Salivary Glands By DMD Students 3rd year

our salivary glands lubricate your mouth, help you swallow, aid in digestion and help protect your teeth against harmful bacteria. You have three major types of salivary glands, including your sublingual, submandibular and parotid.

1. SALIVARY GLANDS

2. FUNCTIONS OF SALIVA Protection Buffering Maintenance of tooth integrity Digestion Defense(antimicrobial action) Taste Tissue Repair

3. 1.PROTECTION Washing action: (1) removal of bacteria, toxins, and debris (2) decrease action of acidogenic bacteria Salivary pellicle (protein receptors) Lubrication

4. 2. BUFFERING Bicarbonate Phosphate

5. 3. TOOTH INTEGRITY Post-eruptive enamel maturation Repair, remineralization → Calcium, Phosphorus

6. 4. DIGESTION Bolus formation Digestion of starch into glucose → amylase Digestion of triglyceride → maltose, lipase Neutralize esophageal contents → phosphate, bicarbonate

7. 5. DEFENSE (Bacteriostatic) Mucins Amylase Lysozyme Lactoferrin Peroxidase Immunoglobulins

8. 6. TASTE Transport of taste substances Protection of taste receptor Solvent

9. 6. TISSUE REPAIR Epithelial regeneration → growth factors Wound healing

10. STRUCTURE OF SALIVARY GLANDS Salivary glands consist of -series of branched ducts -terminating in spherical or tubular secretory end pieces or acini Analogy: Bunch of Grapes Stems- ducts Grapes- secretory end pieces

11. STRUCTURE OF SALIVARY GLANDS Each gland is divided into lobes and lobules by means of connective tissue septa 1. Intercalated ducts (smallest) (intralobular) 2. Striated ducts (intralobular) 3. Excretory ducts (interlobular)

12. STRUCTURE OF SALIVARY GLANDS The basic functional unit of salivary gland is terminal secretory unit called – acini -Serous cells -Mucous cells -Myoepithelial cells Central lumen- star shaped  Ductal system Mucous acini > Serous acini

13. SECRETORY CELLS 1. SEROUS CELLS Spherical form, narrow lumen Rich in zymogen granules More protein rich than mucous Synthesis, secretion and storage of proteins and glycoproteins

14. SECRETORY CELLS 2. MUCOUS CELLS Tubular and/or polygonal configuration with a larger central lumen More carbohydrate rich than protein Synthesis, secretion and storage of mucin

15. SECRETORY CELLS 3. MUCOSEROUS CELLS Serous + Mucous Serous Demilunes of Gianuzzi

16. Secretory cells release their thin, watery secretions into a small lumen in the center of the acinus. From there, the fluid drains into intercalated ducts, then intralobular ducts that anastomose to form larger interlobular ducts located in the surrounding connective tissue

17. DUCTS 1. INTERCALATED DUCTS Lined by single layer of cuboidal cells with a relatively clear appearing cytoplasm In Electron Microscopic studies, the intercalated duct cells resemble serous cells.

18. DUCTS 1. INTERCALATED DUCTS Functions: They modify saliva through secretory and resorptive processes. They contribute to substances like lactoferrin. Intercalated ducts also houses undifferentiated cells which can undergo differentiation and replace damage cells in the end pieces or striated ducts.

19. DUCTS 2. STRIATED DUCTS Lined by tall columnar epithelial cells with centrally placed nuclei. The cytoplasm is eosinophilic and show prominent striations at the basal end of the cells, perpendicular to basal surface.

20. DUCTS 2. STRIATED DUCTS EMstudies : basal cytoplasm of the striated duct cells show deep infoldings of the plasma membrane and many large mitochondria usually radially oriented are located between the infoldings indicating that the cell is involved in active transport.

21. DUCTS 2. STRIATED DUCTS Functions: These are site of absorption of sodium, chloride and excretion of potassium and bicarbonate.

22. DUCTS 3. EXCRETORY DUCTS As the excretory duct enlarges it contains two layers: Mucosa Connective tissue adventitia Does not modify salivary secretion

23. DUCTS 3. EXCRETORY DUCTS The Mucosal epithelium is of pseudostratified columnar epithelium occasionally goblet and ciliated cells are seen. The Ductal epithelium slowly undergoes transformation to cuboidal and finally to stratified squamous epithelium

24. GENERAL SECRETION OF SALIVA Sodium and potassium ions are equivalent Iodide ions are present at an increased concentration Chloride ions are present at a decreased concentration Bicarbonate is present at the same concentration

25. DUCTAL MODIFICATION OF SALIVA Sodium concentration decreases Potassium concentration increases Bicarbonate concentration decreases at rest and increases when stimulated

26. DUCTAL MODIFICATION OF SALIVA Resting saliva Low volume Very hypotonic Neutral or slightly acidic Few enzymes

27. DUCTAL MODIFICATION OF SALIVA Stimulated saliva High volume Less hypotonic than resting saliva Alkaline Many enzymes

28. MAJOR SALIVARY GLANDS

29. Parotid Gland Largest gland From zygomatic process to the angle of the mandible Watery saliva Stensen’s duct CNIX

30. Submandibular Gland Submandibular triangle, below mylohyoid ms. near the inner surface of the angle of the mandible Mixed predominantly serous Wharton’s duct CNVII

31. Sublingual Gland Beneath the submucosa of the anterior part of the floor of the mouth Above mylohyoid ms. Mixed but predominantly mucous Bartholin’s duct CNVII

32. MINOR SALIVARY GLANDS

33. LABIAL & BUCCAL PALATINE ANTERIOR LINGUAL POSTERIOR LINGUAL Glands of root of tongue POSTERIOR LINGUAL Glands of Von Ebner Location LIPS AND CHEEKS POSTERO-LATERAL ZONE OF HARD PALATE AND SUBMUCOSA OF SOFT PALATE NEAR THE TIP OF THE TONGUE - - Duct Opening SURFACE OF LIPS AND CHEEKS - VENTRAL SURFACE OF THE TONGUE DORSAL SURFACE OF TONGUE CANAL SURROUNDING CIRCUMVALLATE PAPILLA Nature MIXED BUT PREDOMINANTLY MUCOUS PURELY MUCOUS MIXED BUT PREDOMINANTL Y MUCOUS PURELY MUCOUS PURELY SEROUS

34. SALIVARY GLANDS MAJOR SALIVARY GLAND 1. Large glands extraorally located & is bilateral 2. Contains three general structure of salivary gland: Secretory cell, duct system, connective tissue capsule MINOR SALIVARY GLAND 1. Small group secretory cell 2. Just beneath oral epithelium at submucosa level 3. No duct system but have short ducts 4. No connective tissue capsule 5. Have secretory cell 6. Named according to location in the oral cavity

35. CONTROL OF SALIVARY SECRETION

36. Superior cervical ganglion - Decreased production of saliva by acinar cells -Increased protein secretion -Decreased blood flow to the glands 1. Sympathetic Innervation

37. Facial and Glossopharyngeal nerve -Acinar cells increase secretion of saliva -Duct cells increase HCO3 secretion -Co-transmitters result in increased blood flow to the salivary glands -Contraction of myoepithelium to increase the rate of expulsion of saliva 1. Parasympathetic Innervation

38. 1. Smell + Taste activate higher centers of the brain 2. Cause salivary nucleus to activate parasympathetic nerves that release Ach which acts at muscarinic receptors to increase saliva secretion (low protein, high fluid volume) Superior salivatory nucleus -> facial nerve -> Submandibular & sublingual Inferior salivatory nucleus -> glossopharyngeal nerve -> parotid gland 3. Sympathetic nerves release NE which act at B adrenergic receptor to increase saliva secretion (protein rich, low volume) ***Saliva secretion starts when neurotransmitters are attached on the cell surface receptors of the acinar cells. Acinar cells contain numerous receptors capable of reacting with several neurotransmitters. The vast majority of acinar cells possess cholinergic (muscarinic) receptors. The neurotransmittory substance is acetylcholine, which acts on the cholinergic or muscarinic receptors. Norepinephrine acts as a postganglial sympathetic neurotransmitter.

39. WHAT ARE THE FACTORS AFFECTING SALIVARY FLOW?

40. FACTORS AFFECTING SALIVARY FLOW 1. Food

41. FACTORS AFFECTING SALIVARY FLOW 2. Anesthetization of the oral mucosa

42. FACTORS AFFECTING SALIVARY FLOW 3. Mastication

43. FACTORS AFFECTING SALIVARY FLOW 4. The sort and the flavor of the food

44. FACTORS AFFECTING SALIVARY FLOW 5. Water

45. FACTORS AFFECTING SALIVARY FLOW 6. Age

46. END