TP1MH1+Delkurs+1020+Sammanfattning+av+saliv


 * Sammanfattning av saliv – TP1MH1 **
 * Delkurs 1020 – Mikrobiologi, immunologi etc. **


 * Oral Anatomy, Histology and Embryology, 4th edition **
 * Berkovitz et al., s. 260-272 **
 * ISBN: 9780723435518 **


 * Saliven – en nödvändighet för tandhälsan, Tandläkartidningen, nr 3, 1997 **
 * Lagerlöf et al. **
 * Enligt gällande kursplan VT-13! **

>> Septa subdivide the gland into major lobes. > >>> >>> >>>>> >
 * SALIVARY GLANDS **
 * Compound – more than one tubule entering the main duct.
 * Tubuloacinar – morphology of the secreting cells.
 * Merocrine – only the secretion of the cell is released.
 * Exocrine – secretes fluid on to a free surface.
 * Secretion of saliva is a reflex function, dependent on afferent stimulation (such as taste).
 * 99% water. Production of mucin. Lubricant during swallowing and speech.
 * Protects mucosa, keeps it moist.
 * Limits activity of bacteria by causing their aggregation.
 * Contains minerals – acts as a buffer.
 * Peptide growth factor produced by submandibular gland – involved in wound healing?
 * Immunoglobulin (IgA) - widespread mucosal immune system.
 * Amylase – aids digestion.
 * Two main elements:
 * o Glandular secretory tissue – parenchyma.
 * o Supporting connective tissue – stroma.
 * o
 * o
 * o Lobes are divided into lobules.
 * § Each lobe contains grape-like structures – acini.
 * Acinus is serous, mucous or mixed.
 * Serous = more protein & less carbohydrate than mucous cells.
 * Secretion of saliva is under control of the ANS.
 * Acini of parenchyma responsible for primary secretion.
 * Major salivary glands: parotid, submandibular, sublingual.
 * Minor salivary glands: labial, buccal, palatoglossal, palatal, lingual.
 * Main regulated pathway – cells store and secrete protein by use of stored granule exocytosis.
 * o Upon receipt of a neuronal signal.
 * Second pathway – continuously by a vesicular mechanism.
 * o Constitutive pathway – some proteins may be secreted as they are synthesized.
 * ** SALIVARY GLYCOPROTEINS AND CALCIUM **
 * o Salivary glands contain a mixture of neutral to acidic glycoproteins.
 * o Serous cells in parotid gland contain neutral glycoproteins.
 * o Mucous cells in submandibular, sublingual and minor glands contain acidic glycoproteins.
 * o Serous cells in submandibular gland contain a mixture of neutral & acidic.
 * o Intercalated duct cells often contain a mixture aswell.
 * o Striated duct cells often contain neutral glycoproteins.
 * o Ca2+ is incorporated in the secretory granule to neutralize the negatively charged parts of the glycoprotein.
 * § Prevents the glycoproteins from repelling each other.
 * § The more acidic glycoprotein à the more calcium is needed.
 * PAROTID GLAND **
 * Largest of the salivary glands.
 * Serous saliva.
 * Granular appearance. Connective tissue contains blood vessels, nerves and collecting ducts.
 * Lumina of the acini are very narrow.
 * Intercalated ducts pass from acini and open into well represented striated ducts.
 * Ultrastructural appearance: cells have a wege-shaped outline.


 * Basal part delineated from surrounding connective tissue by a basal lamina.
 * Luminal part – dense, round secretory granules.
 * Narrow canaliculi run between the cells and join the lumen.
 * Adjacent cell membranes contact at desmosomes, gap junctions and tight junctions.
 * Secretory granules move towards luminal plasma membrane à become more electron-dense as protein content is concentrated.
 * Mitochondria provide energy for secretion of granules.
 * Following synthesis, resting (unstimulated) serous cells contain numerous secretory granules in cytoplasm.
 * Stimulated serous cells contain less secretory granules in cytoplasm. Discharged into the acinus lumini by exocytos.
 * Parasympathetic and sympathetic fibers act collaboratively in production of saliva during feeding.
 * Main neurotransmitter for:
 * o Parasympathetic nerves – acetylcholine.
 * o Sympathetic nerves – noradrenalin.
 * Each axon also contains arrays of neuropeptides.
 * Parasympathetic drive causes: formation and secretion of secretory granules.
 * Sympathetic drive causes: increases the output of preformed components from the cells.
 * Both pathways cause contraction of myoepithelial cells à helps direct fluid from acinar lumen out along the duct system.

> >> >>> >> >>>> >> >> >> >> > >>
 * Hypertonic = högre salthalt än serum.
 * Isotonic = samma salthalt som serum.
 * Hypotonic = mindre salthalt än serum.
 * Salivary glands secrete salt –Na and Cl - into the acinar lumina.
 * o Hypertonic environment is created.
 * Channels in apical acinar cell membrane (toppen) are opened by signals from autonomic nerves.
 * o Acetylcholine from parasympathetic nerves!
 * Cl streams into the acinar lumen.
 * Na moves into the acinar lumen to “utjämna” the difference.
 * Leads to movement of water into the lumen through aquaporin water channels!
 * Isotonic saliva in acina lumen is rendered hypotonic by removal of Na, Cl when passing through striated ducts.
 * Isoton saliv i acini – vid passage genom utförselgångarna reabsorberas ffa Na och Cl, vilket innebär att saliven är hypoton vid utsöndring.
 * § Ju snabbare flöde, desto mindre reabsorption.
 * ** DUCT SYSTEM **
 * Intercalated duct – the smallest.
 * o Cubiodal epithelial tube.
 * o Smooth on both luminal and basal surfaces.
 * o Adjacent cells united with desomosomes.
 * o Contribute to primary secretion.
 * o Several acini drain into each intercalated duct.
 * Striated ducts – much longer and more active component in duct system than intercalated.
 * o Luminal surface have short microvilli.
 * o Basal (abluminal) surface have multiple striations – infoldings of the plasma membrane at the base of the cell.
 * § Mitochondria are packed between the infoldings.
 * § Adjacent cells anchored together by desmosomes.
 * o The created large surface is involved in active transport.
 * o Striations the site of electrolyte resorption (Na, Cl) and secretion (K) without loss of water.
 * o Resorption is against a concentration gradient à requires energy.
 * o Convert an isotonic or hypertonic fluid into a hypotonic fluid!
 * o Cells exhibit small secretory granules that may contain epidermal growthfactor, lysosome, IgA.
 * Collecting duct – main function is to transport saliva.
 * o Compared to intercalated & striated ducts which also modify the composition of the saliva.
 * ** MYOEPITHELIAL CELLS **
 * o Around acini – dendritic cells. Outline of acinus remains smooth.
 * o Around intercalated ducts – elongated. Outline produces a bulge.
 * o Flattened nucleus, numerous contractile actin microfilaments.
 * o Expresses CD44 when in contact with serous acinar cells.
 * § Therefore, may play a role in cell proliferation and differentiation.
 * o Myoepithelial activity can:
 * § Support the underlying parenchyma (secretory part) and reduce back-permeation of fluid.
 * § Accelerate the initial outflow of saliva.
 * § Reduce luminal volume (kontraktion?)
 * § Contribute to the secretory pressure.
 * § Milking effect on any underlying extracellular fluid.
 * ** BASAL CELLS **
 * o Present in striated (less) and collecting ducts (more).
 * o Potential stem cells.
 * **Lymph nodes** are situated both on the surface and within the parotid gland.
 * o Not found within the other salivary glands.
 * SUBMANDIBULAR GLAND **
 * Second largest of the salivary glands. Mixed mucous/serous secretion.
 * The serous cells, duct system, myoepithelial cells and basal cells are the same as in parotid gland.
 * Shorter intercalated ducts, longer striated ducts.
 * ** MUCOUS CELLS **
 * o In the early stages of synthesis of its secretory products, much RER is present.
 * o Have a more conspicuous Golgi apparatus compared to serous cells.
 * § Because of the greater amount of carbohydrate that is added to the secretory protein.
 * o More pale secretory granules than serous cells.
 * o Fewer microvilli and infoldings than that of a serous cell.
 * o When filled with secretory granules, the nucleus is compressed against the basal surface.

> >> >> >>
 * SUBLINGUAL GLAND **
 * Made up of a posterior part (greater sublingual gland) and an anterior part (lesser sublingual gland).
 * 8-30 smaller salivary glands.
 * Mixed gland, but mostly mucous elements.
 * Serous cells in the gland might actually be immature mucous cells!
 * Secrete spontaneously and continuously.
 * ** DUCT SYSTEM **
 * o Much less developed compared to other major salivary glands.
 * o Striated ducts are usually absent à saliva rich in K.
 * MINOR SALIVARY GLANDS **
 * Buccal, labial, palatal, palatoglossal, lingual. 450-750.
 * Primarily mucous.
 * Have collecting ducts. Intercalated and striated ducts are genereally asbent.
 * Like sublingual gland, the duct system doesn’t remove as much salt, so the final saliva is isotonic and rich in K.
 * Parasympathetic nerve impulses.
 * Secrete spontaneously and continuously.

>> >>
 * Saliven – en nödvändighet för tandhälsan **
 * SEKRETION OCH SAMMANSÄTTNING **
 * Sekretion aktiveras av parasympatiska (vatten och elektrolyter) och sympatiska (proteiner) nervsystemen som svar på olika stimuli.
 * Salivflödet påverkar koncentration av de flesta av salivens elektrolyter.
 * o Klor, natrium och bikarbonat ökar med ökat flöde. Fosfat och magnesium minskar.
 * Dygnsrytmen spelar roll för koncentrationer av olika elektrolyter.
 * 0,6 - 1 l saliv per dygn.
 * Vilosaliv påverkas av:
 * o Dygnsrytmen – mindre under sömn. Mest på eftermiddagen.
 * o Årstider – mindre på sommaren.
 * o Kroppsställning – mindre i sittande, mer i liggande & stående.
 * o Hälsotillstånd – Sjögrens syndrom minskar.
 * o Farmaka - tex. antidepressiva med muntorrhet som biverkning.
 * o Psykiska faktorer (ångest) påverkar flödet.
 * o Kön, ålder, vikt etc. spelar mindre roll.
 * Stimulerad saliv påverkas av:
 * o Samma som ovan.
 * o Även smakstimuli – sura smaken salivstimulerande.
 * o Mekanisk stimulering – tuggning.
 * SALIVENS FUNKTIONER **
 * Mekaniskt skydd för tänder och slemhinnor.
 * o Muciner (högmolekylära proteiner förenade med kolhydrater) smörjer.
 * o Binder vatten – motverkar uttorkning av slemhinnorna.
 * Antimikrobiella egenskaper
 * o Lysozym – bryter enzymatiskt upp vissa bakteriers skyddande hölje.
 * o Laktoferrin – binder järn och minskar därmed tillgång av denna viktiga jon för bakterier.
 * o Salivperoxidas katalyserar reaktionen mellan väteperoxid och tiocyanat à bildar toxisk substans för bakterier, hypotiocyanat.
 * o Sekretoriska immunoglobuliner klumpar ihop bakterier till stora aggregat à sköljs bort.
 * o Fluorjonen binder magnesium och hindrar därmed bakteriers ämnesomsättning (enzymet enolas kräver magnesium för glykolysen).
 * Reglering av munhålans pH-värde: 6,5-7,5.
 * o Buffertsubstanser, såsom oorganiskt fosfat och bikarbonat, motverkar förändringar i pH.
 * o Bikarbonat kan även tränga in i plack. Ju tjockare à ju svårare att verka i placket.
 * De- och remineralisation av tandvävnad
 * o Upprätter jämvikten mellan tandsubstansens kalciumfosfater (hydroxylapatit) och omgivande vätskefas.
 * o Intag av syror & minskat pH (erosion) eller syraproduktion i bakteriebeläggningar (karies) minskar möjlighet för remineralisation.
 * o Vid remineralisation kan hydroxylapatitet även fällas ut i saliv (spottsten) och i bakteriebeläggningar (tandsten).
 * § Saliven innehåller utfällningshämmande ämnen för att hindra spottsten.
 * o Fluorjon bromsar demineralisation och accelererar remineralisation.
 * o
 * NEDDSATT SALIVKÖRTELFUNKTION **
 * Kan orsaka kariesskador och skador på slemhinnor på lång sikt.
 * Symtom:
 * o Torr munslemhinna med matt yta – munspegel fastnar då man stryker den mot slemhinnan.
 * o Torra, spruckna läppar med fissurer på insidan (keilit).
 * o Rodnad, blank tunga som ofta är fissurerad och/eller loberad.
 * o Svampinfektioner (candida).
 * o Svårigheter att tala.
 * o Muntorrhet.
 * Salivflödesmätning.
 * o **Vilosaliv:**
 * § Minst en timme utan intag av något slag.
 * § Vila 15 minuter före.
 * § Sitta i kuskställning, låt saliven passivt rinna över underläppen.
 * § Pågår i 15 minuter.
 * § Normalt viloflöde: 0,25-0,35 ml/min. Under 0,1 ml/min mycket lågt.
 * o **Stimulerad saliv:**
 * § Kuskställning.
 * § Tugga på paraffinbit i 5 minuter. Töm saliv vid behov.
 * § Normalt flöde: 1-3 ml/min. Under 0,7 ml/min mycket lågt.
 * Behandlingsalternativ för muntorrhet:
 * o Stimulera salivsekretion mha tuggummi och tabletter.
 * o Sköljlösning och saliversättningsmedel.
 * o Munvårdsprodukter som tillför salivens egna antimikrobiella komponenter (lysozym, laktoferrin etc).
 * KARIESFÖREBYGGANDE ÅTGÄRDER **
 * Kariesutveckling kan bli ett problem på längre sikt.
 * Plackkontroll – instruktioner för rengöring av alla tandytor. Extra tandborstning före/efter måltid.
 * Kostråd – vätskerik och mild kost att föredra. Högst 4-5 måltider per dygn.
 * Fluortillförsel – fluortandkräm. Fluorskölj. Tuggummi / sugtablett.