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245 Cards in this Set

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In order to acquire an infectious disease an individual must be exposed to a ______ or ______ of the potential pathogen and a _________ must exist whereby the pathogen can be ______________ to the human body and gain _________ in sufficient numbers to cause an infection
In order to acquire an infectious disease an individual must be exposed to a RESERVOIR or SOURCE of the potential pathogen and a SITUATION must exist whereby the pathogen can be TRANSMITTED to the human body and gain ENTRY in sufficient numbers to cause an infection
Susceptibility to infection relies on what 5 factors?
There must be a SOURCE of infection. There must be a METHOD of TRANSMISSION.
Host RESISTANCE must let the pathogen slide past.
CIRCUMSTANCES of infection
VIRULENCE of the pathogen
Name a source/ Reservoir?
Animals, Birds, insects.
Food, soil, water.
Inanimate objects.
What is a ZOONOSE?
Zoonoses are pathogens that live in animals and can infect humans.
What does the 1st line of defence involve?
Non Specific.
Prevents entry of foreign invaders into the tissue. Includes physical barriers such as skin, and chemical barriers such as mucous, lysosymes, digestive juices. May include body responses – vomiting, diarrhoea, saliva, mucous, tears (to prevent tissue entry)
What does the 2nd line of defence involve?
Complement proteins (produced by liver) and plasma proteins which are activated by the presence of foreign antibodies.
Phagocytic cells: Neutrophils and macrophages.
Inflammation and fever – part of the bodies way of getting rid of microbes.
What is the 'Complement system'?
In the presence of an antigen antibodies complex will stimulate a pathway (direct,cascade, alternate). polysaccharides on the surface of the microbe will also set in motion the cascade.
Production of the membrane attack complex: pokes holes bacteria membrane
What is cellular immunity?
use of T Cells that target foreign invaders and destroy them
What is Humoral immunity?
use of B cells that produce antibodies specific to the particular antigen. Those antibodies will make antigen antibody complexes firstly decreasing infectiveness, slowing it down and providing a target for macrophages.
What are the 5 signs of inflammation?
functionalesia (loss of function)
What is a bacterium?
Living organisms
Have DNA
Have cell walls
They don’t have nuclei
Describe a virus
Non-living organisms
They have no metabolism
They cant replicate or reproduce on their own
They don’t have organelles, cytoplasm or metabolism
They can be dormant for long periods of time
They are parasitical
What are the differences between a parasite and a virus?
Some viruses have DNA some have RNA
Parasites have different forms of parasitic arrangements.
Anything parasitic gets its energy from the host organism.
Viruses are necessarily intracellular (can only reproduce when inside a cell)
Parasites are usually living and may be intracellular or extracellular and still require our energy,
What are PRIONS?
not very common but similar to viruses.
Contain only protein and NO GENETIC MATERIAL.
What are FUNGI?
can be singular or multi-cellular – mostly yeasts and moulds
include protozoa and are unicellular with no cells walls which is why they are referred to as being of the animal kingdom
What are BACTERIA?
have a cell wall and are usually referred to as being plant in origin
Multicellular organisms: Worms
Name some portals of entry?
mucous membranes
Name some portals of exit?
Any exudate
Any body fluid
What are some methods of transmission?
Exchange of body fluids
What are the the 4 clearance mechanisms of the non specific immune system?
COMPLEMENT (opsonisation & membrane attack complex)-they poke holes in the enemy
PHAGOCYTOSIS (engulfing the microbes)INTERFERON (anti-viral agents)
NATURAL KILLER CELL (apoptis of target cell)
What are the factors which determine if a person gets the disease or not after being exposed to it?
Immune status – presence of antibodies to the particular antigen
What are the factors contributing towards host resistance?
Previous exposure – build up of antibodies
What factors affect the virulence of a pathogenic organism?
What type it is – if it is a virus or bacteria
Whether the person has immunity
Nutritional status
Exposure to the reservoir
Immune evasion ability – bacteria capsule
They may be intracellular so they could escape attack
How does the HIV evade immune defences?
Hiding within cells
Attacking those cells which we need to recognise it and destroy it.
How would you prevent an epidemic involving coughing?
Wearing of masks by the infected person and the uninfected people
What is the common name for HYPERSENSITIVITY I?
Immediate Hypersensitivity.
How long does it take a TYPE I reaction to occur?
5-10 minutes. Immediate Hypersensitivity.
What is the immunoglobulin responsible for TYPE I HYPERSENSITIVITY?
Name some symptoms of a HYPERSENSITIVITY I reaction:
skin rashes, asthma, eczema (atopic or contact dermatitis), hayfever. Allegic conjunctivitis, vomiting, diarrhoea (food allergies)
What is the most severe TYPE I reaction?

What does it involve?

What is the treatment?
aphylaxis is a release of huge amounts of histamine, an extraordinarily dangerous condition. Treatment for this is to administer adrenalin (epinephrine).
What is another name for TYPE II HYPERSENSITIVITY?
Cytotoxic hypersensitivity
Name some disease states linked to TYPE II HYPERSENSITIVITY?
MS, Type 1 diabetes, rheumatoid arthritis
What Immunoglobulin mediates TYPE II HYPERSENSIVIVITY?
What is another name for TYPE III HYPERSENSITIVITY?
Immune complex
What is another name for TYPE IV HYPERSENSITIVITY?
Delayed cell mediated
How long does it take for a TYPE IV HYPERSENSITIVITY reaction to occur?
48 – 72 hours
What kind of substances can cause a TYPE IV HYPERSENSITIVITY reaction?
Cosmetics, dyes, soaps, metals...

the big problem with this type is that it is trying to lucidate what has set off the hypersensitivity
What is incubation?
The time between the infection taking place and the first sign of symptoms.
What are prodromal conditions?
The feeling of being unwell but not having the full symptoms is the prodromal conditions. There are no identifiable symptoms of the disease. The difference between the prodromal illness and the illness itself is the period between the onset of symptoms and the actual diagnosis.
In the recovery phase is the person going to still be infective?
Possibly. Some diseases are not infective in the recovery period but most diseases will still remain infective during that period.
What are some things that may possibly cause cancer to develop?
Damage to DNA – a spontaneous mutation (no reason or cause)
Chemicals (carcinogens – polycyclic aromatic hydrocarbons. they occur when you eat burnt / charcoal organic matter – meat, vegies, charcoal tablets)
Viruses (onco-viruses)
Ionising radiation (sun, x-rays, gamma rays, light)
injuries that are exacerbated continually
What is a differential diagnosis?
It is a system of looking at symptoms in order to determine the most likely cause of the illness.
What sort of tests might be done if a person came in with a condition and the conditions were blood in the stool?
Faeces testing,
barium enema,
barium meal,
CAT scan,
blood tests.
What sort of things does a standard blood test show?
cell count (red blood cells, white blood cell fractions, platelets).
What are B cells?
deal with humoral immunity (liquid – plasma) make antibodies and differentiate into plasma
What are T cells?
deal with cellular immunity and target actual cells specifically
Name 2 types of cells which are Phagocytic:
Neutrophils and monocytes
How do Natural Killer T Cells work?
Natural Killer T cells work in the same way as antibiotics. They break down the wall of the pathogen and allow water to rush in.
Disorganisation of Tissue or change in size/shape.

Eg. Pap smear tests for Dysplasia
Study of statistics involving the determinantsof disease events in populations.
Non specific.
Inflammation and Fever.
Macrophages, NK cells, Neutrophils...

Are all part of...
The 2nd line of defence.
What are the clinical features of a TYPE IV hypersensitivity reaction?
Localised rash. Puritis. Redness. Vesicles. Serous exudate.

Doesnt occur immediately after exposure.
Describe 'Immunological memory'
After secondary response, activated T&B cels join a memory pool.
These T&B cells can be reactivated upon subsequent exposure to the same antigen.
This allows for a more rapid response.
An abnormal and persistent antigen/antibody complex forms and is not cleared by normal mechanisms.
The immune complexes deposit in the tissues or (rarely) circulation.
The inflamation is caused by activation of the complex.
Eg's Rheum arthritis and Lupus.
Programmed cell death without inflammation is called...
Which types of cells are more vaunerable to NEOPLASIA?
Fast dividig cells like Epithelial or hepatocytes.
Objective evidence of a disease is...

Examples may be...

Limp. Digital clubbing.
Thwy recognise antigens, are a part of the third line of defence and are specific.
They are...
What is a hypersensitivity?
An unusual or damaging immune response to normally harmless substances.
there are 4 types.
Dx is an abbreviation for..
What is an example of hypertrophy?
Swelling of one kidney in the event that the other is lost- due to an increased workload.
Muscle cells - exercise.
The Uncontrolled progressive multiplication of cells is:
Cirrosis is an example of what cell change?
IgE features in WHAT hypersensitivity?
Hypersensitivity I
Non specific. Barrier. Skin. Mucous Membranes.

these are part of...
The 1st line of defence
What are some common allergens?
Foods (nuts, shellfish, strawberries)
Drugs (asprin, penecillin)
This antibody defends Mucous membranes in particular
Subjective evidence of a disease or a condition is a...

Examples include...

As percieved by patient. Cough. Tired. Feel unwell.
What is Autoimmunity?
A sustained adaptive immune response to a self antigen, causing tissue damage.
An often reversible abnormal change in the size, shape and organisation of a mature cell is...
Loss of differentiation of cells and their orientation to one another and their framework and blood vessels.
Type IV hypersensitivity operates through the action of which cells?
T Cells.
Hyperplasia is...
An increase in the number of cells, resulting from an incresed rate of cellular division.
The location of the antigen can be a cell surface. It can be against a normal component of the body or foreign (eg blood transfusion).
It involves IgG and IgM immunoglobulins.
Involves activation of the complement and phagocytosis.
The 'antigen' displaying cell is destroyed (lysis).
What hypersensitivity am i?
Type II
What are some examples of 'human disease processes'?
Immune responses
Increase in the size of cells, and consequently the size of the affected organ, is:
A corn or callus is an example of WHAT change in cells?
Skin rash...Extrinsic (wet) asthma, some forms of ezcema, allergic rhinitis, Allergic conjunctivitis, vomiting, anaphalaxis...

This is...
symptoms of TYPE I hypersensitivity reactions.
What is immunodeficiency?
Partial or total loss of one or more components of the immune system
Decrease or shrinkage of cell size is called...
Describe the actions of IgG antibody:
Most common antibody in blood.
Secondary response is more specific and stronger.
Can cross the placenta.
Passive immunity for newborn.
Anti: viral, bacterial, toxin.
What are the 3 possible outcomes of a human disease process?
An example of metaplasia is..
A scar
What do B cells do?
Part of specific (3rd) line of defence.
they produce antibodies.
What are the actions of IgM immunoglobulin?
1st to respond to antigens. Activates te complement.
What is the action if IgE immunoglobulins?
They bind to the mast cells in the skin and mucous membranes. They cause the release of histamine and othe chemicals. They result in imflammation.

They are associated with Hypersensitivity I mainly
Who is responsible for informing the authorities about a NOTIFIABLE disease?
the general practitioner. Labs will also forward the information.
What are some examples of notifiable diseases in Australia?
AIDS/HIV, Cholera, Diptheria, Gonococcal Infection, Anthrax, Botulism
Brucellosis, Yellow fever, Haemorrhagic fevers, Hepatitis, Influenza, Legionellosis, Leprosy, Malaria, Measles, Meningicoccal, Mumps, Plague, Polio, Rubella, Salmonellosis, Shigellosis, Syphillis, Tetanus, TB, Typhoid,
What techniques can be used to identify bacteria?
Microscopy (staining)
Biochemical testing
What are some limitations in identifying bacteria?
Not all are culturable
Poor specimen quality
Mixed infections
Time consuming
May not be treatable
What methods can be used to identify viruses?
What are some problem areas with identifying viruses?
Often cannot culture/isolate
Hard to find viable particles
Diverse families, many unknown (difficult to ID)
Limited treatment options
What methods can be used to identify parasites?
What are the 2 types of immunodeficiencies?
Primary and secondary
What is a primary immunodeficiency?
A basic developmental failure somewhere in the immune system. Inherited. Congenital. Genetic.
What is a secondary immunodeficiency?
Aquired. Loss of immune function due to specific causes. may occur at any time in lifespan.
What are some causes of secondary immunodeficiency?
Infection (particularly viral)
Liver disease (hypoprotienaemia)
Cancer treatment/immunosupressice drugs
Severe stress (prolonged glucocorticoid secretion)
What are some treatment options of Immunodeficiencies?
Replacement of antibodies with gammaglobulins (blood transfusions).
Bone marrow or thymus transplants.
How can microbes be transmitted from one person to another?
CONTACT (direct, indirect, droplet)
VEHICLE (Air/water/food/body fluid)
VECTOR (Mechanical, biological)
Transmission of infection can occur through what vehicles?
Airbourne (by inhalation)
Water-bourne (via ingestion, bathing)
Food-bourne (food spoilage due to microbial growth)
What is a vector?
A carrier of infection. Takes it from A to B. Eg. Mosquito's and flies.
What factors DECREASE the resistance of a host?
AGE (infants and elderly),
What role to resident flora play in prevention of disease?
Resident flora prevent the growth of invading pathogens and assist the host with beneficial processes. If the body's normal defences are impared or the balance of organisms is lost, disease can result.
To result in PATHOGENICITY, what 4 things must happen?
1. Gain ENTRY!
2. Attach and multiply!
3. Evade host defences!
4. Damage tissue and produce disease symptoms!
What advantages can a pathogen have, in order to become more virulent?
*Invasive qualities (eg. small size)
*Adherence factors (Pili or Fimbriae. hook themselves to host)
*Toxic Qualities (toxins/destructive enzymes eg: Gangrene/Butulism...)
*Immune Evasion
*Resistance to treatment
*Pathogenic affect of infection
*Rate of replication
*Low infectious dose
What methods may a pathogen use to evade the immune system?
*Bacterial capsule (survive even acidic conditions!)
*Intracellular Bacteria (hide inside)
*Mutation (change to avoid detection, eg cold virus)
The SKIN is a portal of entry. How can this protective barrier be breached?
Puncture wounds, Needle sticks.
Splits or tears in surface of skin..
Scratching due to itchy bites or stings.
Mucosal surfaces are easily penetrated.
Ears, conjuctiva, tear ducts, Hair follicles, sebaceous glands.
How may pathogens enter the respiratory tract?
Inhalation of
Aerosol droplets, spores, air currents from air conditioners.
Use of shared equuipment such as inhalers, ventilators or nebulisers.
Pathogens can enter the digestive system within contaminated food or water, what mechanisms do they use to survive the acidic conditions?
Enter in a form which is resistant to acid (eg. Spores, eggs and cysts) and hatch later in GI tract.
Low infective dose.
In what manner may pathogens enter the genitourinary system?
-Contamination from faecal route
-Urinary retention
-Sexually transmitted/
Body Fluid exchange
Name 4 Portals of exit
Sputum (phlegm)
Semen and vaginal secretions
What is the difference between an Epidemic and Endemic?
An Epidemic is when a disease spreads among a large area of the population at a rapid rate.
An endemic in where a large section of the population has the condition on a permanent basis.
How does the normal immune respose work?

Which Immunoglobulins respond, and in what order.
Pathogen - Antigen presenting cell.
T Cells recognise -> activate Cytotoxic T cells and B Cells.
B Cells produce Plasma cells and Antibodies (immunoglobulins).

The PRIMARY immunoglobulin to respond is IgM (who activates complement).
Secondary response is IgG (Anti toxin, viral...)
IgA &IgE protect mucous membranes.
In type I hypersensitivity what is the pathway?
Allergen -> Antigen presenting cell.
The T helper cell reacts by activating B cells -> Plasma cells -> Antibodies: mainly IgE which results in mast cell sensitisation -> Mast cells release histamine. Inflammation.
In type II hypersensitivity what is the pathway?
The allergen is bound to a cell.

Pre-formed antibodies (IgM or IgG) -> Immunoglobulin binds to cell and activates complement -> the cell is destroyed -> cell damage leads to inflammation.
In type III hypersensitivity what is the pathway?
The allergen -> Antigen presenting cell -> T helper cell -> activates B cells -> plasma cells -> antibodies IgM or IgG -> immune complex is formed, when activation of complement takes place tissue damage and inflammation will occur.
In type IV hypersensitivity what is the pathway?
The allergen is bound to a cell -> APC -> T helper cell -> cytotoxic T cells -> cell destruction -> cell damage leads to inflammation.
Which immune responses result in inflammation?
ALL immune responses, even the normal response.
Which hypersensitivities result in Auto-immune reactions?
type 2 and 4
What is a PROTAZOA?
Unicellular organism. Similar to bacteria, except they are larger, have a membrane in place of a cell wall, and have visible organelles.
Unicellular organism. Similar to bacteria, except they are larger, have a membrane in place of a cell wall, and have visible organelles...
What am i?
I'm an unusual infective agent, related to a virus. I have protein but no genetic material.
What am i?
A Prion
I'm a unicellular organism that doesn't require living tissue to survive. I'm often regarded a plant, because of my cell wall, but this is not entirely true.
I usually cause opportunistic infection, if i cause it at all. i can be single to multi-cellular. My family ranges from yeasts to moulds. I am...
Describe the structure of a virus
Simple structure containing nucleic acid contained in a protein coat.
There are 2 major divisions of viruses. What is the difference between the two?
They either contain DNA genetic material or RNA genetic material.
What is a capsid, and what are it's benefits?
A capsid is a protein coat covering the nucleic acid of a virus.
They can have antigenic properties, can be involved in attachment and protect the virus.
How does viral replication occur?
Virus attaches to host cell, injects it's genetic material and hi-jacks the cell.
Using the host cells metabolism capacity, the virus produces viral proteins and components.
The new particles are released by lysis or budding.
What does it mean if a virus is 'Latent'?
It means that the virus can enter the cell, but not relplicate until later. May remain hidden for years eg. herpes zoster-> shingles
What is an ACUTE LYTIC infection?

What is an example?
Virus infects host cells, replicates, host cell dies. Virus spreads.

Well defined signs and symptoms; common cold, mumps, influenza
What is a SUBCLINICAL infection?

What are some signs and symptoms?
Patient is infected but doesn't display recognisable symptoms of the disease.

General malaise, slight fever, lymphadenopathy (swollen lymph nodes), occasionally serious side effects.
What is a LATENT viral infection?

What are some examples?
Virus remains dormant in host cells and can be reactivated later.
Initial disease symptoms are followed by apparent recovery. But not all viruses are cleared.

Herpes family, Varicella zoster.
What is a CHRONIC viral infection?

What is an example?
The virus remains in the host and produces at low levels. The carrier state. Can occur in acute illness or subclinical infection.

Hepatitis B and HIV
Some viruses have the ability to alter the host cell DNA. The host cell can lose track of replication. What are these viruses called?
Oncogenic viruses.
What is an oncovirus?
A virus with the ability to enter a cell and disturb its DNA, causing it to lose control of rate of replication.

Various cancers have links to viral strains- eg. papilloma (wart) virus and cervical cancer.
Rotavirus and enterovirus can result in:
A spherical bacterium is called
A bacterium that is a rod shape is called:
a Bacillus
A spiral chaped bacterium is called
a Spirochaete
What is the name for
a single spherical bacterium?
A pair?
A cluster?
A chain?
A spiral shaped bacterium with a flacellum is called?
A Spirilla
What is a mycobacteria?
An encapsulated bacteria
What's a mycoplasma?
A bacteria that hasn't formed a cell wall. They can change shape and squeeze into small spaces.
What is a glycocalyx?

What can it be used for?
A glycocalyx is a sticky polysaccharide containing layer secreted onto the cell surface.

It can help bacterium adhere to host cells, and also be protective against phagocytosis.
What are flagella, pilli and fimbrae.
hat can they be used for?
They are projections from the external surface of a bacterial cell.
What is the major component of a bacterial cell wall?
What are plasmids?

What role do they play in the treatment of bacterial infection?
Plasmids are located in the cytoplasm of the bacterial cell. They are DNA fragments important in drug resistance as they carry DNA responsible for this.
Bacterial growth follows which pattern
Exponential growth rate within limiting factors
What do fungi require as a food source?

What is a fungal infection called?
An organic source of carbon.

What is MYCOSIS?
Fungal infection
An infection that occurs in a patient with a compromised immune sysetem is..
an opportunistic infection.
What are the branches called which mould form the mycelium from?
What are some characteristics of a parasite?
They derive nutrients from a host. Have a complex lifecycle. Often use multiple hosts. Can often evade immune system. Best treatment is prevention.
Where would a protazoa most likely be found?
Water habitats.
What are the 3 life stages of a helminth?
How would helminth infestation be diagnosed?
Presence of ovum in stools
What is an ectoparasite?
A parasite that lives on the outside of the human body. eg fleas, ticks, mites, lice.
Amoebic dysentry, giardiasis, leishmaniasis, malaria, toxoplasmosis and crytosporidium are all caused by which organism?
During the incubation period, what signs and symptoms are present?
None, generally. The infection has not yet taken hold.
What are the signs and symptoms associated with prodromal Illness?
What symptoms are associated with the acute or invasive phase?
Acute, identifiable symptoms.
What is the incubation period for food poisioning?
What properties affect the incubation period?
Properties of the pathogen.
The infectious dose.
Route of entry relative to target organ.
Host resistance.
What are some general symptoms experienced in the prodromal period?
Headache. Nausea. General malaise.
What are the two possible outcomes following prodromal illness?
Progression to Acute or invasive phase.
Host fights off infection.
Also it could possibly be somewhere in between: Subclinical.
What does the Acute/Invasive Stage of infection involve?
Pathogen invades and damages host tissue.
Characterised by fevers or chills caused by the release of pyrogens.
Sometimes will reach a crisis peak.
What are the 2 outcomes of the acute/invasive stage of infection?
Death or recovery.
At which stage of infection is a disease identifiable?
Acute/Invasive stage generally.
Describe the Course of infection:
It begins with incubation - no signs or symptoms. Prodromal illness follows, where there may be mild signs or symptoms. The Acute/Invasive phase is where the acute symptoms appear, and the disease is recognisable and diagnosable. At this point the number of pathogens is at the greatest. The infection has the potential to be fatal if unchecked. The Recovery phase is broken into 2 parts: Decline, where the immune response or treatment decreases the number of pathogens greatly. And Convalescence, where infection is still present, but almost gone.
Describe the decline phase of infection
The onset of protective immunity.
Immune system overcomes effects of pathogen.
Symptoms subside.
Chronic state may occur here (If patient doesn't take it easy!)
What is convalescence?
The stage in which the body repairs itself and regains strength. Energy is focused on regenerating cell damage.
At this stage the body is weakened, and vaunerable to another infection. Care must be taken.
What is Acute illness?
Characteristic symptoms appear and the disease runs its course quickly.
What is Fulminating illness?
Symptoms appear suddenly and the disease runs it's course rapidly, often to a fatal outcome.
What is Chronic Illness?
The disease progresses slowly and persists for long periods with continuous shedding of the pathogen.
What is a latent infection?
The pathogen is dormant in the host and may be reactivated at a later stage.
What is a subclinical infection?
the infection produces an immune response without recognisable symptoms.
What is a localised infection?
Confined to one area of the body
What is a systemic infection?
the pathogen affects more than one organ
What is a mixed infection?
Disease due to more than one pathogen.
What is a primary infection?
The first sign of infection in a healthy host.
What is a secondary infection?
It develops when the defences of the host are lowered due to another infection.
What is a superinfection?
Resultant overgrowth of opportunistic organisms following the destruction of normal flora.
What are some signs of infection?
Inflammation, Pain, Swelling, Redness, Warmth, Exudate (Purulent/Serrous), Fever, Fatigue, Weakness, Headache, Nausea, rash.
What are 7 possible specimens that can be used for diagnosis?
What affect may antimicrobial drugs have on pathogenic infection?

What is a side effect?
Antimicrobial drugs may speed up the destruction of the pathogen and dramatically shorten the length of the invasive phase, sometimes averting a fatal outcome.

Destruction of bacteria may release toxins into the body, leading to serious side effects.
What 2 ways does the body respond to infection?
Fever, inflam, Macrophages, NK cells, Complement

Antibody production, Cytotoxic T cells.
What immune defence are these?

Fever, Inflammation, Macrophages and NK cells, Complement....
NON specific immune defence
What immune defence are these?

Antibody production. Cytotoxic T-Cells.
SPECIFIC immune defences
What ways can the COMPLEMENT system be activated?
Pathogens - The polysaccharide coating on pathogemn
The IgG/IgM antigen/antibody complex.
Whicjh cells will interferon activate?
NK cells
What are the the 2 clearance mechanisms of the specific immune system?
Antibody responses and Cytotoxic T cells.
How may viral latency be a method of survival for a virus?
The virus may remain latent until the immune respose dies off.
What are the steps of the cell cycle?
Mitosis (M), cell growth (G1), synthesis (S), cell growth (G2), mitosis (M)...

Following G1, the cell may undergo synthesis, or it may rest (G0) or it may not divide.
Which cells do not divide in the cell cycle (examples)?
Neurons, Skeletal muscle.
Describe the cell cycle of an epithelial cell:
Epithelial cells are fast dividing and complete the cell cycle (G1, S, G2, M) in a few hours.
How does the cell cycle of a Quiescent (stable) cell dffer from that of an Epithelial cell?
Epithelial cells divide rapidly, completing a cell cycle within a few hours.
Quiescent cells have low levels of replication- cells can spend months on one cell cycle.
have a greater risk of becoming cancerous? why?
Epithelial cells have the greatest risk of becoming cancerous, as they divide the fastest.
What controls the cell cycles?
DNA (genetics)
What happens when cells become disorganised, undifferentiated or their growth is uncontrolled?
They lose control of their specialisation, their growth rate. They may becone cancerous.
What is an alteraton or error in DNA replication?
Why does mutation of cells occur?
Spontaneously during mitosis.
Or due to exposure to DNA damaging agents.
What causes damage to DNA?
Spontaneous mutation during mitosis.
Chemical or radiation exposure.
Viruses- Oncoviruses
Why is it difficult to determine the aetiology of cancer?
Because it results from a sequence of changes over a long period of time.
What is carcinogenesis?
The generation of cancerous cells from normal cells (tumour formation). Loss of cell cycle control. Results in Neoplasm.
What is the 3 step process to tumour formation?
*INITIATING FACTORS (cause of damage to DNA)
*PROMOTERS (repeated exposure)
*Additional changes result in MALIGNANCY.
What affect does the *INITIATING FACTOR* to cancer have on the outcome of the state?
The initiating factor causes damage to part of the DNA. It is irreversable. It can be genetic or environmental exposure.

The result is not an active neoplasia, but an ONCOGENE.
What is an oncogene?

What are the 2 types?
An oncogene is a gene that has been mutated to facilitate neoplastic growth.

The 2 types are *Loss of Tumour suppressor gene *Activation of Proto-oncogene (SUPRESSOR or PROMOTER)
What is Tumour suppressor gene, and what is it's purpose?

What is one common Tumour suppressor gene named?
A tumour supressor gene is a protein designed to prevent rapid mitosis from taking place. The cause cell apoptis (death) where necessary.

TP53 is a tumour supressor, and is found to be damaged in over half of all cancers.
What is a proto-oncogene?
A gene which may result in overactivity of a cells mitosis. These mimic persistant growth factor stimulation.

May have viral origins in some cases, eg wart virus.
Which is true:
this may result in cancer:
a) Inactivation: proto-oncogene & tumour supressor gene.
b) Activation: proto-oncogene, Inactivaton: tumour supressor gene.
c) Inactivation: Proto-oncogene, Activation: tumour suppressor gene
d) Activation: Proto-oncogene & Tumour suppressor gene
b) Activation: proto-oncogene, Inactivaton: tumour supressor gene.
What does 'Promotion' of cancer involve?
Exposure to promoters, such as Hormones or Chemicals, may result in further canges to the DNA. They result in an increase in mitosis.
This may cause the formation of a malignant cancer.
What is the 1st, 2nd and 3rd hit of carcinogenesis?
1st hit- Initiation
2nd hit- Promotion
3rd hit - Cancer/Neoplasia
What is the difference between a benign and malignant cancer?
Benign is not recurrent and has a favourable chances of recovery. Malignant tumours tend to become progressively worse and result in death.
What are some properties of a malignant tumour?
Describe a benign tumour:
Consists of *undifferentiated* cells. Reproduce faster than normal.
Expands but doesn't spread.
Damage is from compression.
Not life threatening (unless location is somewhere like brain.)
Describe a malignant tumour:
Consists of undifferentiated and non-functional cells that reproduce at a faster rate than normal.
Cells infiltrate, spreading into other tissue. Detatches and spreads: Metastasis.
What are the 3 mechanisms involved in the spread of cancer?
INVASION - tumour grows into normal tissue, destroying normal cells.
METASTASIS - Spreads to different sites via blood or lymphatics.
SEEDING - Spread of cancer cells in body fluids or along membranes in body cavities
What causes inflammation around a tumour site?
Expansion of the tumour leads to compression of blood vessels. Normal tissue dies (necrosis), leading to inflammation.
At what point in size will a tumour require it's own blood supply?

What is this creation of blood supply called?
It will require it's own supply around 1-2mm in diameter.

This vascularisation is called ANGIOGENESIS.
How does angiogenesis take place?
Existing capillaries extend their brances to include the tumour.

Tumours can encourage angiogenesis by synthesising growth factors.
What are the local effects of a tumour?
PAIN (in advanced stages)- due to pressure on nerves, stretching, infection, ischaemia, bleeding, chemical irritation.
OBSTRUCTION - Compress duct/ passageway/ bloodflow/ air flow
What are the systemic affects of a tumour?
CACHEXIA- fatigue, weakness, tissue b'down
Additional problems associated with certain tumours.
Substances released from the tumour can affect neurological function, blood clotting, hormonal secretion...
What are 2 ways the body tries to eradicate tumour cells?
Cytotoxic T cells and NK cells
Why is it hard for the body to eradicate tumour cells?
poor innunogenicity; the body doesn;t recognis the cancer as an invader. The tumour doesnt usually provide the sitmulation to activate immune sys.
Antigen variaion; rapid change, hard to keep track.
Immunosupression; some tumours produce cytokines and suppress immune funct.
Availability; some are hard to reach! eg solid tumour.
What is the most important determinant of cancer risk for most comon cancers?
Environmental factors.
What are the risk factors (causes) to cancer?
Diet (chemicals, processing)
How would you reccomend someone to change their lifestyle in the interest of cancer prevention?
Name 4.
Limit sun exposure.
Reduce intake of heated saturated fats.
Increase antioxidant intake.
Avoid carcinogens.
Practice preventative health.
What is the difference between Curative and pallative treatment?
Curative- designed to remove cancer, if is small enough and located easily.
Pallative - aimed at symptom, to control and manage pain.
What are the main treatments for cancer?
What are some side effects of chemotherapy?
Depression of bone marrow- low blood count
Thrombocytopenia- haemorrhage
Leukopenia - infection potential.
Hair loss
Individual drug side effects
What are the important points of Pallative care?
Pain management
Psychological support
Spiritual counselling
Manage symptoms
What are the 4 non-invasive imaging techniques?
X ray
CT Scan
What are some of the more invasive imaging techniques?
Endoscopy, gastroscopy, colonoscopy.
Punch biopsy
Tissue biopsy
What are the limitations of an Xray?
Only 2D imaging
Can miss entire structures.
Cannot view all types of problem.
Radiation hazard
What are some limitation associated with a CT scan?
High cost
Not very available
Can miss some areas
Radiation hazard
What are some limitations to MRI scanning?
VERY expensive.
Cannot be used by persons with any metal inside them - pacemakers, prostheses, screws...
Unknown effects of excessive magnetism on body
What are some limitations of Ultrasound?
Resolution is difficult to maintain.
Can miss entire structures (masked by others)
What is a disadvantage of all invasive diagnostic techniques?
More uncomfortable for patient
Higher risk
What conditions may angiography be used for?

What use does it provide?
Renal neoplasm
Cerebro-vascular accident
Pulmonary emboli

Visulise arteries, biopsy sample, treatment (eg stent)
What is a biopsy?
The removal of a small piece of living tissue from an organ or another part of the body for microscopic diagnosis