Understanding Salivary Glands and Their Functions

Salivary glands Salivary glands Salivary glands and its applied -Dr Pushpa Lata Sachan Associate Prof. Dept. Physiology CIMS & H

These are compound tubuloacinar exocrine glands found in oral cavity that secrete complex fluid known as saliva. CLASSIFICATION OF SALIVARY GLANDS 1-Based on size 2-Based on type of secretory cells

CLASSIFICATION OF SALIVARY GLANDS CLASSIFICATION OF SALIVARY GLANDS BASED ON SIZE: BASED ON SIZE: 1. Major salivary glands- 1. Parotid, 2. Submandibular and 3. Sublingual . 2. Minor salivary glands- Lingual, buccal, labial, palatal glands, glossopalatine and retromolar glands.

CLASSIFICATION OF SALIVARY CLASSIFICATION OF SALIVARY GLANDS GLANDS Based on type of secretory cells 1. Serous - Parotid 2. Mixed (seromucous)- Submandibular 3. Mucous- Minor salivary glands.

Composition of salivary Juice: Composition of salivary Juice:- - Daily secretion :- 1000 ml to 1500 ml PH:- slightly below 7 (6.35 to6.85)- slightly acidic 99.5% water 0.5% solids:- (a)Inorganic sub stances:- Na+,k+,Ca+,Hco3,Cl,So4, Po4, etc. (b) Organic- sub stances:-

(b) Organic- substances:- Salivary protein mucin (glycoprotein) Enzymes:- Ptyalin, or , salivary- amylase (main Enzyme) Lingual lipase Lysozymes (bactericidal) Blood group antigens. IgA (for defence against bacteria & viruses )

Enzymes: - amylase Lysozyme, Lactoperoxidase, Kallikrein, Mucins Lactoferrin and many others. Immunoglobulins. Ptylin is an enzyme for digesting starch. Mucin for lubricating and for surface protective purposes.

Parotid gland Parotid gland Parotid gland -Largest salivary gland 25% of total saliva. Stenson s duct: - runs forward across masseter muscle, turns inwards at the anterior border of masseter and opens at a papilla in the oral cavity just opposite second molar crown. By stenson s duct parotid gland secretions reaches to oral cavity.

Submandibular Submandibular glands glands Almost 75% of total saliva secretions by this glands. Wharton's duct runs forward and opens into the mouth beneath the tongue, lateral to lingual frenum. Serous secretion -That contains Ptylin . Parotid glands secrete almost entirely serous type of secretion while submandibular and sublingual glands secrete both serous secretion and mucus. Buccal glands secrete only mucus.

Functions of Saliva Functions of Saliva Oral hygiene saliva helps prevent the deteriorative processes in several ways. Protective function-saliva contains lysozyme, which is anti- bacterial. IgA in saliva provides local immunity and lactoferrin in saliva is bacteriostatic. Saliva keeps the mouth cavity and tongue moist which facilitates speech. Saliva increases the taste of food Saliva helps in mastication and swallowing .

In the absence of saliva ,deglutition becomes impossible. Saliva contain bicarbonate which buffers gastric acid in this way reduces heart burn. Proline rich protein in saliva protects enamel of teeth and thus provides them strength. Proline also binds with tannin and reduces the toxicity. Saliva prevents the injury to buccal mucosa by diluting the hot and irritant food materials.

REGULATION OF SALIVARY SECRETION: REGULATION OF SALIVARY SECRETION:- - Two varieties of salivary secretion:- SPONTANEOUS SECRETION :- Occurs all the time , without any known stimulus, & -keeps the mouth moist all the time

STIMULATED SECRETION: - Occurs After a known stimulus, e.g. Psychological (thinking of food / sweet) Visual (looking at delicious food / sweet) Taste (tasting good food , in the mouth) Others (if during vomiting) Stimulated secretion of saliva is due to reflex salivary reflex which depends on nerves, supplying salivary glands .

NERVE NERVE SUPPLY TO SALIVARY GLANDS: SUPPLY TO SALIVARY GLANDS:- - (a)Para sympathetic N. supply:- (i) Parotid S.G.- by ix- N. (Gloss pharyngeal) (ii) sub mandibular & sublingual S.G. by VII- N. (facial) Stimulation of sympathetic nervous system decreases secretions of saliva.

Para Sympathetic Para Sympathetic Innervation Innervation To Salivary Glands Glands To Salivary So, VII-cranial nerve supplies: - Sub mandibles & Sublingual salivary gland. & IX Cranial Nerve- Supplies:- Parotid salivary gland. Para sympathetic stimulation increases salivary glands secretion.

Salivary Reflexes Two types of Salivary Reflexes:- UNCONDITIONED REFLEX :- are in born & present since birth . Their presence require no previous experience E.g. salivary secretion in oral phase CONDITIONED REFLEX:- require previous experience, or training , -are not inborn e.g. salivary secretion in Cephalic phase The reflex was discovered by Ivan Pavlov

Mechanism of Salivary Reflex:- (a) -Stimulus (food / sweet) in Cephalic , or oral Phase (b) Afferent- limb - reaches to (c) salivary center (In medulla & lower part of Pons), Nucleus tractus Solitarius To Superior & Inferior Salivary nucleus (d) Efferent limb Para sympathetic nerves (VII & IX- N.) (e) Salivary glands (f) Salivary secretion.

APPLIED APPLIED ASPECTS: ASPECTS:- - HYPO SALIVATION :- Decreased salivary secretion Absence of or deficiency in secretion of saliva -known as - Aptyalism resulting in xerostomia or Dry mouth

Causes of temporary hypo salivation:- Dehydration - (e.g. Diarrhoea , Excessive Sweating , etc. ) Fever Emotional Conditions like fear, depression etc. Shock After Smoking By some drugs Avil, Atropine, etc.

Causes of Permanent- Hypo salivation:- Sialolithiasis -i.e. obstruction of salivary duct by stone. Congenital absence , or , hyperplasia of salivary gland Atyalism. Bell s palsy i.e. paralysis of facial nerve. Irradiation therapy- in area of salivary glands.

Hyper salivation Hyper salivation HYPER SALIVATION: - Excess secretion of saliva. In following Conditions:- Physiological Conditions :- e.g. Pregnancy

HYPER SALIVATION HYPER SALIVATION (b) Pathological Condition:-Also called Ptyalism or Sialorrhea e.g. Dental Caries , tooth decay , oral tumor Disorders of esophagus , stomach & intestine Nausea & vomiting Neurological disorders, e.g. Cerebral palsy - Mental retardation - Cerebral stroke - parkinsonism