L33 and L34: Intro to GI, Esophagus, and Swallowing Flashcards

1
Q

What are the 6 processes of the GI tract?

A
Ingestion
Propulsion
Mechanical digestion
Chemical digestion
Absorption
Defecation
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2
Q

Name the layers of the GI tract (outermost to inner most)

A
Serosa
Longitudinal muscle
Myenteric plexus
Circular muscle 
Submucosa
Submucosal plexus
Mucosa

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3
Q

Name the 3 layers of the Mucosa (out to in)

A

Muscularis mucosae
Lamina Propria
Epithelium

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4
Q

What is the benefit for parallel blood flow of splanchnic circulation?

A

Allows for regulation of flow to individual organs

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5
Q

What is the benefit for series blood flow of splanchnic circulation?

A

Liver is exposed to all absorbed substances.

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6
Q

What comprises the enteric nervous system? How does this interact with the autonomic nervous system?

A

Enteric NS = Myenteric plexus + Submucosal plexus

Afferent modulates the ENS, but ENS does NOT require ANS input to carry out most functions (send afferents to eachother)

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7
Q

What does the myenteric plexus innervate? What does it control?

A

Innervates longitudinal and circular smooth muscle layers

-Control of GUT MOVEMENT

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8
Q

What does the submucosal plexus innervate?

A

Innervates glandular epithelium, endocrine cells, and submucosal blood vessels
-Control of INTESTINAL SECRETION

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9
Q

The effect of the SNS on the GI organs is _____.

A

Inhibitory (NE)

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10
Q

The effect of the PNS on the GI organs is _____.

A

Excitatory (Ach)

Preganglionic projects directly onto gut

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11
Q

GI endocrine cells are not concentrated into ____. They are ____ in the GI tract.

A

glands

dispersed

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12
Q

Name the site of secretion and stimuli for secretion of Gastrin.

A

Site of secretion: G cells of stomach

Stimuli for secretion: Small peptides, AA, distention of stomach, Vagal stimulation (GRP- Gastrin releasing peptide)

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13
Q

What is the action of Gastrin? (2)

A
  • Increased H+ secretion

- Stimulates growth of gastric mucosa

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14
Q

Name the site of secretion and stimuli for secretion of Cholecystokinin (CCK).

A

Site of secretion: I cells of duodenum and jejunum

Stimuli for secretion: Small peptides, AA, and FA

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15
Q

What is the action of CCK? (5)

A
  • Increases pancreatic enzyme secretion
  • Increases pancreatic HCO3- secretion
  • Stimulates contraction of the gallbladder and relaxation of the sphincter of Oddi
  • Stimulates growth of the exocrine pancreas gallbladder
  • Inhibits gastric emptying
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16
Q

Name the site of secretion and stimuli for secretion of Secretin.

A

Site of secretion: S cells of duodenum

Stimuli for secretion: H+ in the duodenum, FA in the duodenum

17
Q

What is the action of Secretin?

A
  • Increases pancreatic HCO3- secretion
  • Increases biliary HCO3- secretion
  • Inhibits gastric H+ secretion
  • Inhibits trophic effect of Gastrin on gastric mucosa
18
Q

Name the site of secretion and stimuli for secretion of GIP (glucose-dependent insulinotropic peptide).

A

Site of secretion: Duodenum and jejunum

Stimuli for secretion: FA, AA, Oral glucose

19
Q

What is the action of GIP?

A
  • Increases insulin secretion from pancreatic Beta cells

- Decreases gastric H+ secretion

20
Q

Paracrines act ____ and are carried by ____ or _____.

A

Locally (while hormones can act at distant locations)

Carried by capillaries or by diffusion

21
Q

What are the 2 paracrines of the GI tract?

A

Somatostatin

Histamine

22
Q

Somatostatin is released from _____ and inhibits the release of _____.

A

D cells

all gut hormones

23
Q

What are the 4 neurocrines? State whether they come from the PNS and SNS.

A

Ach (PNS)
Norepi (SNS)
Vasoactive intestinal peptide (VIP) (PNS, ENS)
Gastrin releasing peptide (GRP) (PNS)

24
Q

Increases secretions
Relaxes sphincters
Increases contraction of wall smooth muscle

What is this neurocrine?

A

Ach

25
Q

Relaxation of smooth muscles
Increases secretions

What is this neurocrine?

A

VIP

26
Q

Sphincter contraction
Relaxation of wall smooth muscle

What is this neurocrine?

A

Norepi

27
Q

Increases gastrin secretion

What is this neurocrine?

A

GRP

28
Q

What is the functional unit of visceral smooth muscle?

A

Packed bundles of cells (thousands of cell/bundle)

29
Q

Visceral smooth muscle cells are long, slender, and connected by _________. What does this allow for?

A

Low resistance gap junctions

Allows for electrical propagation between adjacent fibers