Studied by 2 peoplepathogens
disease-causing organisms
communicable / infectious diseases/ transmissible diseases
diseases that can spread from one person to another
what are the most common pathogens that effect the human body
bacteria and viruses although fungi and animal parasites can also be involved
what are bacteria
prokaryote, unicellular organisms with a simple internal structure
structure of bacteria
lack a nucleus, DNA floats freely in cytoplasm, or in the form of circular plasmids
in what form does DNA exist in bacteria
may float freely in cytoplasm, or it may be in the form of circular plasmids
is all bacteria harmful
no, most bacteria is harmless to our body and is actually essential to break down of organic material and cycling of elements
what are 4 types of bacteria
cocci, bacilli, spirilla, vibrio
cocci
spherical cells, that may exist singularly or in pairs or clusters
bacilli
with flagella
sprillia
twisted cells
vibrio
like curved rods, often shaped like a comma
how can we identify a bacetrium
we must first grow it on an agar plate or growth medium in specific conditions, then only it can be stained and viewed under a microscope
what can viruses be visible under
too small to be seen with a light microscope, must be viewed under an electron microscope
are most viruses harmless like bacteria
most viruses are harmful like HIV
what were all viruses found to contain
all were found to contain genetic material in the form of DNA or RNA but never both
what is the molecule of DNA or RNA surrounded by
by a protective coating and some even have an external lipid envelope
are viruses considered to be living things
no, viruses are not living things, they cant reproduce by themselves.
because they cant reproduce, instead what do they do
instead, they infect a living cell and its DNA or RNA induces the cell to manufacture more virus particles of the viral DNA/RNA
briefly outline the process of viruses infecting other cells
injects DNA or RNA into host cell
causing the cell to manufacture more virus particles
virus particles leave the host cell and infect other cells
during the process, the host cell is left damaged or dead or changed
why do symptoms differ for viruses
because viruses differ in the type of cell they invade, therefore the symptoms shown relate to the tissue that is affected
bacteriophages
some viruses affect bacterial cells, resulting in the death of the bacterium. such viruses are called bacteriophages.
what are the two ways in which pathogens may be transmitted
-direct/indirect contact
direct contact trasnmission
occurs when there is a physical contact between an infected person and susceptible person
indirect constant transmission
when there is no direct human-human contact
how does contact occur in indirect contact transmission
contact occurs from a reservoir to contaminated surfaces or objects
how do direct contact infections spread
occur when disease causing microorganisms pass from infected person to healthy person via direct physical contact with blood or bodily fluids
examples of direct contact
touching, kissing, sexual contact, oral secretions, or contact with body lesions
how do indirect contact infections spread
spread when an infected person sneezes of coughs, sending infectious droplets into the air
transmission by contact
involves spread of pathogen by direct physical contact, may be direct eg, person touching person or indirect, person touching object, person touches object
ingestion
of food or drink contaminated with pathogens results in disease. eg salmonella
transfer of bodily fluids
when blood or bodily fluids comes in contact mucous membranes such as mouth, nose, genitilia or throat or it enters the bloodstream through a needle or break in the skin then pathogens may enter the body of that person
transmission by droplets
may occur when tiny droplets containing the pathogenic organisms are emitted when talking, coughing, sneezing or breathing, these droplets may be inhaled by others or land on food or drink, infecting it, eg COVID 19
airborne transmission
moisture in inhaled droplets evaporates, most the bacteria dies however some still remains, these remain viable for a longer distance than droplets . eg measles
transmission by vectors
transfer of pathogens by other animals such as mosquitos and insects. eg malaria and dengue fever spread thru mosquitoes and bubonic plague through mice
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