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*GIGU I > Lecture 12: DSA Intro to GI Phys > Flashcards

Lecture 12: DSA Intro to GI Phys Flashcards

1
Q

What sphincter is associated with the major duodenal papilla?

A

Sphincter of Oddi

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2
Q

What sphincters/valves are associated with the GI tract in order to restrict the passage of intestinal content and optimize digestion/absorption? (There are 7)

A 
UES
LES
Pyloric sphincter
Sphincter of Oddi
Ileocecal valve
Internal anal sphincter
External anal sphincter
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3
Q

4 functional layers of small intestine wall

A

Mucosa
Submucosa
Muscularis (Circular + longitudinal)
Serosa

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4
Q

2 enteric nervous system components associated with the GI tract and their location within the functional layers of the gut tube

A

Submucosal plexus - at the base of submucosal layer

Myenteric plexus - between circular and longitudinal muscle layers of muscularis

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5
Q

The myenteric and submucosal plexuses are innervated by the ______ autonomic nervous system. They make up an integrating center that can exert its functions without ____ input

A

Extrinsic; CNS

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6
Q

The ENS receives information from what branches of the nervous system?

A

Parasympathetic
Sympathetic

CNS

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7
Q

The ENS receives sensory info from _____ and _____ in the mucosa

A

Mechanoreceptors

Chemoreceptors

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8
Q

Contraction, secretion, and endocrine function of the GI tract are controlled by what specific nervous system?

A

ENS

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9
Q

What some examples of roles of CNS in regulation of GI function?

A

Vasovagal reflex (gastric receptive relaxation reflex)

Modulation of ENS responses

Centers that control food intake

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10
Q

The vasovagal reflex associated with GI function is based around vagal efferents from the ______ in the brain, and vagal afferents from the sensory ganglion of the vagal nerve, aka the ____ ganglion

A

NTS (nucleus of the tractus solitarius)

Nodose

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11
Q

Parasympathetic innervation modulates GI function via the ____ and _____ nerves.

Preganglionic cell bodies are located in the ____ or _____ spinal cord

Postganglionic neurons lie in the ____ of the organ

Synapse between pre and post ganglionic cell is _______

A

Vagus; pelvic

Brainstem; sacral

Wall

Nicotinic (nAChRs)

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12
Q

Sympathetic innervations modulate GI functions via nerves running between the _______ and the prevertebral ganglia, and between these ganglia and _______

Preganglionic efferent fibers arise in _____ ______ and end in the ______ ______

Postganglionic fibers from the __________ innervate ____ and _____ plexuses

A

Spinal cord

Spinal cord; prevertebral ganglia

Prevertebral ganglia; myenteric; submucosal

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13
Q

Mostly, sympathetic preganglionic efferent fibers release _____, while postganglionic efferents release ____

A

ACh; NE

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14
Q

Cellular communication is key in the regulation of GI function. ______ regulation involves LOCAL action of peptides (e.g. somatostatin) or other messenger molecules (e.g. histamine), wherein signals reach their target cells by diffusion over short distances

A

Paracrine

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15
Q

_______ is secreted by D cells of GI mucosa

A

Somatostatin

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16
Q

Stimulus of somatostatin secretion from D cells of GI mucosa

A

Decreased luminal pH

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17
Q

Actions of somatostatin

A

Inhibits gastric H secretion

Inhibits secretion of other GI hormones

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18
Q

Somatostatin is secreted by D cells of the GI mucosa. Where else in the body is somatostatin secreted?

A

Hypothalamus

Delta cells of exocrine pancreas

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19
Q

_______ in the stomach is stored and secreted by enterochromaffin-like cells (ECLs) in gastric glands

A

Histamine

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20
Q

Target of histamine in the stomach

A

Parietal cells

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21
Q

Action of histamine in the stomach

A

Stimulates acid production

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22
Q

Enteroendocrine cells contain secretory granules filled with hormones that are released upon stimulation. What path do these hormones take to get to their target cells upon their release?

A

First they enter portal circulation, then travel to the liver, then into systemic circulation, then to their target cell which has a specific receptor for that hormone

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23
Q

Hormone family and site of secretion of gastrin

A

Family: gastrin-CCK

Site of secretion: G cells of stomach

24
Q

Stimulus for gastrin secretion

A

Small peptides and amino acids

Distension of the stomach

Vagal stimulation (via GRP)

25
Q

Gastrin actions

A

Increases gastric H+ secretion

Stimulates growth of gastric mucosa

26
Q

Hormone family and site of secretion for CCK

A

Family: Gastrin-CCK

Site of secretion: I cells of the duodenum and jejunum

27
Q

Stimulus for CCK secretion

A

Small peptides and amino acids

Fatty acids

28
Q

Actions of CCK

A

Increases pancreatic enzyme secretion

Increases pancreatic HCO3 secretion (indirectly by potentiating effect of secretin)

Stimulates contraction of gallbladder and relaxation of sphincter of Oddi

Stimulates growth of the exocrine pancreas and gallbladder

Inhibits gastric emptying

29
Q

Hormone family and site of secretion for secretin

A

Family: Secretin-glucagon

Site of secretion: S cells of the duodenum

30
Q

Stimulus for secretin secretion

A

H+ in duodenum

Fatty acids in duodenum

31
Q

Actions of secretin

A

Increases pancreatic HCO3 secretion

Increases biliary HCO3 secretion

Decreases gastric H secretion

Inhibits trophic effect of gastrin on gastric mucosa

32
Q

Hormone family and site of secretion for glucose-dependent insulinotropic peptide (GIP)

A

Family: secretin-glucagon

Site of secretion: Duodenum and jejunum

33
Q

Stimulus for secretion of GIP

A

Fatty acids

Amino acids

Oral glucose

34
Q

Actions of GIP

A

Increases insulin secretion from pancreatic beta cells (incretin effect)

Decreases gastric H+ secretion

35
Q

Which of the following can act as paracrine signals?

A. Gastrin
B. CCK
C. Secretin
D. GIP
E. B and C
A

E. B and C

36
Q

Which would be more effective in increasing insulin secretion: oral glucose or IV glucose administration?

A

Oral glucose, bc it stimulates GIP which stimulates insulin secretion and also has a direct stimulatory effect on beta cells of pancreas

37
Q

Once an action potential is generated at a sensory neuron, it travels along that neuron to a ______, then a secretoromotor neuron which releases NT at target cell.

A

Interneuron

38
Q

Ach source in the GI tract

A

Cholinergic neurons

39
Q

NE source in the GI tract

A

Adrenergic neurons

40
Q

Vasoactive intestinal peptide (VIP) source in the GI tract

A

Neurons of the ENS

41
Q

Nitric Oxide (NO) source in the GI tract

A

Neurons of the ENS

42
Q

Gastrin-releasing peptide (GRP) source in the GI tract

A

Vagal neurons of gastric mucosa

43
Q

Enkephalins source in the GI tract

A

Neurons of the ENS

44
Q

Neuropeptide Y source in the GI tract

A

Neurons of the ENS

45
Q

Substance P source in the GI tract

A

Co-release with ACh by neurons of the ENS

46
Q

ACh actions in the GI tract

A

Contraction of smooth muscle

Relaxation of sphincters

Increased salivary, gastric, and pancreatic secretions

47
Q

NE actions in the GI tract

A

Relaxation of smooth muscle in wall

Contraction of sphincters

Increased salivary secretion

48
Q

VIP actions in the GI tract

A

Relaxation of smooth muscle

Increased intestinal secretion

Increased pancreatic secretion

49
Q

NO actions in the GI tract

A

Relaxation of smooth muscle

50
Q

GRP actions in the GI tract

A

Increased gastrin secretion

51
Q

Enkephalins actions in the GI tract

A

Contraction of smooth muscle

Decreased intestinal secretion

52
Q

Neuropeptide Y actions in the GI tract

A

Relaxation of smooth muscle

Decreased intestinal secretion

53
Q

Substance P actions in the GI tract

A

Contraction of smooth muscle

Increased salivary secretion

54
Q

Which of the following is not released from neurons of the ENS?

A. Norepinephrine
B. Nitric oxide
C. Enkephalins
D. Neuropeptide Y
E. Vasoactive intestinal peptide
A

A. Norepinephrine

55
Q

What is the incretin effect?

A

The ability of a GI hormone promote secretion of insulin (GIP is classified as an incretin)

*GIGU I (67 decks)

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