immunolgy & Disease (Option Module) Flashcards Preview

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Definition of Pathogenic?

A pathogenic organism causes disease or illness to its host by disrupting normal physiology.


Examples of Pathogenic Organisms.

Bacteria - E.coli
Viruses - Smallpox, flu
Protoctista - Plasmodium = Malaria.


What does it mean to be an infectious disease?
& how can it be prevented?

Can be passed through breathing, touching, eating, bites, sex etc..
Vaccines, medicine & washing hands.


A Long term host of a pathogen, with few/no symptoms is known as a..?

Disease Reservoir.


What is a Carrier?

Infected organism, no symptoms but can infect others.


What is the difference between an Endemic and an Epidemic?

ENdemic = EXPECTED. Disease occurring frequently, predictable rate in specific location/population. e.g. Chickenpox.

EPIdemic = UNEXPECTED Rapid spread of disease, large number of people, short period of time.


What does an Epidemic become when it crosses international boundaries and affect an even larger number of people?

A Pandemic. E.g. Swine Flu.


What is a vaccine made of?

-Weakened/killed pathogen.
- Toxins
- One of the Antigens (protein molecule on pathogen surface)


Why can't antibiotics be used to treat a virus?

Because antibiotics inhibit bacterial growth and virus is not a bacteria.


What is an Antigen?

A substance which triggers your immune system to produce Antibodies.


What is an Antibody?

A protein produced by the immune system in the response to an antigen.


What is antibiotic resistance and how is it required?

Microbes not killed by antibiotics show resistance.
This can be gained through new mutuation through the overuse of antibiotics and is incredibly dangerous as it could create 'Superbacteria'.


An organism that carries and transmits an infectious pathogen into another living organism is called a..?

Female Mosquito = Vector for plasmodium/malaria.


A poisonous substance found within living cells/organisms is a..?



Different individuals of a pathogenic species may have altered surface proteins, this is known as having..?

Different Antigenic Types.
A vaccine is specific to a antigenic type, so whenever a new antigenic type is found a specific vaccine must be made. Influenza has many antigenic types so one vaccine does not protect from all.


How is Cholera transmitted and what are its symptoms?

-Infected water/food
- After 2/3 days bacteria produce a toxin in the small intestine causing extreme diarrhoea, dehydration and a drop in blood pressure. Death can occur within hours.


How can Cholera be prevented/treated?

Prevention -Oral Vaccine (Only for high risk people, don't want cholera to become resistant)
- Clean water, proper sanitation & washing hands after food/toilet. (Best Answer)
Treatment - Rehydration and electrolyte replacement.
- Single dose of antibiotics can speed up recovery.
- Vaccine gives TEMPORARY protection.


How is Tuberculosis spread & what tissue is effected?

Spread - Inhalation of cough/sneeze droplets of infected person. Crowded area = rapid spread.
Afffected Tissue - Lungs & Lymph Nodes in neck, bones + nervous system.


How is Tuberculosis prevented/treated?

Prevention = BCG Vaccine for babies/children or at risk people.
Treatment = 6 Months of Antibiotics.


What type of organism is Smallpox?



How is Smallpox transmitted?

Inhalation of saliva droplets, infected bodily fluids or though handling clothes/sheets.


How many antigenic types does Cholera have?

Around 200.


What tissue does Smallpox effect?

-Enters blood and effects internal organs, then re-enters the blood and heads to the skin, causing a rash.
-Vaccination gives 10 years immunity but having smallpox gives permanent immunity.


Prevention and treatment methods for Smallpox?

Isolate infected people.
One antigenic type.
Intravenous fluid/medicine to control fever/pain.
Antibiotics for secondary bacterial infections.
60% of infected people die.


What type of organism is influenza and how many antigenic types does it have?

= RNA Virus woth 3 subgroups, A,B & C.
= 25 antigenic types.


How is flu transmitted and where does it effect?

= Droplets in coughs and sneezes.
= Mucous membranes especially in upper respiratory tract (mouth and throat area)


How can influenza be prevented/treated?

= Wash hands often, clean surfaces, bin tissues etc..
= Rest,warm,fluids, paracetemol.


What organism causes malaria and what type of organism is it?

A protoctist called Plasmodium.


What is the vector for plasmodium?

Female mosquito - males don't feed on blood.


How can Malaria be prevented? (Need to know 3 options)

- Draining stagnant water (breeding ground)
-Introducing fish to the water that eat mosquito larvae.
- Insecticide treated nets for homes.


Why is there no vaccine for Malaria?

Plasmodium falciparium mutates frequiently so there are too many antigenic types for an effective vaccine.


Outline the life cycle of a plasmodium withing a human.

1. Plasmodium (sporozoites) enters blood from female mosquito saliva and travels to liver.
2. Asexual reporductions of sporozoites in liver to become merozoits.
3. Merozoits in liver.
4.Asexual reproductions of meroziots in RBC.
3.Gametocytes in blood.


Outline the life cylce of plasmodium within a female mosquito.

1. Sucks the blood of an infected person = gametocytes in gut.
2. Meiosis occurs hich creates sporozoites in the salivary glands, ready for later infection of humans.


What are the names of the two cycles for how virus' can reproduce?

LYTIC cycle = Virus immeditaley reproduces, using host metabolism to copy their own nucleic acid & synthesise a new protein coat.

LYSOGENIC cycle = Delayed Lytic cycle, virus integrates its nucleic acid in the host cell and can wait several cell generations, causing no harm, before being triggered.


Outline Cell Lysis.

Cell Lysis = cell bursting.
When a bacteriophage virus infects a cell it continues reproducing until the cell is so full that it bursts, releasing the virus to infect other cells.


Many virus' contain toxins, whatprocesses are toxins known to inhibit?

= RNA, DNA & Protein synthesis.


How can a virus cause cancer?

= A virus can cause cell transformation by integrating into host chromosome . If this happens to a pro-oncognen it can cause rapid, uncontrolled division to form a tuimour = cancer.


What is immune supression?

When a virus stops B & T Lymphocytes from maturing = reduces antibodies & less phagocytic cells to engulf microbes.


Give 3 examples of anitmicrobials.

- Antiseptics (used on living tissue)
-Disinfectants (Used on non living surfaces)
-Antibiotics. ( produced by fungi and act on bacteria)


What is the difference between broad & narrow spectrum bacteria?

Broad = Effect many different bacteria, both gram neg & poz. e.g. tetracycline.
Narrow = Much more selective e.g. penicillin only kills gram positive bacteria.


What do you you call antibiotics that inhibit growth?

Bacteriorstatics. They work by inhibiting protein synthesis and DNA replication.
(Static = still)


How do bacteriocidal antibiotics kill bacteria?

Cidal = Kill
Inhibits cell wall synthesis, without a cell wall the bacteria bursts and dies.


Why do anitbiotics work on Gram Positive bactoeria but not gram negative?

Gram positive = Peptidoglycan makes up most of their cell walls, which contains pores. Letting the molecules in so suceptible to attack from lysozyme and penicillin.

Gram negative = Very little peptidoglycan surrounded by a layer of lipopolysaccharide, which protects it totally from antimicrobials.


With gram stain technique what colour does gram positive bacteria go?

= Purple


What colour is gram negative bacteria when stained?

= Red.


What does overuse of antibiotics lead to?

Bacteria can develop a resistance that they can then pass on when they reporduce, increasing the resistant population.
- This can be through mutation during DNA replication.
-Bacteria may aquire plasmids which can carry a resistant allele from the environment.


What is the action of Penicillin?

-Stops peptioglycan synthesis = no more cell wall.
-Stops transpeptidase.
No cell wall = Cell lysis
Cell indirectly killed.


What do penicillin resistant bacteria secrete?

B-lactamase which breaks down penicllin or stops it binding.


Explain the action of Tetracycline?

- Binds to 30s Ribosomes, blocking the second tRNA binding site, stopping protein synthesis.
-No proteins = no cell wall = osmotic lysis
Indirectly killing the cell.


How does some bacteria resist tetracycline?

-Pumps tetracycline out of the cell
-Dislodges bound tetracycline
-Prevents it attaching to the ribosome.


Give an example of resistant bscteria.

MRSA- Methicillin, resistant to Penicillin.


Outline bacterial resistance to antibiotics?

-All Bacteria can mutate.
-All Bacetria show variation, some are resitant to antibiotics, some are not.
-Resistant bacteria are more likely to survive and breed.
-Resistant is passed to offspring = increase in resistant population.
-This is natural selection by evolution.


Your skin is an example of?

= A natural barrier to infection, part of the innate immune response.
Kerstin makes your skin waterproof and collagen makes it tough.


Give 3 Examples of natural barriers to infection, other than skin,

= Mucus & Cilla in the respiratory pathways -trap microbes in inhaled air.
= Stomach Acid - kills microbes in food & drink.
=Tears, mucus & saliva contain lysozyme, an enzyme which hydrolyses peptidoglycan in bacterial cell walls and kills them.


What does the humoral response result in?

= The production of antibodies.


Where do B-Lymphocytes mature and then what do they do?

=Mature in spleen & lymph nodes.
= Respond to the foreign antibodies in the blood and then divide to make:
- Plasma cells which release specific antibpdies
-Memory cells which remain dormant in blood until same antigen is encountered again.