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BDS1 > Oral environment 2 > Flashcards

Oral environment 2 Flashcards

1
Q

Function of amylase

A

Enzyme that hydrolyses alpha 1,4- glycosidic bonds in starch to maltose. Potential defence role

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2
Q

Which ion is required for amylase secretion?

A

Ca2+

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3
Q

Which ion is a cofactor for amylase?

A

Cl- (activates amylase)

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4
Q

Where is amylase present?

A

Most mucosal gland secretions (including tears - defence role)

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5
Q

Why is starch cariogenic?

A

Starch is broken down into maltose which can be used by bacterial to lower pH of dental plaque causing caries.

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6
Q

Which is the most cariogenic sugar?

A

Sucrose

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7
Q

Alternative name for lysozyme

A

muramidase

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8
Q

Function of lysozyme / muramidase

A

ubiquitous non-specific defence role. Attacks bonds in bacterial cell walls causing lysis (antibacterial)

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9
Q

Where is lysozyme / muramidase present?

A

many secretions e.g. tears, saliva, vaginal mucus

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10
Q

Function of lactoperoxidase / sialoperoxidase

A

catalyses the reaction of 2 H2O2 -> 2 H2O + O2 which enables the oxidation of SCN- (thiocyanide) to OSCN- (hypothiocyanate) which has an antibacterial role.

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11
Q

Where is lactoperoxidase / sialoperoxidase secreted from?

A

salivary glands and some bacteria

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12
Q

Function of cystatins

A

Inhibit cysteine proteases especially in bacteria. Antimicrobial role (antibacterial and antiviral)

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13
Q

Alternative name for gustin

A

carbonic anhydrase VI

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14
Q

Function of gustin

A

facilitates taste by activating taste buds. (somehow to do with CO2 + H2O <-> H+ + HCO3-

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15
Q

Which ion is found in gustin / carbonic anhydrase VI?

A

Zn

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16
Q

Why might taste changes be a side effect of Viagra?

A

Gustin is the protein that facilitates taste and it is a potent PDE 5 activator which can be affected by Viagra (uses PDE 5 (phosphodiesterase 5) inhibitors).

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17
Q

What are histatins?

A

Histidine-rich proteins

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18
Q

Function of histatins

A

antibacterial (inhibits Streptococcus mutans) and antifungal (inhibits Candida albicans). Also inhibits CaPO4 precipitation which allows saturation of Ca and PO4 in saliva for remineralisation.

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19
Q

What are immunoglobins?

A

(Ig) - antibodies

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20
Q

Which cells secrete immunoglobins?

A

Plasma cells in salivary glands

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21
Q

Which immunoglobin is secreted in saliva?

A

IgA (short term memory) so would have to do yearly vaccinations against S. mutans

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22
Q

Why are there no vaccinations against S. mutans?

A

Because only IgA is secreted in saliva so would have to do yearly vaccinations. However, if someone is repeatedly vaccinated with the same antibody, the risk of anaphylactic shock increases.

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23
Q

Function of immunoglobins

A

Specific immunity against bacteria, fungi, viruses (Antibacterial, antifungal and antiviral)

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24
Q

Function of lactoferrin

A

Binds to Fe3+ so acts as an antibacterial especially against bacterial that require Fe (can grow on blood agar, relevant for gingival sulcus bleeding)

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25
Q

Where is lipase released from?

A

von Ebner glands (serous glands near circumvallate papillae) therefore called lingual lipase

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26
Q

Function of lipase

A

hydrolyses triglycerides (may assist in milk digestion)

27
Q

Alternative name for mucoproteins

A

mucins

28
Q

Structure of mucoprotein / mucin

A

CHO-protein macromolecule (lots of carbohydrate/CHO side chains) which can bind to tooth and epithelial surfaces

29
Q

Function of mucin/ mucoprotein

A

binds to tooth and epithelial surfaces to lubricate and forms component of primary pellicle (part of biofilm). Promotes bacterial aggregation making clearance easier. Also helps bolus formation.

30
Q

Function of proline-rich proteins (PRPs)

A

inhibit the growth of Ca3PO4 crystals, adsorbs onto hydroxyapatite, regulates bacterial attachment.

31
Q

What is the advantage of proline-rich proteins inhibiting the growth of CaPO4 crystals?

A

Allows the supersaturation of Ca and PO4 in saliva which aids mineralisation

32
Q

What is the advantage of proline-rich proteins adsorbing onto hydroxyapatite?

A

Acts as a diffusion barrier, decreases mineral loss, resists acid attacks, allows remineralisation

33
Q

Function of statherins

A

prevent precipitation of Ca3PO4 from saliva so it is supersaturated with Ca and PO4, allowing remineralisation. Also has an anti-calculus effect.

34
Q

Which plasma-derived substances ‘spill over’ into saliva?

A

Proteins (e.g. albumin), immunoglobins (IgG), hormones and drugs

35
Q

Why can the presence of drugs / hormones be tested using saliva?

A

Drugs and hormones are plasma-derived substances that can enter saliva

36
Q

Which salivary constituents have antimicrobial functions?

A

Immunoglobins, lactoferrin, lysozyme, mucins, histatins, cystatins, lactoperoxidase

37
Q

Which salivary constituents have buffering functions?

A

Proteins (Histatins), phosphate, bicarbonate,

38
Q

Which salivary constituents have digestive functions?

A

Gustin (Zn), amylase, lipase, (protease, DNAase, RNAase) mucin

39
Q

Which salivary constituents have lubricative function?

A

mucoprotein/mucin

40
Q

Which salivary constituents have remineralising function?

A

Prolin-rich proteins (PRPs), slatherin, histatins (inhibit CaPO4 precipitation), Ca, PO4

41
Q

How can control of salivary secretion be divided?

A

Unconditioned (innate) and conditioned responses (learned through association)

42
Q

What are the unconditioned salivary stimuli?

A

mechanical (pressure on PDL / oral mucosa) and chemical (gustation, olfaction, common chemical sense)

43
Q

Which major salivary glands produces the most saliva during chewing/mechanical stimuli?

A

Parotid gland (50%)

44
Q

Does pressure / chewing on one side of the mouth stimulate ipsilateral or contralateral gland secretion?

A

Ipsilateral - e.g. chewing on left side, stimulates secretion from left gland

45
Q

Where are gustatory receptors on taste buds located?

A

Tongue dorsum, palate, epiglottis

46
Q

Order of potency of saliva stimulation of different tastes

A

acid > umami = salt > sweet > bitter

47
Q

Where are olfactory receptors located?

A

In the olfactory epithelium (very weak salivary stimulus)

48
Q

What is common chemical sense?

A

An unconditioned chemical stimuli that contributes to taste of spices

49
Q

Why is the common chemical sense a primitive response to irritants/injury?

A

It increases saliva for protection (e.g. in case of vomiting)

50
Q

Which receptors mediate the common chemical sense?

A

Nociceptors in mucous membranes

51
Q

Examples of conditioned salivary stimuli

A

psychic (thinking about food), visual, auditory (e.g. Pavlov)

52
Q

What happens if conditioned stimuli are not regularly reinforced?

A

response is lost / becomes extinct

53
Q

How do conditioned responses arise?

A

Start with an unconditioned stimulus UCS (e.g. food) which causes salivation and a conditioning stimulus CS (e.g. bell) which doesn’t cause salivation. UCS and CS are repeated together which causes salivation. When the CS occurs on its own it will cause salivation.

54
Q

Which nerves control salivation?

A

Parasympathetic and sympathetic nerves

55
Q

Effect of parasympathetic nerves on salivary secretion

A

increase secretion (ACh)

56
Q

Effect of sympathetic nerves on salivary secretion

A

increase secretion

57
Q

Effect of parasympathetic nerves on blood vessels near the salivary glands

A

vasodilation (blood directed to digestive system)

58
Q

Effect of sympathetic nerves on blood vessels near the salivary glands

A

Vasoconstriction (reduce blood flow)

59
Q

What are the 2 stages in the mechanism of salivary secretion?

A

Primary secretion in acinus and secondary modification in ducts

60
Q

Overview of how primary secretion occurs in the acinus

A

ACh binds to receptor on acinar cell causing Ca2+ to be released in the cell which opens the Cl- channel. Cl- enters the cell via Cl-/K+ pump and diffuses through cell into intercalated duct. Na+ moves from blood to lumen via diffusion though acinar cell. Water follows NaCl by osmosis. CO2 from the blood diffuses into acinar cell. CO2 + H2O -> H+ + HCO3 - (carbonic anhydrase). HCO3- enters lumen of duct.

61
Q

Which ions are reabsorbed / secreted in the secondary modification in the ducts?

A

Na+ and Cl- are reabsorbed into the acinar cells whereas K+ and HCO3- are secreted into the saliva.

62
Q

How is Cl- and Na+ reabsorbed and K+ secreted in secondary modification?

A

Cl-/Na+ pump transports both ions into acinar cell. Cl- diffuses out into the blood via a Cl- channel and Na+ moves into the blood via a Na+/K+ pump which simultaneously moves K+ into the acinar cell. K+ enters saliva.

63
Q

Comparison of final saliva to blood plasma

A

saliva is hypotonic to plasms (Na+ and Cl- ions removed from saliva)

BDS1 (50 decks)

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