1 Intro To GI Phys Flashcards

1
Q

Functions of the GI tract

A

Digestion, absorption of nutrients, motility, secretions

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2
Q

GI sphincters name (7) and function

A

UES, LES, pyloric, sphincter of Oddi, Ileocecal valve, internal and external anal sphincter

Fx: restrict passage of intestinal content and optimizes digestion and absorption

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3
Q

Functional layers of the GI tract

A

Mucosal, submucosa, muscle (circular and longitudinal), Serosa

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4
Q

What part of the Enteric Nervous System is in the layers of the GI tract?

What layers?

Innervated by what?

Does it need the CNS?

A

Submucosal plexus: submucosa

Myenteric plexus: muscle

Extrinsic autonomic nervous system

NO

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5
Q

Where does the ENS receive its information?

A

Parasympathetic and sympathetic NS and CNS

Sensory info from mechanoreceptors and chemoreceptors in the mucosa

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6
Q

Function of the ENS

A

Controls contraction, secretion, and endocrine function of the GI tract

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7
Q

CNS role in the regulation of the GI tract (3)

A

Vago-vagal reflex

Modulate ENS response

Centers that control food intake in brain

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8
Q

Sensory ganglion of the Vagal N

A

Nodose ganglion

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9
Q

Example of a vago-vagal reflex

A

Gastric receptive relaxation reflex

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10
Q

NTS

A

Nucleus of the tractus solitarius

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11
Q

Nerves of the parasympathetic innervation

A

Vagus and pelvic nerves

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12
Q

Location of the parasympathetic preganglionic nerve cell bodies

A

Brainstem or sacral spinal cord

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13
Q

Location of the parasympathetic postganglionic neurons

A

Wall of the organ (enteric neuron in the gut wall)

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14
Q

What type of synapse is between the parasympathetic pre and post ganglionic cells?

A

Nicotinic (nAChRs)

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15
Q

Where do the sympathetic preganglionic efferent fibers begin and end?

A

Begin in spinal cord (thoracic and lumbar)

End in prevertebral ganglia

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16
Q

Sympathetic postganglionic fibers from the prevertebral ganglia innervate _________

A

Myenteric and submucosal plexuses

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17
Q

Sympathetic preganglionic efferent fibers release______.

Sympathetic postganglionic efferent nerves release ______.

A

Ach

NE

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18
Q

Long preganglioic fibers, short postganglionic fibers

A

Parasympathetic NS

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19
Q

Short preganglionic fibers, long postganglionic fibers

A

Sympathetic NS

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20
Q

How do paracrine signals reach their target cells?

Where do they act?

A

Diffusion over short distances

Locally

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21
Q

Function of paracrine regulation

A

Action of peptides or other messenger molecules

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22
Q

Examples of paracrine signals

A

Somatostatin and histamine

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23
Q

Secreted by D cells in the GI mucosa

A

Somatostatin

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24
Q

Inhibits secretion of gastric H+ and other GI hormones

A

Somatostatin

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25
Q

Somatostatin is secreted by_______.

A

D cells of the GI mucosa

Hypothalamus

Delta cells of the exocrine pancreas

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26
Q

Stimulated by a decrease a in luminal pH

Why?

A

Somatostatin

Low pH signals somatostatin to inhibits gastric H+ secretion

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27
Q

Stored and secreted by enterochromaffin-like (ECL) cells

A

Histamine

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28
Q

Histamine is secreted in the _____.

A

Gastric glands of the stomach

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29
Q

Histamine targets and action

A

Parietal cells in the stomach gastric glands

Stimulates acid production

30
Q

Action of histamine

A

Stimulates acid production

31
Q

Endocrine regulation

A

Action of hormones

Hormones secreted into circulation

32
Q

EECs

A

Enteroendocrine cells

Contain secretory granules filled with hormones that are released upon stimulation

33
Q

Examples of endocrine regulation (4)

A

Gastrin, cholecystokinin, secretin, glucose-dependent insulinotropic peptide (GIP)

34
Q

Gastrin site of secretion

A

G cells of stomach

35
Q

Stimuli of gastrin (3)

A

Small peptides and amino acids

Distention of stomach

Vagal stimulation via GRP

36
Q

Actions of gastrin (2)

A

Increase gastric H+ secretion

Stimulate growth of gastric mucosa

37
Q

Cholecystokinin (CCK) is secreted from _____.

A

I cells of duodenum and jejunum

38
Q

Stimuli of CCK (3)

A

Small peptides and amino acids

Fatty acids

39
Q

Actions of CCK (7)

A

Increase pancreatic enzyme secretion

Increase pancreatic HCO3- secretion

Stimulate contraction of the gallbladder

Relax sphincter of Oddi

Stimulate growth of the exocrine pancreas and gallbladder

Inhibit gastric emptying

Act as a paracrine signal

40
Q

T or F: the increase of pancreatic HCO3- by CCK is a direct effect

A

FALSE

This is a indirect effect

It potentiates the effects of secretin

41
Q

T or F: when CCK stimulates the growth of the exocrine pancreas and gallbladder, it is a trophic effect.

A

TRUE

42
Q

Secretin is secreted by ______.

A

S cells in the duodenum

43
Q

Stimuli of secretin

A

H+ in the duodenum

Fatty acids in the duodenum

44
Q

Actions of secretin (5)

A

Increase pancreatic secretion of HCO3-

Increase biliary secretion of HCO3-

Decrease gastric H+ secretion

Inhibits trophic effect of gastrin on gastric mucosa

Acts as a paracrine signal

45
Q

GIP

A

Glucose-dependent insulinotropic peptide

46
Q

GIP secreted from _______.

A

Duodenum and jejunum

47
Q

Stimuli of GIP (3)

A

Fatty acids

Amino acids

Oral glucose

48
Q

Actions of GIP (2)

A

Increase insulin secretion from pancreatic beta cells

Decrease gastric H+ secretion

49
Q

What is more effective in increasing insulin secretion? And why?

A. Oral glucose

B. Intravenous glucose

A

A. Oral glucose stimulates GIP-> stimulates insulin secretion and has a direct stimulatory effect of beta cells of the pancreas

50
Q

Neural regulation

A

Action of neurotransmitters

51
Q

What is needed for a neurotransmitter release?

A

Action potential

52
Q

Neurotransmitters diffuse across the ______ and bind to their _______ in the ________.

A

synapse

specific receptor

postsynaptic cell

53
Q

Cellular communication is the key to _______.

A

Regulation of the GI tract

54
Q

Source of ACh

A

Cholinergic neurons

55
Q

Actions of ACh (5)

A

Contraction of smooth m.

Relaxation of sphincters

Increase salivary secretion

Gastric secretion

Pancreatic secretion

56
Q

Source of norepinephrine

A

Adrenergic neurons

57
Q

Actions of NE (3)

A

Relaxation of smooth m in wall

Contraction of sphincters

Increase salivary secretion

58
Q

Source of vasoactive intestinal peptide

A

Neurons of the ENS

59
Q

Actions of VIP (3)

A

Relaxation of smooth m

Increase intestinal secretion

Increase pancreatic secretion

60
Q

Source of nitric oxide (NO)

A

Neurons of the ENS

61
Q

Action of NO

A

Relaxation of smooth m

62
Q

Source of gastrin-releasing peptide (GRP)

A

Vagal neurons of gastric mucosa

63
Q

Action of GRP

A

Increase gastrin secretion

64
Q

Source of enkephalins

A

Neurons of the ENS

65
Q

Actions of enkephalins

A

Contraction of smooth m

Decrease intestinal secretion

66
Q

Source of neuropeptide Y

A

Neurons of the ENS

67
Q

Actions of neuropeptide Y

A

Relaxation of smooth m

Decrease intestinal secretion

68
Q

Source of substance P

A

Co-release with ACh by neurons of the ENS

69
Q

Actions of substance P

A

Contraction of smooth m

Increase salivary secretion

70
Q

Incretin Effect

A

???????