Saliva and Salivary glands Flashcards
Name the 3 major salivary glands?
Parotid, Submandibular, sublingual
Functions of saliva? (6 answers)
Digestive Antibacterial Mineral protection Lubricate Taste Hormone production
Hypotonic or isotonic??? Parotid, Submandibular, sublingual
Hypotonic, Hypotonic, Isotonic
Serous or mucous??? Parotid, Submandibular, sublingual
Serous, Mixed (mainly serous), Mucous
minor glands are essentially 100% ………………….. with one exception.
mucous
In the dorsum of the tongue beneath the circumvallate papillae, the …………. are minor serous producing glands
glands of Von Ebner
Serous cells produce a ……………..
watery protein-rich fluid
mucous cells produce a more viscous……………..
mucin-rich product containing proteins linked to a greater amount of carbohydrate
Composition of saliva……………
Saliva is over 99% water, yet the very small amount of additional inorganic and organic compounds
Composition of salivary glands………..
they are compound, tubulo-acinar structures.
The primary functional units ……………….
being a combination of tubules and globe-like secretory units called acini.
composition of salivary glands what does the term compound refer to?
a salivary gland is made up of multiple secretory units with their tubules entering a main duct.
What does the duct system do?
modifies and transports the saliva to be finally secreted on to a free oral mucosal surface
salivary glands are described as?
exocrine
Non spontaneous secretor glands?
Parotid, Submandibular
Spontaneous secretor glands?
Sublingual
Glands where the collecting ducts end in single main duct
Parotid, Submandibular
Glands where the collecting ducts end in many main duct
Sublingual
Glands that have striated ducts present?
Parotid, Submandibular
Sublingual gland and part of the submandibular, the mucous regions of the gland, the acini are more……
in the form of tubes rather than spheres
In mucous region of the gland the acini essentially form their own duct system, meaning……..
There are no intercalated or striated ducts in the mucus areas of the gland.
A frequent feature of mucous acini is the presence of….
a ‘cap’ of serous secreting cells termed a ‘serous demilune
what part of the NS controls salivation?
autonomic NS
Are salivary glands exocrine or endocrine?
EXOcrine, thus have ducts associated with them
Location of Parotid gland?
right in front of the ear behind the mandible
postion of parotid ducts?
Through the MASSETER piereces the BUCCINATOR, opens up on the cavity on cheek opposite to U6
Blood supply of parotid
Braches of the EXTERNAL carotid artery
Nerve supply of parotid
glossopharyngeal nerve (9)
synapses at OTIC GANGLION
post-ganglionic nerve fibres travel via the AURICULO-TEMPORAL NERVE (V3 of trigeminal nerve)
insert into parotid
Does the facial nerve innervate the parotid
no simply passes through the protid on its way to facial muscles but does not innervate it
location of submandubular glad
under the mandible (one either side)
how many submandibular duct are there
One discrete duct
nerve supply of submandibular and sublingual?
draw the pathway?
FACIAL nerve (7) branch called CHORDA TYMPANI and branch of LINGUAL nerve (branch of V3) both synapse at the SUB-MANDIBULAR GANGLION the post-synaptic ganglionic fibres insert into submandibular and sublingual glands
Location of sublingual glands
under the tongue anterior to sub mandibular duct
what are the glands of von ebner
Location of glands in circumvallate papillae on the dorsal surface of the tounge
serous secrection
nerve supply: glossopharngeal nerve
what are ‘secretomotor cells’
nerve fibers which cause salivary gland secrection
what percentge secrection by the 3 main salivary gland
submandibular: 70%
Parotid: 25%
sublingual: 5%
on avergae day how much saliva is secreted
1,500 ml/day
Struture of salivary duct
- secretory epithelial cells arranged into a bundle= acini
- acini cells surrounded by myoepithelial cells
- the intercalated duct connects the acinus with the striated duct
- secondary modification occurs in striated duct
- excretory duct=saliva secreted
function of myoepithalial cells
contains smooth muscle which contracts= alters the flow rate of saliva
Ionic composition of saliva compared to plasma…………
HCO3- and K+ HIGHER in saliva than plasma NA+ and CL- LOWER in slaiva than plasma
Saliva is intilly …….. , as its composition changes, it becomes,………
intially isotonic- primary secretion
hypotonic- secondary secrection. more ions less water
NA entry and exit in salivary ducts……
NA enters across apical membrne via:
- ENac Na+ transporter
- Na-H exchange
NA exists across the basolateral membrane via:
Na-K pump
Cl- entry and exit in salivary ducts……..
CL- enters across apical membrne via:
Cl-HCO3 exchanger
more Cl exists across basolaterl membrane into intersitil fluid via: -Cl- ioin channels
HCO3 entry and exist?
enters on basolateral side dont know how
exits on apical membrane of cell via: CL-HCO3 exchanger
K+ entry/ exit
enters on basolateral side via:
Na-K pump
Exists on apical membrane side via K-H exchanger
the final composition of saliva is DEPENDANT onSALIVA FLOW RATE why??
more time for secondary ductal modification
Which Ion secrection is NOT dependent on saliva flow rate
Bicarbonate- it is strongly influenced by STIMULI causing the increased flow rate of saliva thus even at high flow rates, the HCO3 concentration is always high due to it function as a buffer to protect in acidic enviroment
Ehat is the evidence for 2 stage hypothesis
- mapping flow rate curve
- acinar/intercalated duct micropuncter
- poly-lysine injection- poison duct, there is no secondary re-absorbtion process
Saliva is dependent on the autonomanic NS. the composition is different is stimulation is via parasympathetic NS how??
para:watery saliva with MORE volume
Symp: rich in enzymes, but SMALLER volume
where in the brain is the salivary centre
Hypothalamus- responds to taste, smell, chewing
also have the higher centre which respond to dehydration, fear, mental effort = dry mouth
Hormones lso control saliva secrection, which hormone?
aldosterone
what ion in saliva does aldosterone affect?
NA+
high aldosterone= low salivary na+
low aldosterone (addinson disease) = high salivary na+
name all the organic components of saliva?
lg
Statherin
PRPs
Histatin
Lactoferrin
cystatin
mylase
lysosyme
peroxidase
core structure of N-linked sugars
3 mannose
2 N-acetly-glucosamine asparagine
further sugars are added to this common core such as sialic acid, galactose
sialic acid is commonly found in the oligosaccharide component of salivary mucins. what is another word for sialic acid?
n-acetlyneruaminate
what is the generic srudture of a mucin monomer
- 1 carboxyl and amino terminal that are rich in CYSTEINE residues
- a repeat structure of 10-80 aa that is high in serine/threonine= saturted with O-linked oligosaccharides
salivary secrection contain 2 distinct mucins- MG1 and MG2. decribe features of MG1?
- 1MDA
- made of many mucin monomers joined by s-s bonds
- mixture of 3 gene products
- produced in different amounts by different salivary glands
- can complex with other proteins( amylase, histatin, PRPs)
Muncins are glycoproteins that can have an o/n - linked sugars attched to them during post-translation modification
what is the difference between o/n - linkeds sugars
o- linked suagrs are added to serine or threonine residues within the mucin polypeptide chain
N -linked sugars are added to the amide nitrogen of the side chain of asparagine residues within the mucin polypeptide chain
salivary secrection contain 2 distinct mucins- MG1 and MG2. decribe features of MG2?
- only 250 kDa
- one monomer
- 1 gene product
- produced in different amounts by different salivary glands
- binds to candida albicans and steptoccoci and other perio pathogens
Functions of Mucins
lubrication
physical barrier againsit colonisation: they can form a permeable diffusion barrier between oral and external enviroment
MG2 can kill oral bacteria and candida alnicans
bind tooth and soft tissue surfaces… may play a role in directingg bacterial colonisation to these surfaces
What is the typical PH in adults
neatural pH 7
- more alkaline in babies
- depend on flow rate
at what pH does HAP dissolve/ de mineralisation (stephen curve)
below pH 5.5- critical pH
why does pH fall after eating a meal?
fermentation of carboyhates by plaque micro-organism produces ORGANIC acids
how is pH restored back to neatiiral so the HAP can re-mineralise
salivery buffer properties
how long does it take for pH to be restore back to normal?
20-49minutes?
the effect of surcrose on plaque was shown via…
telomeric data from lmfeldt
what are the key findings from lmfeldt and co.data
- the grter the amount of surcrose given the lower the resulting plaque
- the longer the acidic pH, the more HAP will dissolve
- as saliva flow rate increase= the buffering capacity also increase
list all the inorganic componenets of saliva?
H+ ions
Bicarbonate (HCO3 -) ions
Na+ ions
K+ ions
MG2+ ions
Ca2+ ions
Phosphate ions
Fluoride Fl- ions
what is the impotance of bicarbonate ions and why are they able to perform this function?
- important buffer system of saliva
- pKA= 6.1 therefore at pH 6.1 the concentration of H2CO3 is equal to HCO3 (carbonic acid=Bicarbonate ion)
cocnentration of bicarbonate ins timulated and unstimulated saliva
60mM= stimulated saliva
1mM= unstimulated saliva
function of carbonic anyhdrase in salivary glands
generates carbonic acid… therefore bicarbonate
carbonic nhydrase found in salivary pellicle
what is the concentration of carbonic acid in plasma
stable at 1.3 mM equilibrium with the alveolar carbon dioxide concentration
sodium is the counter ion for
bicarbonate
potassium is the counter ion for
phosphate
function of both sodium and potassium
to preserve the electrical neutrality
salivary sodium concentration in stimulated and un sitmulated saliva
increases when saliva flow rate increses
stimulated: 30 mM
unstimulated: 6mM
salivary potassium concentration in sitmulated and unstimulated saliva
remains constant as salivia flow rate increase
stimulated/unstimulated: 14-32 mM
why does salivary potassium concentration remain constant?
potassium is added to ductal fluid throughout their passage through the duct
salivary magnesium concentrations in stimulated and unstimulated salivia
Decrease already low at unstimulaated: 0.4mM
stimulated: 0.2mM
dilution effect
origin of mg2+ ions in saliva
not identiified
- cellular degradtion within oral cavity
- from the dissolution of mineral
salivary Calcium
in simulated and unstimulated saliva
calcium can exist in pure form/complexed to proteins/other ions
pure ca2+ in unstimulated saliva: 1-2nM
genrally remains contant in simulated saliva as well
Which gland have high Ca2+ and which one has low?
submandibular high ca2+
parotid low ca2+
what is the fuction of ca2+ in saliva
maintaining HAP re-mineralising it and preventing dissolution
what is the function of phosphates in saliva
- buffer especially in UNSTIMULATED saliva
- repaire HAP and inhibit dissolution (alongside ca2+)
concentrtion of phospates depending on flow rate?
varies from 2-13mM depending on flow rate INORGANIC orthophosphate concentration DECREASES with salivary flow rate
why does inorganic othophosphates concetration decrease with incres salivia flow rate
phosphate is added actively as it passes through the ducts- if fast moving daliva less time to add phosphate
HAP will spontaneously ……….. out of solution when its ….. product is ………
precipitate
solubility
exceeded
govered by the concentration of it constituent ions in solution (ca2+, phospate and hydroxly ions)
so at low concentrtions of ca/phosphate, HAP will spontaneously
dissolve
so at normal levels of ca/phospahte, HAP will spontaneously
re-precipitate
saliva is superstaurated with respect to HAP at neutral pH. what does super saturated mean?
saliva contains OVER teh threshold/sufficient ions of a given salt for its spontaneous precipitation to occur
why does pH have such a profound effect on the soluility product of HAP
the protonation of the phospate group in pH dependant
symbol for orthophospate
PO43-
in acidic conditions the phophate group will be…
increasing protonated - H3PO4
and vice versa
fluoride ion concentration in saliva is….
0.001-0.005 mM varies very little with flow of saliva
the fluoride ion concentration is hgiher in plaque than in saliva. how does fluoride affect HAP
replaces the OH in HAP to make a more stables mineral that is less soluable in acid, promots the rapir of HAP mineral
example of a weak acid
acetic acid
Ka =
h+ x conjugate base/weak acid
it tells us the degree of dissociation to determin if weak or strong acid
pH=
- log (H+)
pKa=
-log (Ka)
henderson- hassebalch equation
pH = pKa +log (conjugate base conc. /acid conc.)
define buffer
molecules that resist pH changes by the small addition of acs or base to a system
usually mixture of weak acid/ its conjugate base or weak base and conjuate acid
midpoint of titration tells us
where the buffer system buffers- can extend 1pH unit either side of the pKa value
titration
What is the midpoint
point where pH = pKa
when the conjugate base concentration is higher then this buffer is good at buffering
added acid
when the acid concentration is higher then this buffer is good at buffering….
added bases
how is INTRA-cellular pH maintained at 7.4
phosohate and histiidine side chain or proteins
how is EXTRA-cellular pH maintain at 7.4
the bicarbonate buffer system
name the 3 buffering systems in saliva
- bicarbonate- most important in stimulated saliva
- phopsphate
- proteins- histidine chains
