Saliva

Saliva 

Major salivary glands -

1. Parotid glands -

These are one pair. 

Weight of each gland 20-30gm. 

These are largest salivary glands. 

Contribution in saliva 25%. 

Secretion drain into oral cavity through Stensen duct (35-40mm long).

2. Sub mandibular/sub maxillary glands -

Two in no or one pair. 

Contribution in bsaliva 70%. 

Weight of each gland 8-10gm. *secretion drain into the oral cavity through Wharton's duct (40mm long).

3. Sub lingual glands -

These are smallest salivary glands in major salivary glands. 

These are also two in no. *weight of each salivary gland 2-3gm.

Secretion drain into oral cavity through Duct of Revinus (it consist of 5-15 small ducts, in which largest duct Bartholin duct).

Minor salivary glands -

1. Lingual serous gland.

2. Lingual mucus gland. 

3. Buccal gland. 

4. Palatal gland.

5. Labial gland.

Classification of salivary glands -

1. Serous glands : like parotid glands and lingual serous gland.

2. Mucus glands : like buccal gland, palatal gland and lingual mucus glands. 

3. Mix glands : like sub mandibular glands, sub lingual glands and labial glands.

Properties of saliva -

Volume - 1000-1500 ml /day, 1 ml /min

Reactions - slightly acidic

pH - 6.35-6.85

Specific gravity - 1.002-1.012

Tonicity - hypotonic to plasma

Composition of saliva -

1. Water - 99.5%

2. Solid - 0.5%

A. Organic substances - 

a. Enzymes :  Amylase, Maltase, Lingual lipase, Lysozyme, Phosphate, carbonic anhydrase, kallikrein.

b. Other organic substances : Mucin, Albumin, proline, Lactoferrin, IgA, Blood grouping antigens, Free amino acids, Urea, Uric acid, Creatinine, Xanthine, Hypoxanthine.

B. Inorganic substances -  Sodium, Calcium, Potassium, Bicarbonate, Bromide, Chloride, Fluoride, Phosphate.

C. Gases - Oxygen, Carbon dioxide, Nitrogen.

Functions of saliva - 

1. Preparation of food for swallowing, Mucin lubricates the bolus.

2. Appreciation of taste.

3. Digestive function - it has three digestive enzymes...

a. Salivary amylase : it is carbohydrate digesting enzyme. It act on starch and convert into maltose. It can't act on cellulose.

b. Maltase : it act on maltose and convert into glucose.

c. Lingual lipase : it is lipid digesting (lipolytic) enzyme. It act on triglyceride and convert into fatty acids. It digest milk fats ( pre emulsified fats).

4. Cleaning - high quantity of saliva cleaned mouth.

5. Protective function -

a. Lysozyme : kills bacteria like staphylococci, streptococcus, brucella.

b. Proline : it has antimicrobial property and neutralise toxic substances like tannins.

c. Lactoferrin : it has antimicrobial property.

d. IgA : it has antimicrobial and antiviral action.

e. Mucin : lubricates the mouth.

6. Role in speech.

7. Excretory function - 

a. Physiological : organic and inorganic are excreted in saliva.

b. Pathological : Glucose - in diabetes mellitus, Urea - in nephritis, Calcium - in hyperparathyroidism.

8. Regulation of body temperature.

9. Regulation of water balance.

Download book ( physiology symbulingum)