Transcript 2. Cystatins

COMPOSITION, FUNCTIONS AND PHYSIOLOGICAL
ASPECTS OF SALIVA
BY ;DR QAZI IMTIAZ RASOOL
OBJECTIVES
1. Describe the secreto-motor nerve supply of the salivary glands
2. Discuss the composition of salivary secretion.
3. Describe the mechanism and regulation of salivary secretion
4. Enumerate the functions of saliva
CLASSIFICATION OF SALIVARY GLANDS
1. ANATOMY;1.Major salivary glands
1) Parotid;- 20 grams , serous (20-25%)
2) Submandibular;- 10 gram mixed (70%)
3) Sublingual;-5gram mucus (5-10%)
2.Minor salivary gland
1. Not found in gingiva and anterior part of the hard palate
2.Von Ebner below the sulci of the circumvallate and folliate
papillae of the tongue
3.Glands of Blandin-Nuhn: ventral tongue
4.Palatine, glossopalatine glands
5.Weber glands
2. PHYSIOLOGY;1.Serous salivary glands
2.Mucous salivary glands
3.Mixed salivary glands
Nerve supply
1. No direct inhibitory innervation
2.
Both parasympathetic (more prevalent) and sympathetic impulses
3. Parasympathetic impulses may occur in isolation, evoke most of the fluid to be
excreted, cause exocytosis, induce contraction of myoepithelial cells (sympathetic
too) and cause vasodilatation.
Inferior salivary nucleus
Glossopharyngeal nerve
Tympanic branch
Tympanic plexus
9th
Lesser petrosal nerve
Otic ganglion
Lesser
petrosal N.
2-Sympath.Fs. : plexus of nerves around external carotid artery.
3-Sensory Fs. : auriculotemporal N. (branch of mandibular N.) ascends
from upper end of parotid gland
Nerve supply :
2-Symp.Fs. : from plexus of nerves around Facial +Lingual arteries.
3-Sensory : lingual N.
sup.salivary.N
Facial N
chorda tympani N
lingual N
submandibular ganglion
lingual N
SECONDARY FACTOR
1.Para-sympathetic Nerve- moderately dilate-blood vessels
2. Salivation itself directly dilates B.V,
3
3.. Also vasodilator effect is caused by kallikrein secreted
by activated salivary cells,
Acts on α2-globulin
2
Bradykinin (vasodilator).
1
Chemical composition and
functions of saliva
COMPOSITION
97-99.5% water
1-2L/day, (1ml / gm/ min - 60 times that of pancreas).
Basal flow rate 0.5→ 5mL/min
pH slightly acidic (pH 5.8 -7.4) Hypo-osmotic
Solid Composition 0.5%-1%
1. Inorganic salts (1/3) Na+40, K+15, Cl–25, PO4, HCO3–30(mmol/L)
2. Digestive enzyme S.Amylase, lingual lipase,
3. Proteins – Mucin, Lysozyme, Defensins, and IgA , RNA-ease Statherins,ProlinerichProteins,Histatins, Cystatins,
4. Metabolic wastes – urea , uric acid
5. Hormones – Kallikaren , Lactoferrin , Somatostatin ,Glucogan , Lactoperioxidase,
Salivary peroxidase
6.
Heavy metals- Hg , Pb
7. Nerve growth factors,
renin
8. Specific blood groups A,B,O, Le secretors
9. Cellular component Desquameted Ep; cells, WBC,
Major salivary components
Histatins
Statherins
Lysozyme
Proline-rich proteins
Carbonic anhydrases
Amylases
Peroxidases
Lactoferrin
Mucin 2 (MG2)
IgA
Mucin 1 (MG1)
1
10
100
Size (kDa)
1000
10000
Formation and Secretion of Saliva
2 stage hypothesis
1. Primary saliva
1.
2.
Serous and mucous cells
Intercalated ducts
2. Modified saliva
1.
2.
Striated and terminal ducts
End product is hypotonic
Modified saliva /Secondary/Ductal secretion
Effects of Stimulation
Responses
Parasympathetic
Sympathetic
Saliva output
Copious
Scant
Sustained
Transient
Composition
Protein poor
↑ K+ and HCO3
high Protein-rich,
↓ K and HCO3
Response to
↓secretion
atrophy
↓ secretion
Response
denervation
•
•
•
-potency of stimuli= sour>salt>sweat>bitter
Lemon combinig sour+sweet is the strongest
Dry>moist, round objects>irregular
Functions of Saliva
1. MUCIN FUNCTIONS
( mol ;- amphoteric properties buffering of acid+alkalies)
1. Lubrication Tissue Protective coating for hard and soft tissues i.e., oral cavity and esophagus,
and food basically never directly touches the epithelial cells of those tissues
2. Binding mucus binds masticated food into bolus that slides easily through esophagus without
inflicting damage to the mucosa.
3. Moistens food
4. Dilutes hot and irritant substances
5. React with bacterial adhesins Mucin-coated bacteria may be unable to attach to surface
Bacterial adhesion, thereby blocking them
2. DIGESTION
1.α-Amylase breaks down starch amylose , amylopectin,
,glucose into smaller molecules (pH 6.8)
- stops functioning at pH 1.5 (stomach)
2. Lingual Lipase Secreted (von Ebner’s glands of tongue)
Hydrolyzes medium- to long-chain triglycerides
Important in digestion of milk fat in new-born highly hydrophobic
enters fat globules
3. Maltase
converts maltose to glucose
3. SOLUBILIZES DRY FOOD
in order to be tasted, the molecules in food must be solubilized
4. DEHYDRATION
Good messenger ,mouth dryness sensation
of thirst.
5.PRECIPITATION OR CRYSTALLIZATION
1.Statherins prevent precipitation of CaPO4(TARTAR)
2. Proline-rich Proteins (PRPs) Inhibitors of CaPO4 crystal growth
(initially formed enamel )
6. EXCRETORY FUNCTION
1.Certain waste matter such as urea + K+- thiocynate
2. Drugs iodide, pencillin, alcohol
3.Viruses;- Rabies, hepatitis, Mumps. Polio viruses.
7. ANTI-FUNGAL ACTIVITIES
1. Histatins
-A group of small histidine-rich proteins
Candida albicans growth
Potent inhibitors of
2. Cystatins
A. inhibitors of cysteine-proteases protective ( against
unwanted proteolysis (bacterial proteases, lysed WBC)
B. inhibit proteases in periodontal tissues effect on CaPO4
precipitation
8.ANTI-MICROBIAL ACTIVITIES
Inhibition of bacterial adhesion to tooth surfaces Inhibition of glucose uptake
and acid production
1. Lysozyme ;- derived
1. Major and
2. Minor salivary glands,
3. Phagocytic cells and
4.Gingival crevicular fluid
2. Sialoperoxidase (SP, salivary peroxidase)
Readily adsorbed to various surfaces of mouth enamel,
salivary sediment, bacteria, dental plaque
3. Myeloperoxidase (MP) From WBC entering via gingival crevice 15-20%
of total peroxidase in whole saliva
9. PROTEOLYTIC ENZYMES
Thiocyanate and Lactoferrin ions
— lysozyme—
(a) attack the bacteria,
(b) aid the thiocyanate ions in entering the bacteria where these
ions in turn become bactericidal, and
(c) digest food particles, thus helping further to remove the
bacterial metabolic support. protein antibodies that can destroy oral bacteria
–10. PROTECTIVE EFFECT
–1. keeps the mouth and teeth clean
–2. Ig A and lysozymes (defense against bacteria)
–3. HCO3- prevents dental carries
–4.Diluting noxious substances and the corrosive HCL+ pepsin →
esophagus and mouth during vomitting
11. MECHANICAL FUNCTION.
1. For taste sensation , by dissolving them.
2. Assistance in chewing and swallowing(↓ resistance for slippage)
3. It helps for speech
4. It helps for washing away the food particles mouth clean
5. Sensory analysis by touch, temperature,+ taste receptors
6.Salivary epidermal growth factor promotes the healing of wounds.
22
Animals instinctively lick their wounds
Regulation of Saliva Secretion
1. Cephalic (reflex) phase: few minutes prior to food entry
2. Gastric phase: after food enters the stomach
3. Intestinal phase: a) brief stimulatory effect as partially food enters the duodenum,
b) followed by inhibitory effects (enterogastric reflex and
enterogastrones)
Mechanism of Secretion
is reflex action---- reflex pathway which will consist of;1) Sensory pathway from tongue. ( taste, touch, temperature etc
2) Superior and Inferior Salivary centre in brain.
3) Motor pathway (parasympathetic and sympathetic).
1. Conditional Reflex which is developed by habit as follows reflex from higher
cortical centres
a.By sight
b.By smell
c.Even by sound
d.Thought
2. Unconditional Reflex i.e. , mouth, Oesophagus, stomach, ileum.
Clinical Considerations
1.
2.
3.
4.
5.
6.
Obstruction (Calculus formation)
Role of drugs
Systemic disorders (Sjögren syndrome )
Bacterial or viral infections (Mumps)
Therapeutic radiation
Formation of plaque and calculus
SUMMARY
Amylases, Cystatins,
Histatins, Mucins,
Peroxidases
Carbonic anhydrases,
Histatins
AntiBacterial
Cystatins,
Mucins
Buffering
Amylases,
Mucins, Lipase
AntiViral
Digestion
Salivary
Families
Histatins
Mineralization
AntiFungal
Tissue
Coating
Amylases,
Cystatins, Mucins,
Proline-rich proteins, Statherins
Lubrication &Viscoelasticity
Cystatins,
Histatins, Prolinerich proteins,
Statherins
Mucins, Statherins
Today’ s thought
1. The modern day chewing gums are made of four major ingredients
including synthetic rubber, plastic, sugar, and coloring (dye).
2. Instead of telling customers what they are really eating, ‘gum base’ is
used to generalize a list of ingredients that is never published
3. Most chewing gum is sweetened with aspartame. Long term use of
aspartame has been linked with cancer, diabetes, neurological disorders,
and birth defects
4. You are using 8 muscles during chewing, over use of jaw joint causing
unnecessary tears in cartilages
5. Wastage of 6 glands secretions, more intake of sugars, allergy