✅1.9 PHYSIOLOGY - GI Flashcards
Location of submucosal plexus
Between submucosa and inner circular muscle
Basic GI layers
Mucosa
Submucosa
Muscularis
Serosa
Other name for submucosal plexus
Meissner’s plexus
Function of submucosal plexus is mainly for
Secretion
Function of myenteric plexus
Motility
Other name for the myenteric plexus
Auerbach’s plexus
Location of the myenteric plexus
Between inner circular and outer longhitudinal muscle
3 parts of the mucosa
Epithelium
Lamina propria
Muscularis mucosa
Innervation of the muscularis mucosa (mucosa)
Meissner’s plexus
Brunner’s glands vs peyer’s patches
Function, location (gross and layer)
Brunner’s - duodenum, HCO3 secretion, submucosa
Peyer’s patches - ileum, IgA secretion, lamina propria
Which layer is not seen in the esophagus?
Serosa
Strongest layer of the esophagus
Submucosa
Bolus vs chyme vs feces
Bolus - esophagus and stomach
Chyme- mixed with HCl, SI
Feces - nutrients absorbed, found in the LI
Function of CCK
Bile secretion and inhibition of gastric emptying
3 incretins
Glucagon
GLP-1
GIP
Number one trigger of CCK secretion
Fatty acids
CCK is secreted by what cells in the _____
I cells
Duodenum and jejunum
Motilin does not have effects on the
Large intestine
Stimulus for motilin
Fasting
“Janitor” GI hormone
Motilin
Motilin is from what cells in the ______
M cells
Duodenum and jejunum
Function of motilin
Interdigestive/migrating myoelectric complex
GIP is produced from what cells in the _____
K cells , duodenum
Function of GIP
Increases insulin secretion
3 parts of the mucosa
Epithelium
Lamina propria
Muscularis mucosa
2 muscles in the muscularis layer
Inner circular
Outer longhitudinal
Other name for serosa
Adventitia or mesothelium
Muscular layers in the stomach
Inner oblique
Middle circular
Outer longhitudinal
The myenteric plexus is mainly excitatory except for which regions
Pyloric sphincter and ileocecal valve
Cell source of CCK
I cells duodenum
Cell sources of GIP and GLP-1
GIP- k cells
GLP-1 L cells
Main stimulus for CCK
Fatty acids
Main stimulus for incretins
Oral glucose
Effect of motilkn
Stimulates interdigestive myoelectric complexes
Stimulus for motilin
Fasting
Effect of CCK
Inc bile
GB contraction
Inhibits gastric emptying time
Most potent stimuli for gastrin secretion
Phenylalanine
Tryptophan
Methionine
Neurocrine from vagus nerve to G crlls
GRP / Bombesin
GI hormones classified as incretins
GLP-1
GIP
Candidate GI hormones
Pancreatic polypeptide
Enteroglucagon
GLP-1
Function of enteroglucagon
Secreted by intestinal cells in response to hypoglycemia
GI paracrines
Somatostatin
Histamine
Mnemonic for function of somatostatin
Somato STOP IT
inhibits release of all GI hormones
Histamine is secreted by
Mast cells of GI mucosa
Function of ACH and norepi in sphincters
ACH relaxes sphincters while Norepi contracts sphincterd
Inhibits appetite and is found in the ventromedial nucleus
Satiety center
Stimulates appetite and is found at the lateral hypothalamic area
Appetite/hunger center
Sends signals to satiety and hunger centers
Arcuate nucleus
Releases POMC to decrease appetite
Anorexigenic neurons
Releases neuropeptide y to increase appetite
Orexigenic neurons
Stimulates anorexigenic neurons and inhibits orexigenic neurons
Leptin, insulin, GLP-1
Inhibits anorexigenic neurons
Ghrelin
Inhibits ghrelin
Peptide YY
Mnemonic for satiety and hunger centers
Ventromedial
VUCHOG
Satiety center
Lateral hypothalamic area
LAMON
Hunger center
2 types of GI smooth muscle contractions. Differentiate
Tonic - slow - false action potentials
Phasic- spike pptentials - true potentials
Slow waves are generated by the GI pacemaker called
Intertstitial cells of cajal
Slowest slow wave frequency is found in the
Stomach
Fastest slow wave frequency is found in the
Small intestines
Type of GI contraction for mixing and propulsion
Phasic contractions
Most common stimulus for GI peristalsis
Distention
What is the myenteric reflex?
Muscles upstream contract, muscles downstream exhibit receptive relaxation
What is the law of the GUT?
Myenteric reflex +anal direction of peristalsis
How long does it take to transfer material from pylorus to ileocecal valve?
From ilececal valve to colon?
3-5 hrs
8-15 hrs
Chewing is always voluntary. T or F.
It may be involuntary
Other name for amylase
Ptayalin
Phases of swallowing
Oral
Pharyngeal
Esophageal
Swallowing center
Medulla
Esophageal peristaltic contraction
2 phases - primary and secondary
Primary peristalsis propels the food to the stomach while secondary persistalsis is for clearance of remaining food.
Receptive relaxation of the orad stomach is mediated by
VIP
Relax pag may VIP
Capacity of the stomach
1.5 L
____ increases distensibility of orad stomach
CCK
Caudad stomach contracts ___x per minute
3-5x
Back and forth movement of the SI with no net forward motion for mixing chyme with enzymes
Segmentation contraction
Sac like segments due to the segmental contractions in the large intestine
Haustra
Function of proximal vs distal colon
Proximal - absorption of water
Distal - storage of feces
Urge to defecate is felt once rectum is ___%filled
25%
Definition of valsalva maneuver
Expiration on a closed glottis
Odor in stool is due to bacteria producing
Indole
Skatole
Mercaptan
Hydrogen sulfide
Incomplete vomiting / closed UES
Retching
Vomiting is a wave of reverse peristalsis that begins from the
Small intestine
GI organ with the most volume of secretion
Small intestines
1800ml
Only essential secretion of the stomach
Intrinsic factor
Other name for parietal cells
Oxyntic cells
Other name for chief cells
Peptic cells
Secretes serotonin
Mnemonic
Entrochromaffine cells
Ser pls ENTER
Secretes histamine
Enterochromaffin LIKE cells
3 substances that stimulate HCL secretion and corresponding receptord
Histamine - H2
Ach -M3
Gastrin -CCK-B
Inhibitors of HCL secretion
Low pH (
Phases of HCL secretion
Cephalic
Gastric
Intestinal
Most common component of bile
Water
Active component of bile
Bile salts
Primary bile acids
Cholic acid
Chenodeoxycholic acid
Secondary bile salts
Deoxycholic acid
Lithocolic acid
Bile salts from deoxycholic acid
Glycodeoxycholic acid
Taurodeocycholic acid
Bile salts from lithocolic acid
Glycolithocolic acid
Taurolithocolic acid
Bile salts are utilized ____x before excreted in the feces
17x
How do you absorb glucose and galactose from lumen to intestine
SGLT-1
How do you absorb fructose from lumen to intestine
GLUT 5
Mnemonic: 5 letters
FRUIT and LUMEN
How do you absorb glucose, galactose and fructose from intestinal cell to the blood?
GLut 2
Two letters
BM - basement membrane
Is pepsin essential for protein digestion?
No. Trypsin (“aka nuclear bomb”) is the essential one for digestion
What is the optimum pH for pancreatic lipase activity?
6.0
Bile salts inactivate pancreatic lipase. What coenzyme is secreted to prevent this from happening?
Prolipase—> colipase
Only product of TGL metabolism that is not hydrophobic
Glycerol
What type of fatty acids go directly to the portal vein instead of lacteals?
Short and medium chain FA
Main site for water absorption
Jejunum
Primary ion secreted in the intestinal lumen
Cl
Needed to absorb calcium
Cholecalciferol
1,25 OH2
Needed to absorb iron
Vitamin C
Part of the metabolism of these vitamins involve the colonic flora
Vit K, B1, B2, B12
Liver models
Classic liver lobule
Liver acinus model
Zones of the liver acinus model
Zone 1 periportal
2 midzonal
3 centrilobular
Special liver cells for vitamin storage
Ito cells
Space of disse
Liver macrophages
Kuppfer cells
Liver sinusoids