Salivary Glands (continuation of oral environment) Flashcards
what are the two main elements that make up the salivary glands
parenchyma and stroma
what is the parenchyma
glandular secretory tissue
what is the stroma
supporting connective tissue
where are the contractile myoepithelial cells of the salivary glands located
between the basal lamina and the basal membranes of the acinar secretory cells and intercalated duct cells
what branch of the nervous system controls saliva secretion
the autonomic nervous system
what do the parenchyma cells produce
primary saliva
where do the ducts of the salivary glands open into
the oral cavity
why are salivary glands described as compound
more than one tubule entering the main duct
what is released from the salivary glands into the oral cavity (the answer is not just saliva)
only the secretions of the cell are released
why are salivary glands described as merocrine
only the secretion of the cells are released into the oral cavity
what are salivary glands dependent on for function
afferent stimulation
what is the major role of salivary glands related to - the answer isnt saliva
their major function is related to the production of mucin which acts as a lubricant during mastication
what is the function of mucins in the oral cavity
act as a lubricant during mastrication, swallowing and speech. mucin also aids pellicle formation and remineralisation
what are peptide growth factrors produced by
the submandibular gland
what are peptide growth factors believed to be involved in
wound healing alongside mucin
describe the basic anatomy of salivary glands
- exocrine
- main regulated secretion is caused by reflex parasympathetic and sympathetic stimulation
- acinar secretory cells which are either serous or mucous
- major and minor
what do acinar cells produce
primary secretion which is either serous or mucous, which is modified as it passes down the ducts
what are the three major salivary glands
parotid
submandibular
sublingual
where are the minor salivary glands located
scattered throughout the oral mucosa
what is cystatin
an inhibitor of harmful cystein proteinases produced by bacteria and dying neutrophils
what are some antibacterial agents found within the oral environment
lysozome
histatin
lactoferrin
defensins
what is statherin
an inhibitor of mineralisation
what is gustin
a detector of taste
what is amylae
a polysaccharaide hydrolysing enzyme
what do septa do in the salivary glands
they subdivide the gland into major lobes which are further subdivided into lobules
what does each lobe of the salivary glands contian
numerous secretory units consisting of clusters of grapelike structures called acini positioned around a lumen
do serous cells secrete more or less protein than mucous cells
more protein
do serous cells secrete more or less carbohydrates than mucous cells
less
why are there capsules surrounding the salivary glands
protection
what do the acinus empty their secretions into
via the lumen, they empty into the intercalated duct which is lined with cuboidal epithelium, which joins a larger striated duct formed from columnar cells
which ducts within salivary glands are intralobular, affecting the compositiion of the secretion passing through them
the intercalated and striated ducts
what do striated ducts empty into
collecting ducts
what do the collecting ducts join to form
the main duct
where is the main duct located on the salivary glands
the hilum
what is the function of the main salivary gland duct
carry the saliva to the mucosal surface and may be lined near its termination by a layer of stratified squamous epithelial cells
what carries the blood and nerve supply into the parenchyma
the connective tissue septa
in which salivary gland do the fat cells show variability
the parotid gland
what is contained in the connective tissue stroma of the salivary glands
fibroblasts
collagen
fat cells
what do plasma cells secrete
the immunoglobins found in the stroma of the gland, around intralobular ducts
what are the acini of the parenchyma responsible for
production of primary secretion
what is saliva the product of (do NOT say the salivary glands)
an active secretory process
what are serous cells the source of
amylase
what is found around the acini and intercalated duct cells
contractile cells with several processes - represent the myoepithelial cells
where are salivary glands not found in the oral cavity
the gingiva or the anterior two third of the dorsum of the tongue
how is the secretion of the parotid and submandibular affected by anaesthetic
almost completely stopped as these glands are entirely nerve mediated
does the parotid produce more or less protein than glycoprotein
more protein
what are the two methods of saliva secretion
a first and main regulated pathway and a second pathway
describe the first and main regulated pathway of saliva secretion
cells store and then secrete proteins by a process of stored granule exocytosis upon receipt of a neuronal signal. time taken from synthesis to exocytosis is about 3.5 hours
describe the second pathway of saliva secretion
cells do not sore the protein but secrete it continuously through a vesciular mechanism. vesicles travel directly from the golgi apparatus to the plasma membrane
describe the parotid gland
largest of all the glands, enclosed within the parotid capsule.
the acini are serous
has a characteristic granular appearance as a result of numerous refractile granules in the luminal portion of the cell adjacent to the lumen
connective tissue septa can be seen subdividing the secretory parenchyma into lobes and then into lobules
connective tissue contains blood vessels, nerves and collecting ducts
the lumina are small and the nuclei are round
what does control of innervation depend on
reflex nerve impulses, involving afferent limbs, salivary nuclei within the medulla and the efferent limbs which comprise the sympathetic and parasympathetic secremotor (secretory motor) nerves supplying the various glands
which receptors are stimulated before during and after ingestion of food and drink
gustatory
masticatory
olfactory
psychic
visual
thermoreceptive
nociceptive
what does stimulation of gustatory receptors lead to
reflex secretion of saliva
what is the gustatory salivary reflex
stimulation of gustatory receptors leading to reflex secretion of saliva
where are gustatory receptors mainly found
in the taste buds
which glands does the olfactory salivary reflex involve
the submandibular and sublingual glands
which autonomic fibres innervate the acini
both parasympathetic and sympathetic
what is the main neurotransmitter for sympathetic fibres
noradrenaline
what is the main neurotransmitter for parasympathetic fibres
acetylcholine
what does parasympathetic drive
formation and secretion of secretory granules and fluid by the secretory units
what does sympathetic drive usually cause
increase in the output of preformed components from the cells
which autonomic fibre pathways cause contraction of the myoepithelial cells to direct fluid from the acinar lumen out along the duct system
both parasympathetic and sympathetic
what do myoepithelial cells function in
directing fluid from the acinar lumen out along the duct system
describe the composition of primary saliva
a salt secreting epithelium like sodium and chloride, bicarbonate and other less abundant anions which are transported into the acinar lumina
usually slightly hypertonic or isotonic before modification in the striated ducts.
describe the intercalated duct
this is the smallest and most distal of the ducts in salivary glands and leads from the serous acini into the striated duct
usually compressed between the acini
lined by cuboidal epithelial cells
contributes to primary secretion
long, narrow and branching in the parotid gland
which duct is the smallest in the salivary glands
the intercalated ducts
what are intercalated ducts lined by
cuboidal epithelium
which ducts contribute to primary secretion of saliva
intercalated ducts
describe the appearance of intercalated ducts in the parotid gland
long narrow and branching
describe striated ducts
intralobular, forming a much longer and more active component of the duct system
large and spherical centrally located nuclei
short microvilli on the luminal surface
site of electrolyte resorption and secretion without loss of water
what do the striated ducts do and why is this important
they are the site of electrolyte resorption and secretion without loss of water, which is important to convert isotonic or slightly hypertonic fluid into hypotonic fluid
what is found on the luminal surface of the striated ducts
microvilli
what do the cells of the striated duct exhibit
small secretory granules in the luminal region that may contain epidermal growth factor
what do the striated ducts lead into
the collecting duct
what is the function of collecting ducts
transporting the saliva
when does the lining of the main duct change
it becomes stratified as it merges with the stratified squamous epithelium of the surface oral epithelium
where are myoepithelial cells found in salivary glands
lying between the basal lamina and the basal membrane of thea cinar secretory cells and the intercalated duct cells
describe the structure of myoepithelial cells
stellate shaped body containing the nucleus and some tapering processes radiating from it
what do myoepithelial cells contract as a result of
activity of both parasympathetic and sympathetic stimulation
what attaches the myoepithelial cells to the underlying parenchymal cells
desmosomal attachments
what attaches adjacent myoepithelial cells
gap junctions
what attaches the hemidesmosomal attachments with the basal lamina
gap junctions
describe the functions of myoepithelial cells
- support the underlying parenchyma
- reduce back permeation of fluid
- accelerate the intial outflow of saliva
- reduce luminal volume
- contribute to the secretory pressure
- help salivary flow to overcome peripheral resistance
what can lead to sialectatic damange of striated ducts which increases overall permeability
caused by the saliva flow having excessive resistance to peripheral resistance
where can a population of basal cells be located in salivary glands
the striated and collecting ducts
where are lymph nodes situated
on the surface and within the parotid gland - not found within the other salivary glands
describe the submandibular gland
the second largest of the saliva glands, producing a serous mucous mixture
has a connective tissue capsule
intercalated ducts are shorter than in the parotid and the striated ducts are longer and more conspicuous
which cells in the parotid gland contain neutral glycoproteins
serous cells
what do the mucous cells in the major salivary glands contain
acidic glycoproteins
where are neutral glycoproteins found
the parotid gland and the submandibular secretory cells
striated ducts contain them too
where are acidic glycoproteins found
the mucous cells of the major salivary glands and serous cells of the submandibular
describe the sublingual gland
made up of a posterior part that is not always present and an anterior part that consists of 7 to 15 small salivary glands, each with its own duct system
where do the duct systems of the sublingual gland empty into
the sublingual fold
is the duct system of the sublingual gland well developed
not when compared to the other major glands
describe the duct system of the sublingual gland
no striated duct, the acini can lead to intercalated ducts but these may also be absent. the acini usually just lead to the collecting ducts
what is sublingual saliva rich in
sodium
why is sublingual saliva rich in sodium
lack of striated ducts
describe anterior lingual glands
these glands are embedded within muscle near the ventral surface of the tongue and have short ducts opening near the lingual frenum
where are the posterior lingual glands located
the root of the tongue
