Secretion of Saliva

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Secretion of Saliva:

Secretion of Saliva Prof. Husan Bano Department of Physiology Al- Tibri Medical College, Isra University

Learning Objectives:

Learning Objectives At the end of this lecture you should be able to: Know the types of salivary glands Know the types of its secretion Enlist the general characteristics of Saliva. Describe the composition of saliva Describe the functions of saliva

Secretion of Saliva:

Secretion of Saliva Saliva is secreted from salivary glands which are of 3 types . 1. Parotid gland 2. Sub –maxillary or sub mandibular gland 3. Sub lingual gland.

Types of Secretion. :

Types of Secretion. Serous secretion (Enzymes) Mucus secretion (Mucus)

Glands & Types of Secretion:

Glands & Types of Secretion Parotid gland : (Entirely serous secretion): contain entirely enzymes 2. Sub –maxillary or sub mandibular gland: ( Serous & mucus secretion): It is mixed gland secrete both mucus &serous secretion. (more serous less mucus). 3. Sub lingual gland. (Entirely mucus secretion):

General Characteristics of Saliva:

General Characteristics of Saliva Saliva is alkaline in nature. Its pH ranges from 6-7 Daily secretion of saliva is 1000-1500 ml/day .

Composition of Saliva:

Composition of Saliva Saliva Liquid Solid Water Inorganic Organic NaCl Alkaline Phosphate Acid phosphate Enzymes Alpha salivary amylase Lingual lipase Carbonic anhydrase Phspatase Bactriolytic enzymes Lysozymes B. Mucin C . Urea , amino acids D. Thiocynate , Iodin

Functions of Saliva:

Functions of Saliva Mechanical Functions: It keep the mouth moist and helps in speech . Decrease in salivary secretion causes impairment of speech eg in case of nervousness. It helps in mastication of food. It act as lubricant .

Functions of Saliva:

Functions of Saliva Mechanical Functions: It dilute the hot and irritant substances and prevent the injury to mucus membrane. Constant flow of saliva washes the mouth from food debris and prevent the bacterial growth. It helps in sensation of taste.

Functions of Saliva:

Functions of Saliva Digestive Functions: Saliva contain alpha salivary amylase which convert starch into maltose. Excretory Functions: Saliva excretes urea , some metals , thiocynate , iodine etc.

Functions of Saliva:

Functions of Saliva Water Balance : Saliva keep the mouth moist. When moisture reduced in mouth, certain nerve endings at the back of tongue stimulate and give the sensation of thrust. .

Functions of Saliva:

Functions of Saliva . Buffering Action : Saliva act as buffer, especially bicarbonate, phosphate and mucin present in saliva act as buffer.

Regulation of Salivary Secretion:

Regulation of Salivary Secretion Unique aspects of control of salivary secretion Secretion rate depends entirely on neural control - ANS both Parasympathetic and Sympathetic lead to increase secretion

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