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
