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BDS1 BAMS: Oral Morphology, Histology and Physiology > The Oral Environment 1-3 > Flashcards

The Oral Environment 1-3 Flashcards

1
Q

What are the functions of oral fluids?

A

Protective: cleansing, mucosal protection, buffering, remineralisation, antimicrobial

Digestive: taste, digestive enzymes, lubricates bolus for chewing, swallowing

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2
Q

What is a prominent symptom for patients with salivary gland disease?

A

Xerostomia (dry mouth)

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3
Q

What effects can reduced salivary flow have on oral health?

A
  • Increased incidence of dental caries

- Caries present on buccal and labial surfaces

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4
Q

Caries resulting from lack of salivary flow would likely be present on which tooth surfaces?

A

Buccal and labial surfaces

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5
Q

What type of glands are salivary glands?

A

Exocrine

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6
Q

What type of secretions do salivary glands produce?

A

Serous and/or mucous secretions

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7
Q

What arrangement do salivary glands have?

A

Compound, tubulo-acinar arrangement

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8
Q

Which layer of the oral mucosa contains minor salivary glands?

A

Lamina propria

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9
Q

What are the major salivary glands?

A

Parotid, submandibular, sublingual

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10
Q

What are the minor salivary glands?

A
  • Buccal
  • Labial
  • Lingual
  • Palatal
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11
Q

Which major salivary gland has serous secretions?

A

Parotid

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12
Q

Which major salivary gland has mixed serous/mucous secretions?

A

Submandibular

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13
Q

Which major salivary gland has mucous secretions?

A

Sublingual

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14
Q

Describe the type of secretions produced by the minor salivary glands

A

Buccal - mucous
Labial - mucous
Lingual - serous and mucous
Palatal - mucous

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15
Q

What is gingival crevicular fluid (GCF)?

A

Fluid from the epithelium lining the gingival crevice (sulcus)

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16
Q

Describe the flow rates of gingival crevicular fluid in health and inflammation states

A

Little GCF from healthy gingivia, but flow increases with inflammation e.g. gingivitis

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17
Q

Which salivary gland is produces most saliva when you sleep?

A

Submandibular gland

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18
Q

When is salivary flow rate the highest: sleeping, awake or eating?

A

Eating

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19
Q

When is salivary flow rate the lowest?

A

Sleeping

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20
Q

What is the average daily salivary flow in ml?

A

500-700ml

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21
Q

Which is the major salivary gland when eating?

A

Parotid

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22
Q

Which salivary gland produces most saliva when awake (not eating)?

A

Submandibular

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23
Q

Which factors can affect unstimulated salivary flow rate?

A
  • State of hydration
  • Previous stimulation
  • Circadian rhythms
  • Circannual rhythms
  • Medications
  • Salivary gland disease
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24
Q

Describe the composition of saliva

A

Inorganic:
Water = 99.5%
Ions = 0.2%

Organic:
Proteins - 0.3%

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25
Q

When is bicarbonate ion concentration highest?

A

At higher salivary flow rates

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26
Q

What is bicarbonate important for in the oral cavity?

A

Buffering plaque acids

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27
Q

What is the function of fluoride in saliva?

A
  • Antibacterial
  • Forms fluoroapatite
  • Promotes remineralisation
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28
Q

What is the function of calcium and phosphate in the saliva?

A

Remineralisation

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29
Q

What is the role of thiocyanate in the saliva?

A

Antibacterial

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30
Q

When is bicarbonate most effective at buffering?

A

At high salivary flow rates, when [HCO3] is highest

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31
Q

When are phosphates important for buffering?

A

At rest

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32
Q

Which pH do proteins have their main buffering action at?

A

pH <5

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33
Q

Which enzyme converts water and carbon dioxide into carbonic acid (H2CO3)?

A

Carbonic anhydrase

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34
Q

Describe the stages in saliva secretion

A
  1. Acetylcholine (ACh) induces calcium release
  2. Calcium works on channels to bring Cl- to the lumen
  3. ATP exchange (3Na+ in, 2 K+ out), sodium is brought through the membrane to pair with chloride (NaCl)
  4. Osmotic pressure drives water into the lumen
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35
Q

What is amylase?

A
  • Enzyme produced in saliva

- Hydrolyses alpha-1,4-glycosidic bonds in starch

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36
Q

What is lysozyme?

A
  • Role in non-specific defence
  • Present in many secretions: saliva, tears, vaginal mucous
  • Attacks bonds in bacterial cell walls, causing lysis
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37
Q

What is lactoperoxidase?

A
  • Enzyme from salivary glands and some bacteria
  • Allows oxidation of SCN- -> OSCN-
  • Has antibacterial action
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38
Q

What are cystatins?

A
  • Inhibit cysteine proteases, especially in bacteria

- Antimicrobial function

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39
Q

What is gustin?

A
  • Zinc-containing protein
  • Facilitates taste by activating taste buds
  • CO2 + H2O -> H+ + HCO3-
  • Potent PDE 5 activator
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40
Q

What are histatins?

A
  • Histidine rich proteins
  • Inhibit CaPO4 precipitation
  • Antimicrobial
  • Inhibits: candida albicans, streptococcus mutans
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41
Q

What is the role of immunoglobulins in the saliva?

A
  • From plasma cells in salivary glands
  • Secretory IgA
  • Confers specific immunity against bacteria
  • Basis of vaccination vs. S mutans
42
Q

What is lactoferrin?

A

Iron-binding protein
Binds Fe3+
Antibacterial

43
Q

What is lipase?

A
  • Breaks down lipids/hydrolyses triglycerides
  • Lingual lipase
  • From von Ebner glands on tongue
  • May assist in digestion of milk
44
Q

What are mucoproteins (‘mucins’)?

A
  • CHO-protein macromolecules
  • Bind to tooth and epithelial surfaces
  • Protective role, lubrication
  • Affects bacterial adhesion
  • Promotes bacterial aggregation -> easier clearance from mouth
45
Q

What are proline-rich proteins (PRPS)?

A
  • Inhibit growth of Ca3PO4 crystals
  • Anticalculus effect?
  • Adsorbs onto hydroxyapatite
  • Decreases mineral loss
  • Resists acid attack
  • Allows remineralisation
  • Regulates bacterial attachment
46
Q

What are statherins?

A
  • Prevent precipitation of Ca3PO4 from saliva
  • Saliva is supersaturated with Ca2+ and PO4
  • Anticalculus action
47
Q

What are some examples of plasma-derived substances that ‘spill over’ into saliva?

A
  • Proteins e.g. albumins
  • Blood group substances
  • Immunoglobulins (IgG)
  • Hormones
  • Drugs
48
Q

What are conditioned responses?

A

Learned; acquired by association

e.g. Pavlov’s experiments

49
Q

What are unconditioned responses?

A

Unlearned, innate responses

50
Q

Give examples of unconditioned salivary stimuli

A

Mechanical: pressure on the PDL/oral mucosa
Chemical: gustation, olfaction, common chemical sense

51
Q

Define ipsilateral

A

Same side of the body

52
Q

What does pressure on the PDL (e.g. chewing) result in?

A

Increased salivary flow from ipsilateral glands

53
Q

Where are taste buds located?

A

Tongue dorsum, palate and epiglottis

54
Q

Describe the order of potencies for producing saliva from high to low

A

Acid > umami > sweet > bitter

55
Q

Which ‘taste’ is salivary response greatest for?

A

Acidic

56
Q

Which ‘taste’ generates the lowest salivary response?

A

Bitter

57
Q

What is common chemical sense?

A
  • A primitive response to irritants, injury
  • Mediated by nociceptors in mucous membranes
  • Contribute to ‘taste’ of spices
58
Q

What is conditioned salivary stimuli?

A

Learned responses to:

  • ‘psychic’ stimuli (thinking about food)
  • visual stimuli
  • auditory stimuli e.g. Pavlov’s experiments
  • Responses are easily lost (become ‘extinct’) if not regularly reinforced
59
Q

How can a conditioned stimulus cause a response on its own?

A

Pair conditioned stimulus (e.g. buzzer) with an unconditioned stimulus (e.g. food), repeat the 2 stimuli together. Eventually, conditioned stimuli will produce a response on its own.

60
Q

How is salivation controlled?

A

By the autonomic nervous system
Both parasympathetic and sympathetic nervous systems act to increase salivary secretion
Sympathetic nervous system stimulates more mucous salivation

61
Q

Describe the parasympathetic controls of saliva secretion

A

Parasympathetic nervous system: increases saliva secretion, increases blood flow (vasodilation)

62
Q

Describe the sympathetic controls of saliva secretion

A

Sympathetic nervous system: increases saliva secretion, decreases blood flow (vasoconstriction)

63
Q

Describe the 2 stage mechanism of salivary secretion

A

Stage 1: primary secretion in acinus

Stage 2: ductal modification

64
Q

Describe stage 1 of salivary secretion (primary secretion in acinus)

A
  • Chloride is pumped into the lumen, Na+ crosses over membrane and combines with chloride forming NaCl
  • Water forced into lumen by osmotic pressure
  • Carbon dioxide from blood combines with water in presence of carbonic anhydrase, forms carbonic acid
  • Carbonic acid dissociates to form bicarbonate and hydrogen
65
Q

Describe stage 2 of salivary secretion (ductal moification)

A
  • Primary saliva is modified as it moves through the striated duct
  • Na+ and Cl- reabsorbed
  • HCO3- and K+ secreted
  • Final saliva is hypotonic to plasma
  • Some proteins are secreted by the ducts
66
Q

What is the volume of saliva in the mouth?

A

~1.1 ml (range = 0.5-2.1 ml)

67
Q

What area is saliva in the mouth dispersed over?

A

~200 cm2

68
Q

How thick is the film of saliva covering the mucosa?

A

50-100 micrometres thick

69
Q

Salivary flow velocity rates vary in different regions of the mouth. Where is it highest/lowest?

A
  • Highest in lower lingual region

- Slowest in labial and buccal regions

70
Q

Differences in salivary flow velocity rates in different regions of the mouth may influence what?

A

The incidence of caries in different regions of the mouth - cariogenic sugars are retained longer in regions where flow is slowest

71
Q

Which region of the mouth has the highest salivary flow velocity rate, anterior or posterior?

A

Posterior (increase in flow rate moving from anterior to posterior region)

72
Q

Where does calculus tend to build up?

A

Lower regions

73
Q

What is calculus?

A

The mineralisation of dental plaque - increased saliva in lower lingual regions -> increased calcium phosphate -> increased calculus in these regions

74
Q

What is ‘clearance’?

A

Clearance refers to the rate at which substances are removed from the mouth

75
Q

Which factors influence clearance?

A
  • Salivary film velocity

- Location in the mouth

76
Q

What is the benefit of low salivary flow rates?

A

Retention of beneficial substances e.g. fluoride, chlorhexidine

77
Q

What is the benefit of high salivary flow rates?

A

Removal of harmful substances e.g. sucrose

78
Q

What is the Stephan curve?

A

A graph of the plaque pH change over time is called a Stephan curve

79
Q

What is the critical pH on a Stephan curve?

A

The pH at which plaque can start to remove elements form the tooth. Anything below critical pH creates caries. Above critical pH = remineralisation

80
Q

How does chewing gum increase salivary flow?

A

Stimulates the periodontal ligament (mechanoreceptors)

81
Q

What effect does chewing gum have on the sugar challenge?

A

pH drop is reduced, returns to normal pH quicker.

82
Q

What is the sugar challenge?

A

Cup of sugary liquid held in the mouth, spit it out. Measure pH changes over time.

83
Q

How does increased salivary flow neutralise plaque acid?

A

By increasing bicarbonate content of saliva. Bicarbonate acts as a buffer - resists pH changes

84
Q

How is plaque protected against salivary flow?

A

Structural network of insoluble sugars inside plaque

85
Q

Which carbohydrates (mainly) cause caries?

A

Fermentable carbohydrates

86
Q

What is the benefit to oral health of alternative sweeteners?

A

Alternative to fermentable carbohydrates: have a sweet taste but not metabolised to acids by plaque bacteria

87
Q

What are the types of sweeteners?

A
  • Bulk caloric/low caloric sweeteners

- Non-calorie, high intensity sweeteners

88
Q

Which sweeteners are classed as bulk caloric (cariogenic)?

A

Sucrose, fructose, glucose, lactose

89
Q

Which sweeteners are classed as non-caloric/high intensity?

A

Aspartame, cyclamates, saccharin, sucralose

90
Q

Which sweeteners are classed as low caloric?

A

Mannitol, sorbitol, xylitol

91
Q

Which sweetener is commonly found in chewing gum?

A

Xylitol

92
Q

Which sweetener has a laxative effect?

A

Xylitol

93
Q

When do patients tend to complain of dry mouth?

A

When salivary flow rates fall below 50% of normal levels

94
Q

What would cause a reduction by 50% of normal salivary flow rate?

A

Loss of function of more than one major salivary gland

95
Q

What are the causes of decreased salivary flow?

A
  • Side effect of many drugs
  • Radiotherapy (for head and neck tumours)
  • Diseases: specific salivary gland disease, systemic diseases that affect salivary glands, fluid/electrolyte loss
96
Q

What is the BNF and what does it do?

A

British National Formulary

Provides up-to-date information on medicines

97
Q

What is Sjorgen’s syndrome?

A

Autoimmune condition that affects salivary glands. Most common glad affected is lacrimal glands. Dry eyes and dry mouth are symptoms.

98
Q

What type of caries are associated with reduced salivary flow

A

Smooth surface caries

99
Q

What are the consequences of reduced salivary flow?

A
  • Increased dental caries
  • Increased oral diseases (stomatitis, fissured lips)
  • Dysaesthesia (burning mouth)
  • Impaired oral function (chewing, swallowing, speaking)
  • Diminished taste perception
100
Q

What is oral dysaesthesia?

A

Sensation of having a burning mouth

101
Q

How can xerostomia be managed?

A
  • Depends on the cause
  • If there is functioning salivary gland tissue present: stimulate salivary flow by chewing, or drugs
  • If there is no functioning salivary gland tissue, saliva substitutes may be used: mucin based; cellulose based

BDS1 BAMS: Oral Morphology, Histology and Physiology (10 decks)

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