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Flashcards in GI Physiology Deck (93)
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Basic GI layers

Mucosa, Submucosa, Muscularis, Serosa

1

Refers to movement of food from stomach to duodenum

Gastric emptying

2

Function of the GI tract for secretion and absorption

Mucosa - Epithelium

3

Part of the mucosa innervated by the Meissner's plexus

Muscularis mucosa - smooth muscle cells controlling the eptihelium

4

GI tract structure: composed of collagen, elastin, glands and blood vessels

Submucosa - composed of connective tissue

5

GI tract structure: composed of muscle layer

Muscularis

6

Muscle layer that causes decreases diameter of the lumen

Inner Circular Muscle layer

7

GI muscle layer: shortens segment of the GI tract

Outer Longitudinal Muscle layer

8

Muscle layer of the GI tract: refers to the actual peristalsis

Outer longitudinal muscle layer

9

Serosa layer of the GI tract is also known as?

Adventitia or mesothelium

10

GI plexus located between submucosal and inner circular muscle layer

Meissner's plexus - also known as Submucosal plexus, for secretion, absorption and contraction of muscularis mucosae.

11

GI plexus between inner circular and outer longitudinal muscle layer.

Auerbach's plexus - also known as Myenteric plexus. For motility

12

GI layer not seen in esophagus

Serosa

13

Strongest layer of the Esophagus

Submucosa

14

Muscle layer of the Stomach

Inner oblique, middle circular and outer longitudinal layer

15

Myenteric plexus is mainly excitatory except in what region?

Pyloric sphincter and ileocecal valve - relaxation

16

Extrinsic innervation of GI tract: excitatory of esophagus to upper large intestine

Vagus nerve

17

Excitatory extrinsic innervation of Gi tract from lower large intestine to Anus

Pelvic nerves

18

Refers to the alternate movement of inner circular and outer longitudinal muscle layers

Reciprocal innervation

19

Three main function of VIP: Vasointestinal peptide

1. Relaxation of pyloric sphincter and ileocecal valves
2. Receptive relaxation of LES
3. Receptive relaxation of Stomach

20

GI hormone: stimulated by gastric distention causes increase gastric H+ secretion and stimulates growth of gastric mucosa

Gastrin

21

Main inhibitory of Gastrin

H+ and somatostatin

22

GI hormone: stimulated during fasting.

Motilin

23

From M cells, causes activation of migrating myoelectric complex or interdigestive myoelectric complex

Motilin

24

GI hormone: increases pancreatic and biliary HCO3- secretion. And decreases effect of gastrin on gastric mucosa

Secretin - from S cells

25

Protective hormone for the duodenum against the acid of the stomach

Secretin

26

GI hormone: main trigger of release is Glucose. Increases insulin secretion and inhibits gastric emptying

Glucose dependent insulinotropic peptide - from K cells

27

Different Incretin hormones

GIP from K cells
GLP from L cells
Glucagon

28

GI hormone: produced by I cells in respond to all foods (FA: main trigger)

Cholecystokinin - CCK

29

Function of CCK

Gallbladder relaxation
Sphincter of Oddi Relaxation
Increaes pancreatic enzyme and HCO3- secretion
Inhibits gastric emptying

30

Motilin has an action on GI tract except on what region?

Motilin act only on stomach and small intestine and not on Large intestine

31

Most potent stimuli for gastrin secretion

Protein - phenylalanine, tryptophan and methionine

32

Neurocrine from vagus nerve to G cells

GRP/ Bombesin

33

GI hormone: secreted in response to hypoglycemia thus resulting to glycogenolysis and gluconeogenesis

Enteroglucagon

34

Incretin hormone secreted by L cells of small intestines that stimulates insulin secretion

Glucagon like peptide 1 ( GLP-1)

35

GI hormone: that inhibits release of all GI hormones and gastric H+ secretion

Somatostatin

36

GI hormone: secreted by mast cells of gastric mucosa that increased H+ secretion, potentiates gastrin and Ach action

Histamine

37

GI hormone: that inhibits appetite, found at the ventromedial hypothalamus

Satiety center

38

Location of the Appetite/hunger center

Lateral hypothalamus - stimulates appetite

39

It sends signals to Satiety and Hunger Center

Arcuate nucleus pathway

40

It releases POMC to decrease appetite

Anorexigenic neurons

41

It releases Neuropeptide Y to increase appetite

Orexigenic neurons

42

It stimulates anorexigenic neurons and inhibits orexigenic neurons

Leptin (fat cells), insulin and GLP-1

43

It inhibits anorexigenic neurons

Ghrelin (gastric cells)

44

Inhibits Ghrelin

Peptide YY

45

It refers to constant level of contraction or tone without regular periods of relaxation

Tonic contractions - orad stomach, lower esophageal, ileocecal and internal anal sphincters

46

Tonic contractions are due to _ waves

Subthreshold slow waves - not true action potential but capable of irregular contractions

47

It refers to periodic contractions followed by relaxation for mixing and propulsion purposes.

Phasic contractions - in esophagus, gastric antrum and small intestines

48

Phasic contractions are due to?

Spike potentials - true action potentials

49

Refers to GI pacemaker

Interstitial cells of Cajal

50

Depolarization during slow wave is due to?

Sodium influx

51

With slowest frequency

Stomach - 3waves/min

52

Fastest frequency

Duodenum - 12 waves/min

53

Spike potentials are due to?

Calcium influx - threshold of -40mV

54

What is the most common stimulus for Gi peristalsis?

Distention

55

It refers to muscles upstream contract, muscles downstream exhibit receptive relaxation

Myenteric reflex

56

What is the Law of the Gut?

Myenteric reflex + anal direction of peristalsis

57

How long does it take to transfer material from pylorus to ileocecal valve?

3-5 hours

58

How long does it take to transfer material from ileocecal valve to colon?

8-15 hours

59

Swallowing center?

Medulla

60

Three phases of swallowing?

Oral phase
Pharyngeal phase
Esophageal phase

61

Phase of swallowing that prevents aspiration of food contents

Pharyngeal phase - soft palate pulled upward, glottis covered, upper esophageal sphincter relaxes

62

Peristalsis that creates high pressure behind bolus of food propelling it towards the stomach

Primary peristaltic contraction - accelerated by Gravity

63

Relxation of the lower esophageal sphincter is vagally-mediated using?

VIP or vasoinstestinal peptide

64

Peristalsis that clears the esophagus of remaining food?

Secondary Peristaltic Contraction

65

Three muscle layers of the stomach

Inner oblique layer
Middle circular layer
Outer longitudinal layer

66

Three anatomic division of the stomach

Fundus, body and antrum

67

Two functional division of the stomach

Orad stomach ( thin-walled) and Caudad stomach ( thick-walled)

68

Refers to food propelled back to stomach for further reduction in particle size and mixing with gastric juice

Retropulsion - due to inner oblique muscle layer

69

Propelling of food from stomach to duodenum

Gastric emptying - 3 hours

70

Gastric emptying is inhibited by what?

Fat ( due to CCK)
H+ in duodenum (due to direct neural reflex)

71

Refers to the back-forth movement with no net forward motion.

Segmentation contraction - mixes chyme with pancreatic enzymes

72

It propels chyme towards the large intestines

Peristaltic contraction - actual peristalsis

73

What is reciprocally innervated means?

When one is contracted, the other is relaxed, and vice-versa. Prevent opposing each other

74

Sac-like segments due to segmental contractions of the large intestines

Haustra

75

It function merely for water absorption, to dry up feces

Proximal colon - 1.5L of water

76

Function as storage for feces

Distal colon

77

Refers to movement of colonic contents over long distances (from transverse colon to sigmoid colon)

Mass movement - occur 1-3x a day

78

Maneuver against closed glottis that assist defecation

Valsalva maneuver

79

Odor of the stool is due to what bacterial products?

Mercaptan, indole, skatole and hydrogen sulfide

80

Refers to increase peristalsis in ileum and relaxation of the ileocecal sphincter due to presence of food in the stomach

Gastroileal reflex

81

Food in the stomach increases peristalsis in the colon and frequency of mass movements

Gastrocolic reflex - mediated by parasympathetic NS, CCK and Gastrin

82

Refers to a reverse wave peristalsis that begins from the small intestines

Vomiting - preceded by Nausea

83

Vomiting center

Medulla

84

Incomplete vomiting

Retching

85

Gland with serous secretion only

Parotid gland

86

Gland with mixed secretion of mucus and serous

Submandibular and sublingual glands

87

Innervation of parotid gland

Cranial nerve 9

88

Innervation for submandibular and sublingual glands?

CN 9

89

Effect of sympathetic NS on salivation

Decreases salivation

90

Effect of parasympathetic NS on salivation

Increases salivation

91

Initial saliva is high in?

Sodium and Chloride ions

92

Final saliva is high in?

Bicarbonate and potassium ions