Dealing with disease 9 Flashcards
Pathogen
cellular and non cellular agents that cause disease
which include bacteria, viruses,
fungi, protozoa, prions, and worms
Disease
- Conditions where part or all of an organisms normal bodily functions are upset or fail to function
properly - can be infectious, contagious and/or
genetic
Infectious Disease
-Condition that impairs normal function of an organism
- caused by the invasion
/ growth of a pathogen within an organism and can be passed from one host to another
Endemic: (low level)
a disease restricted to a region or part of a region and is present in a
relatively low level of the population
Epidemic: (mid-level)
- A disease that affects a large number of individuals at the same time
- Disease usually travels quickly and is easily transmitted
Pandemic: (global)
-A disease that is worldwide distributed and affects everyone.
- This disease is easily
transmitted
Control infectious disease:
- Behavioural Control (Ex: Condoms/thongs/sunscreen)
- Modifying the environment (Draining swampy ground / spraying disinfectants)
- Treatment (Antibiotics/Antivirals)
- Immunisation
Transmission of disease:
Vector Transmission – bites from variety of animals can introduce pathogens (mosquitos / dogs)
Vehicle Transmission – transmission via medium such as blood, water, food or air
Other disease types
society – drug abuse, alcohol, heart disease | environment – safe drinking water,
sanitation, food | genetics – familial, spontaneous
Antigen
-a substance that is recognized by the immune system as either foreign or self. -foreign antigen -->trigger an immune response
There are two types of antigens: Self and non self, what is non self?
molecule from
outside the body that is recognised
by the immune system and
initiates an immune response
Major histocompatibility complex
(MHC) proteins
- a group of proteins present on the surface of cells that enable the immune system to distinguish between self/non-self material.
Autoimmune disease
a condition where the immune system no
longer recognizes self-antigens as self and B and T cells attack cells
as they are seen as foreign/non-self
Allergen
a non-pathogenic antigen
that triggers an allergic reaction
Allergic reaction
an inappropriate
immune response to a
non-pathogenic antigen
What are the two MHC classes and where are they present:
Class I MHC Antigens – on surface of all body cells (except
RBC), cells invaded by virus have Class 1 MHC Markers altered by
the viral proteins and thus recognised as non-self
Class II MHC Antigens – are restricted by antigen presenting
what are the features/Nature of Disease and describe them,
Virulence – intensity of the pathogenic effect, degree pathogen inflict damage on host
Resistance – individual’s level of susceptibility to pathogen
Incubation Period – the time between infection and symptom development, depends on pathogen achieving
sufficient number, reaching target tissue and toxin accumulation
Cellular pathogens
a pathogen that has a cellular structure and exhibits the processes of a living organism. Examples include bacteria, fungi, protozoa, and parasites such as worms
Non-cellular pathogens
a pathogen that has a cellular structure and exhibits the processes of a living organism. Examples include bacteria, fungi, protozoa, and parasites such as worms
Bacteria
- Unicellular prokaryotes that can infect almost any part of the body
- cellular
- meningitis, tetanus
Fungi
-Eukaryotic organisms like yeasts and moulds and contain long, branching filaments called hyphae. -cellular - They can cause a variety of diseases in humans including thrush, athlete’s foot.
Worms
-Multicellular invertebrate parasites whose development include egg, larval, and adult stages -cellular - Parasite (e.g. tapeworm) infection leading to malnutrition
Protozoa
-Single-celled eukaryotes that can be free-living or parasitic. -cellular -Plasmodium causing malaria
Viruses
-An infectious agent composed of genetic material (DNA or RNA) inside a protein coat (capsid) and surrounded by a lipid envelope. Viruses are not able to independently reproduce, instead they insert their genetic material into a host’s cell and using the cell to replicate. - Non cellular - Rhinovirus causing the common cold -Influenza causing the flu -Ebola virus causing ebola
Prions
-Abnormally folded proteins that can induce normal proteins nearby to become misfolded. Only occur in mammals and only affect the brain and other neural structures. Currently the only known infectious agents that don’t contain nucleic acids - Non-Cellular -Creutzfeldt–Jakob disease, Bovine spongiform encephalopathy (also known as mad cow disease)
First Line of Defence
A component of the innate immune system characterised by the presence of physical, chemical, and microbiological barriers to keep pathogens out of the host organism
Physical barrier
a component of the first line of defence that features solid or fluid obstacles that block pathogen entry e.g. skin, mucus
Chemical barrier
a component of the first line of defence that features solid or fluid obstacles that block pathogen entry e.g. skin, mucus
Microbiological barrier
n invasion microbiological barrier a component of the first line of defence in which the presence of normal flora limits the growth of pathogenic bacteria
Examples of physical barriers in Human
• Intact skin and surfaces between external and internal environments
(e.g. respiratory, gastrointestinal, and genitourinary tracts)
• Mucous secretions and/or hairs in the respiratory tract that trap organisms,
and cilia that sweep them away from the airways and into the thr
Examples of chemical barriers in Human
• Presence of lysozyme enzymes in tears and saliva that destroy bacterial
cell walls
• Antibacterial compounds in earwax
• Stomach acid that destroys pathogens that have been eaten/swallowed
• Acidic sweat that destroys pathogens growing on the surface of the body
• Antibacterial proteins in semen
• Low pH in the vagina
Examples of microbiological barriers in Human
- Presence of bacteria on the skin and in the lower gastrointestinal tract
- Non-pathogenic organisms in the vagina
Examples of physical barriers in Human
• Waxy cuticles of leaves
• Thick bark
• Formation of galls to prevent the spread of infection
• Closing of stomata to prevent pathogen invasion during carbon dioxide
uptake
• Presence of thorns and trichomes to deter insects and grazers
Examples of chemical barriers in Plants
• Chitinases – enzymes that occur in a number of different plants and have
antifungal properties
• Oxalic acid – a substance that can be toxic if ingested
• Phenols – secreted by wounded plants, phenols repel or kill many
microorganisms
• Saponins – disrupt the cell membranes of various fungi
• Glucanases – defend plants against fungi
• Defensins – small peptides that are toxic to microbes and fung
innate immune system: Second line of deference
a component of the immune system that is comprised of generalised and non-specific defences and/or responses to pathogens. Also known as the non-specific immune system
