Biochemical composition of saliva 1 Dr Sara Amjad 9 1 2019

Introduction of Gastro Intestinal tract Every cell of living system needs energy Unicellular organisms: Exists in the sea of nutrients Can satisfy their nutritional need just by Proteins present at the cell membrane

Multi cellular organisms In multi cellular organisms, a groups of cells converted to a tissue , to perform specific function A number of systems are evolved in vertebrates including humans To provide nutrients to all the systems The Gastro intestinal tract is accounted for extraction of nutrients from the food

The Food The most of the food we eat are macromolecules , it can not cross the cell membrane easily so it must be converted to monomers Gastrointestinal tract is to make the food in absorbable form by help of chewing and mixing with various enzymes in mouth to small intestine

Digestive system

Components of GIT Oral Cavity Oesophagus Stomach Duodenum Jejunum Various parts Glands includes Oral Cavity Salivary glands Oesophagus Gastric glands Stomach Pancreas Duodenum Jejunum Liver and biliary system Ileum Intestinal glands Jejunum Endocrine glands Cecum Enteric nervous system Colon Circular smooth muscles Rectum and anal canal Longitudinal muscles

Saliva Colorless Viscoelastic Various biologic functions In adult total volume 750-1000ml/day Specific gravity 1.002 -1.012 Average pH 6.75

Structure of salivary Glands

Major salivary glands Parotid Sub maxillary Sublingual

Minor salivary glands Labial Lingual Buccal Palatal

95 percent secretion 5 percent secretion Submandibular glands 60 percent Parotid glands 30 percent Sublingual glands 5 percent

During sleep parotid and sublingual glands do not secrete saliva , submandibular glands secrete saliva to keep oral cavity and tongue wet and clean

Types of salivary gland cells Terminal secretory units Three types of cells Serous Mucus Myoepithelial cells

Parotid gland…serous gland Sublingual gland ….mucous gland Submandibular gland….mixed gland

Formation of saliva Primary secretion or primary saliva Terminal secretary unit Intercalated ducts Striated ducts excretory duct oral cavity

Composition of primary saliva primary saliva(intercalated duct) Saliva (oral cavity) Isotonic fluid Hypotonic fluid Na K HCO3

Primary saliva lacks lysozyme, lactoferrin and kallikrein Difference in composition Electrolyte exchange Secretion of proteins Striated ducts secrete K in and actively reabsorb Na from primary secretion

Striated duct cells also secrete kallikrein and glycoprotein's Intercalated ducts secrete antibacterial proteins ,lysozyme and lactoferrin Water secretion at terminal secretary units

Concentration Gradient Proteins Na+& Cl- K+ ©Reeves 2013 Hypotonic Final Saliva Concentration Gradient Concentration Gradient H2O Water and electrolytes Isotonic Primary Saliva

Factors Stimulating Salivary Secretion Psychic stimuli Chemical stimuli Mechanical stimuli

salivary secretion Resting level of salivary secretion is 0.25 to 0.4ml/min Stimulus 1 to 3 ml/min

Regulation Of Saliva Secretion of saliva is under autonomic nervous system Salivary gland are innervated by both parasympathetic (cholinergic) and sympathetic (adrenergic) nerve fibers Neurotransmitters at neurosecretory junction are acetylcholine and nor epinephrine respectively

Cholinergic…..watery saliva Adrenergic……thicker saliva

BIOMEDICAL IMPORTANCE OF SALIVA

Lesion in cavity…excessive salivation Opiorphin …pain killing substance Diabetes mellitus …enlargement of parotid gland Sjogren,s syndrome…little secretion Cushing's syndrome …Na content increases

Antihypertensive drugs, antidepressants drugs causes xerostomia Hypo secretion causes dental caries

Artificial saliva Saliveze , xialine 1, xialine 2 Composition of artificial saliva Water Electrolytes Mucoadhesive polymer No digestive and antimicrobial enzymes

Diagnostic significance of saliva Isolation of virus Detect presence of antibodies against virus causing AIDS, measles, Hepatitis A, B and C Sialochemistry helps in determination of ovulation time