Flashcards
Pathogens and Diseases
Flashcards do conjunto (72)
- 1Diseasean abnormal condition of an organism that impairs bodily functions
An infectious disease is any disease caused by foreign organisms, invading the body and multiplying there - 2Pathogensdisease causing organisms
Includes bacteria, viruses, fungi, animal parasites, parasitic worms and flukes - 3Epidemicdisease introduced to a region, spreading and then disappearing until the next outbreak
e.g. flu - 4Endemicdisease always present in the region
e.g. malaria - 5Pandemicdisease outbreak more widespread than epidemic
e.g. whole continent - 6Bacteriaunicellular organisms (have DNA & RNA) but no nuclear membrane and can form a resistance spore that remains dormant until conditions improve
Most are harmless to humans and are essential for life – responsible for decaying of dead organic matter and recycling of nutrients
e.g. skin protects against other invading organisms - 7Bacterial EffectsEnzymes attack living tissues
Toxins (wastes) poison living tissue
e.g. tetanus, pneumonia, gonorrhoea - 8Bacteria GroupsCocci
Bacilli
Spirochaetes
Spirilla
Vibrios - 9CocciWith a spherical shape
Cells may occur singly, in pairs, clusters or chains
e.g. pneumonia or sore throat - 10BacilliRod-shaped bacterial cells many have flagella and are motile
e.g. bubonic plague, salmonella, tuberculosis - 11SpirochaetesVery fine filaments, highly coiled into tight spiral
e.g. syphilis, Lyme disease - 12SpirillaTwisted but not as tightly as spirochaetes
- 13VibriosLess twisted, being more like curved rods and often assuming the shape of a comma
e.g. cholera - 14Bacteria ExamplesAnthrax
Cholera
Chlamydia
Leprosy
Whooping cough - 15Animal ParasitesParasites live on or in another living thing, the host and gain food and shelter from it. May cause little harm
Humans are hosts to fleas and lice that live on the surface of the body - 16Animal Parasite TypesProtozoans
Platyhelminthes
Nematodes
Arthropods - 17ProtozoansAmoebic meningitis
Malaria
Toxoplasmosis - 18PlatyhelminthesBlood flukes
Liver flukes
Tapeworms - 19NematodesHookworms
Roundworms
Threadworms - 20ArthropodsLice
Scabies
Ticks - 21VirusesNon-living, DNA/RNA surrounded by a protein
Multiplies by entering cell nucleus and taking over DNA so the cell makes only new viral particles
Called obligate parasites e.g. polio
Viruses can infect bacteria and are controlled by vaccination - 22Viruses ExamplesInfluenza
HIV
AIDS
Chickenpox
Ebola - 23FungiUsually unimportant in humans
Most pathogenic fungi cause diseases of the skin
e.g. ringworm, thrust, tinea - 24ProtozoaSingle-celled animals
Common disorders – malaria, toxoplasmosis - 25Transmission of Communicable DiseasesIngestion – food or drink contaminated by pathogens e.g. salmonella
Airborne transmission – when moisture is exhaled droplets evaporates, many bacteria die but some bacteria & viruses can remain & cause infection when inhaled e.g. coughing - 26Modes of TransmissionContact – involves spread of pathogens through contact, can by direct (touching infected person – AIDS, leprosy, cold sores) or indirect (touching object in contact with infected person)
Vectors – organisms, usually animals, spread disease e.g. fleas spread plague and mosquitos spread malaria - 27Factors Affecting Susceptibility to Infectious DiseaseExposure to pathogen
Age
Personal habits
Effectiveness of immune system
General health - 28Non-Specific Disease MechanismWorks against all pathogens, body’s first line of defence
External defences, chemical defences, protective reflexes, phagocytosis, inflammation - 29External Defences - Primary DefenceSkin impervious barrier (keratin) has friendly bacteria, produces sebum (oil) which is an antiseptic
Sweat inhibits bacterial growth
Eyes – blind reflex, tears – lysozyme
Ears – produces cerumen – ear wax repels insects
Nose – hairs traps materials
Trachea & bronchi – goblet cells traps microbes
Urethra – flushing action of urine
Mouth cavity – cleansed by saliva – lysozyme kills pathogens - 30Chemical DefencesSecond line of defence
Complement proteins
Puncture cell membrane of pathogen causing lysis (cell bursting)
Enhances immune and inflammatory response
Intensify phagocytosis and inflammation - 31Protective ReflexesSneezing
Coughing
Vomiting
Diarrhoea - 32SneezingStimulus for sneezing is irritation o walls of nasal cavity
Irritation can be from noxious fumes or dust particles, which are likely to be carrying micro organisms
Forceful expulsion of air from lungs carries mucus, foreign particles and irritating gases out through nose and mouth - 33CoughingStimulus is irritation in lower respiratory tract – bronchi and bronchioles
Air is forced from lungs to try to remove irritant
Air drives mucus and foreign matter up trachea towards throat and mouth - 34VomitingPsychological stimuli, excessive stretching of stomach and bacterial toxins can induce vomiting
It is not contraction of stomach but contraction of muscles of the abdomen and the diaphragm that expels the stomach contents - 35DiarrhoeaIrritation of small & large intestines by bacteria, viruses/protozoans can cause diarrhoea
Irritation causes increased contractions of the muscles of walls of intestines so that the irritant is removed quickly
Material does not stay in large intestine long enough for water to be absorbed - 36PhagocytosisPhagocytes are mobile white blood cells which engulf and destroy microorganisms/cellular material
Squeeze through walls of blood capillaries to enter tissues
Macrophages are large phagocytic cells from other white blood cells called monocytes - 37PhagocytesDetect non-self particles and destroy
Alert immune system to invasion by pathogens-initiate immune response
Counteract infection and play role in cleaning up debris once infection is overcome - 38InflammationTissues become hot, red and swollen
Histamines from injured cells
Function is to dispose of toxins material at injury site
Prevent spreading
Prepare site for tissue repair - 39Fevermacrophages which are actively by pathogens produce chemicals to reset the body’s thermostat in the hypothalamus
Higher temperatures inhibit growth of microorganisms - 40Helping Body's Non-Specific DefencesGood hygiene
Mechanical barriers - 41Specific Defence MechanismsDirected at one particular pathogen and will not work against any other virus or bacterium
e.g. if you get infected (or vaccinated) with chickenpox virus, body will make antibodies to combat virus - 42Immune Responsehomeostatic mechanism that works to destroy foreign particles to return the body’s internal environment to its normal state
2 parts which are both found in lymphoid tissue:
Humoral response/antibody-mediated immunity and cell-mediated response - 43Inflammatory Response: Damage to Tissues1) When stimulated by mechanical damage/local chemical changes, mast cells release histamine, heparin & other substances into tissue fluid. Stimulate inflammation
2) Histamine increases blood flow through area & causes walls of capillaries to become more permeable so fluid is filtered from blood. Increased blood flow causes redness & heat
3) Heparin prevents clotting, so release of heparin prevents the clotting in the immediate area of injury. A clot of fluid around the damaged area forms& this slows the spread of the pathogen into healthy tissue
4) Chemicals released by mast cells attract phagocytes. Macrophages & leucocytes actively consume micro-organisms and debris by phagocytosis
5) Abnormal conditions in the tissue stimulate pain receptors so person feels pain in inflamed area
6) Phagocytes, filled with bacteria, debris and dead cells die. Dead phagocytes and tissue fluid forms pus
7) New cells produced by mitosis and repair of damaged tissue takes place - 44Lymphatic SystemFunction –
Circulation and drainage of tissue fluid that escapes from blood capillaries
Transports dietary fats
Carry out immune response in the lymph
Components –
Blind-ended capillaries
Lymphatic vessels
Lymph nodes containing lymphoid tissue
Lymph originates from this tissue - 45Humoral Response/Antibody-mediated ImmunityInvolves production of antibodies which circulate around the body and attack invading agents
- 46Cell-mediated ResponseInvolves formation of special lymphocytes that destroy invading agents
- 47Two types of CellsB-cells – provide antibody-mediated immunity found in bone marrow
T-cells – provide cell-mediated immunity found in bone marrow - 48AntigensAntibody-mediated immunity and cell-mediated immunity are triggered by antigens
Antigen is a substance capable of causing a specific immune response and reacting to the product of that response
Antigens are large molecules, can be proteins, CHO, lipids or nucleic acids, virus particles or a whole micro-organism - 49Antigen TypesSelf-antigens are large molecules produced in a person’s own body that do not cause an immune response
Non-self antigens are foreign compounds that trigger an immune response
The immune system is programmed to distinguish between both - 50AntibodiesSpecialised protein that is produced in response to a non-self antigen
Belong to a group of proteins known as immunoglobulins (Ig)
Five classes: IgA, IgD, IgE and IgM
Antibody produced in response have specific active sites and can combine with that antigen to form an antigen-antibody complex - 51Antibody-Mediated ImmunityInvolves production and release of antibodies into blood and lymph
Provides resistance to viruses, bacteria and bacterial toxins before these micro-organisms/substances enter the body’s cells
When an antigen activates B-cells, they enlarge and divide into a group of cells called a clone which most become plasma cells that secrete specific antibodies that attach to antigen active sites
These antibodies circulate in the blood, lymph and extracellular fluid to reach site of invasion of foreign compounds - 52Antibodies may:Combine with foreign enzyme/bacterial toxins, or inactivate them by inhibiting reaction with other cells or compounds
Bind to the surface of viruses and prevent viruses from entering cells
Coat bacteria so that bacteria are more easily consumed by phagocytes
Cause particles such as bacteria, viruses or foreign blood cells to clump together – process called agglutination
Dissolve organisms
React with soluble substances to make them insoluble and thus more easily consumed by phagocytes - 53How do Antibodies work to provide resistance to infectionAll antibodies combine with antigen for which they are specific to form an antigen-antibody complex
The response that then occurs varies according to the antibody and antigen - 54B-Cells of CloneDon’t become plasma cells and remain as memory cells
Spread to all body tissues to allow the response to occur more rapidly should the antigen enter the body again
On first exposure to an antigen the immune reaction is called the primary response
With a second exposure to the same antigen, the response is faster due to the activity of the memory cells, with this secondary response, plasma cells form very quickly - 55Cell-mediated ImmunityProvides resistance to the intracellular phase of bacterial and viral infections
These pathogens specialise in invading and replicating inside host’ own cells making them difficult to overcome
Provides resistance to fungi and parasites, and is involved in the rejection of transplants of foreign tissue - 56T-LymphocytesResponsible for cellular immunity
Occur in the same lymphoid tissue as B-cells but occupy different areas of the tissue
When a foreign antigen, such as a virus or bacterium enters the body, the particular type of T-cells that are specifically programmed for that antigen become activated/sensitised
Occurs after a B-cell/macrophage encounters foreign antigen, travels to nearest lymph node and presents it to the T-cells - 57Types of ImmunityNatural Immunity
Artificial Immunity
Active Immunity
Passive Immunity - 58Natural Immunityoccurs without human intervention
Can occur naturally when antibodies from mother pass across placenta to a developing foetus/ when a mother’s antibodies are passed to baby in breast milk
Short-lived and only lasts until antibodies are broken down and excreted - 59Artificial Immunityresults from giving a person an antibody or an antigen
Can occur when a person is injected with antibodies to combat a particular infection
Often done when a person is exposed to pathogens that cause serious diseases e.g. tetanus and rabies
Is prolonged as while the amount of antibody produced decreases, the ‘memory’ of that antigen persists through the memory cells once the antigen has been dealt with - 60Active Immunityresults when the body is exposed to a foreign antigen and manufactures antibodies in response to that antigen
- 61Passive Immunitywhen a person is given antibodies produced by someone else
- 62AbbreviationsAA – vaccine using antigen
AP – vaccine using antibodies
NA – catching an antigen
NP – from breast milk - 63Natural vs. Artificial ImmunityPassive Immunity – Natural: antibodies enter bloodstream across placenta/in breast milk
Passive Immunity – Artificial: antibodies are injected into bloodstream
Active Immunity – Natural: ability to manufacture antibodies results from an attack of a disease
Active Immunity – Artificial: ability to manufacture antibodies results from being given an antigen by vaccination - 64VaccinesImmunisation means programming the immune system so that the body can respond rapidly to infecting micro-organisms (artificial/natural)
Vaccination is the artificial introduction of antigens of pathogenic organisms so that the ability to produce the appropriate antibodies is acquired without the person having to suffer the disease
Vaccine is the antigen preparation used in artificial immunisation - 65Ethical Concerns of VaccinesMain concern is around how the vaccine was manufactured, how it was tested and the risks associated with its use
Viruses can only reproduce in living cells; the manufacture of viral vaccines require host tissue e.g. influenza virus cultured in chicken embryos
Many vaccines require human tissue as some viruses cause disease in humans do not grow well in cell derived from other species. The use of human tissue avoids the problem of cross-species infection form unknown viruses e.g. rubella vaccine is manufactured from cells of tissues of aborted human foetuses
Testing of vaccines is an issue, most are produced in developed countries but are destined for use in developing countries.
Before clinical trials on humans, most vaccines are tested on animals, the animals used are usually mice, but other mammals are also used - 66Vaccinations of PopulationUse of vaccines in mass immunisation programmes has either eradicated/greatly reduced the incidence of certain diseases throughout the world
Greatest success is the global elimination of smallpox
Other vaccination programs are on a smaller scale and are frequently used to prevent the possibility of a serious outbreak of a highly infectious disease
Federal gov. supports program to vaccinate the young an elderly against influenza and such vaccination programs not only reduce the chance of disease in the most susceptible individuals but also increase immunity of population = Herd immunity which depends on a large proportion of individuals being immunised
Vaccination shouldn’t be too soon after birth as child’s blood contains mother’s antibodies, if they are the antibodies in the child’s bloodstream from the mother eliminate the foreign materials in the vaccine - 67ToxoidsMade from filtrates of bacterial cultures containing toxins
Toxin produced by the bacteria can be inactivated, so that when they are injected into someone they do not make the person ill.
Used to protect against: diphtheria and tetanus - 68Risk of VaccinesTested for safety and effectiveness in clinical trials and then larger trials before they are made available for general use
Before approved, they are evaluated by the Therapeutic Goods Administration to ensure they are effective and safe
Main risk is allergic reactions which may occur from a reaction to the medium that the vaccine is cultured from e.g. influenza vaccines are manufactured in fertilised eggs and people allergic to egg protein need to be aware of this
Impossible to completely isolate 1 virus from others in an animal tissue that is being used as a culture medium posing the risk of cross-species disease introduction - 69Vaccine DeliveryMost common method is using a syringe but other forms of delivery can be used
Medical researchers are investigating other methods of delivering vaccines
The use of a very fine spray into the nostrils has been trialled for a number of vaccines
Skin patches for delivering vaccines have been tested with promising results (adv. Can be self-administered) - 70Dead Micro-OrganismNot usually as prolonged as it would be with immunisations using live attenuated micro-organisms
Used to protect against: cholera, bubonic plague, typhoid, whooping cough, influenza etc. - 71Problems with VaccinesHave been very effective, but have certain problems with some risk of side effects e.g. about 1 child in 1 million vaccinated with dead whooping cough bacteria dies from damage to the NS.
Some older vaccines, such as cholera vaccine, give good protection against the disease but are effective for a short period
Developers of modern vaccines try to produce vaccines that are effective for prolonged periods and produce no side effect - 72Living-Attenuated Micro-organismContains micro-organisms with a reduced ability to produce disease symptoms, so that the immunised person does no contract the disease but manufactures antibodies against the antigen
Used to protect against: measles, mumps, rubella, rabies etc.
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- Year 12 Human Bio (Pathogens and Diseases) FlashCards sobre Pathogens and Diseases, criado por Gemma Anderson em 16-05-2019.
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- Gemma Anderson
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