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PMCOL 344 > GI 1 - intro > Flashcards

GI 1 - intro Flashcards

1
Q

what are 4 roles of the GI tract

A

digestion, absorption, elimination, endocrine

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2
Q

what does the GI eliminate and how

A

waste and toxins with defacation and vomiting

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3
Q

what are 4 main endocrine hormones in GI

A

5-HT, gastrin, ghrelin, cholecystokinin

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4
Q

what does the GI absorb and digest

A

nutrients and orally available drugs

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5
Q

what 2 main parts are in the digestive system

A

the digestive tract (hollow organ) and the organs of digestion

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6
Q

what are the 4 main things in the digestive tract (not accessory organs)

A

mouth, esophagus, stomach, intestines

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7
Q

what are the 5 main accessory organs in the digestive tract / organs of digestion

A

tongue, salivary glands, pancreas, gallbladder, liver

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8
Q

what are the 2 main muscle types in the GI tract

A

circular and longitudinal muscles

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9
Q

what do the circular and longitudinal muscles do

A

transport and mix food for digestion

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10
Q

what layer of the GI tract is the outermost / where food is exposed

A

the mucosa

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11
Q

what are the 2 nerve plexus in the GI tract

A

submucosal and myenteric plexus

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12
Q

where is the mucosa

A

outer most layer (exposed to food)

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13
Q

what kind of neural network is the enteric nervous system

A

intrinsic

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14
Q

what are 4 things the enteric nervous system regulates

A

motility, secretion, blood flow, immune response

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15
Q

what is the enteric nervous system integrated with

A

the autonomic nervous system

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16
Q

can the enteric nervous system act independently with the CNS

A

yes

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17
Q

what does the submucosal plexus innervate

A

epithelia and muscle cells

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18
Q

what does the myenteric plexus do

A

regulates gut motility and secretion

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19
Q

where is the myenteric plexus

A

between muscle layers

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20
Q

which fibres does the enteric nervous system receive (sym or para)

A

both
para- vagus nerve
sympathetic too

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21
Q

what are 4 roles of vagal para fibres in the ENS

A

excitatory, increases gut motility, dilate sphincters (facilitate transit), increases secretions (ACh)

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22
Q

what are 2 roles of sympathetic fibres in the ENS

A

decrease gut motility, constrict sphincters (slow down digestion, more chance to absorb)

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23
Q

what do the sensory nerves in the ENS sense

A

mechanical and chemical stimuli

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24
Q

what are 3 pathways after the ENS detects mechanical and chemical stimuli

A
  • spinal and brainstem reflexes regulate digestive function
  • input to central autonomic circuits that regulate feeding and illness behaviours
  • transmit painful and non painful sensations
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25
Q

what is peristalsis

A

food moving from mouth to anus

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26
Q

why is segmentation helpful

A

mixing food to facilitate digestion, more surface area of food for acid and enzymes to act on

27
Q

what are the 3 main forms of gut motility

A

peristalsis and segmentation and isolated contraction

28
Q

what main 2 things determine gut motility

A

smooth muscle properties and chemical inputs

29
Q

what 3 types of chemical inputs can effect gut motility

A

nerves, hormones, paracrine signals

30
Q

do all regions in the GI have the same type of motility (explain)

A

no, like tonic contractions in sphincters and phasic contractions in small intestine and colon

31
Q

what drives phasic activity in SI motility

A

slow waves

32
Q

what causes contractions in the SI to cause motility

A

rhythmic electrical activity

33
Q

what happens to wave propagation with more distal segments

A

it slows down

34
Q

what happens once a slow wave reaches threshold (4)

A

VGCC open, Ca++ enters, APs fire, muscles contract

35
Q

what is isolated contraction

A

when the contents move both orally and aborally

36
Q

what is segmentation

A

mixes contents over short length of intestine

37
Q

what is peristalsis

A

propelling contents aborally (going down towards anus)

38
Q

what causes peristalsis

A

contraction and relaxation

39
Q

what causes segmentation and peristalsis

A

longitudinal and circular muscle coordinated movement

40
Q

how do the muscles work to make peristalsis

A

contraction wave in ring muscle, moving aborally behind an aboral relaxation wave

41
Q

how do the muscles work to make segmentation

A

alternating ring contraction to help mix contents

42
Q

what triggers the peristaltic reflex

A

mechanical stretch and mucosal stimulation

43
Q

what does the peristaltic relax activate (2)

A

excitatory motorneurons above bolus and inhibitor motor neurons below (relax)

44
Q

how do the excitatory motorneurons above bolus in the peristaltic reflex work

A

they release 5HT from enterochromaffin cells

45
Q

what do enterochromaffin cells release in the peristaltic reflex

A

5HT

46
Q

what cells release 5HT in the peristaltic reflex

A

enterochromaffin cells

47
Q

what happens when you activate inhibitor motor neurons below the bolus (peristaltic reflex)

A

relaxes gut wall below bolus

48
Q

what are 5 hormones released from the gut

A
  • gastrin
  • 5-HT
  • motilin
  • cholesystokinin (CCK)
  • glucagon-like peptide 1 (GLP-1)
49
Q

where is gastrin made

A

in mucosal enteroendrocrine cells

50
Q

what does gastrin do

A

stimulate acid secretion by parietal cells in stomach

51
Q

what cells are affected by gastrin

A

parietal

52
Q

which hormone stimulate acid secretion by parietal cells in stomach

A

gastrin

53
Q

where is 5HT made

A

enterochromaffin cells

54
Q

what do enterochromaffin cells release

A

5HT

55
Q

where is motilin made

A

mucosal cells

56
Q

what does 5HT from enterochromaffin cells do

A

release of ACh from nerves in ENS

57
Q

what hormone do mucosal cells make

A

motilin

58
Q

what does motilin do

A

stimulates GI smooth muscle contraction

59
Q

where is CCK released from

A

small intestine enteroendocrine cells

60
Q

what does CCK stimulate

A

pancreatic enzyme secretion

61
Q

which enzyme stimulates pancreatic enzyme secretion

A

CCK

62
Q

which enzyme is released from small intestine enteroendocrine cells

A

CCK

63
Q

what 3 things does glucagon-like peptide (GLP-1) do

A

stimulates insulin release, inhibits glucagon release, promotes satiety

64
Q

what are 2 things that enteroendrocrine cells respond to (local signals to release hromones)

A

nutrients and neurotransmitters

PMCOL 344 (27 decks)

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