Oral Gastric Biochemistry Flashcards
Purpose of saliva
Provides lubrication that aids in swallowing
Aids in the digestion of food and enzymatic cleavage
Produces growth factors for epithelial cells
Neutralizes bacterial acids
Mediates taste sensations
Provides defense against bacterial pathogens
Neve for parotic
Glossopharyngeal XI
nerve for sublingual/submandibular
Facial VII
Primary secreation from saliva
pytalin, alpha amylase, mucus, extracellular fluid
In saliva, what is abosorbed?
Na+ actively
Cl- passively
In saliva what is secreated?
K+ activly
HCO3- passively
Role of Lysozyme (part of saliva)
Kills gram positive but not gram
negative bacteria
Cleaves beta 1-4 linkages between NAM and NAG in GRAM POSTIVE bacterial
Cleave beta 1-4 links in in chitodextrins (fungus)
Enzyme that kills bacterial by producing reactive bromide and iodine molecules
Peroxidase
Protein that binds iron and prevents bacterial and some fungal growth
Lactoferrin
Secretory immunoglobulins that upon recognition and binding to bacteria induce
immune reactions
IgA
Antimicrobial polypeptides that form pore complexes on microbial cell membranes
Defensins
Large highly glycosylated proteins that modulate adhesion of bacteria to oral tissues
including teeth
Mucins
Saliva contains Mucin which functions in:
Lubricants
Antimicrobial
Found throughout the GI tract
Highly O-glycosylated specific glycoproteins
Whats important about high HCO3- in saliva?
High HCO3 Neutralizes bacterial produced acids
Is there a lot of Na or Cl- in saliva?
nope
Shit that can carry viruses in saliva
Human Herpes Herpes Simplex Epstein Barr Mumps Rabies HIV
Xerostomia is caused by what two pathologies
Cystic fibrosis
–Mutant chloride transporters to plasma
Sjögren’s syndrome
–Autoantibodies to salivary gland proteins
What happens in cephalic phase of gastric secreation?
occurs from vagaus–> Ach–> causes secraetion of pepsin (chief) and acid (parietal)
What occurs in teh Gastric Phase
Local nervous secreatory reflexes
vagal reflexes
Gastrin-histamine stimulation
What happens during the intestinal phase?
Nervous and hormonal mechanisms
The VAgus nerve stimulates the relesase of what two things?
Acetycholine and Gastric relesase peptide
What does Ach cause stimulation of?
inhibition of?
Ach stimulates: Parital cells–> HCl and ECL cell –> histamine
Ach inhibits: D Cell–> somatostatin
Gastric releasing peptide stimulates secreation of waht?
G cell (antrum) to release Gastrin
What stimulates D cells to release Somatostatin?
HCl
What inhibits D cells from releasing SST
Acetycholine
Somatostatin inhibits secreation of what three things?
Gcell–> gastrin
ECL–> histamine
Parietal cell–> HCl
What stimulates G cells to release gastrin?
What inhibits it
GPR
inhibited by SST
Gastrin stimulates the release of what three things
D cell–> somatostatin
ECL–> histamine
Parietal Cell–> HCl
What stimulates and inhibits ECL cells to release histamine?
Stimulated by Ach
inhibitd by SST
What 1 thing does histamine stimulate the release of?
Parietal cell –> HCl
What 3 things stimulate release of HCL from parietal cells?
ACh, Histamine, Gastrin
Stomach acid content (H+) will ______ within an hour of eating a meal
drop, thus pH will rise
When do we see a rise in H+ secreation after a meal?
starts to rise about the same time it drops (d/t food buffering) so around 1 hour and peaks at 3
Role of IF?
VitB12 absorption
What digests fats?
salivary lipase from salivary glands
Gastric lipase from chief cells
Pepsinogen for protein digestion and is secreated from:
secreation induced by:
activated by:
Chief Cells
Secretion induced by acetylcholine (vagus and myenteric nerves),gastrin (G-cells), secretin (duodenum) and cholecystokinin (duodenum)
Activated by HCl or Pepsin via accessing active site
Mucous cells in stomach are made of
mucins, phospholipids, electorlytes, water
Funxtion of mucous in stomach
protection, lubriation
How does mucous protect stomach?
HCO3; Neutralizes acid within mucous and is Released by superficial epithelial cells
Mucins also protective
What relseases HCO3 in stomach
superficial epitherlial clls
Stomach fnx in storage by
Food in concentric circles stretches the stomach causing _____to relax stomach wall
“vasovagal reflex”
Secreted digestive enzymes mixed with food by weak peristalic constrictor waves (mixing waves) initiated at _____stomach wall and propagated to the antrum
mid to upper
_____muscle contraction pushes food towards the mid stomach
Pylorus (retrograde)
How much food is released to duodenum at a time?
Only about a few milliliters of food is released into the duodenum (chyme)
When empyting the stomach:
Intense peristaltic contractions in stomach antrum begin in_____and propagate
mid-stomach
As stomach empties, the contractions start
further up the stomach wall
In stomach:
Stretching of the stomach wall by food
stimulates_____ reflexes to increase
activity of pylorus pump to empty stomach
myenteric
IN stomach emptying:
____ stimulation of the pylorus pump.
Gastrin
In Duodenum to control emptying of stomach:
Duodenum nerves send signal in response to
wall distension, mucosal irritation, and chyme
acidity and osmolality
Duodenal Signals sent through the____ nervous system, extrinsic nerves and vagus nerves in parallel to inhibit stomach contractions and increase tone of the pyloric sphincter.
enteric
