Salivary Flow and Its Factors

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Questions and Answers

What is the typical pH range of saliva?

6.7 - 7.4 (correct)

7.5 - 8.0

7.0 - 8.5

5.0 - 6.0

Which protein in saliva is primarily responsible for aiding in the disposal of bacteria?

Mucin

Immunoglobulins (correct)

Amylase

Lactoferrin

What is the role of lysozyme in saliva?

Inhibits bacterial metabolism

Destroys harmful bacteria by lysis (correct)

Breaks down starches

Neutralizes acids

Which enzyme catalyzes the endonucleolytic cleavage of RNA?

Ribonuclease Signup and view all the answers

How do mucin proteins affect the consistency of saliva?

They give it a viscous/sticky consistency. Signup and view all the answers

What by-product of cell metabolism can neutralize acids found in saliva?

Urea Signup and view all the answers

Which component of saliva helps reduce the acidity that contributes to tooth decay?

Waste products Signup and view all the answers

Which of the following statements about saliva's protein content is true?

Several hundred different proteins are present. Signup and view all the answers

What triggers increased salivary flow during mastication?

It activates the salivary glands and mechanoreceptors. Signup and view all the answers

Which condition is most likely to reduce salivary flow due to its effects on the nervous system?

Drugs Signup and view all the answers

How does hunger increase salivary flow?

It triggers the salivary glands in anticipation of eating. Signup and view all the answers

What is the primary effect of alcohol on salivary production?

It causes dehydration of the body. Signup and view all the answers

Which of the following conditions is associated with decreased salivary flow due to dehydration from high blood sugar levels?

Diabetes Signup and view all the answers

What physiological response occurs during teething to increase saliva production?

Nervous stimulation from discomfort. Signup and view all the answers

What effect does fear have on salivary flow?

It decreases salivary production by affecting the nervous system. Signup and view all the answers

Radiotherapy can affect saliva production by damaging which type of glands?

Salivary glands Signup and view all the answers

What role does salivary amylase play in digestion?

It helps break down cooked starches. Signup and view all the answers

How may xerostomia affect taste sensation?

Limits taste detection due to lack of saliva. Signup and view all the answers

Which of the following describes the protective function of saliva?

Saliva protects against harmful bacteria. Signup and view all the answers

What impact does the salivary pellicle have on teeth?

Increases bacterial adherence. Signup and view all the answers

What changes in saliva quantity are observed from day to night?

Decreases significantly to about 10ml at night. Signup and view all the answers

What is the immediate effect of a fall in pH in the mouth?

Increases migration of ions from enamel and plaque. Signup and view all the answers

How does saliva help manage acid in the mouth?

By acting as a buffer to control pH levels. Signup and view all the answers

What may happen to patients with impaired salivary flow?

Rapid plaque deposition and increased periodontal disease. Signup and view all the answers

What happens to mineral ions when the pH falls below 5.5?

Mineral ions leave the enamel to enter the plaque. Signup and view all the answers

Which mechanism stimulates saliva flow in response to sensory inputs?

Neural signals. Signup and view all the answers

What is the effect of sympathetic stimulation on salivary flow?

Decreases salivary flow due to vasoconstriction. Signup and view all the answers

How does parasympathetic stimulation affect the salivary glands?

It increases saliva flow. Signup and view all the answers

What occurs when the buffering action is effective and pH rises in the plaque fluid?

Mineral ions return to the enamel from the plaque. Signup and view all the answers

At what pH level does the solubility limit for plaque fluid begin to affect calcium and phosphate ion concentrations?

At 5.5. Signup and view all the answers

What type of nerve actions control the salivary glands?

Sympathetic and parasympathetic nerves. Signup and view all the answers

What is the primary effect of salivation in response to favorable sensory stimuli?

Enhanced digestion process. Signup and view all the answers

What is the pathway for the parasympathetic supply to the submandibular and sublingual glands?

From the superior salivary nucleus via the facial nerve to the submandibular ganglion Signup and view all the answers

Which nerve carries taste sensation from the posterior third of the tongue?

Glossopharyngeal nerve Signup and view all the answers

Which structure is the postganglionic pathway of the parasympathetic supply to the parotid gland associated with?

Auriculotemporal nerve Signup and view all the answers

What type of nerve supply increases saliva production in the submandibular and sublingual glands?

Parasympathetic supply from the facial nerve Signup and view all the answers

Which ganglion is involved in the synapse for the parasympathetic supply to the parotid gland?

Otic ganglion Signup and view all the answers

Which nerve does taste information from the anterior two-thirds of the tongue travel with to the nucleus solitarius?

Chorda tympani Signup and view all the answers

What is the source of sympathetic supply to the submandibular and sublingual glands?

Facial artery Signup and view all the answers

Which of the following factors is likely to cause an increase in salivary flow?

Thought of food Signup and view all the answers

Study Notes

Salivary Flow

Increased flow
- Mastication - mechanical stimulation of the salivary glands
- Irritants - triggers the salivary glands to fight infection
- Gingival conditions - triggers the salivary glands to promote healing
- Hunger - brain anticipates food and stimulates the salivary glands
- Smell/sight of food - brain anticipates food and stimulates the salivary glands
- Teething in babies - more saliva is created to soothe irritated gums
Reduced flow
- Drugs - interfere with the nervous system that regulates saliva flow
- Alcohol - dehydrates the body
- Diabetes - dehydration and high blood sugar levels cause saliva gland hypofunction
- Fear - the nervous system is affected
- Radiotherapy - damage to the saliva glands
- Surgery - anesthesia used suppresses the nervous system

pH of Saliva

Average pH is 6.7-7.4, which is neutral
pH can vary depending on what has been eaten and the time of day
Low pH leads to higher caries
High pH leads to more calculus formation

Components of Saliva

Proteins:
- Various proteins with antibacterial properties
- Mucin and enzymes are also proteins
Immunoglobulins:
- IgA, IgG and IgM
- Destroy bacteria by clumping them, preventing adherence to the oral cavity
Enzymes:
- Lysozyme - destroys bacteria by lysis (cell wall destruction)
- Lactoferrin - binds free iron, inhibiting bacterial metabolism
- Lactoperoxidase - also inhibits bacterial metabolism
- Amylase - begins the breakdown of cooked starches
- Ribonuclease - cleaves RNA
- Phosphatase - involved in the process of calculus formation and remineralisation of caries
Mucin:
- Gives saliva its viscous consistency
- Two types:
  - Muco-proteins - contain more than 4% carbohydrate derivatives
  - Glyco-proteins - contain less than 4% carbohydrate derivatives
Waste products:
- Urea - neutralizes acids
- Uric acid
- Ammonia - formed from urea; raises pH
- All are by-products of cell metabolism

Other components of Saliva

Cells:
- Desquamated epithelial cells - worn/dead cells are replaced
- White blood cells - from the gingival crevice, especially during inflammation
Digestion:
- Salivary amylase breaks down cooked starches and helps to form the bolus
Taste:
- Taste sensation can only be detected when substances are in solution

Functions of Saliva

Antimicrobial:
- Proteins and Immunoglobulins help destroy or prevent colonization by harmful bacteria
Tooth integrity:
- Ions in saliva aid maturation of immature enamel and aid repair from acid attacks

Saliva and Caries

Viscosity:
- The salivary pellicle, formed by glyco-proteins, protects against acids but also encourages adherence by bacteria
Supersaturation of Inorganic Ions:
- Acts as a buffer to control acid in solution and continually aids control of demineralization and remineralization
Serous Saliva:
- Cleansing action reduces the amount of fermentable carbohydrate available for conversion to acid
Quantity:
- Changes from day to night
- Stimulated by eating
- Affected by drugs, illness and radiation

pH Fluctuations

The salivary buffering system can reduce the extent of the fall in pH when sugars enter the mouth
Prolonged episodes can exhaust the system's ability to contain ion removal
A fall in pH below 6.0 increases:
- The free energy of the ions at the enamel/plaque interface
- The migration of ions from both enamel and plaque

Demineralization and Remineralization

When the solubility limit of the plaque fluid exceeds the calcium and phosphate ion products, these ions leave the enamel
This occurs at around pH 5.5
Below this level, enamel begins to demineralize
If the buffering action is effective and the pH rises, the additional mineral ions in the plaque fluid will exceed its capacity to hold them in solution. This will cause the mineral ions to return to the enamel, and the enamel will remineralize.

Mechanism of Salivation

Salivation is a reflex mechanism stimulated by sensory inputs:
- Sight
- Smell
- Taste
Also controlled by the sympathetic and parasympathetic nervous systems:
- Sympathetic: Reduces salivary flow
- Parasympathetic: Increases salivary flow

Salivary Gland Innervation

The sympathetic and parasympathetic nerves have opposite effects on the salivary glands.
Sympathetic:
- Reduces flow via vasoconstriction
Parasympathetic:
- Increases flow via vasodilation

Glands and Innervations

Hard and Soft Palate:
- Sympathetic: From the internal carotid artery to the sphenopalatine ganglion
- Parasympathetic: From the superior salivary nucleus via the facial nerve to the sphenopalatine ganglion
Submandibular and Sublingual Glands:
- Sympathetic: From the facial artery via the submandibular ganglion to the sublingual and submandibular glands
- Parasympathetic: From the superior salivary nucleus via the facial nerve to the submandibular ganglion.
Parotid Glands:
- Sympathetic: From the middle meningeal artery via the otic ganglion to the parotid
- Parasympathetic: From the inferior salivary nucleus via the glossopharyngeal nerve to the otic ganglion

Taste

The anterior two-thirds of the tongue:
- Taste buds via the lingual nerve to the submandibular ganglion
- Then travel with the chorda tympani and the facial nerve to the nucleus solitarius in the brain.
The posterior third of the tongue:
- Taste buds via the glossopharyngeal nerve to the nucleus solitarius in the brain

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Description

This quiz covers the factors that influence salivary flow, including both increased and reduced flow causes. It also examines the pH levels of saliva and how they can vary based on diet and time of day. Test your knowledge of the physiological aspects of saliva and its significance in oral health.