GI Flashcards
What is the role of the inner circular muscle of the GIT?
decreases diameter of lumen
What muscle shortens the segment of GIT?
Outer longitudinal layer
What layer of the GI muscle controls GI secretions?
Muscularis Muscle
What is the extrinsic, parasympathetic nerve supplying the esophagus and upper large intestine
vagus nerve
What is the role of the intrinsic innervation in the GIT?
coordinates and relays info from ANS to GIT
What is intrinsic innervation between the submucosa and inner circular muscle layer?
Meissner Plexus
Remember: Miss Sub Secs
Meissner = Submucosa = Secretion
What is the intrinsic innervation between inner circular and outer longitudinal muscle layer of the GIT
Auerbach Plexus
Remember, My Back
Myenteric = Aurbach
Which intrinsic innervation plays a role in GI secretion?
Meissner = Submucosal plexus = Secretions
What intrinsic innervation plays a role in GIT motility?
Myenteric = Auerbach = Motility
Remember, My Bach Moves
What layer is not seen in the esophagus
serosa
What is the strongest layer of the esophagus?
submucosa
What are the 3 layers of the stomach?
inner oblique, middle circular, outer longitudinal
Myenteric plexus is inhibitory in which part of the GIT?
- Pyloric Sphincter
2. Ileocecal Valve
[GI Hormone]
Its release is triggered by proteins and amino acids
Gastrin
What amino acids trigger gastrin release
MWF
G cells secreting gastrin is located in which part of the stomach?
antrum
What are the actions of gastrin?
- Stimulate parietal cells in fundus to secrete HCl
2. Growth of gastric mucosa
[GI Hormone]
What hormone is triggered by fatty acids
CCK
What cell secretes CCK?
I cells
Which part of the GIT tract where I cells secrete CCK
duodenum
What are the actions of CCK
- GB contraction, sphincter of oddi relaxation
- Increase GET
- Increase pancreatic enzyme secretion
What triggers the release of secretin?
- Presence of H+ in the duodenum
2. Fatty acids in duodenum
What cells secrete the hormone secretin?
S cell
S cells that secrete secretin is located in which part of the GIT?
duodenum
What are the actions of your secretin?
- Inhibit HCl secretion
2. Increases biliary and pancreatic HCO3
What GI hormone is not affected by the hormine secretin?
pancreatic enzyme
The release of GIP is triggered by ____
increase in oral glucose
What cell in the GIT secrete the hormone GIP
K cells
What is the action of your GIP?
- Inhibit gastric emptying above normal physiologic levels
What triggers the secretion of motilin
Fasting
What cell in the GIT secrete motilin?
M cells
M cells that secrete motilin is seen in which part of the GIT?
duodenum and jejunum
What are the actions of your motilin?
- Activate interdigestive/MMC
2. Acts only on the stomach and small intestine
What hormone opposes the release of HCl?
Secretin
What is the net effect of the release of GIP
increased insulin
What cells in the GIT secrete GLP-1?
L cells of the small intestin
What GI hormone is stimulated by CHO rich meal?
GLP
What are examples of you incretin?
- GIP
- GLP
- Glucagon
What are examples of your GI paracrine hormones?
- Somatostatin
2. Histamin
What hormone inhibits the release of ALL GI hormones
Somatostatin
What cells in the gastric mucosa secrete histamine?
mast cell
What is the action of histamine int he GIT?
- Increase H+ secretion
- Inhibits insulin
- Inhibit glucagon
What are examples of you GIT neurocrines?
- VIP
- Enkephalin
- GRP (bombesin)
VIP is a neurocrine hormone of the GIT that relaxes what structures int eh GIT?
- Relaxes LES
- Orad stomach
- Pyloric sphincter
- Ileocecal valve
Ultimate muscle relaxant
What is the role of VIP in HCO3 and H+?
- Stimulates HCO3 secretion
2. Inhibits gastric H secretion
what hormone is involved in your pancreatic cholera?
VIP
What neurocrine hormone inhibits the secretion of fluids and electrolytes in the GIT?
Enkephalins
What are the types of enkephalins seen in the GIT?
- met enkephalin
2. Leu enkephalin
What is the action of enkephalin in the GIT sphincters?
- Contracts LES
- Contracts Pyloric sphincter
- Contracts Ileocecal valve
What neurocrin stimulates the release of gastrin from G cells?
GRP (Bombesin)
[Brain part]
inhibits appetite, found in the ventromedial hypotalamus
satiety center
[Brain part]
the appetite/hunger center is located in which part of the brain?
Lateral hypothalamic
The arcuate nucleus is important in GIT. It sends signals to ____
Satiety and hunger center
Which neuron releases POMC to decrease the appetite?
Anorexigenic neurons
What is released by your orexigenic neurons to increase appetite?
Neuropeptide Y
What hormones stimulate anorexigenic neurons and inhibits orexigenic neurons?
- Leptin
- Insulin
- GLP-1
What hormone inhibits anorexigenic neurons that is secreted by gastric cells?
ghrelin
What inhibits the secretion of ghrelin?
Peptide YY
Which part of the GIT tract is not made up of unitary smooth muscle?
- Pharynx
- Upper 1/3 of the esophagus
- External anal sphincter
Tonic contractions of the GIT can be seen in _____
- Upper region of the stomach
- Lower esophagus
- Ileocecal
- Internal anal sphincter
Tonic contractions of the GIT is due to?
Subthreshold slow waves
Phasic contractions are seen in which part of the GIT?
- Esophagus
- Gastric antrum
- Small intestine
This causes the phasic contraction of the GIT?
spike potential
[Electrical activity of GI smooth muscle]
determines the pattern of contraction; due to the interstitial cells of cajal; slow, oscillating membrane potentials
Slow waves
not true action potentials
brings you closer to threshold
[Electrical activity of GI smooth muscle]
slow waves has a slowest frequency in which part of the GIT?
Stomach
[Electrical activity of GI smooth muscle]
Slow wave is fastest in which part of the GIT?
Duodenum
[Electrical activity of GI smooth muscle]
What causes the depolarization of spike potentials?
Calcium infux
What is the pacemaker of the GIT?
Interstitial cell of Cajal
What is the most common stimulus fo GI peristalis?
Distention
How many hours will it take to transfer the material from the pylorus to ileocecal valve?
3-5 hours
How many hours will it take to transfer digested material from ileocecal valve to colin?
8 to 15 days
What nerve is utilized during swallowing?
CN IX, X
in the medulla
What are the events during the pharyngeal phase?
- Soft palate pulled upward (closes the nasopharynx]
- glottis covered prevents aspiration
- Upper esophageal sphincter relaxes
What triggers the secondary peristalsis?
Gastric acid reflux to the esophagus
What enzyme is deficient in achalasia?
Yep! Enzyme.
NO synthase that makes NO.
Deficient myenteric plexus, deficient neurocrine release (NO, VIP), decreased receptive relaxation
What hormones facilitate receptive relaxation of the lower esophagus?
NO, VIP
What hormones facilitate receptive relaxation of Orad stomach?
- VIP
2. CCK
What nerve stimulates gastric contractions?
Parasympathetic via Vagus Nerve
What is the capacity of the stomach?
1.5L
Motilin stimulates gastric contractions every ___
90 minutes
motilin = motility
What facilitates gastric emptyong?
- isotonic contents
2. chyme formation
What inhibits gastric emptying?
- Fat (via CCK)
2. H+ in the duodenum
What initiates the decreased gastric emptying time?
hyperosmolality of duodenal contents
What increases the rate of gastric emptying time?
Intragastric volume
If madami content, fat, acid sa small intestine, mag stop ang gastric emptying
What type of contraction allows mixing of chyme with pancreatic enzyme?
Segmentation contraction
In peristaltic contractions, in order to propel the bolus forward, the longitudinal muscles should ___
- Contract behind the bolus
2. relax infront of bolus
What prevents reflux of chyme from the cecum to the ileum?
Ileocecal valve
What is the primary role of proximal colon?
absorption of water
What is the primary role of your distal colon?
storage of feces
The movement of colonic contents called mass movement occurs how many times a day?
1-3x per days
Urge to defecate is felt when the rectum is filled by how much? (percent)
25%
Internal anal sphincter is involuntary
What relaxes the internal anal sphincter?
Rectal contents = rectosphincteric reflex
In order for defecation to occur, you external and internal anal sphincters should
Relax.
Normally, internal anal sphincter is contracted, you external anal sphincter is contracted
___ reflex refers to when food in the stomach increases peristalsis in the ileum, and relaxation of the ileocecal sphincter
Gastroileal reflex
___ reflex refers to food in the stomach increases peristalsis in the colon
Gastrocolic reflex
What mediates the gastrocolic reflex?
- Parasympathetic NS
- CCK
- Gastrin
What causes the normal bowel movements in newborn?
Gastrocolic reflex
Reverse peristalsis, like in vomiting, begins in which part of the GIT?
Small intestine
Vomiting center: Medulla
Which part of the brain is triggered by emetics, radiation and vestibular stimulation
Chemoreceptor Trigger Zone (area postrema)
___ refers to incomplete vomiting through a closed upper esophageal sphincter
Retching
[GI Juices]
most basic
- Brunners gland secretions
2. Pancreatic Juice
[GI Juices]
how many mL of HCl is secreted per day?
1.5L
What organs produce saliva
- Parotid
- Submandibular
- Sublingual
What electrolytes are high in the saliva?
High in K and HCO3
Low in Na, Cl
hypotonic
What digestive enzymes are present in the saliva?
- Amylase
2. Lingual lipase
[Effect to salivation]
parasympathetic stimulation
Increases salivation
[Effect to salivation]
sympathetic salivation
Increases salivation
High flow rates, saliva has high Na, Cl low K, HCO3
What electrolytes are high in initial saliva?
Na, Cl
the final saliva is High in K, HCO3
What hormone plays a role in reabsorbing Na in the ductal cells making the final saliva low in K and HCO3?
Aldosterone
Relative to plasma, salava is ___ (hyper/hypotonic)
Hypotonic
Oxyntic glands is located in which part of the stomach?
Body
Contains:
- Mucus neck cells
- Parietal cells
- Chief Cells
Pyloric glands is located in which part of the stomach?
Antrum
Contains:
- G cells
- Mucus cells
What cells secrete mucus and HCO3?
- Mucus cells
2. Mucus neck cells
What cells secrete HCl and IF?
Parietal or Oxyntic Cells
What cells secrete serotonin in teh GIT?
Enterochromaffin cells
What cells secrete histamine in the GIT?
Enterochromaffin-like cells
What cells secrete pepsinogen?
chief/peptic cells
Intrinsic factor is secreted in which part of the stomach?
Gastric Fundus
What stimulates HCl Secretion?
- Histamine on H2 receptors
- Ach on M3 receptors
- Gastrin on CCKb receptors
What increases the basal acid output in the stomach?
Alkalinize the antrum
What inhibits HCl secretion?
- Low pH (<3)
- Somatostatin
- Prostaglanding
What drug class inhibits both gastrin and acetylcholine mediated acid secretion?
H2 blockers
What hormone is high in Zollinger-Ellison Syndrome?
Gastrin = gastrinoma
resulting to high HCl
What is the tonicity of your pancreatic secretions?
Isotonic
contains high HCO3 to neutralize acids
What hormones stimulate the release of pancreatic enzymes?
- Secretin
- CCK
- Acetylcholine
What are the effects of pancreatectomy?
- Loss of exocrine pancreatic secretions
2. Loss of insulin secretion
What is the most common component of bile?
water
What is the active component of bile?
Bile acid
What are your primary bile acids?
- Cholic Acids
2. Chenodeoxycholic acid
What are your secondary bile acids?
- Deoxycholic acids
2. Lithocholic acids
What is added to you secondary bile acids to make bile salts?
- Taurine
2. Glycine
What causes GB contraction?
- CCK
2. Ach
What causes sphincter of Oddi Relaxation?
- CCK
The release of bile is characterized as ______
pulsatile spurts
What will be the effect of surgical resection of ileum?
- Increased water content of feces
What transporter is used to transport glucose and galactose from the lumen of the SI to the cell?
SGLT1 (secondary active transporter)
What transporter is used to transport fructose from the lumen of the SI to the cell?
GLUT-5
FRUIT = 5 letters = glut 5
What is the transporter of monosaccharides from the cell to the basolateral side?
GLUT 2
What are the brush border enzymes that is required for assimilation of protein?
Enterokinase/Enteropeptidase
What enzyme cleaves the C terminus of a polypeptide?
Exopeptidase = Ends/C terminal
What are the essential pancreatic proteases?
- Trypsin
- Chymotrypsin
- Elastase
- Carboxypeptidase A and B
What facilitates the absorption of your free amino acids in the luminal side?
Na-aa symport
What transports AA from the cell to the basolateral side?
Facilitated diffusion
Between dipeptides and free amino acids, which is absorbed faster?
Dipeptides
and tripeptides too
Lipids enter the intestinal cell via?
micelles
Lipids leave the cell via?
chylomicrons
What enzyme is inactivated by gastrinoma
pancreatic lipase
Gastrinoma = High gastrin = low gastric pH
Short chain fatty acids absorption almost exclusively happens in which part of the GIT?
colon
Vitamin B 12 is absorbed in which part of the GIT?
ileum
Iron and Vitamin C is absorbed in which part of the GIT?
Duodenum
Fat, proteins, carbohydrates and water are absorbed in the ___
jejunum
Vitamin ADEK are absorbed in the
ileum
IF-B12 complex and bile salts are absorbed in teh
ileum