Cellular Processes [Chloride Secretion] Flashcards
Description of Chloride Secretion (include the transporter, sodium)
A cotransporter in the basolateral membrane accumulated Cl- above its gradient. This enables it to leave the cell via a channel in the apical membrane. Sodium moves paracellular w H2O to preserve electroneutrality.
Step 2 of chloride secretion
Sodium pump sets up ion gradients
Step 3 chloride secretion
The NaK2Cl symporter uses the energy of the Na+ gradient to actively accumulate Cl above conc gradient.
Entry step.
Step 4 chloride secretion
Cl- leaves the cell by passive diffusion through an ion channel.
Exit step.
Step 5 chloride secretion
Na+ exits via the basolateral sodium pump and K+ exits via its channel.
This makes the gradient more -ve, attracting Cl.
Step 6 chloride secretion
Cl- transport induces Na+ and H2O movement paracellular into the lumen.
How is cystic fibrosis caused?
Chloride channel responsible for Cl exit is defective.
The two stages of sweat formation
- Primary isotonic fluid secretion by acinar cells.
2. Secondary reabsorption of NaCl to produce a hypotonic solution.
How is cystic fibrosis sweat formation different?
The failure of epithelial cells in the ducts of sweat glands to reabsorb NaCl produces salty sweat.
4 ways of clinical management for cystic fibrosis
Chest percussion
Antibiotics
Pancreatic enzyme replacement
Nutrition
Cystic fibrosis - airways
Clogging and infection of bronchial passages. Can cause lung disease.
Cystic fibrosis - liver
Plugging of small bile ducts impedes digestion in 5% of patients
Cystic fibrosis - pancreas
Occulusion of ducts prevents the pancreas delivering enzymes for digestion to the bowel. Can diabetes.
Cystic fibrosis - small intestine
Obstruction of the gut by thick stool. Surgery in newborns.
Cystic fibrosis - reproductive tract
Absence of fine ducts. Infertile. Occasionally women’s mucus blocks sperm.
