 Hello everyone, welcome back to another session in dentistry and more. So we are continuing our salivary client session. So this session is about the histology basically, the types of cells that is asinine units. We have suera cells, mucus cells and myo epithelial cells. Then the dectal system that is endocalate dex, striated dex and terminal dex. So before that the structure. So as you see here the picture, the salivary gland consists of series of branched dex which is terminating in spherical or tubular secretory end pieces or asinine. It looks like grapes. So analogy is a bunch of grapes. So you can see here bunch of grapes that is the analogy. So analogy is bunch of grapes for the dectal system. So the stems of this bunch of grapes that is the dex and the grapes which is at the end piece, they are the secretory end pieces and the main secretory dex which empties into the oral cavity. So this is the main secretory dex which empties into the oral cavity. So this picture shows the gland. So each gland is divided into lobes and lobules by means of connective tissue septa. So intercalated dex which is the smallest or also known as intralobular which is present within the lobules which is the smallest one. So intercalated dex is the smallest one. Then we have intralobular dex which is known as striated dex which is also intralobular. And finally we have the excretory dect which is a inter lobular, inter lobular dex. So this is a sequence, this is a excretory dect which excretes the secretion into oral cavity. This is the biggest one, this is the smallest and this is the biggest one. Excretory is the biggest. Okay now we have the histology. So we have the asinine units and dectal system. So the basic functional unit of celebrate gland is terminal secretory unit which is known as asinine. Okay so asinine. So as you see the picture here you have all the parts that is myopithelial cells, intercalated dex, mucus NPCs, serous demilions, intercellular canaliculus, the lumen striated dect, serous NPCs. So the basic functional unit as I mentioned it is known as asinine. So the secretory unit is made of serous, mucus and myopithelial cells. So the cells in the asinine rest on a basement membrane and the junctional complexes hold the cells together and the myopithelial cells are located on the surface of asinine. So the central lumen as you see here is star shaped because of the extension. So you can see the extension of lumen between the cells that is the intercellular canaliculi and the mucus asinine has larger lumen than the serous asinine. And the central lumen which continue via fine series of dex which finally form the excretory duct that is the ultimate ductile system. So the picture you can see all the parts. Now first starts with the serous cells. So it is basically as you see here it is pyramidal with broad base on the basement membrane and apex towards the lumen. The spherical nucleus placed at the basal region. And the basal cytoplasm is packed with parallely sacked area that is rough entoplasmic reticulum which is placed basal and lateral to the cell nucleus. You can see here the lumen usually has finger like extension located between the adjacent cells called intercellular canaliculi that increases the size of the luminal surface of the cell. And the secretory granules which is known as zymogen. So these zymogen granules contains glycolated proteins which is stored in a vacuum. So the apical cytoplasm shows secretory granules that is around 1 mm in diameter. So this is apical region. And these granules are closely opposed but retain their individuality. So it can be utilised in sections using toluidine blue or any special stains. So there will be metrogranules which is paler in density and metrogranules will be dense. So there are intercellular junctions between the serous cells. They are tight junctions. They are adhering using dysmosome and there are gap junctions which allow the passage of ions and small molecules between the cells. Now we have the mucous cells. The picture you can see here it is little different than the serous one. The mucous cells its structure differs from serous cells that is the apex of the cell appears empty except for thin strand of cytoplasm forming a trabecular network. Okay. And the nucleus and the rims of cytoplasm are compressed against the base of the cell which is compressed before it was a round one now it is compressed. This of the mucous cell is oval or flattened in shape and located just above the base cell plasma membrane. So mucous cells show accumulation of large amount of secretory product in apical cytoplasm. So this mucous cell is seen to be filled with pale translucent secretory droplets which is containing scattered flocculent material. Okay which can be stained using PAS and Alcian blue stains and they are also joined by dysmosomes. Mucous secretion differs from serous secretion in two ways. One is they have little or no enzymatic activity okay no enzymatic activity compared to the serous one and mainly serves for lubrication and protection of the oral tissues that is the main function of mucosa that is a mucous secretion and the ratio of carbohydrate to protein carbohydrate to protein is larger and greater in mucosa compared to mucous cells compared to the serous cells and the amount of cialic acid is also large. So this is the picture you can see very clearly this is the serous cells come see this is the mucous cells how it is different serous cells we have very round nucleus this is a flattened nucleus. Now we have the myo epithelial cells. Myo epithelial cells are contractile cells associated with secretory end pieces and intercalated decks of salaric glands because it is almost similar to smooth muscles but which are derived from epithelium these cells are located between the basal lamina and secretory or dectal cells. So the plasma membrane of these myo epithelial cells joins the basal membrane of paranchymal cells by dysmosomes and there are these are the stellate or spider-like cells with flattened nucleus you can see the flattened nucleus here and flat perinuclear cytoplasm and long branching process that embraces the secretory and decels. So their appearance is like basket, basket cradling the secretory unit so known as the basket cells. So myo epithelial cells is also known as basket cells because their appearance is like the basket cradling the secretory unit. The cell organelles are restricted to perinuclear cytoplasm. So the structure is almost similar to smooth muscle we already mentioned and the studies indicated that it has got myosin and actin they helps to contract and there is a regular pulsative movement of the entire unit is happening. So that is about the myo epithelial cells and its functions are accelerate the initial outflow of saliva from SNI. So it's contractile action inject or it secretes the saliva from the main excretory dect it contributes to the secretory pressure in the SNI or dect and it supports the underlying parenchyma and reduce the back permeation of the fluid. So that is the functions that is mainly so the main functions are initial outflow and contribute to secretory pressure and reduce the back permeation of the fluid. Now the dex we already seen it starts from the intercalated dex then the striated dex both are intra lobular dex within the lobule whereas excretory dect or terminal dect which is the inter lobular which is present between the lobules. So it is almost like a grape branches of a grape bunch of grapes can see the spherical secretory NPs here the tubular secretory NPs the canalicules between the cells intercalated dect the striated dect and the excretory dect finally the main excretory dect. So the first one intercalated dect which is lined by single layer of cuboid cells with relatively clear cytoplasm and functions they modify saliva through secretory and resopptive processes they contribute to substance like lactoferrin and these dex also house undifferentiated cells which can undergo differentiation and replace the damaged cells in the NPs or the striated dect. The next one striated dect which is lined by columnar epithelium with centrally placed nucleus cytoplasm is isnophilic and show prominent striations at the basal end of cells which is perpendicular to the basal surface as you see here picture and their functions they are the site of absorption of sodium chloride execution of potassium and bicarbonate the reabsorption is against the concentration gradient so it needs more energy and the final excretory or terminal dect so as excretory dect enlarges it contains two layers that is mucosa and connective tissue the mucosa epithelium is pseudo stratified columnar epithelium and occasionally the goblet ancillated cells the dectal epithelium shows undergoes transformation to cuboidal and finally to stratified squamous epithelium so that is the dectal system and the connective tissue connective tissue is like fibroblast macrophages mass cell leucosides all those things so this connective tissue forms a capsule for the gland and it divides the gland into various lobules so the vascular supply of the gland is also embedded within the connective tissue now let's move on to the minor salivary glands so we were studying major salivary glands now we have the minor salivary glands so these glands are located beneath the epithelium in almost all parts of oral cavity they open by short dex directly into mouth and they lack distinct capsule and instead mixing with the connective tissue mucosa so salivary glands are absent in anterior lateral part of heart palate and gingiva ok so in gingiva and anterior lateral part of heart palate is divided of minor salivary glands so we will start with the labial and buccal glands ok so the labial and buccal glands labial and buccal minor salivary glands the glands of the lips and cheeks are known as labial and buccal glands they are mixed glands consisting of mucous sni and serous demilions and intercalated dex are variable in length and intralibular dex possess only a few cells with basal striation next is the glossopalatine gland they are pure mucous glands they localize to the region of isthmus in the glossopalatine fold but may extend from posterior extension of sublingual gland to the glands of soft palate now we have the palatine glands they are pure mucous glands several hundreds of glandular aggregates in the lamina propria in this posterior lateral region not the anterior lateral posterior lateral region and in the submucous of soft palate and uvula the excretory dex have a regular contour and their opening on the palatal mucous are large and easily recognizable and we have also lingual glands they are known as bluntin and none that is anterior lingual glands bluntin and none they are located near the apex of the tongue chiefly mucous in nature but the posterior regions are mixed the dex open near the ventral surface of tongue near the lingual frena posterior lingual mucous glands they are located posterior and lateral to the violet papilla is a circumvalid papilla and in association with lingual tonsil and they are mucous in character their dex open on the dorsal surface of tongue now we have one more glands that is one ebner's gland they are located between the muscle fibers of the tongue below the violet papillae they are purely serious glands their dex open through the violet papillae functions the ability to wash out the trough of the papillae then it has got enzymes and peroxidase which has got antibacterial properties and also lingual lipase enzyme that is about the minor salivary glands and the last part of salivary gland is saliva saliva the functions of saliva the components of saliva so saliva is the accretion of all this major and minor salivary glands along with discriminated epithelium micro organisms food debris serum components and inflammatory cells so each glands accretion differs in amount and content so parotid gland which is more of watery saliva so parotid is more of watery saliva and it consists of enzymes that is MLAs proline rich proteins and glycoproteins whereas a submantibular gland saliva it's like in addition to the ebo it has got musins ok this more of having musins whereas a sublingual gland saliva is like viscous saliva compared to these two and composition is various components present here you can see the table here the daily volume is 600 to 1000 ml per day electrolytes it has got sodium potassium chloride bicarbonate calcium magnesium phosphate all those things and the proteins MLAs musins proline rich protein histamine peroxidase immunoglobulin it has got IgA IgG IgM then it has got glucose amino acid uric acid so the flow rate that is resting 0.2 to 0.4 stimulated is 2 to 5 and pH is around 6.7 to 7.4 and the functions the functions protection buffering tooth integrity antimicrobial activity tissue repair digestion and taste so protection is by water musins like a protein function that is clearance lubrication thermal and chemical installation then pellicle formation whereas a buffering that is a pH maintenance or neutralization of acids by help of bicarbonate phosphate and basic protein and ammonia tooth integrity that is a enamel menstruation and repair by the help of calcium phosphate flow rate and such ions then antimicrobial activity by physical barrier immune defense are nonimmune defense by secretary IgA and all other things then the tissue repair by wound healing and epithelium that is by regeneration and growth factors digestion it has got MLAs lipase water musin polys formation triglyceride digestion finally the taste that is a solution of molecules maintenance of taste buds they are the functions of saliva that is all about salivary glands the last session was a little lengthier so we were discussing the first session was about the introduction that is the types classification the endocrine exocrine gland the serious mucus and all those things the second session we learned about the anatomy its structures and its arterial supply venous supply nervous supply and the third part is basically about the functional part that is SNI units and the ductile system so it's a very very important chapter so lots of questions will be asked from this SNI units ductile system and you need to draw pictures for everything and one more thing which I forward to mention that is serious demilion which is very commonly asked short note okay serious demilion it's nothing but cellular formation and the shape of half moon okay the shape of half moon so you see the picture here because of this half moon it got this name that is demilion which is present on some salivary gland okay so what is important because serious demilions are the serious cells at the distal end of mucus secretory unit of certain salivary glands so these demilion cells secrete proteins that contain the lice enzyme lysosine okay so which is present over the mucus glands that is a serious cells which is the which is at the distal end of mucus secretory unit of salivary gland that is serious demilions also basket cell is also important which is a myopathyler cells so hope you understood the salivary gland it is a very very important chapter lots of questions short notes short essay and long essay so you need to draw well labeled picture for every question that is SNI units let it be serious mucus myopathyler or dectal system need to draw that a bunch of grapes that analogy and we need to write point wise so I'll come with a new topic in dentistry and more thank you