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TRANSCRIPT
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The doctor started the lecture talking about how important is the previous
lecture ( oral muscosa) and said that there 's going to be 20% of the final
exams questions on that topic .And here we start the lecture entitled
Salivary glands , please read it carefully as many slides are not required .
Salivary glands :
Salivary glands are: -
_ compounds ,which means more than one tubule entering the main duct
(it's not simple that consists of one duct )
- Tubuloacinar , we have tubules and acini (singular :acinus ) ; these are
the areas where saliva is synthesized (saliva is synthesized in acinus and
secreted into ducts )
-Merocrine, because only the secretion of the cells is released (y3ne we
dont have any material from blood that comes into saliva , thats why we
call saliva as marocrine secretion )
-Exocrine , secretion into a free surface (opposite to endocrine ;secretion
into blood )
Physiology:
we will not mention it as we are going to discuss it in details in oral
physiology .
classification of salivary glands :
we classify salivary glands due to size into :Major and Minor glands .
_Major salivary glands :Parotid ,Submandibular ,Sublingual . (wealready learnt about that in anatomy )
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** just to remember quickly : the parasympathetic
activity of the parotid gland from glossopharyngeal nerve .
but the parasympathetic activity of both Submandibular and
Sublingual glands is from facial nerve through chorda
tympanie . (thats not important )
_minor salivary glands :
They are scattered throughout oral mucosa .
Labial, buccal, palatoglossal, palatal, and lingual mucosae ; all have
salivary glands ,
Its notpresent in in the gingival (important note ) , and also its not
present in the mid palatine propria ( middle area in the hard palate ) .(Important information for fifth year mshan ma erasebna sani khamse :P )
Acoording to secretion we classify glands to : mucous , serous and mixed
.
If the secretion was mucoid( ) then its mucous .
If there secretion was watery ()then its serous .
If mixed ( ) then its mixed . (serous and mucous at the same
time )
Saliva & fuction of saliva :
We will not discuss saliva as we are going to dicuss it in physio .
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Sali ary glands :
The mai ti e element in the sali ary gland : any sali ary gland has
t main elements : glandular secret ry tissue ( the gland itsel ) & the
surrounding connecti e tissue .
The glandular connecti e tissue is called parenchyma , and it s ectodermal
in origin (y3ne da2eman el gland aselha invagination mn el epithelium el
5areje )
*** Remember: All major and minor salivary glands originate from oral
mucosa ::
Invagination duct form the gland .
And also the supporting connective tissue here in this picture we see theparenchyma ( the yellow color with blue , this is the glandular part , but
the whole structure is surrounded by a connective tissue ( the supporting
connective tissue )
The supporting is called strome ,and this is mesodermalin origin (not
ectodermal ).
-From macro to microscopic level: we have:
Glands divided into a number of lobes each lobe is a
number oflobules each lobule we find a number of secretory
units called Acini (singular:acinus ) .
-The secretory units in the salivary glands :
These are A grape-li e cluster of parenchymal cells around a lumen
( ) .
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There are three types of acini : serous , mucous and mi ed (mucous
covered with serous ) .
So when we have mi ed acini , the cells that are related to lumen are :
mucous ; and from outside :serous ( we callit serous semiluned (
) .
In addition to that we have cells that are called myoepithelial cells that
are located around acini . these cells function in squeezing the contents (
here saliva is formed and it s collected in lumen so we need a big cellto
contract and squeeze saliva and getitinside ) .7these are contractile cells
with several processes ,,, also called basket cells .
The duct system :
We have : - Acinus lumen:the place where cells secrete directly and anumber of lumens empty in an Intercalated duct and a number of
intercalated ducts empty in Striated duct .
Acinus lumen Intercalated duct Striated
duct .
These are called intra-lobular (located within the lobule ) .
The collecting ducts are located between lobules that s why collecting
ducts are usually surrounded by connective tissue .
*The inter-lobular system is inert, the composition of saliva doesn't
change as soon as it arrives in the collecting duct .
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As long as saliva is in the lumen , in the intercalated duct , in the striated
duct ; the composition of saliva can change ,we can have addition or
absorbtion of electrolytes , proteins . Etc .
Strome :
Is a connective tissue that surround the salivary gland , it's mesenchymal
in origin .
From Macro-to-Microscopic levels :
Capsule inter lobar (spaces between lobes ) interlobular
(spaces between lobules ) inter acinus (between acini ) .
As any connective tissue it contains : collagen fibers , fibroblasts and fatcells .
*remember that fat cells increase with age .
For example : in foreinsic we found only salivary gland that belongs to a
dead person and we want to know his age ; we take it and examine the
amount of fat cells , if we found many fat cells then the person is old and
if we find less he is young .
Synthesis of saliva :
Synthesis of saliva is active (it needs energy ) , thats why its not a blood
ultra filtrate (saliva isn't filtrated blood , its synthesis is active process and
needs energy ) .
_serous cells , they actually secrete Watery proteinaceous fluid contains
Amylase . amylase is an important enzyme that digests starch into
dissacharide .
_mucous cells , contains Proteins linked to a greater amount ofcarbohyrates
_ Plasma cells ,secrete IgA immunoglobulin A for protection .
Secretion of saliva :
we will not be asked about it as it is oral physiology topic .
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we need to know the difference between serous cells and mucous cells
, if we see serous cell , how can we know that this is a serous or
mucous cell ?
In light microscopy : serous cells are basophilic ( they stain dark )
Mucous cells , pale (almost white ) as they contain
carbohydrates
Second , serous cells contain round prominent nucleus .
in mucous cells ,flattened .
ONLY those thing are required to distinguish between them
SLIDE 14 this picture wasnt discuused .
, dont worry about it .Myoepithelial Cells
we have to know one function of it : to squeeze the content ofJust
acinus to empty the content of acinus into intercalated and striated
ducts .
intercalated ducts :The
.Drainage from several acini.
_ Compressed between the acini : because they are thin and small .
_contain Cuboidal epithelial cells : one single layer .
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Prominent nuclei
In Parotid, they are long, narrow, and branching .
(important , at least one question ):Striated ducts
_Larger and longer than ICD ._ Simple columnar epithelium surround with one layer of cells .
_Cells have large centrally-located nuclei : nuclei located in the
middle of the cell .
Called striated because the basal surfaces of the cell have many
folding , the folding produce striations .
_ the luminal part also the cell membrane has folding and
microvilli to increase the surface area for secretion and absorption .
_cells are attached by desmosomes .
_at the level of striated ducts we have much of the change in the
composition of saliva .
Collecting ducts :
Collecting ducts are bilayered .
**** how can we distinguish between collecting ducts and striated??
e around the duct and ifif you dont see connective tissu Rule :
you only see one single layer this is striated .
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if you see more than one layer and see much connective tissue
around the duct its collecting .
its bilayered epithelium , luminar part is columnar epithelium layer
and basal part is cuboidal .
the collecting ducts approach to the surface of oralmucosa it becomes more than two layers , the bigger itis , the more connective tissue it has .
so Terminated as stratified epithelium to merge with the oralmucosa.
:Parotid gland
its the largest gland and it contains serous acini .
Parotid gland only gives watery secretion it doesnt produce mucous .
* so in the exam if there are glands , and in the glands all the acini arebasophilic (purple in colour ) know that this is a parotid gland , its
possible that it is von ebners gland .
*the white parts here are fat cells .
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Submandibular gland :
We see light cells and dark cells so its mixed , if theres more mucous its
submandibular .
Intercalated ducts are short and difficult to locate_
Striated ducts are long and obvious
Although submandibular glands are mixed there is more mucous
than serous .
Sublingual glands :
Are mixed and have more mucous than serous (most of the cells
are light in colour )
They lacks striated ducts .
Minor salivary glands :: are primarily mucous .
As you go posteriorly there is a tendancy for the glands to become
mucous ,
In the picture orange areas glands are mucous , blue area such as
:tip of the tongue , lips , cheeks are mixed glands .
We have the only serous minor salivary gland which von ebnergland which is associated with circumvallate papilla .
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FINALLY : WISH YOU ALL GOOD LUCK AND SORRY FORANY
MISTAKE!!!!,
Watch your thoughts; they become words.
Watch your words; they become actions.
Watch your actions; they become habits.
Watch your habits; they become character.
Watch your character; it becomes your destiny. ;)
Special thanks to my brother saif who helped me a lot , and thanks to my
friends too
wish you all good luck in your exams