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Structure and Function of Cell Membrane
- - Made up of a lipid bilayer which prevents solutes from entering the cell through diffusion
- - contains specialised receptors
- - keeps the cell shape
- - acts as a barrier
Function of Endoplasmic Reticulum
- - Functions as the the transport system of the cell
- - moves proteins and other substances around the cell
- - also is involved with synthesising of proteins
Smooth and Rough ER (Rough has ribosomes attached)
Function of Ribosomes
Function of Golgi Apparatus
- Modifies proteins that are given to them when the golgi appartus and endoplasmic reticulum fuse together
Function of Mitochondria
Provide cell with energy through aerobic respiration
Function of Lysosomes
- eat foreign particles within the cell as self-defence
Function of the Nucleus
- - Stores genetic material
- - cell division
- - regulating cell function
Function of the Nucleolus:
- - Ribosome and protein production
- - Storage of genetic material - Chromatid - DNA Helix with proteins which form chromosomes.
Function of the cytoplasm
- consists of the all the viscous material within a cell and keeps everything in shape and place
Types of Cell (4)
- - Bacterial
- - Plant
- - Yeast
- - Mammalian
Four Types of Transportation of Particles in and out of a Cell:
- - Diffusion: passive form of transport involving water
- - Active transport: mediated by carries or channels
- - Endocytosis: uptake of particles that dont fit through the cell membrane
- - Phagocytosis: ingestion of particles
- - Exocytosis: release of large particles out of a cell
Function of Centrioles
Found at polar regions of the cell and serve a purpose in cell division
Function of Cilia
Hair like structures on the cell that wave in a co-ordinated way
Function of Flagellae
Propellar system used for movement of the cell
Explain how the structure of certain cells can affect their function
Cardic cells - lots of mitochondrion cells so the cells never get tired - need lots of energy
Sperm cells- have flaggelae for movement within the fallopian tubes
Salivary Glands - contain heaps of ER, ribosomes and have a prominent GA to produce he secretion of saliva
Name the Four Types of Tissues
- - Epithelium
- - Nervous
- - Muscle
- - Connective
Explain what epithelium consists of and its functions:
Epithelium consists of sheet of cells that are joined together. It does not contain any blood vessels but is rick in nerves.
- = protects us from injury -> can regenerate and detect potential threats i.e. fire, burning - nerves tell us to pull hand away from flame
- = Gas exchange and absorption of nutrients
- = Secretes lubricants
Explain the classifications of Epithelium and Give examples of their whereabouts:
- - Simple Squamous: sacs of lungs
- - Simple cuboidal: kidneys
- - Simple columnar: digestive organs
- - Stratified squamous: skin, vagina
- - Stratified cuboidal: lines sweat gland ducts
- - Stratified columnar: mammary glands
Explain what Connective tissue consists of and its functions; List some types
Consists of intracellular substances, fibres and cells.
Its main function is to support and connect other tissues. It also binds them to the skeleton
Types: Adipose tissue, bone, cartilage, blood, areolar connective tissue
Describe what Muscular tissue is made out of and list the types and functions:
Muscle tissue is composed of specialised cells which are able to contract or shorten in length and subsequently relax again to move the body.
- 3 Types:
- - Smooth: no cross striations and is involuntary
- - Striated or Skeletal: voluntary under somatic nerve control with striations
- - Cardiac: involuntary with striations
Explain nervous tissue and what its function is:
Nervous tissue is highly specialised and its main function is to transmit impulses from one part of the body to another.
It has a effective relaying system to provide appropriate and fast responses to stimuli
How do the tissues work together?
If muscle tissue did not work together with nervous tissue, muscles would not be able to contract - they are under voluntary control.
Why is Microbiology important in Dentistry?
- - To be able to see what kind of envrionment the patient has inside their mouth and why
- - Certain bacteria = create oral diseases and thrive in certain environments, dentists and microbiologists can get to the bottom of patients diseases
What is an example of a normal bacteria living in the oral cavity?
Explain three points of Cellular Life and give examples:
Examples: Bacteria, Fungi and Protozoa
- - Nuclear Material is separated form the cytoplasm
- - Reproduce by binary fission (Externally)
- - Either Prokaryotes or Eukaryotes
Explain Four points of Non-cellular Life and give an example:
- - Needs a host, cannot produce its own energy
- - Genetic material is either DNA or RNA
- - NO cytoplasm
- - reproduce by disassembling genetic material and reassembling new generation of viruses inside the cell
List some characteristics of Prokaryotic Cells:
- - DNA is floating around the cytoplasm (single, circular, double stranded)
- - divide by binary fission
- - transfer of genetic material is by conjugation, transduction or transformation
- - Energy is produced through the cytoplasmic membrane
- - contains 70s ribosomes
- - peptidogylcan cell wall flaggelae
- - has a that contains the protein flaggellin
List some characteristics of a Eukaryotic cell
- - DNA is enclosed within its own membrane
- - cells divide by mitosis
- - transfer of genetic material is by sexual reproduction
- - contains membrane bound organelles
- - contains 80s ribosomes
- - some have polysaccharide cell walls of either cellulose or chittin
Name and Describe the Three types of Cell Division we must know:
- Binary fission: is asexual reproduction which cell replicates own DNA and then divides into two daughter cells that are exactly the same as the parent cell
- Lytic Cycle: Attachment, Penetration, Replication, Assembly and Exit *if virus not enveloped, when it exits the cell it ruptures the wall and causes the cell to die.
- Mitosis: One parent, DNA replicate = 2 daughter cells each with half of original chromosomes and then they divide again and are fertilized
Name and Describe the three types of genetic material exchange:
- - Conjugation: through direct cell to cell contact or a bridge like connection e.g. pillus
- - Transduction: Uses a vector to transfer material
- - Sexual Reproduction: parent cell, DNA replicates (2 daughter cells), chromatids are pulled apart and separated so 4 daughter cells come about and then are fertilized.
Name the components of a bacterial cell:
- - Nucleoid - one single circular chromosome
- - Ribosomes
- - Cytoplasm: semi permeable, used for energy production, synthesis of cell precursors and secretion of enzymes and toxins
- - Storage granules for energy
Describe the bacterial Cell Wall:
- - gives rigidity and shape
- - is permeable to small molecules
- - almost all contain a peptidoglycan layer ( difference of how big of a layer they have is between Gram + and Gram - bacteria)
- - some contain outer layer of a lipopolysaccharide layer which contains endotoxins
What is a Gram Stain?
- - Diagnostic tool used for identification of unknown bacteria.
- - Was developed by Hans Christian Gram in 1882
- - By using crystal violet, iodine, an alcohol wash and safranin on a piece of cell wall we can tell by the colour (pink or purple) whether or not the bacteria is gram negative or positive -> can then use a decision tree to identify it
- - Gram+ (purple) Bacteria contain more of a peptidoglycan layer and a smaller S- protein layer
- - Gram - (pink Bacteria contain a small peptidoglycan layer and a lipopolysaccharide layer.
What is the function of a Bacterial Capsule?
- - attaches to host cells
- - protects it from phagocytic engulfments
- - is a reserve of nutrients/ protection
How is bacteria Classified?
- - morphology/ shape
- - cellular arrangement
- - cell wall structure.. etc.
What is Normal Oral Flora?
Normal oral flora is a diverse group of organisms that live within the oral cavity without causing any harm or without disturbing the rest of the oral flora in the mouth.
List and Describe some factors that affect the oral environment:
- - crowding of the teeth: reduces cleaning efficiency
- - presence of diseases: changes oral environment and therefore the flora within it
- - amount of fermentable carbohydrates consumed: the stickyness and abrasive-ness of them
- - Medication and immunosuppressants
- - amount of saliva that is present to clear out the oral cavity
- - general health of patient - illness changes diet and hygiene practices
Why is saliva important within the oral cavity?
- - acts as a buffering system
- - maintains the pH
- - clears the oral cavity
- - lubricates the hard and soft tissues
- - acts as a nutrient source - remineralises enamel
- - provides the tooth with a pellicle (thin layer of salivary glycoproteins)
What is dental plaque?
A complex microbial community found on tooth surfaces.
It is comprised of living, dead and dying bacteria that is embedded in a matrix of polymers mainly derived from saliva.
Four Examples of Supragingival Plaque:
- - Streptococci mutans
- - Streptococci mitis
- - Streptococci salivarius
- - Streptococci anginosus
Five Examples of Subgingival Plaque:
- - Actinomyces
- - Prevotella
- - Porphyromonas
- - Fusobacterium
- - Veillonella
List the steps in the formation of plaque:
- 1. Gram positive cocci attach to pellicle
- 2. bacteria reproduce
- 3. new bacteria attach onto already attached bacteria cells
- 4. keeps reoccurring until it is a mature biofilm
- 5. during this all extracellular matrix of salivary glycoproteins are being embedded into the biofilm
Calcified mature plaque - usually found around salivary gland ducts.
Define Dental Caries:
- - Is the localised destruction of the tissues of the tooth by fermentation of dietary carbohydrates.
- - It is a chronic endogenous infection (caused by changes within the normal oral flora)
*Cavitation can occur when plaque micro-organisms metabolise dietary carbohydrates and produce acid which demineralises the tooth structure.
What is the Clinical Presentation of Caries?
- 1. "White Spot" lession -> chalky white spot on tooth that can be remineralised to become inactive
- 2. Cavitation -> no longer reversible and an intervention must occur to prevent the cavity from becoming bigger.
What are the Four Causes of Caries? Explain them:
- 1. Host Factors
- - tooth structure: enamel quality, fluoride, morphology
- - Saliva: composition, flow rate, buffering and remineralising capacity
- 2. Diet
- - frequency of intake of carbohydrates and the form of it
- - sugary and acidic foods drop the pH of the oral environment - take up to an hour to remineralise again by the acid diffusing out and saliva creating the buffering effect.
- - repeated and frequent composition is bad
- 3. Time
- - carious process consists of periods of destruction and repair
- 4. Plaque Micro-organisms
- - Streptococcus mutans is involved with enamel lessions and loves low pH's. It can also rapidly metabolise sugars and can produce intracellular polysaccharides which act as their own food storage.
- - Lactobacili is involved in progression of the lession into the dentine
- - Actinomyces is involved in root caries
- - Veillonella is also commonly found to be involved but not 100% sure
What does the Stephan Curve describe?
The Stephan curve describes the change in pH the oral cavity experiences after the intake of dietary carbohydrates. it takes 15 minutes to recover and return to a normal pH.
Explain the specific plaque hypothesis for caries:
This hypothesis believes that one or more specific bacterial groups are principally involved in caries i.e. Streptococcus mutans.
Explain the Non-specific plaque hypothesis in dental caries:
Believes their is a heterogeneous mixture of non-specific bacteria (lots of different bacteria that can cause the disease).
Explain the Ecological plaque hypothesis in relation to caries:
Believes that the intake of sugar affects the oral environment which changes the growth of certain nasty bacteria in the mouth.
What are saliva tests used for?
- They can be used to establish the numbers of certain bacterias within the oral cavity e.g. Streptococcus mutans
For bacteria to be able to grow and develop what three things does it need?
- - Access to the habitat/ oral cavity
- - Adherance - stick to the surface or bacteria already there and
- - Growth - must have the desired environment to grow
Define Periodontal Disease:
- - A disorder of the supporting structures of the teeth including gingivae, periodontal ligament and alveolar bone.
- - Two Catergories: Gingivitis and Periodontitis
What is the difference between gingivitis and periodontitis?
- - Is a reversible inflammation that involves the marginal gingivae.
- - Where the inflammation extends deeper into the periodontium.
- - is characterised by the loss of attachment of the tooth and alveolar bone loss
- - Irreversible
What factors need to be present with periodontal disease?
- - Plaque is necessary
- - Environment of the oral cavity need to be desirable
- - Time - long process
- - Host Susceptibility - host must be susceptible
- - Key Microorganisms need to be present.
Explain what happens after long periods of not brushing your teeth:
- 1. Plaque starts to accumulate
- 2. Gram positive bacteria present
- 3. Population of Gram negative bacteria overcome population of Gram positive
*Normally only Gram positive cocci.
Explain the plaque associated with gingivitis and periodontitis:
- Gingivitis: more Gram positive rods (Actinomyces) and Gram negative organisms
- Periodontitis: More Gram negative organisms found subgingivally.
Explain the non-specific plaque hypothesis for periodontal disease:
Based on the accumulation of plaque being the sole cause.
This however does not explain how some people have lots of plaque and no disease and others have little plaque but heaps of disease.
Explain the specific plaque hypothesis of periodontal disease:
Is the result of the overgrowth of one or a small group of a specific organism.
Explain the Ecological plaque hypothesis in relation to periodontal disease:
- Includes Three Factors:
- 1. Specific pathogens are presents
- 2. Conditions in the oral cavity are optimal
- 3. Host is susceptible
*Plaque causes inflammation
What are the two factors to tissue destruction?
- - Host defence systems
- - Virulence factors of bacteria i.e. do they have fimbriae to attach to tissues
Name two baddies for periodontal disease:
- 1. Spirochaetes
- 2. Aggregatibacter actinomycetemcomitans
* Difficult to define the species involved as they are difficult to culture and obtain and different sites may have different pathogens. Also sometimes opportunistic species grow at the same time and are often in small numbers but are very aggressive.
Stages of Periodontal disease:
- 1. Initial - few neutrophils and lymphocytes
- 2. Early Lesion - 4-7 days plaque accumulation and formation of dense lymphoid cell infiltration i.e. swelling
- 3. Established - Lymphoid infiltrate characterised by plasma cells - loss of connective tissue and junctional epithelium (2-3 weeks)
- 4. Advanced Lesion - loss of alveolar bone and widespread manifestations of inflammation and tissue damage.
What is the difference between Endogenous and Exogenous pathogens?
- - come from within the natural environment. Are controlled by host response.
- - are not apart of the normal oral flora and need to be completely removed from the oral cavity via antibiotics.
Risk factors of Periodontal disease:
- 1. presence of the pathogens
- 2. Local environment is encouraging it
- 3. host is susceptible
Homeostasis describes the the body state where all internal conditions are in balance with eachother.
The three stages of Homeostasis are:
- 1. Receptor
- 2. Control Centre - receives and processes
- 3. Effector
Result = Homeostasis.
Explain the two Types of Control Mechanisms for Homeostasis:
- Negative Feedback System:
- - reverses or negates the change e.g. shiverring when cold to get warm again
- - minimizes the change to keep within normal limits.
- - e.g. blood pressure
- Positive Feedback System:
- - is where the response enhances the change in the original condition
- - e.g. breast feeding
Describe what is meant by Individual Variation
Different people have different homeostatic set points which allows there to be some range of normal when looking at, for example, body temperatures. Can change due to gender, race, general health and natural environment.
*If the balance between host defences and pathogen virulence - infection can occur.
Name the two internal defences of the body (Two immune responses):
- - Innate or Natural (Uses phagocytic cells)
- - Learned or Adaptive (More Specific to certain infections/ diseases and uses lymphocytes)
Define and Explain Innate immunity:
- - Is our inbuilt, native and natural immunity to resist infection.
- - has cellular and humoral components
- Cellular: involves neutrophils, macrophages, natural killers and eosinophils
- Humoral: Complement system and lysosomes or acute phase response
What is the Complement Cascade? And take note of Acute Phase Responses:
- - It is a biochemical series of chemical reactions that helps clear pathogens from an organism.
- - it enhances the uptake of a particle and can active various cells, participate in regulation of antibody responses and can manufacture those that make cells burst (Osmotic lysis).
- - Has alternative and Lectin pathways - classical pathway is a mechanism of the adaptive humoral immunity
*Acute phase responses involves looking at the concentration changes of plasma proteins during infection. Looks at C-reactive proteins (Activates the classical pathway in the absence of an antibody) and Serum Amyloid
Two Classifications of Lymphocytes: Explain them:
- - have markers on their cell surface (CD Antigens)
- - can be divided into two sub groups -> CD4 and CD8 cells
- - CD4 cells produce soluble factors and help T and B cells
- - CD8 cells kill virus infected cells (Cytotoxic T cells)
- -make mediators and kill virus infected cells
- B- cells :
- - make antibodies
Explain the Adaptive Immunity and Explain primary and secondary lymphoid organs:
Have cells that have been educated for specific recognition of their targets.
- Primary lymphoid organs are in the bone marrow and the thymus
- Secondary lymphoid organs include the spleen, lymph nodes etc.
Define Apoptosis and Necrosis:
- Programmed cell death and unplanned accidental cell depth respectively.
Explain the General Scheme of an Immune Response:
- 1. Epithelial cells - first like of defence to block entry of micro-organisms
- 2. pathogens damage epithelium and since they are damaged they are "activated" which means chemokines and cytokines are then released
- 3. Chemokines guide lymphocyte cells to area and cytokines change the morphology of the epithelial cells so permeability is reduced. Also trigger release of phagocytic neutrophils via IL2. --> Inflammation is caused (Heat swelling redness and pain)
- 4. Phagocytes then come to infection and neurtrophils and monocytes phagocytose micro-organisms
Describe the Clonal Selection Theory:
Produces more cells with a specific antigen to help fight disease.
Define the role of the MHC and explain the two Classes :
Direct the response of T cells to foreign antigens and can present the foreign particles to them.
- Class I:
- - all cells express MHC I
- - regulation of immune responses to intracellular parasites
- - activates normal T cells: CD8
- Class II:
- - regulation of immune responses to extracellular parasites
- - not all cells express it
- - activates CD4 T cells.
What happens to antibody affinity after repeated injections of the same antigen?
It increases - affinity maturation
What must happen for T cells to be able to recognise an antigen on a cell surface?
it must be processed within the cell and loaded onto the MHC Molecules
What is Somatic Recombination?
it is a way of producing a number of different receptors with difference specifities.
*Diversity is obtained by altering the way in which genes are combined.
Why must some T cells mature in the thymus?
So they can recognize self .
Define Oral Mucosa and State the Functions of it:
- - Lines the oral cavity
- - moist lining
- - protection of underlying tissues from trauma
- - Sensation - contains specialised nerve endings so can detect touch pain and pressure to furthure protect the tissues from damage
- - Secretion - lubrication of the tissues so they can rub over each other freely and easily without causing harm.
Describe the layers of Oral Mucosa
- Lamina Propria
- Submucosa - has fat, glands, vascular and muscular tissue
- *Between the Epithelium and Submucosa is where the Lamni Propria lies - it has projections in the epithelium which contain fine nerve fibres (rete pegs)
Where is there no submucosa? And where does it attach?
- Attached Gingiva
- Hard palate
- It attaches to the mucoperiosteum - directly to bone.