Lesson #3 - Saliva

Saliva

A term applied to the accumulated excretory and secretory products which is a viscous fluid discharged by the salivary glands into the oral and vestibular cavities through the major and minor ducts.

Saliva

A mixed fluid present in the mouth.

Saliva

A hypotonic fluid relative to plasma.

• inorganic

• organic constituents

Composition of Saliva

Electrolytes

Inorganic constituents present in saliva.

Sodium (Na⁺)

An electrolyte found in saliva.

Chloride (Cl⁻)

An electrolyte found in saliva.

Bicarbonate (HCO₃⁻)

An electrolyte responsible for buffering action.

Potassium (K⁺)

An electrolyte found in saliva.

Phosphate

An electrolyte contributing to buffering capacity.

Salivary Composition

Strongly depends on flow rate, whether sticky or flowable.

Types of Saliva

Pure saliva, mixed saliva, and active saliva.

Saliva Composition Percentage

99.5% water and 0.5% organic and inorganic constituents.

pH of Saliva

Ranges from 5.6 (acidic) to 7.6 (alkaline) with an average of 6.8.

Normal Daily Production of Saliva

0.5 to 1.5 liters per day.

Bhaskar Daily Saliva Secretion

750 mL of saliva secreted per day.

Submandibular Glands Contribution

60% to 70% of total saliva.

Parotid Glands Contribution

25% to 35% of total saliva.

Sublingual Glands Contribution

5% or less of total saliva.

Pure Saliva

• Obtained directly from the salivary gland.

• Clear and colorless fluid.

• Does not contain other constituents.

Mixed Saliva

Frothy and opalescent fluid.

Mixed Saliva

Contains water, proteins, mineral salts, ptyalin, mucin, food particles, desquamated epithelial cells, and salivary corpuscles.

Active Saliva

Saliva produced as a result of stimulation.

Active Saliva Composition

0.5% to 1% organic and inorganic constituents.

Proteins

Organic constituents of saliva.

Amylase (Ptyalin)

Enzyme responsible for carbohydrate digestion, converting starch into disaccharides or polysaccharides.

Lysozyme

Antibacterial enzyme present in saliva.

Glycoproteins

Organic components contributing to saliva function.

IgA

Immunoglobulin present in saliva for immune defense.

Blood Protein Traces

Small amounts of blood proteins found in saliva.

Nitrogenous Compounds

Organic constituents of saliva containing nitrogen.

Amino Acids and Peptides

Nitrogenous compounds present in saliva.

Urea

Nitrogenous waste product present in saliva.

Creatinine

Nitrogenous compound present in saliva.

Uric Acid

Nitrogenous compound present in saliva.

Ammonia

Formed by bacteria from urea and amino acids.

Glucose

Organic constituent present in saliva, especially in excess.

Resting Saliva

Saliva produced in the absence of excitation or stimulation, usually minimal and produced at night during sleep.

Active Saliva Stimulation

Results from sight or smell of food or stimulation of the oral cavity.

Properties of Saliva

Physical and chemical characteristics of saliva.

Spinnbarkeit

Ability of saliva to be drawn out into long elastic threads due to mucous components.

Viscosity

Sticky consistency of saliva.

Buffering Power

Ability of saliva to resist changes in pH when acids or alkalis are added, mainly due to bicarbonate, phosphate, and proteins.

Reducing Power

• Ability of saliva to reduce compounds of high molecular weight into lower molecular weight compounds

• because saliva is composed of 99–99.5% water.

Functions of Saliva

Are divided into two main categories based on its physical state and chemical components.

Physical Functions of Saliva

Functions made possible by virtue of its liquid state.

Excretion

Removal of waste substances through saliva.

Solvent Action

Ability of saliva to dissolve food substances.

Lubricant Action

Presence of glycoproteins that lubricate food, important during swallowing.

Cleansing Action

Helps wash away food debris and microorganisms.

Aid in Deglutition

Assists in swallowing by moistening and forming the food bolus.

Chemical Functions of Saliva

Functions affected by the chemical components of saliva.

Bacteriolysis

Ability to kill some microorganisms; also has fungicidal and virucidal action.

Digestion

Begins carbohydrate digestion through the enzyme amylase.

Decrease of Blood Clotting Time

Saliva helps shorten clotting time.

Parotid Gland

A large salivary gland located near the posterior part of the ramus of the mandible.

Submandibular Gland

Major producer of saliva (60%–70%), mixed but predominantly serous, located below the mandible.

Sublingual Gland

Mixed but predominantly mucous gland, located below the tongue, with Bartholin’s duct or ducts of Rivinus.

Salivary Glands

Glands important for metabolism as they play a role in modification, absorption, utilization, and excretion of food substances.

Salivary Glands Classification by Secretion

Classified as exocrine glands because their secretions pass through ducts.

Salivary Glands Classification by Behavior

Classified as merocrine glands because there is no change in the cytoplasm of the gland.

Primary Function of Salivary Glands

To transform and secrete materials coming from the circulatory fluid of the body.

Secondary Function of Salivary Glands

To excrete certain substances.

Classification of Salivary Glands According to Size

Divided into major and minor glands.

Major Salivary Glands

Also called extrinsic glands.

Parotid Gland

One of the major salivary glands.

Submandibular (Submaxillary) Gland

One of the major salivary glands.

Sublingual Gland

One of the major salivary glands.

Minor Salivary Glands

Also called intrinsic glands.

Labial Glands

Minor salivary glands located in the lips.

Buccal Glands

Minor salivary glands located in the cheeks.

Lingual Glands

Minor salivary glands located in the tongue.

Palatine Glands

Minor salivary glands located in the palate.