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Salivary Glands - Coggle Diagram

- - - - To parotid glands
        
        It originates from the cells in inferior salivary nucleus i.e. dorsal
        nucleus of glossopharyngeal (IX) nerve.
      - To Submandibular and
        sublingual glands
        
        It originates from the cells of superior salivary nucleus i.e.
        dorsal nucleus of facial (VII) nerve.
    - - It originates from the lateral horn cells of T1,2 segments of the
        spinal cord; axons via ventral roots enter paravertebral sympathetic
        chain to synapse with the cells in superior cervical ganglion to
        supply the salivary glands.
- - - - Salivary secretion increases either by:
        i. taste of food within 20-30 seconds (inborn reflex); or
        ii. by sight, smell or thought of food (Psychic or conditioned reflex).
        
        Dry food, particularly if finely ground, is a powerful stimulus for the mouth receptors, and causes secretion of greater amounts of saliva than does moist food.
  - - - via activation of the parasympathetic NS by
        
        food in mouth
        
        smells
        
        conditioned reflexes
        
        nausea
    - - via inhibition of the parasympathetic NS by:
        
        sleep
        
        dehyration
        
        fear
        
        anticholinergic drugs (atropine)
- - - - These ducts join to form intralobular and interlobar ducts which lead
        into the main duct.
- - - - ptyalin or salivary α-amylase
        
        lysozymes (bactericidal)
        
        kallikrein, a proteolytic enzyme
        
        lipase, a lipolytic enzyme (secreted by glands on the tongue, therefore, also called lingual lipase).
      - Mucin,
        
        (glycoprotein)
        
        IgA
        
        first immunological defence against bacteria and viruses
        
        pH:
        
        slightly below 7.0 (under resting state);
        
        8.0 (during active secretion)
        
        Cations:
        
        Na+ 15-20 mEq/L - plasma level(145 mEq/L)
        
        K+ 20-25 mEq/L - plasma level(5 mEq/L)
        
        Ca2+ - traces
        
        Anions:
        
        Cl- 15-20 mEq/L - plasma level(110 mEq/L)
        
        HCO3- 10-15 mEq/L - plasma level(27 mEq/L)
        
        phosphate - traces
        
        bromide - traces
        
        Organic contents:
        
        1 more item...
- - - - it lubricates the food, thus assists mastication and facilitates swallowing
        
        it protects the oral mucosa
        
        it aids speech by facilitating movements of lips and tongue.
      - It keeps the mouth moist and serves as a solvent for the molecules that
        stimulate the taste buds.
        
        It minimizes risk of buccal infection and dental caries as it contains:
        
        Lysozymes which kill the bacteria (bactericidal)
        
        IgA which provides immunological defense against bacteria and viruses
        
        Lactoferrin which binds iron and arrests the bacterial multiplication
        
        Buffers and ‘proline’ rich proteins in saliva help to bind toxic tannins and
        
        maintain the oral pH at 7.0.
        At this pH saliva is saturated with calcium,
        therefore, teeth do not lose calcium to oral fluids.
        
        Thus it protect tooth enamel.
        
        Acidic oral pH causes calcium loss from the
        teeth.
        
        Buffers in saliva also help to neutralize gastric acid and relieve heart burn when gastric juice is regurgitated into the oesophagus.
        
        It is a vehicle for the excretion of certain drugs, e.g. alcohol, and
        morphine; and of certain inorganic ions e.g.
        K+
        , Ca2+
        , HCO3-
        , iodine and
        thiocyanate (SCN-)
- - - - At rest, saliva contains more of K+ and less of Na+
        , Cl- and HCO3 -
        compared to their plasma concentrations.
        As salivary flow increases
        there is less time for ions exchange in the ducts, as a result saliva becomes less hypotonic (almost isotonic i.e. resembles the primary secretion). Na+, Cl-
        and HCO3-
        concentration increases and K+
        concentration decreases.
        
        i. Na+ concentration increases to a plateau concentration of 80-90 mEq/L, and
        
        ii. Cl- concentration increases to 50 mEq/L.
        Na+ and Cl- concentrations of saliva are always lower than that in the plasma.
        
        iii. HCO3- concentration increases and exceeds that in the plasma, and
        
        iv. K+ concentration decreases to 15-20 mEq/L.
        As a result of this, pH of saliva which is < 7.0 at low secretory rates increases to approx. 8.0 as the rate of salivary secretion increases.
        
        Iodide and thiocyanate, which are excreted in saliva, are also actively transported from plasma directly into the lumen of the ducts wall.
        They are not transported by the acinar cells.
        
        Aldosterone increases the K+ concentration and decreases Na+ concentration of saliva.
        Thus, a high salivary Na+ /K+ ratio is seen when
        aldosterone deficient (Addison’s disease)