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GI physiology > Oral and esophageal response to a meal > Flashcards

Oral and esophageal response to a meal Flashcards

1
Q

Describe the roles of inner circular and outer longitudinal muscles during peristalsis.

A

During peristaltic propulsion, the longitudinal muscle in the segment ahead of the luminal contents contracts, while the circular muscle relaxes simultaneously. This simultaneous shortening of the longitudinal intestinal axis and relaxation of the circular muscle in the same segment results in expansion of the lumen, which therefore becomes a RECEIVING SEGMENT for the forward moving contents.
The associated component of the reflex is relaxation of the longitudinal muscle layer in the the segment behind the intraluminal contents and simultaneous contraction of the circular muscle. This results in constriction of this region and conversion of it to a PROPULSIVE SEGMENT that forcing the luminal contents ahead into the receiving segment.

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2
Q

What are the roles of the inner circular and outer longitudinal muscles during the receiving segment of peristalsis?

A

inner circular: relaxed

outer longitudinal: contracted

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3
Q

What are the roles of the inner circular and outer longitudinal muscles during the propulsive phase of peristalsis?

A

inner circular: contracted

outer longitudinal: relaxed

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4
Q

What are 2 neurotransmitters that would cause relaxation of the gut muscles during peristalsis?

A

NO and VIP

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5
Q

What are 2 neurotransmitters that would cause constriction of the gut muscles during peristalsis?

A

ACh and SP

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6
Q

Distension of the intestinal wall activates what type of receptors?

A

Mechanoreceptors

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7
Q

Distension of the intestinal wall cause the release of what neurotransmitter? Which cells release this neurotransmitter?

A

5-HT (sertonin) from the EC cells.

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8
Q

For each of these neurotransmitters, state whether its excitatory or inhibitory:

a. ACh
b. NE
c. NO
d. VIP
e. 5-HT

A

a. ACh—-excitatory
b. NE—-inhibitory
c. NO—-inhibitory
d. VIP—-inhibitory

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9
Q

Histamine increases gastric acid secretion by use of which receptor?

A

H2

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10
Q

What is the function of somatostatin?

A

It inhibits gut motility and secretion. Inhibits the release of gastrin and secretin

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11
Q

What is the function of prostaglandins?

A

They stimulate ion (bicarbonate) secretion by gastric surface epithelial cells to protect the gastric barrier function.

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12
Q

What is the function of 5-HT in the gut?

A

Initiate peristaltic and secretory responses. Plus the activation of cholinergic sensory fibers. It also sends “gut discumfort” signals to the CNS via extrinsic sensory nerves.

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13
Q

What is the function of adenosine?

A

Alterations in sensory neuron activity and changes in blood flow

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14
Q

Where is somatostatin secreted?

A

D cells in the pancreas and gastrointestinal mucosa

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15
Q

Where is ghrelin secreted?

A

Fundus of stomach

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16
Q

Where is gastrin secreted?

A

G cells in Antrum to Jejunum

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17
Q

Where is CCK secreted?

A

Duodenum to Ileum

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18
Q

Where is Secretin secreted?

A

Duodenum to Ileum

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19
Q

Where is GIP secreted?

A

Duodenum to Jejunum

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20
Q

Where is Motilin secreted?

A

Duodenum to Jejunum

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21
Q

What is the function of GABA?

A

Inhibitory on motility and secretion

22
Q

What is brain-gut-axis?

A

Many peptides are present with both the brain and the gut

23
Q

Ingestion of protein and amino acids will have what affect on hormones?

A

INCREASED: gastrin and CCK
DECREASED: Motilin

24
Q

Ingestion of carbohydrates will have what effect on hormones?

A

INCREASED: GIP
DECREASED: Motilin

25
Q

Ingestion of fatty acids will have what effect on hormone levels?

A

INCREASED: CCK, GIP, secretin
DECREASED: motilin

26
Q

Increased Luminal acid pH has what effect on hormone levels?

A

INCREASED: secretin
DECREASED: gastrin

27
Q

Increased distention will have what effect on hormone levels?

A

INCREASED: gastrin

28
Q

Increased parasympathetic activity has what effect on hormone levels?

A

INCREASED: gastrin, CCK, motilin

29
Q

What is the function of gastrin? Which receptor does it use?

A

Gastrin increases gastric acid secretion, motility, and mucosal growth.
Gastrin uses the receptor CCK-B

30
Q

What is the function of CCK?

A

INCREASE: pancreatic enzyme secretion, gallbladder contraction
DECREASE: Sphincter of Oddi contraction, gastric emptying

31
Q

What is the function of secretin?

A

INCREASED: pancreatic and biliary bicarbonate secretion
DECREASED: gastric acid secretion

32
Q

What is the function of GIP?

A

increase pancreatic insulin secretion

33
Q

What is the function of Motilin?

A

INCREASED: gastric and intestinal motility

34
Q

What is the function of Ghrelin?

A

INCREASED: GH secretion, feeding, and weight gain

35
Q

What type are gastrin/CCK receptors?

A

G-protein coupled receptors.

36
Q

What are the six functions of saliva?

A
  1. oral hygiene (contains lysozyme, peroxidases, etc
  2. maintain mineralization of teeth
  3. Lubrication-mucin
  4. Digestive function-amylase and lipase
  5. Solvation (enables you to taste
  6. Lytic- hypotonic fliud cell lysis (can be protective)
37
Q

Which glands secrete amylase (ptyalin)? What cells produce it? What is its function?

A

Amylase is produced in the PAROTID and SUBMANDIBULAR glands by the ACINAR CELLS. Amylase digests starch.

38
Q

What glands secrete Lipase? What cells produce it? What is its function?

A

Lipase is secreted by the SUBLINGUAL glands and is produced by ACINAR cells.
Lipase is used for fat digestion

39
Q

What glands secrete kallikrein? Wha cells produce it? What is its function?

A

Kallikrein is secreted by all 3 major salivary glands: parotid, submandibular, and sublingual. It is produced by DUCT CELLS.
Kalliekrein is a serine protease that helps control salivary blood flow.

40
Q

Control of salivary secretion is under which nervous system? And what is the effect? What receptors are involved?

A

Both PNS and SNS control salivary secretion.
PNS: M3 receptor; copious flow of watery saliva
SNS: alpha-adrenergic and beta-adrenergic receptors; less effect on volume of saliva, but rich in enzymes

41
Q

What are the two stages of salivary secretion? What are their characteristics?

A
  1. PRIMARY SALIVARY SECRETION- Isotonic, ECF-like composition, proteins (enzymes, mucin)
  2. SECONDARY DUCTAL MODIFICATION: hypotonic, absorption of Na and Cl, secretion of K and Bicarb, low H2O permeability of ducts,
42
Q

High flow rate will have what effect on saliva concentration?

A

increased Na and Cl.

Bicarb and K are flow dependent so as flow increaeses, bicarb and K secretion also increases.

43
Q

Low flow rate will have what effect on saliva concentration?

A

Greater modification so Na and Cl concentration decreases. Bicarb and K are flow dependent so both decrease proportional to flow

44
Q

What is Xerostomia?

A
  • dry mouth
  • fairly common with increasing age
  • various drugs (tricyclics, etc)
45
Q

What is Sjogren syndrome?

A
  • progressive autoimmune

* obstructed ducts

46
Q

What is Sialolithiasis

A
  • Ca stone formation (most commonly in submandibular glands)
  • obstructed ducts
  • dehydration, infections
47
Q

What neurotransmitters are responsible for baseline LES muscle tone?

A

EXCITATORY: ACh
INHIBITORY: NO and VIP

48
Q

Administration of Atropine will have what effect on LES muscle tone?

A

Atropine will inhibit ACh release at the LES so the only neurotransmitters that will be working are NO and VIP, which will cause dilation of the LES

49
Q

Administration of an NOS inhibitor will have what effect on LES muscle tone?

A

NOS inhibitor will inhibit the release of NO and VIP at the LES so the only working neurotransmitters will be ACh, which will cause constriction of the LES muscle.

50
Q

Bilateral vagotomy will have what effect on the LES muscle tone?

A

The tone will be the same as baseline.

51
Q

What is Dysphagia?

A

difficulty swallowing

52
Q

What is Achalasia?

A

failure to relax lower esophagus due to the destruction of the parasympathetic ganglia of the myenteric plexus. Lower esophagus also has paristaltic failure.

GI physiology (3 decks)

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