• endpiece
• myoepithelial cells
• intercalated cells
• striated duct
• excretory duct

• blind sac lined by pyramidal (acinar) or tubular cells
• can either be serous or mucus in type

• stellate shape
• innervated by sympathetic nervous sytem
• contraction accelerate flow of saliva
• function- prevent distension of endpiece and extravasation of saliva

• low cuboidal epithelium
• lined by elongated myoepithelial cells
  • lie parallel to duct

• simple columnar epithelium
• infoldings of basement membrane and presence of columns of mitochondria
  • striations in basal aspect of cells
• ionic composition and osmolarity of saliva is modified in duct

• columnar epithelium
• function- modifies secretion

• reabsorption of sodium
• absorption of chloride
• potassium secretion exchange for sodium
• bicarbonate secretion exchange for chloride

LOW permeability of duct cells of water

Saliva becomes hypotonic

• increasing flow rate will increase osmolality
  • decreased reabsorption of sodium and chloride
  • concentration of potassium and bicarbonate exceeds that in blood

• basolateral side
  • Na/K pump
  • Na/Cl cotransport
• Na paracellular transport into lumen
• apical side
  • potassium channel
  • bicarbonate channel
  • chloride channel

• basolateral side
  • Na/K pump (Na out, K in)
  • Cl channel (Cl into blood)
• apical side
  • Na/Cl cotransport (into cell)
  • Cl/HCO3 (Cl into lumen, HCO3 into cell)
  • Na/K antiport (Na into cell, K into lumen)

• low volume output
• transient
• protein rich
• high K and HCO3

• large volume
• watery
• protein poor
• lower K and HCO3

If denervated, we would get decreased secretion and glandular atrophy. It appears parasymp. provides most important control of secretion.

• protective (mucus, antibacterial action)
• enzymes (amylase, lipase)
• lubrication (mucus)

• oxyntic gland (upper 2/3)- secrete acid, mucus, pepsinogen
  • fundus
  • corpus/body
• antrum (lower 1/3)- secrete mucus, gastrin, somatostatin, pepsinogen

• HCl
• K
• IF
• water

• pepsinogen
• water

• mucus
• bicarbonate
• sodium
• potassium
• chloride
• water

• lubricates ingested food
• coats surface of stomach
  • provide barrier between acid in lumen and epithelial cells

• used as an index of non-parietal cell ion secretion

• causes the alkaline tide
• this will raise the blood pH locally

Part of gastric mucosal barrier

1. Na/K pump (Na into blood, K into cell) cause low conc. of Na and high conc. of K in cell
2. potassium in cell moves down its gradient into the lumen (lumen negative potential), than it is put back into cell via H/K pump (H into lumen, K back into cell)
3. H2O and CO2 via CA produce H2CO3 which dissociates into H and HCO3
4. HCO3 goes out of cell and Cl goes into cell via antiport producing alkaline tide
5. Cl move into lumen
6. combines w/H to form HCl

• alkaline tide (via HCO3/Cl antiport)
• layer of mucus coats epithelial cells
  • contains bicarb that neutralizes acid
  • creates pH gradient btw lumen and adjacent cell
• morphology of surface cells
  • tight junction btw cells barrier to H and cells can neutralize intracellular H
• mucusal blood flow increases during acid secretion
  • ENS increases blood flow upon mucosal damage
• cell turnover- upon damage to surface, there is immediate re-epithelialization of injured area

• histamine from ECL cells in fundus and antrum
• gastrin from G cells in antrum
  • stimulate somatostatin secretion from D cells in antrum and fundus
  • stimulated BY peptides, AA's
  • stimulated BY GRP from vagus N.
  • stimulates ECL cells to secrete histamine
• ACh from vagus N.

• somatostatin from D cells
  • stimulated by antral acid
  • inhibit ECL cells from secreting histamine
  • inhibit G cells from secreting gastrin 
• antral acid

1. release ACh and gastrin to stimulate pepsinogen release
2. in presence of acid, pepsinogen converted to pepsin
3. protein is broken down into peptide and AA
4. peptide and AA stimulate G cells to release more gastrin

1. cephalic
2. gastric
3. intestinal

• mediated by vagus N.
  • ACh release stimulate parietal cell to release HCl
  • GRP release stimulate G cells to release gastrin
  • inhibits D cells from somatostatin
• accounts for 30% of total response to meal
• initiated by sight, smell, taste, thought of food
  • mimic by sham feeding, hypoglycemia, interference of glucose metabolism

• initiated by arrival of food in stomach
• mediated by gastrin
  • released in response to presence of protein digested products in stomach
• swallowed food distends stomach, activating neural reflexes
  • vagovagal reflex- GRP and ACh released
  • local reflexes- activated by stretch receptors and use intramural fibers in wall of stomach
• accounts for 50% of total response

• initiated by arrival of food in duodenum
  • inhibitory to acid secretion
• 5% of total response to meal
  • digested protein in duodenum releases a small amount of gastrin
• inhibition of gastric secretion via:
  • secretin
  • CCK
  • GIP
  • enteroglucagon
    • activation of neural reflexes following entry of chyme in duodenum

• gastrin is a trophic hormone
• if it continues to secrete, it could cause cancer

• reduce acid secretions
  • H2 antagonists
  • proton pump (H/K ATPase) inhibitors
  • antacids
  • anticholinergics
  • PG's (also enahcne mucosal barrier)