Salivary Secretions Flashcards
What is lactoferrin?
Iron collator that removes iron from the mouth, which then prevents bacteria growing as they require iron
What is Xerostomia?
A condition of which symptoms include a dry mouth and an increased number of cavities, due to a reduced amount of salvia. Usually a system of a condition such as radiation to the head in cancer.
What are the 3 major salivary glands?
- Submandibular (70% sero-mucin)
- Parotid (25% serous)
- Sublingual (5% mucin)
How much saliva is secretion in a day?
1,500mL/day
What is serous?
A watery solution containing high amounts of proteins secreted from serous cells
What is mucin?
Glycoproteins that are highly viscous and secreted from mucin cells
What are acini?
Clusters of epithelial cells
What is a salivon?
Salivary duct, which is a blind end acinus, made up of acinar cells. They secrete primary secretions
What are myoepithelial cells?
Cells that surround the epithelial cells, which contain smooth muscle which contract/relax influencing the rate of the secretion
What are the main constituents of saliva?
Water, electrolytes and enzymes
- Na+ and Cl- are lower in the saliva than the plasma
- K+ and HCO3- are higher in the saliva than plasma
As saliva moves through the ductal system, secondary modification occurs, during the stage, what happens to the ionic composition?
Na+ and Cl- are reabsorbed from the duct
K+ and HCO3- are secreted back into the duct, to a lesser extent that the reabsorption Na+ and Cl-
What is expected as ions leave the duct?
Water would follow by osmosis
Why is it more more difficult for water to follow ions by osmosis in the ductal system and how is this solved?
Ductal epithelium has a low water permeability making it more difficult for water to follow. So during secondary modification, the solution becomes hypotonic, so has lots of water but a low electrolyte concentration
What happens to the composition of saliva at low flow rates?
More time available for reabsorption/secretion, saliva is hypotonic
What happens to the composition of salvia at high flow rates?
Less time available for reabsorption/secretion - composition approaches primary secretion, more similar to plasma
What nervous is dominant in saliva secretion?
Parasympathetic, the saliva tends to be waterier
Mechanism behind parasympathetic control
Parasympathetic control uses the NT ACh acting on the muscarinic receptors, this controls the myoepithelial cells increasing saliva flow rate. VIP is released, which causes vasodilation and increases blood flow and oxygen delivery to the salivary glands, increasing secretion.
Mechanism behind sympathetic control
Sympathetic control uses the NT, A and NA acting on adrenoceptors, contract myoepithelial cells to decrease saliva flow rate.
What does the cephalic reflex do to saliva production?
The thought of food stimulates the secretion of saliva via the ANS
What inputs from the salvia centre increase secretions?
Smell, tactile, chewing and taste
What inputs from the saliva centre decrease secretions?
Fear, mental effort and dehydration
What is siaolithiasis?
Calcified mass in the salivary gland. Majority cause no symptoms but larger can cause pain and discomfort by interfering with the flow of saliva. Antibiotics and analgesic treatment, siaendoscopy, basket retrieval and salivary lithotrisy
What id sialaddenitis?
Infection of the salivary gland, causes by virus/bacteria. Parotid/submandibular gland most commonly affected. Pain, tenderness, swelling.
Treatment include antibiotics, fluid hydration and electrolyte management
What is Siogren’s syndrome?
Long term autoimmune disease in which the moisture producing glands of the body are affected. Combination of genetic factors with an environmental trigger, cause unclear. Dry mouth, dry eyes, dry skin and tiredness.
Which is the largest of the salivary structures?
Parotid glands - secretes a fairly watery saliva, other 2 secreted a more viscid saliva
Where are other small salivary glands located?
Covering the palate, buccal areas, lips and tongue
What is the origin of salivary glands?
Ectoderm layer
What is the blood supply to the salivary glands?
Distributed by branches for the external carotid artery. The direction of arterial blood flow within the substance of each salivary gland is opposite to the direction of he flowing saliva. Arterioles break up around each acini to form capillaries
