Bella Brown Flashcards
Which microbes are living
Bacteria
Archaea
Eukaryote
Which microbes are non living
Prions
Viruses
Define commensals
A microorganisms living on or in the body that is not pathogenic and may confer beneficial effects on host
What are oral flora
Microorganisms that normally inhibit the oral cavity
What beneficial effects do oral flora have
Prevents pathogenic colonisation through competition
Antagonises other bacteria
May make vitamins beneficial to host
Effects immune signalling
What are Kochs postulates for definition of pathogen
4
Suspected pathogen must be present in all cases of disease and absent from healthy animals
Suspected pathogen must be grown in pure culture
Cells from pure culture must cause disease in healthy animal
Suspected pathogen must be re isolated and shown to be same as original
What colour do gram negative bacteria stain
What colour do gram positive stain
Pink
Purple
What does superoxide dismutase metabolise
Oxygen radicals
What does catalase metabolise
H2O2 hydrogen peroxide
Which enzymes do obligate aerobes possess
Which enzymes do facultative anaerobes posess
SOD and catalase
SOD and catalase
Which enzymes do obligate anaerobes posess
Which enzymes do aerotolerant anaerobes posess
Neither SOD or catalase
SOD but not catalase
How do bacteria cause disease
Adhesion pili Exotoxins Endotoxins Agressins Immune damage Biofilm formation
Define biofilm
An aggregate of interactive bacteria attached to a solid surface or each other encased in an extracellular polysaccharide matrix
Why are biofilms hard to treat
3
Evolve rapidly
Exchange genetic information
Can be encased within extracellular polymetric substance
What are the three types of virus
DNA viruses
RNA viruses
Retroviruses
How do DNA viruses function
Replicate using host transcription and translation machinery
How do RNA viruses function
Use own RNA polymerase to transcript but use host translation machinery
How to retroviruses function
Converts its RNA genome into DNA that is inserted into host genome
What are the two structures of fungi
Yeast
Filamentous/mould
Define prions
An abnormal form of a constituent protein of brain cells
Misfolded
What are mammelons
Enamel bumps when tooth newly erupted
Which tooth may appear to have twisted roots
Lower lateral incisor
How many roots does maxillary first premolar have
61% have 2
How many roots does maxillary 2nd premolar have
1
How many cusps does the upper first molar have
Which cusp is biggest
4 cusps
MB MP DB DP
MP biggest
What is a feature of wisdom tooth roots
Fused roots
How many cusps does lower 6 have
5 cusps
Define communicable disease
An illness due to specific infectious biological agents or its toxic products, capable of being directly or indirectly transmitted from man to man, animal to man, animal to animal or environment toman or animal
Define incidence
Number of new cases of disease % per year
Define prevalence
Numberof cases of disease in population at given time %
Define endemic
A disease commonly found within specific population
Define epidemic
A widespread occurrence of infectious disease in a community at particular time
Define zoonosis
Infections naturally transmitted from animal to man
Define resevoir
The environment in which an infectious agent usually lives, grows and multiplies
Define iatrogenic infections
An infection that arises as result of medical intervention
Define opertunistic infection
An infection that doesn’t normally cause disease but becomes pathogenic when bodies immune system impaired
Define caries
An infectious disease with progressive destruction of tooth surface beginning on the external surface by demineralisation of enamel or cementum
Which factors need to be present for caries to arise
4
Tooth surface
Plaque
Free non milk extrinsic sugar
Time
Define plaque
A biofilm consisting of a community of microorganisms enclosed in a matrix of extracellular material derived from the cells and their environment adhered to tooth surface and each other
Stages of plaque formation at times
Pellicle seconds after surface exposed Single bacterial cells 4 hrs Microcolonies 4-24hrs Microbial sucession 1-14 days Maturation 7-14 days
Define acidogenic
Consume sugars and produce lactic acid
Define aciduric
Bacteria thrive at low pH
What are some evidence bacteria are involved in plaque
Bacteria free animals dont get caries
Antibiotics reduce caries
Unerupted teeth don’t develop caries
Oral bacteria can demineralise enamel and dentine in vitro
What are the three categories of sugars
Intrinsic
Milk sugars
Non milk extrinsic sugars
How does saliva help protect against cavities
Clears away carbohydrates
Contains ions to re mineralise tooth surface- fluoride, hydroxyl, calcium phosphate
Acts as buffer to resist acid build up
Contains lysozyme and antibacterial components
What forms enamel
Prisms of hydroxyapatite crystals
What causes white spot lesions
Enlargement of intercrystalline spaces when crystallites shrink as minerals removed
How are dental caries detected
Visual examination
Transillumination
Radiographic examination
What is the critical pH value of enamel
5.5
What are examples of preventative dentistry
Fissure sealants
Plaque control
Diet analysis and advice
Fluoride
Define extracellular matrix
A three dimensional network of extracellular macromolecules such as collagen, enzymes and glycoproteins that provide structural and biochemical support to surrounding cells
What is ECM made by
Made by cells then secreted and modified outside of cells by enzymes
What are the functions of extracellular matrix
Support for cells Provides structure Regulates polarity Regulates cell division Functions as adhesive substrate Presents growth factors to their receptors during developement Sequesters and stores growth factors Senses and transduces mechanical signals
What are the components of extracellular matrix
4
Fibrous proteins
Adhesive proteins
Hydrated matrix
Glycoproteins
What are the two main fibrous proteins
Collagen elastin
What are some properties of collagen
Tensile strength and elasticity
Made by fibroblasts and some epithelial cells
Triple helix
Assembled by enzymes outside cell
What causes scurvy
Insufficient collagen vitamin c deficiency means hydroxylation cannot take place so proline cant be converted to hydroxyproline, a protein in collagen
Too few H bonds are formed in collagen leading to weakness
What are properties of elastin
Uncoils when stretched and re coils when relaxed
Composed of a core of cross linked elastin embedded within peripheral mantle of microfibrils which act as scaffold
Synthesised by fibroblasts and smooth muscle
What part of ECM are proteoglycans
Hydrated matrix
What are proteoglycans
What are they responsible for
Group of proteins with multiple polysaccharide chains Hyaluronic acid backbone Link proteins Core proteins Keratin sulphate Chondroitin sulphate
Responsible for volume of extracellular matrix as each sugar has -ve charge that holds H2O
What are two examples of adhesive proteins
Lamnin and fibronectin
Describe the structure of laminin
Cross like structure composed of three subunits with binding domains
What does laminin do
Guides cells during development
Cells migrate along laminin containing surfaces
What is the role of fibronectin
Migration and differentiation of cells
Attaches cells to matrices containing fibrous collagen
Define matrix metalloproteinases
Group of enzymes responsible for the degradation of extracellular matrix proteins during organogenesis, growth and normal tissue turnover
What happens when medulla oblongata cut at top
Alters but doesn’t abolish respiration rhythm
What happens when medulla oblongata cut at bottom
Abolishes respiratory rhythm
What is the flow of input during respiration
Higher centres
Pons
Medulla oblongata
Inspiration and expiration drive
What are the two centres in pons and what do they do
Apneustic
Promotes respiration by stimulating neurones in medulla
Pneumotaxic
Antagonises apneustic to inhibit respiration
What type of receptors are pulmonary stretch receptors
Where are they found
What do they do
Slowly adapting
Smooth muscle of small and large airways
Protect lung from over inflation by hering breuer reflex
What type of receptors are irritant receptors
Where are they found
What do they do
Rappidly adapting
Epithelial cells of upper airways and trachea bronchi tree
Coughing, bronchoconstriction, mucus secretion
Where are juxta capillary/j receptors located
What do they detect
Located in alveolar wall
Detect chemicals in pulmonary circulation
What do j receptors stimulate
Via which nerve
Rapid, shallow breathing
Vagus nerve
Where are bronchial c fibres located
Bronchial blood vessels
What do bronchial c fibres detect
What do they stimulate
Pulmonary emboli- clump of material in lung artery
Oedima- fluid build up in tissues
Stimulates apnoea
Tachypnoea- rapid breathing
Dyspnoea- difficult or laboured breathing
Difference between slow and fast adapting nerve fibres
Slowly adapting monitor ongoing stimulation
Rapidly adapting monitor changing stimuli
What do internal, external and innermost intercostal muscles govern
Forced exhalation
Inhalation
Forced exhalation
Describe hering breuer reflex
Negative feedback system to protect lungs from over inflation
Volume of air inspired detect by lung stretch receptors which sends impulses to brainstem nuclei which initiates inhibition of inspiratory muscles
What is the blood brain barrier
Complex surrounding most blood vessels in brain allowing only certain substances to cross from blood into brain
Does carbon dioxide cross blood brain barrier
Yes
Does hydrogen ions cross blood brain barrier
No
Define hypoxia
Body deprived of its oxygen supply
Define hypercapnia
CO2 levels in blood abnormally elevated
Define apneusis
Abnormal breathing pattern characterised by deep gasping inspirations followed by brief partial expirations
Which cells form dentine and where are they located
Odontoblasts located at dentine pulp junction
What is pre dentine
Layer of unmineralised dentine that lies next to odontoblast cells
What are calcospherites
Globules of mineral that will eventually mineralise the dentine
Where does dentine form first
Amelo dentine junction
What are the odontoblast processes
How far do they penetrate and what is the rest filled with
Processes left behind by odontoblast cells as they form dentine and move inward towards the pulp
1/4 of the way
Dentinal fluid
What are the incremental lines of von ebner
How far apart are they
Show 24hr depositions of dentine
4 micrometers
Knoop value of dentine
64
What are the diameter of dentine tubules
2.5 micrometers at amelo dentine junction to 1 micrometers at pulp
What is the S shape tubules form called
Primary curvature
Sigmoid curve
What is primary dentine and when is it complete
Dentine that makes up bulk of tooth, mantle dentine, circumpulpal dentine
3 years after eruption
What is secondary dentine
Dentine that continues to form after tooth completed which reduces size of pulp
What are the types of tertiary dentine
What is its purpose
Reactionary- in reaction to trauma
Reparative- in response to stimulus
Protects pulp of tooth
What is intertubular dentine
All dentine between the tubules
What is interglobular dentine
Where is it located
What is its role
Hypomineralised dentine
Cusps or incisal regions
Shock absorber
What is intratubular dentine
Highly mineralised brittle dentine caused by minerals leaking out of odontoblast processes into tubules
What is intratubular dentines significance in forensic dentistry
Filling of tubules with intra tubular dentine begins at apex so indicates age
What percentage of enamel is inorganic
96-97
Why is decidous enamel whiter
Less mineralised so less translucent
Knoop value enamel
296
What is the crystallite formula of enamel
[Ca10 (PO4)2 (OH)2]
What are perikymata
Small horizontal lines running across tooth surface which are surface manifestations of striae of retzius
What are enamel prisms
What are crystallites
Fundamental units making up enamel
Small hexagonal rods that make up prisms
What makes crystallites
Ameloblasts
What is the diamof enamel prisms
Four to five micrometers, widening towards tooth surface
What are interprismatic regions
Regions between prisms characterised by sharp change in crystallite direction
Whats the difference between head and tails of prisms
In head crystallites well organised with no space for water or organic matrix so hard and brittle but in tail less well organised so more water and organic matrix to act as shock absorber
What are cross striations
Lines every 4 micrometers across prisms showing daily enamel formation
What is gnarled enamel and where is it located
Enamel which prisms show organised spiralling coarse to withstand forces of occlusion, present at cusps and incisal regions
What is surface enamel
Highly opaque last region of prism to form, it contains high concentrations of flouride and carbohydrates so it harder and less soluble
Whatever are striae of retzius
How far appart
Weekly incremental lines that appear as brown bands
28 micrometers apart
What is neo natal line
An accentuated incremental line caused by change in environment and nutrients at birth
What shape is amelo dentinal junction
Scalloped
What is a plaque biofilm
Complex microbial community of bacteria that developes on hard material embedded in a matrix if polymers of bacterial and salivary origin
Where is supragingival plaque
Where is subgingival plaque
Where is marginal plaque
Above gingival margin
Below gingival margin between tooth and gingival pocket epithelium
Along gingival margin
Moving from cervical portion down to apical how does the substances in plaque change
Gram positive to gram negative
Lots of filaments to no filaments
More aerobic to more anaerobic
What percentage of plaque is bacteria
70-80%
Define gingivitis
Reversable inflammation of gingival tissue characterised by redness, swelling, false pocket formation and glazed appearance
Define periodontitis
Inflammation of the supporting tissues of the teeth resulting in permanent tissue destruction and bone loss
What is materia alba
Loosely organised accumulation of salivary proteins, epithelial cells and food debris that can be easily displaced by water spray
What is calculus
Hard deposits formed by mineralisation of dental plaque usually covered by an unmineralised layer of plaque, it cannot be removed by tooth brushing
What does the oleary plaque index record and how is it calculated
Records presence of plaque on individual tooth surfaces
Plaque index=
Number of tooth surfaces containing plaque/total number of available surfaces
What are the goals of cross infection control
3
Minimise transmission
Patient to patient
Patient to clinician
Clinician to patient
Define sterilisation
Removal of all living microorganisms
Define disinfection
Removal of all pathogenic microorganisms
Which microorganisms are highly resistant to disinfection
Spores
What diameter does water lines in dental chair units have
1-2 mm
What pathway do the water lines of dental chair units follow
Laminar pathway
Why should detergent be used when cleaning instruments rather than disinfectant
Disinfectant can precipitate proteins, making them resistant to removal
What are the sterilisation options and which is favoured
4
Dry heat
Chemical
Ionising
Steam- preferable
How long does autoclaving at 121 take
30 mins
How long does autoclaving at 126-129 take
10 mins
How long does autoclaving at 134-139 take
3-5 mins
What is the width of enamel prisms
4-5 micrometers
Chemical composition of dentine
70% inorganic mineral
20% organic proteins
10% water
What are schrager lines
Primary curvature of dentine
What are dead tracts
Empty tubules of dentine where odontoblast killed leaving dark tubes
