary glands

39
Q

what is the only hormone secreted outside of the GI tract that has controlling function

A

aldosterone

40
Q

what do glucocorticoids do

A

increase the activity of the Na/K ATPase

PHYSIOLOGY III (31 decks)

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