Sunday, July 17, 2011

Introduction to salivary glands and functions of saliva...... With ppt Downloads

Oral Glandular Tissue (saliva secreting)
Begins development at 6 weeks gestation and is completed by about the 12th week
The glandular tissue continues to enlarge until birth


NORMAL FUNCTION OF SALIVA
       Hydrating–moisturizing
       Cleansing
       Lubrication
       Digestion
       Remineralization of dentition(pH maintenance, buffering)
       Maintenance of mucosal integrity
       Immunity mediator
       Antimicrobial (antifungal, antibacterial)
       Stimulation of minor salivary glands
       Cellular maintenance
       Enables swallowing
       Enables tasting         
          Enables speech articulation


Mechanisms of Salivary Production
Sympathetic-Causes very dry, thick, ropy saliva
Parasympathetic-Causes thin, watery, profuse salivation
The two divisions work in opposition and have the ability to physiologically alter the quality as well as the quantity of the saliva


Salivary Gland Classifications by Secretion
       Serous: very thin and watery
o        parotid gland
o    lingual glands of von Ebner (serous glands of von Ebner)

       Mucous: very thick and viscous
o    palatine glands
o    posterior lingual glands
o    labial buccal glands

       Mixed secretions: mix of the two
       Sublingual glands
                                                      Mostly mucous with some serous
       Submandibular glands
                                                      Mostly serous with some mucous
       Anterior lingual glands
                                                     Mixed secretion

Salivary Gland Classifications by Major or Minor Glands
        Major glands
o   Secrete saliva intermittently
       Minor glands 
o   Secrete saliva continuously
The Major Glands
       Parotid gland

o   Largest of the 3 major glands
o   Produces 30% of total saliva output
§   Parotid duct is also known as  Stenson’s duct
      •  Parotid/Stenson’s duct exits opposing the maxillary second molar
o   Located anterior but inferior to the external auditory meatus
o   Innervated by sympathetic and parasympathetic divisions
o   Secretes serous type saliva
       Submandibular gland

o   Second largest salivary gland
o   Produces  65-70% of total saliva output
o   The duct is called Wharton’s duct
o   Wharton’s duct exits on the floor of the mouth opposing the lingual surface of the tongue
o   Located in a depression on the lingual side of the mandibular body
o   Innervated by parasympathetic nerve endings and possesses NO sympathetic receptors
o   The parasympathetic fibers arrive through the facial and glossopharyngeal nerves
o   Mixed secretion – mostly serous
 
       Sublingual glands

o   Smallest of the major glands
o   Produce less than 5% of total saliva output
§  Saliva delivered via the ducts of Bartholin
§  The Bartholin ducts exit on the base of the lingual surface of the tongue
o   Innervated by parasympathetic fibers
o   Little or no sympathetic influence
o   Mixed secretion – mostly mucous
The Minor Salivary Glands
Minor salivary glands are found throughout the mouth:
      Lips
      Buccal mucosa (cheeks)
      Alveolar mucosa (palate)
      Tongue dorsum and ventrum
      Floor of the mouth
Together, they play a large role in salivary production.
Salivary Flow
       Unstimulated Flow (resting salivary flow―no 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
       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
       The average person produces approximately 0.5 L – 1.5 L per day
       Salivary flow peaks in the afternoon
       Salivary flow decreases at night when the parotid gland shuts down
       There is a difference in the quality between stimulated and unstimulated saliva
Salivary Composition
       90% of saliva is water
       10% is composed of inorganic and organic ions, and cellular components
o    sodium, potassium, and calcium are positive ions (cations)
o    chloride, bicarbonate, and phosphates are negative ions (anions)
       The cationic and anionic components play an important role in the function of saliva
Ions and Salivary Flow
As saliva passes through the salivary ducts, cations (sodium and chloride) are reabsorbed into the adjacent blood vessels.

As saliva passes through the salivary ducts, cations (sodium and chloride) are reabsorbed into the adjacent blood vessels. In exchange, bicarbonates and potassium are transferred from the blood vessels into the salivary ducts.
Stimulated Salivary Flow
       Saliva passes through the salivary duct very rapidly (a negative result of fast flow)
o   It impedes the exchange of sodium and chloride for potassium and bicarbonate
Unstimulated Salivary Flow
       Has a high content of potassium and bicarbonate (a positive result of slow flow)
o   The quality of unstimulated saliva will change when flow increases because of a stimulus (chewing gum, thinking about lemons, looking at a food you crave)
Fluoride and Saliva
Fluoride is also secreted in saliva.
Unlike the ions in saliva, the fluoride content (level) is not altered whether the salivary flow is simulated or unstimulated.
Organic Components of Saliva
Enzymes:
  • Amylase – converting starch into glucose and fructose
  • Lysozymes – prevents bacterial infections in the mouth
  • Histatins – prevents fungal infections
  • Secretory IgA – immunity mediator
  • Lactoperoxidases – stimulation of minor salivary glands
  • RNase and Dnase – cellular maintenance
  • Lipase – initiates digestion of fat
  • Kallikrein – vasoreactive substances
Cellular Composition of Saliva
The cellular composition consists of:
      • Epithelial cells
      • Neutrophils
      • Lymphocytes
      • Bacterial flora
Factors that Affect Salivary Flow
       Medication
       Autoimmune disease (Sjogren’s syndrome, lupus)
       Systemic diseases (diabetes, asthma, kidney, sarcoidosis, HIV)
       Stress/anxiety/depression
       Radiation therapy to the head and neck
      30 Gy = glandular fibrosis (gland can still produce some saliva)
      60-70 Gy = glandular destruction (gland can no longer produce saliva)
       Gender (70 % female, usually postmenopausal)
       Sympathomimetic medications (stimulate the sympathetic nervous system)
       Parasympatholytic medications (inhibit the parasympathetic nervous system)
       Circadian rhythms (decreases in the fall and increases in the spring)
Over 400 Medications Can Produce the Side Effect of Xerostomia
       Antacid
       Antianxiety
       Anticholinergic
       Anticonvulsant
       Antidepressant
       Antiemetic
       Antihistamine
       Antihypertensive
       Antiparkinsonian
       Antipsychotic
       Bronchodilator
       Cholesterol reducing
       Decongestant
       Diet pills
       Diuretic
       Hormonal replacement therapy
       Muscle relaxant
       Narcotic analgesic
       Sedative
   ......... Download ppt..........

SALIVARY GLANDS LECTURE NOTE....PPT

Salivary Gland Diseases.... Download ppt lecture note 

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