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Secretion of Saliva and its function Tallat Naz.potx

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Tallat Naz
Tallat Naz

MBBS Physiology Lecture Saliva Function of saliva composition of saliva secretion of saliva By Tallat Naz YT Channel`s name is Guyton Academy.

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Salivary Secretions 1
By the end of this lecture students will be able to understand the: 2 LEARNING OBJECTIVES Types and secretions Salivary glands Composition of Saliva Stages of Saliva secretion Neural regulation Flow and reflexes
INTRODUCTION The important glandular secretions involve in GIT proper functioning may include: Salivary glands secretion. Gastric glands secretion. Exocrine pancreas secretion. Liver secretion.
4 SALIVA Saliva is an extracellular fluid produced and secreted by salivary glands in the mouth.
Saliva (Physical characteristics) Saliva is colorless LIQUID Moderately viscous pH is slightly acidic 6-7 (6.7 average) pH become BASIC during activity of glands Average pH of Saliva is =8 due to Bicarbonate 1 liter of saliva / day ( 800 - 1500 ml/day). Hypotonic to Plasma (Less Na+, Cl- and more K and HCO3)
Saliva (Chemical characteristics) Inorganic Buffers Bicarbonate ions Soluble Calcium salts: Ca(HCO3)2, Ca(H2PO4)2 Some electrolytes: Na+ ,CL- , HCO3 - & K+ Organic Mucin Digestive enzymes Ptyalin and Lingual lipase Antimicrobial agents Lysozyme, Lactoferrin and IgA Proline-rich-protein Constitute nearly 70% of Salivary protein) 1-Water = 97% - 99.5% 2- Solids = 0.5%
Salivary Glands
Salivary Gland is any cell or organ discharging a secretion into the oral cavity. 8 Major and minor Salivary Glands SALIVARY GLANDS Major (Paired) Parotid Submandibular Sublingual Minor Those in the Tongue, Palatine Tonsil, Palate, Lips and Cheeks
Sublingual gland Submandibular and buccal glands Parotid glands 5% viscous viscous saliva that contains mainly mucin. 75% mixed moderately viscous saliva that contains mucin + enzymes+ ions. 20% serous watery secretion that lacks mucin but contains enzymes and ions.
SALIVARY SECRETORY UNIT Acinar cells It secretes primary secretion which is Isotonic to Plasma Ptyalin and/or Musin, and electrolytes with ionic concentration similar to ECF 10 Salivary secretion is two stage process by Salivary unit consist of 1) Acini and 2) Ducts Salivary ducts When primary secretion flow through ducts, its ionic composition changes through active processes
As saliva passes through the salivary ducts, cations (sodium and chloride) are reabsorbed into the adjacent blood vessels. 11 IONS AND SALIVARY FLOW
Mechanism of saliva secretion Acinar cells Ducts Secretory portion Produce Primary secretion By active process Modify primary secretion by Reabsorption secretion Na+ actively K+ actively Cl - passively HCO3 - Passively and actively Electronegativity -70 millivolts Balance
Secretion of Saliva and its function Tallat Naz.potx
14
Sodium and chloride ions conc. reduced about 1/7th to 1/10th of that plasma Conc. = 15 mEq/L each. Potassium ions concentration increased 7 times of that Plasma Conc. = 30mEq/L Bicarbonate concentration increased 2 to 3 times that of plasma Conc. = 50 to 70 mEq/L. The net result under resting conditions
Rate of formation of Primary secretion from Acini increased 20 times. Due to rapid flow of primary secretion from ducts, ductal conditioning become reduced Saliva Na-Cl conc. become 2/3rd Potassium conc. Become 4 times increased During maximum Salivation
Resting salivary flowno external stimulus o Typically 0.2 mL 0.3 mL per minute o Less than 0.1 mL per minute means the person has hyposalivation Hyposalivation not producing enough saliva 17 UNSTIMULATED FLOW STIMULATED FLOW Response to a stimulus, usually taste, chewing, or medication eg, at mealtime o Typically 1.5 mL 2 mL per minute o Less than 0.7 mL per minute is considered hyposalivation
18 NEURAL REGULATION PARASYMPATHETIC PATHWAY Signals such as smell ,taste, sight AND tectile stimuli is conveyed through facial and glossopharangeal nerves to salivatory nuclei in brain stem It leads to discharge of parasympathetic nerves Increasing the rate of secretion by 20 fold Para. Sym stimuli dilate blood vessels
Parasympathetic nervous regulation of salivary secretion. The salivatory nuclei are located approximately at the juncture of the medulla and pons. They are stimulated by both taste and tactile stimuli from the tongue and other areas of the mouth and pharynx
Salivatory nuclei are excited by Taste and tactile stimuli from tongue and other areas of mouth and pharynx Stimuli from esophagus and stomach (due to stimulation of vagal afferent fibers) (unconditioned reflex) Stimuli arising from higher centers of brain due to sight, smell or thought of food (conditioned reflex). 20 Pavlov with his dog
21 NEURAL REGULATION SYMPATHETIC PATHWAY Slightly increase Salivation Nerve originate from superior cervical ganglia travel towards blood vessels supply to the Sala. Glands
Facilitation of swallowing and speech. Cleaning(hygiene) :of the mouth and teeth by washing and antibacterial effect of lysozymes &IgA. Buffer function: by bicarbonate &phosphate. Digestion: By salivary amylase to start digestion of cooked starch &by salivary lipase initiate lipid digestion. Excretory function: for waste product, lead, mercury, iodide, fluoride, some drugs &alcohol. Facilitate taste sensation. Regulation of water balance (decrease in dehydration and give thirst sensation). FUNCTIONS OF SALIVA
Main function: maintaining the well-being of the mouth Other important functions: Protection Buffering Action Digestion Facilitation of Taste Defensive Action against Microbes Ionic Exchange between Tooth Surface 23 FUNCTIONS OF SALIVA
1. The flow of saliva helps wash away pathogenic bacteria, as well as food particles that provide their metabolic support. 2. Saliva contains several factors that destroy bacteria. One of these is thiocyanate ions and another is several proteolytic enzymesmost important, lysozymethat (a) attack the bacteria, (b) aid the thiocyanate ions in entering the bacteria where these ions in turn become bactericidal, and (c) digest food particles, thus helping further to remove the bacterial metabolic support. 3. Saliva often contains significant amounts of antibodies that can destroy oral bacteria, including some that cause dental caries. In the absence of salivation, oral tissues often become ulcerated and otherwise infected, and caries of the teeth can become rampant. Function of Saliva for Oral Hygiene

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Secretion of Saliva and its function Tallat Naz.potx

  • 2. By the end of this lecture students will be able to understand the: 2 LEARNING OBJECTIVES Types and secretions Salivary glands Composition of Saliva Stages of Saliva secretion Neural regulation Flow and reflexes
  • 3. INTRODUCTION The important glandular secretions involve in GIT proper functioning may include: Salivary glands secretion. Gastric glands secretion. Exocrine pancreas secretion. Liver secretion.
  • 4. 4 SALIVA Saliva is an extracellular fluid produced and secreted by salivary glands in the mouth.
  • 5. Saliva (Physical characteristics) Saliva is colorless LIQUID Moderately viscous pH is slightly acidic 6-7 (6.7 average) pH become BASIC during activity of glands Average pH of Saliva is =8 due to Bicarbonate 1 liter of saliva / day ( 800 - 1500 ml/day). Hypotonic to Plasma (Less Na+, Cl- and more K and HCO3)
  • 6. Saliva (Chemical characteristics) Inorganic Buffers Bicarbonate ions Soluble Calcium salts: Ca(HCO3)2, Ca(H2PO4)2 Some electrolytes: Na+ ,CL- , HCO3 - & K+ Organic Mucin Digestive enzymes Ptyalin and Lingual lipase Antimicrobial agents Lysozyme, Lactoferrin and IgA Proline-rich-protein Constitute nearly 70% of Salivary protein) 1-Water = 97% - 99.5% 2- Solids = 0.5%
  • 8. Salivary Gland is any cell or organ discharging a secretion into the oral cavity. 8 Major and minor Salivary Glands SALIVARY GLANDS Major (Paired) Parotid Submandibular Sublingual Minor Those in the Tongue, Palatine Tonsil, Palate, Lips and Cheeks
  • 9. Sublingual gland Submandibular and buccal glands Parotid glands 5% viscous viscous saliva that contains mainly mucin. 75% mixed moderately viscous saliva that contains mucin + enzymes+ ions. 20% serous watery secretion that lacks mucin but contains enzymes and ions.
  • 10. SALIVARY SECRETORY UNIT Acinar cells It secretes primary secretion which is Isotonic to Plasma Ptyalin and/or Musin, and electrolytes with ionic concentration similar to ECF 10 Salivary secretion is two stage process by Salivary unit consist of 1) Acini and 2) Ducts Salivary ducts When primary secretion flow through ducts, its ionic composition changes through active processes
  • 11. As saliva passes through the salivary ducts, cations (sodium and chloride) are reabsorbed into the adjacent blood vessels. 11 IONS AND SALIVARY FLOW
  • 12. Mechanism of saliva secretion Acinar cells Ducts Secretory portion Produce Primary secretion By active process Modify primary secretion by Reabsorption secretion Na+ actively K+ actively Cl - passively HCO3 - Passively and actively Electronegativity -70 millivolts Balance
  • 14. 14
  • 15. Sodium and chloride ions conc. reduced about 1/7th to 1/10th of that plasma Conc. = 15 mEq/L each. Potassium ions concentration increased 7 times of that Plasma Conc. = 30mEq/L Bicarbonate concentration increased 2 to 3 times that of plasma Conc. = 50 to 70 mEq/L. The net result under resting conditions
  • 16. Rate of formation of Primary secretion from Acini increased 20 times. Due to rapid flow of primary secretion from ducts, ductal conditioning become reduced Saliva Na-Cl conc. become 2/3rd Potassium conc. Become 4 times increased During maximum Salivation
  • 17. Resting salivary flowno external stimulus o Typically 0.2 mL 0.3 mL per minute o Less than 0.1 mL per minute means the person has hyposalivation Hyposalivation not producing enough saliva 17 UNSTIMULATED FLOW STIMULATED FLOW Response to a stimulus, usually taste, chewing, or medication eg, at mealtime o Typically 1.5 mL 2 mL per minute o Less than 0.7 mL per minute is considered hyposalivation
  • 18. 18 NEURAL REGULATION PARASYMPATHETIC PATHWAY Signals such as smell ,taste, sight AND tectile stimuli is conveyed through facial and glossopharangeal nerves to salivatory nuclei in brain stem It leads to discharge of parasympathetic nerves Increasing the rate of secretion by 20 fold Para. Sym stimuli dilate blood vessels
  • 19. Parasympathetic nervous regulation of salivary secretion. The salivatory nuclei are located approximately at the juncture of the medulla and pons. They are stimulated by both taste and tactile stimuli from the tongue and other areas of the mouth and pharynx
  • 20. Salivatory nuclei are excited by Taste and tactile stimuli from tongue and other areas of mouth and pharynx Stimuli from esophagus and stomach (due to stimulation of vagal afferent fibers) (unconditioned reflex) Stimuli arising from higher centers of brain due to sight, smell or thought of food (conditioned reflex). 20 Pavlov with his dog
  • 21. 21 NEURAL REGULATION SYMPATHETIC PATHWAY Slightly increase Salivation Nerve originate from superior cervical ganglia travel towards blood vessels supply to the Sala. Glands
  • 22. Facilitation of swallowing and speech. Cleaning(hygiene) :of the mouth and teeth by washing and antibacterial effect of lysozymes &IgA. Buffer function: by bicarbonate &phosphate. Digestion: By salivary amylase to start digestion of cooked starch &by salivary lipase initiate lipid digestion. Excretory function: for waste product, lead, mercury, iodide, fluoride, some drugs &alcohol. Facilitate taste sensation. Regulation of water balance (decrease in dehydration and give thirst sensation). FUNCTIONS OF SALIVA
  • 23. Main function: maintaining the well-being of the mouth Other important functions: Protection Buffering Action Digestion Facilitation of Taste Defensive Action against Microbes Ionic Exchange between Tooth Surface 23 FUNCTIONS OF SALIVA
  • 24. 1. The flow of saliva helps wash away pathogenic bacteria, as well as food particles that provide their metabolic support. 2. Saliva contains several factors that destroy bacteria. One of these is thiocyanate ions and another is several proteolytic enzymesmost important, lysozymethat (a) attack the bacteria, (b) aid the thiocyanate ions in entering the bacteria where these ions in turn become bactericidal, and (c) digest food particles, thus helping further to remove the bacterial metabolic support. 3. Saliva often contains significant amounts of antibodies that can destroy oral bacteria, including some that cause dental caries. In the absence of salivation, oral tissues often become ulcerated and otherwise infected, and caries of the teeth can become rampant. Function of Saliva for Oral Hygiene

Editor's Notes

  1. As saliva passes through the salivary ducts, cations (sodium and chloride) are reabsorbed into the adjacent blood vessels.
  2. 1.5.6-7.8 ph 2. lavage, lubrication, pellicle (calcium binding proline-rich salivary proteins)= protection 3. toothbrush, sialin, calculus 4. Candida albicans 4. Digestion---bolus 5. Speech, repair of tissue