Gastrointestinal Physiology Flashcards
Increases H+ secretion and stimulates gastric mucosal growth?
Gastrin
Increases both exocrine and endocrine secretion of pancreas?
CCK
Increases HCO3 secretion?
Secretin
Increased insulin secretion and decreases H+ secretion?
GIP
Inhibits all GI hormones .
Somatostatin
Stimulate gastrin release?
Bombesin
Satiety center?
Ventromedial nucleus of Hypothalamus
Feeding Center?
Lateral Hypothalamic Area
Vagovagal Reflex initiated by distention of the stomach and is abolished by vagotomy?
Receptive Relaxation
The orad region of the stomach relaxes to accommodate the ingested meal.
CCk participates in receptive relaxation by increasing the distensibility of the orad stomach.
GI secretion high in HCO3 and is hypotonic?
Saliva
Saliva becomes hypotonic in the ducts because the ducts are relatively impermeable to water. Because more solute than water is reabsorbed by the ducts , the saliva becomes dilute relative to plasma.
GI secretion high in HCO3 and is isotonic?
Pancreatic secretion
Hormone responsible for increased reabsorption of Na+ and secretion of K+ in salivary ductal cells?
Aldosterone
GI secretion high in HCO3 and is isotonic ?
Pancreatic secretion
Hormone responsible for increased reabsorption of Na+ and secretion of K+ in salivary ductal cells?
Aldosterone
Autonomic innervation causing increase in saliva production?
Saliva production is unique in that it is increased by both parasympathetic and sympathetic activity .
Drug that directly inhibits H+K+ ATPase pump?
Omeprazole (PPI)
Drug that blocks H+ secretion by inhibiting cholinergic muscarinic receptors on parietal cells?
Atropine
Released from neurons in the GI tract and produces smooth muscle relaxation?
VIP
Site of intrinsic factor secretion?
Gastric fundus
Intrinsic Factor is absorbed in the ileum with B12
Mechanism of diarrhea due to vibrio cholerae?
Increase Cl- secretory channels in crypt cells.
Cholera toxin activates adenylate cyclase, increasing CAMP , activating Cl- secretory channels.
Similarity of CCK and Gastrin?
Both have 5 identical C-terminal amino acids
Because CCK heptapeptide contains 5 common amino acids, it is logical that CCK should have some gastrin-like properties.
Transport process used by amino acids?
Na+ dependent co-transport
49/M with severe Crohns disease, S/P Ileal resection, now complains of steatorrhea. Reason for steatorrhea?
Micelles do not form in the intestinal lumen, impaired fat absorption.
With Ileal resection, most of the bile acids are excreted in the feces and in the liver pool is significantly diminished. Bile acids are needed for micelles formation to stabilize the products of lipid digestion.
CCK inhibits which gastric function?
Gastric emptying
CCK helps to slow the delivery of food from the stomach to the intestine during periods of high digestive activity.
Abolishes receptive relaxation of the stomach?
Vagotomy
Receptive Relaxation (VAGOvagal Reflex) of the orad stomach is initiated when food enters the stomach from esophagus.
Secretion of this hormone is inhibited by low pH?
Gastrin
Site of gastrin secretion?
Gastric Antrum
HCl and Intrinsic Factor is secreted in the Fundus.
Which vitamin /s requires micelle formation?
Vitamin A , D, E, K (Fat Soluble)
Internal anal sphincter action during defecation
Relaxed
Tonicity of the Saliva?
Hypotonic relative to plasma
Secreted in response to an oral glucose load?
Glucose-dependent insulinotropic peptide (GIP)
Effect of CCK on pancreatic enzyme enzyme secretion?
Pancreatic enzyme secretion is increased by CCK (Cholecystokinin)
Must be further digested before it can be absorbed by specific carriers in intestinal cells?
a. Fructose
b. Sucrose
c. Dipeptides
Sucrose
Only monosaccharide can be absorbed by intestinal epithelial cells.
Disaccharides such as sucrose , must be digested to monosaccharide before they are absorbed.
Resting Membrane Potential of Small Intestinal slow waves?
Oscillating membrane potentials.
The slow waves bring the membrane potential toward threshold , but are not themselves action potentials.
How does peristalsis of the small intestine occur?
Involves contraction of circular smooth muscle behind the food bolus and relaxation of circular smooth muscle in front of the bolus.
38/M with a duodenal ulcer is treated with cimetidine. MOA of drug?
Blocks H2 receptors on parietal cells
cAMP , the second messenger for histamine , would decrease.
Parietal cells secrete ? (2)
Intrinsic Factor & HCl
44/F with Zollinger-Ellison Syndrome. Can manifest similarly to what disease/ illness?
Peptic ulcer disease
ZES or Gastrinoma is one of the tumors of the pancreas.
This tumor secretes gastrin which then increases H+ secretion and contributes to formation of peptic ulcers.
Site of Na+ Bile acid co-transport?
Ileum
Secreted in the mouth , but acts in the stomach?
Lingual lipase (acid-stable)
Errors in embryogenesis that will result to chronic pancreatitis / abdominal pain but mostly asymptomatic?
Pancreas divisum
Percentage of calories expended by Basal Metabolic Rate?
60-70% of calories
Mechanism of V. Cholerae causes diarrhea?
Increases Cl- secretory channels in crypt cells
Not a neurotransmitter of GI system ?
CCK
- serotonin and dopamine are possible NTs
Repeated involuntary passing of stool into clothing by children
Encopresis
MOA of prostaglandins inhibiting gastric HCl secretion?
Inhibition of release of gastrin and histamine
Characteristic of Gastric HCl? (3)
- pH of 0.8
- Secreted at rate of 160 mmol/L
- Hydrogen concentration 3 million x higher than arterial blood
Biologic activity of Gastrin and CCK resides in?
C-terminal tetrapeptide amide sequence
Carbohydrate absorption begins in the ?
Small intetsines
-Carbohydrate DIGESTION begins in the mouth because of ptyalin
Converts primary bile acids to secondary bile acids in the intestines?
Bacteria
Gastrin acts on these cells?
Parietal cells on the Oxyntic glands found on the body and fundus of the stomach.
Secreted by pancreatic alpha cells?
Glucagon
Insulin stimulates / targets the following organs for glucose uptake? (3)
- Liver (hepatic)
- Skeletal muscle
- Adipose (not brain)
Stages of swallowing? (3)
- Oral Phase
- Pharyngeal Phase
- Esophageal Phase
Mechanism of Achalasia?
- Progressive degeneration of ganglionic cells in the myenteric plexus of esophagus
- LES does not relax during swallowing
- Loss of peristalsis in the distal esophagus
Amino acids that triggers Gastrin Secretion ?
- Phenylalanine (F)
- Tryptophan (W)
- Methionine (M)
MWF
Stomach action for mixing food ?
Peristalsis
Food that enters the small intestines?
Chyme - partially digested food due to stomach action
Stimulates parietal cells in oxyntic glands in the body and fundus of stomach for HCl secretion , growth of gastric mucosa.
Gastrin
Protects gastric mucosa from HCl?
Prostaglandins
Synonymous with enterochromaffin cells ?
Kultchitsky cells (Secrete serotonin)
Location of GI kulchitsky cells? (3)
- Small intestines
- Colon
- Appendix
Patient with Zollinger -Ellison Syndrome (ZES) would likely present with?
Severe PUD
Ranitidine inhibits?
H-2 receptors
Bleeding in the subcutaneous area can cause death if it is in the ?
Liver
Small intestinal contraction fasting ?
Peristaltic contraction
Normal daily K intake? (4)
3,400mg adult males
2,600 mg adult females
2,900mg pregnant women
2,800mg lactating women
Contains skeletal muscles instead of smooth muscles?
- Pharynx
- upper 1/3 esophagus
- External anal sphincter
Relaxes LES, PS, ICV, Orad, Stomach , Bronchial smooth muscles?
VIP ( Vasointestinal Peptide)
Also called the second brain , since it utilizes neurons and neurotransmitters similar to the CNS?
Enteric Nervous System
- local innervation/ intrinsic innervation of the GIT
Contracts muscularis mucosa?
Meissner Plexus (Submucosal Plexus)
Sight, Smell ,Thought of food causes HCl secretion?
Cephalic Phase
Contracts muscularis mucosa?
Meissner Plexus ( Submucosal Plexus)
Where is iron absorbed in the small intestine?
Duodenum
Protein -energy malnutrition with (+) edema: __________
Kwashiorkor
BMI of obese persons?
> 30
Inactivated at gastric pH >5.0 ?
Pepsin
Allows the absorption of nutrients across the small intestinal epithelial brush borders by secondary active transport with sodium?
Fatty acids
Intrinsic Factor is secreted in this part of the stomach?
Gastric fundus
Location of Chief cells that produces HCl & IF
Gastrinoma associated with peptic ulcer disease?
Zolinger Ellison Syndrome
May spark hypertensive crisis?
MAOI and Tyramine rich foods
Has the greatest percentage of cells in the Islets of Langerhans?
Beta cells ( produces insulin)
Elevated serum anion gap occurs when unmeasured anions leads to the substitution of HCO3. What are these anions? (4)
B-hydroxybutyrate
Formate
Phospate
Lactate
High! BF ko Po paLa