Physiology -- Gastric Secretion Flashcards
Volume of mixed gastric juice produced per day
1.5 - 2 L/d
Ionic composition of mixed gastric juice
- Na+
- K+
- Cl-
- H+
Isotonic*
pH of mixed gastric juice
1 - 2
Proteins found in mixed gastric juice
- Pepsinogen
- Intrinsic factor
- Mucin
Composition of fluid secreted by cardiac and pyloric glands
Alkaline, mucin-rich fluid
Location of main gastric glands
Fundus and Corpus
Cells of gastric glands that secrete HCl
Parietal (oxyntic) cells
Cells of gastric glands that secrete pepsinogen
Chief cells (zymogenic)
Cells of gastric gland that secrete mucin
Mucous neck cells
Describe the ionic concentrations of the various maxied gastric juice ions based on the secretory rate of this substance
Explain the 2 component theory of gastric secretions
Comprised of non-parietal (secrete small volume) and parietal components (secrete large volume)
Ions secreted by non-parietal cells
- Na+
- K+
- Cl-
- HCO3-
Quantitty of Na+ secreted by non-parietal cells
150 mEq/L
Quantity of K+ secreted by non-parietal cells
10 mEq/L
Quantity of Cl- secreted by non-parietal cells
115 mEq/L
Quantity of HCO3- secreted by non-parietal cels
45 mEq/L
Resultant pH from non-parietal secretions
pH = 7.6
Quantity of H+ secreted by parietal cells
150 mEq/L
Quantity of Cl- secreted by parietal cells
150 mEq/L
Resultant pH of parietal secretions
pH = 0.8
At low rates, what is the contribution of parietal cells?
Low
At high rates of secretion, what is the contribution of parietal cells
High
Where does HCl secretion occur in the parietal cell?
Canaliculi
Describe the role of Cl- in the canaliculi
Cl- actively transported across canalicular membrane (yellow)
Describe the role of H+ in the canaliculi
H+ available from dissociation of intracellular water (green) is actively pumped into canaliculi in exchange for K+ (blue)