Physiology Flashcards
How many cells thick are the villi?
One
What PSNS nerves innervate the transverse colon?
Vagus
What PSNS nerves innervate the ascending colon?
Vagus
What PSNS nerves innervate the descending colon?
Pelvic splancnics
What it the GI circulation called?
Splanchnic circulation
How long do cells last on average in the GI tract?
3-5 days
What is the pH of stomach acid?
1.5
What is the pH of chyme in the jejunum?
7-7.5
What is borborygmi?
Sounds that are heard as gases move in and out of the intestines
What is the threshold potential for depolarization in the GI tract?
-40mV
What two substances initiate contraction in peristalsis and where does this occur?
Small intestine - behind food bolus
Tachykinin and Ach/PSNS cholinergic
What substance initiates relaxation in peristalsis and where does this occur?
Small intestine - in front of food bolus
VIP
What phase of the MMC is most significant for propulsion?
III
Where is motilin secreted from?
M cells of small intestine
What is the function of the myenteric net of the ENS?
Movement
What is the function of the submucosal net of the ENS?
Secretion
What structure is affected in Hirschsprung disease and what structure is dilated?
Internal anal sphincter does not open - megacolon
What structure is affected in Achalasia and what structure is dilated?
Lower esophageal sphincter does not open - esophageal dilation
What is digested fasted?
H20 and carbs
What is digested slowest?
Lipids
Where is the sphincter of Oddi found?
Gallbladder - releases bile into duodenum
Name 5 substances that would cause depolarization of the slow wave in the GI tract.
Stretch Ach/PSNS Gastrin Serotonin (5-HT) Substance P (tachykinin)
What is another name for serotonin?
5-HT
What is another name for 5-HT?
Serotonin
What is another name for substance P?
Tachykinin
What is another name for tachykinin?
Substance P
Name 3 substances that would cause hyperpolarization of the slow wave in the GI tract.
NE
NO
VIP
What is ilius?
Lack of movement
Where does a food bolus become chyme?
Stomach
What is the difference between exocrine and endocrine glands?
Exo - secrete into ducts - allows for modifications
Endo - secrete directly
Is heliobacter gram + or -?
Negative
What is the narrowing portion of the stomach called?
Antrum
Which hormones stimulate pancreatic enzyme release?
CCK
Which hormones stimulate pancreatic buffer release?
Secretin
Where do the majority of digestive enzymes come from?
Pancreas (75%)
What activates pancreatic amylase?
Cl-
Where in the GI tract are acinar cells found and what is their function?
Exocrine cells - salivary and pancreatic exocrine glands, secrete into ducts
Is saliva hypo or hypertonic as compared to plasma?
Hypotonic
What are two other names for TC-1?
R-protein or R-binder
Which portion of the stomach is gastrin released from?
G-cells in antrum
Where does protein digestion begin?
Stomach - pepsins
Where does starch digestion begin?
Mouth - alpha amylase
Where does lipid digestion begin?
Mouth - lingual lipase
Is the plasma leaving the stomach’s microcirculation acidic or basic and why?
Slightly basic due to exchange of HCO3 for Cl during acid secretion
What ion balances are of concern for a patient with chronic vomiting?
Alkalemia - loss of HCl
Hypokalemia - loss of K from gastric secretion as well as saliva
What pancreatic cells release enzymes?
Acinar
What pancreatic cells release buffer?
Centroacinar
When does vagal action on the GI system stop?
When the stomach has no chyme
Is primary bile hydrophobic?
Amphipathic - cholesterol backbone and AA polar head group
Is secondary bile hydrophobic?
Yes
What amino acids are found on bile?
Taurine and glycine
What enzyme synthesizes cholesterol?
HMGA CoA Reductase
What monosaccharides make up sucrose?
Glucose and fuctose
What monosaccharides make up lactose?
Glucose and galactose
What monosaccharides make up maltose?
Glucose and glucose
What transporters carry glucose and galactose?
Sglt1
What transporters carry fructose?
Glut-5
What does SGLT-1 carry?
Glucose and galactose
What does Glut-5 carry?
Fructose
What does Glut-2 carry?
Monosaccharides from enterocytes to intersitium
In what population is lingual lipase most significant?
Neonates
From what glands is lingual lipase secreted?
Von Ebner’s Glands in the tongue
Is iron oxidized or reduced in enterocytes? What compound in responsible?
Reduced from Fe3+ to 2+ by ferrireductase
Is bifidobacteria a good or bad gut bacteria?
Good
Is bacteroides a good or bad gut bacteria?
Bad
What is Mallory-Weiss Syndrome?
Tears of esophageal lining from repeated retching
What blood supply feeds hepatocytes?
Portal vein
What blood supply feeds the bile duct?
Hepatic artery
What is the primary cause of secretory diarrhea?
Cholera
What gene and channel does cholera effect?
CFTR gene activating Cl- channel in enterocytes
What is the normal ECF to ICF ratio?
1/3:2/3
What antibiotic would you use to treat cholera?
Tetracycline
What is another name for chief cells?
Zymogenic cells
What enzyme converts CO2 and H2O to H+?
Carbonic anhydrase
When and where would you expect to see canaliculi?
In parietal cell when actively making acid - cytoskeleton reconstruction
Where do goblet cells first appear in the GI tract?
Small intestine
Where is Meissner’s plexus in the GI lining?
Submucosa
Where is Auerbach’s plexus in the GI lining?
Between circular and longitudinal muscles in the muscularis externa
Where along the GI tract would you expect to find stratified squamous epithelium?
Esophagus and anus
Where are Brunner’s glands?
Duodenum
Where along the GI tract would you expect to find simple columnar epithelium?
Stomach and rectum
Where in the stomach do you find deep gastric pits?
Pylorus
Where in the stomach do you find shallow glands?
Cardia
Where in the stomach do toy find short pits?
Body / fundus
Where in the GI tract would you find Peyer’s patches?
Jejunum / Ileum