Saliva Formation And Secretion Mechanisms

Saliva Formation And Secretion Mechanisms

Describe the composition, functions, and formation of saliva.
Answer:

Composition of saliva:

• Saliva contains 99% water and 1% organic and inorganic substances.

1. Composition of saliva –  Inorganic substances:

• Main electrolytes Na, K, Ca, CI, HCO3, and HPO4
• Electrolytes in small

2. Composition of saliva – Organic substances:

• Secretory proteins.
• Amylase, proline-rich proteins, mucins, histatin, cystatin, peroxidase, lysozyme, lactoferrin.
• Enzymes ribonuclease, kallikrein, acid phosphatase.
• Serum constituents.
• Albumin, blood clot factors, immunoglobulins IgA, IgM, IgG

3. Composition of saliva – Small organic molecules:

• Glucose, amino acids, urea, uric acid, lipids, hormones.

4. Composition of saliva – Other components:

• EGF, insulin, cyclic adenosine monophosphate.

Functions of saliva:

1. Protection of oral cavity:

• Provides washing action by flushing nonadherent bacteria and other debris.
• Mucins lubricate the oral tissues and protect against thermal and chemical insult.

2. Buffering action:

• Saliva maintains its pH through its bicarbonate and phosphate ions.
• It neutralizes the acid produced by bacteria.

3. Pellicle formation:

• Salivary proteins bind to the tooth surface and form a salivary pellicle.

4. Antimicrobial action:

• Salivary proteins, mucins, and immunoglobulins in saliva contribute to its antimicrobial action.

5. Tissue repair:

• Growth factors, peptides, and proteins promote tissue growth, differentiation, and wound healing.

6. Digestion:

• Water and mucin help in bolus formation which facilitates swallowing.

7. Taste:

• Saliva solubilizes food substances that are sensed by taste receptors.

8. Speech:

• It lubricates the oral tissue which facilitates speech.

9. Excretion:

• Many substances from blood reach saliva and are used as a route of excretion.

10. Maintenance of tooth integrity:

• Saliva reduces dissolution, increases the surface hardness of enamel, and increases resistance to demineralization.

Mechanism Of Saliva Formation

Formation of Saliva:

• The formation of saliva occurs in two stages.

1. Formation of Saliva First stage:

• Cells of the secretory end pieces and intercalated ducts produce primary saliva, which is an isotonic fluid containing most of the organic components and all of the water that is secreted by the salivary glands.

2. Formation of Saliva Second stage:

• Primary saliva is modified as it passes through the striated and excretory ducts mainly by reabsorption and secretion of electrolytes.
• The final saliva that reaches the oral cavity is hypotonic.