Physiology Flashcards

1
Q

Enteric nervous system comprises what

A

Myenteric and submucosal plexuses

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2
Q

Vagal-Vagal reflex: afferents go where

A

Nodose ganglion

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3
Q

Vagal vagal reflex: Efferents come from where?

A

NTS: Nucleus Tractus Solitarius

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4
Q

Gastrin: Source?

Stimuli of secretion

A

-G cells of stomach

  • small peptides and aa
  • Distention
  • vagal stimulation (via GRP)
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5
Q

CCK: source?

Stimuli of secretion?

A

I cell of duodenum and jejunum

  • Small peptides and a.a.
  • Fatty acids
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6
Q

Secretin: source?

Stimuli of secretion?

A

S cell of the duodenum

  • H+ in duodenum
  • Fatty acids in duodenum
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7
Q

GIP: source?

stimuli of secretion?

What does it do?

A

Duodenum and jejunum

  • Glucose
  • stimulates insulin
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8
Q

What does the NT VIP do?

A
  • relaxation of smooth muscle

- increase intestinal and pancreatic secretion

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9
Q

what does the NT GRP do?

A

-increases Gastrin secretion

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10
Q

What 2 NTs are used for food intake regulation

A
  • Neuropeptide Y

- Substance P

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11
Q

What is it called when the GI smooth muscle, even subthreshold depolarizes and can produce weak contraction

A

Basal Contractions

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12
Q

Sub thrshold depolarization and repolarization of the GI membrane potential

A

slow waves

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13
Q

What 3 things stimulate depolarization of the slow waves?

what stimulates hyper polarization?

A
  • stretch
  • ACh
  • Parasympathetics
  • Norepinephrine
  • Sympathetics
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14
Q

pacemaker for GI smooth muscle

A

Interstitial cells of Cajal (ICC)

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15
Q

slow waves occur spontaneously in the ICC and spread how

A

gap junctions

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16
Q

Smooth muscle cells response to slow wave depolarization with increased what?

A

Ca2+ channel open probability

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17
Q

3 phases of swallowing

A
  • Oral phase
  • pharyngeal phase
  • Esophageal phase
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18
Q

involuntary swallowing reflex is controlled by what?

A

the medulla

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19
Q

What nerve sends afferent sensory input due to food in the pharynx to the swallowing center in the medulla?

A

Glossopharyngeal N.

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20
Q

Esophageal phase of swallowing contains what 2 types of peristaltic waves?

A

primary and secondary

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21
Q

Which wave of the esophageal phases can still occur after a vagotomy

A

secondary

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22
Q

Receptive relaxation occurs in what region of the stomach

A

orad

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23
Q

What does CCK do to the contractions and distensibility of orad region upon reception of food

A
  • decreases contractions

- increases distensibility

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24
Q

how long does gastric emptying take

A

3 hours

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25
Q

What secretion from the duodenum inhibits gastric emptying

A

CCK

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26
Q

Large particles of undigested residue remaining in the stomach are emptied by what

A

Migrating myoelectric complexes (MMC)

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27
Q
  • intervals for MMCs
  • when do they occur?
  • what mediateds them?
  • when are they inhibited?
A
  • 90 min
  • during fasting
  • Motilin-mediated
  • inhibited by feeding
28
Q

What type of contractions:

  • back and forth movements
  • No forward propulsive movement
A

segmentation

29
Q

What type of contrations:

-Circular and longitudinal muscles work in opposition and are reciprocally innervated

A

peristaltic

30
Q

what does the myenteric plexus do?

A

regulates relaxation/contraction of intestinal wall

31
Q

What does submucosal plexus (Meissner) plexus do?

A

sense the lumen environment

32
Q

what inhibits contraction in small intestine via and interneuron and causes relaxation DISTAL (caudad) to the signal of distention

A

VIP and NO

33
Q

what excites and stimulates contraction in the small intestine via and interneuron and causes relaxation PROXIMAL (Orad) to the signal of distention

A

ACh and substance P

34
Q

What is released by ECCs and binds to receptors in IPANs, initiating peristaltic reflex

A

serotonin

35
Q

Colon Absorbs what?

A

water and vitamins

36
Q

What 2 things can cause achalasia

A
  • Lack of VIP

- enteric system has been knocked out

37
Q

LES stays closed during swallowing and elevation of LES resting pressure

A

Achalasia

38
Q
  • slow emptying of stomach/paralysis of stomach

- 20% of type 1diabetics have this

A

gastroparesis

39
Q

Causes of Gastroparesis

A

Damage to vagus nerve from:

  • idiopathic
  • high blood glucose (diabetic gastroparesis)
40
Q

Ganglion cells absent from segment of colon

A

Hirschsprung disease

41
Q

Failure to pass meconium

A

Hirschprung

42
Q

what levels are low in Hirschsprung

A

VIP

43
Q

What is saliva composed of

A
  • H2O
  • electrolytes
  • a amylase
  • lingual lipase
  • Kallikrein
  • mucus
44
Q

Tonicity of saliva

A

HYPOtonic compared to plasma

45
Q
  • K+ and HCO3 in saliva

- Na and Cl?

A
  • increased

- decreased

46
Q

What cells form isotonic plasma like solution in the first step of salivary secretion

A

Acinar cells

47
Q

What cells modify the isotonic solution that was created by Acinar cells to make it hypotonic

A

Ductas cells

48
Q

How do vasopressin and aldosterone modify the composition of saliva

A
  • decreases its Na

- increases its K

49
Q

Parasympathetics to acinar and ductal cells for salivary secretions

A
  • Vagus and Glossopharyngeal

- IP3 and Ca

50
Q

Sympathetic to Acinar and ductal cells for salivary secretions

A
  • T1-T3

- cAMP

51
Q

What are the 2 unusual features in the regulation of salivary secretion

A
  • EXCLUSIVELY under control of ANS

- increase by BOTH parasympathetics and sympathetics

52
Q

What is required for absorption of vitamin B12 in the ileum

A

intrinsic factor

53
Q

What kind of gland is in the proximal 80% (body and fundus) of the stomach and secretes acid

A

Oxyntic gland

54
Q

What kind of gland has chief cells?

These secrete what?

A

Oxyntic

pepsinogen

55
Q

What kind of gland is in the distal 20% (antrum) and synthesizes and releases gastrin

A

pyloric gland

56
Q

What kind of gland has D cells?

These secrete what?

A

pyloric gland

somatostatin

57
Q

What are the 2 Gq pathways leading to increase in IP3/Ca2 and H+ secretion in gastric parietal cells

A
  • G cells –>Gastrin –> CCKB receptor

- Vagus –>Ach –>M3 receptor

58
Q

What is the Gs pathway leading to increased cAMP and H+ secretion in gastric parietal cells

A

-ECL cells–> Histamine –> H2 receptor

59
Q

What are the 2 Gi inhibitory pathways that decrease cAMP and inhibit secretion of H+ in gastric parietal cells

A
  • D cells –> somatostatin

- Prostaglandins

60
Q

Falling pH inhibits what?

A

gastrin release so decreases HCl secretion

61
Q

what are the 2 pathways that the vagus nerve uses to stimulate HCl secretion from parietal cells

A
  • Directly on parietal cells

- indirectly through GRP and G cells –> gastrin –> to parietal cells (atropine doesn’t block this pathway)

62
Q

What is in the protective layer of the mucosa to protect stomach from H+ and pepsin?
What secretes each?

A

mucus .. . mucous neck cells

HCO3- . . . Gastric epithelial cells

63
Q

Unconjugated Jaundice diseases

A
  • Gilbert’s

- Crigler-Najjar syndrome

64
Q

Conjugated Jaundice diseases

A
  • Dubin-Johnson

- Rotor syndrome

65
Q

transporter for fructose from lumen to cell?

cell to blood?

A

GLUT5

GLUT2

66
Q

transporter for Glucose and Galactose from lumen to cell?

-cell to blood?

A
  • SGLT 1

- GLUT2