Physiology Secretion Flashcards
Name the three major classes of secretions.
Lubricants - water (dilution), mucus (protective effect)
Chemicals - enzymes, acids, electrolytes (sodium/chloride)
Controls - hormones (endocrine, paracrine in small amounts)
Name the classification of GI secretions.
Exocrine (chemicals, water and mucus - lubricants)
Endocrine (hormonal secretions)
Give examples of some endocrine secretions.
Gastrin, secretin, CCK, GIP, somatostatin
What secretes the peptide hormones?
Enterochromaffin cells in mucosa
What is the function of endocrine secretions?
Co-ordinate and control motility and secretion.
When are endocrine secretions secreted?
Usually in response to luminal contents
List examples of exocrine secretions.
Water/electrolytes, mucus, enzymes
What is the function of exocrine secretions?
Prepare food for absorption by dilution, optimizing pH and digestion.
Lubricate luminal contents.
Protect mucosa
How many litres are secreted into the GIT lumen/day?
8 litres
Where does secretion via epithelia take place?
At the interface
Name the two cells involved in secretion at epithelia.
Asymmetrical cells - apical and basolateral cells
Which cells secrete HCl?
Oxyntic cells
What affects the secretion via epithelia?
If the junctions between the cells are tight or leaky
Tight junctions are more selective and occur at distal epithelia
What happens to the secretions in the lumen of the GIT?
Remember the lumen is the outside world.
Secretion results in a loss of fluid unless reabsorption takes place.
What is the main secretion of the salivary glands?
Mucus
Alpha amylase
