infective organs Flashcards
what is a pathogen?
its anything that causes diseases
what does a pathogen cause?
cliniical symptoms
it also causes pathogenic effects
- these can vary with organism
- it can affect different parts of the body- may not be related to the site of entry of the pathogen
- can vary in severity
- can be restricted to certian populations due to their genetic material
- can be accute or chronic
- study of different organisms to understand them- useful for food, medical reasons and commercial interest
what are the characteristics of a virus?
- theyre small
- theyre made up of genetic material
what is the structure of a virus?
core- 1 or 2 molecules of DNA/ RNA
capsid- RNA/DNA enclosed in a protein coat
envelope- some have an outer layer which can have lipids, carbohydrates and proteins in it
virion- a virus particle, 10-400nm
what is the life cycle of a virus?
- an extracellular virion enters the host cell and begins its ‘intracellular phase’
- specific cell target ‘virus factory’ relases virions
- retroviruses make host cells create their DNA from RNA viral template
what does the host have to control to stop a virus infecting itself?
- the virus particles (virions)
- the virus infected cells
- viral toxins
what is measles?
its a viral infection caused by the measles virus
the virus is an envloped single-stranded RNA virus of the genus morbillivirus
its also very contagous and responsible for 6 million deaths in the 1960s
what is coronavirus?
its a viral infection caused by (SARS)-CoV-2
what is the structure of (SARS)-CoV-2?
it has positive-sense single-stranded RNA virus
it also has an envelope and glycoproteins on its surface
e.g. spike protein is 50-200nm
what is transmission of (SARS)-CoV-2 caused by?
- its mainly caused by respiritory droplets, direct human contact and fecal-oral route may also occur
what does (SARS)-CoV-2 affect?
- it affects the respiritory tract, initial symptoms of common cold, fever, dry cough, nasal congestion, sore throat, diarrhoea, severe pneumonia, difficulty breathing and can be fatal
what are bacteria?
theyre microspopic organisms that can be free-living or parasitic
what are the three main shapes of bacteria?
- rod
- spherical
- spiral
what is more complex: viruses or bacteria?
bacteria
what are some of the structures bacteria have?
- cell wall
- a capsule around the cell wall
- outside structures i.e flagellum and/or pilli
- BUT the structure depends on the species
what is salmonella?
its a bacteria which is gram-negative and intracellular
theres over 2500 types (serovars)
how is salmonella transmitted?
by faecal-oral route and 94% of cases are from contaminated food
what are the symptoms of salmonella?
diarreal disease
what is TB and how is it transmitted?
its a bacterial pathogen which initially infects the lungs by droplet infection then spreads to other parts of the body
its an intra-macrophage pathogen
why is TB such a concern?
as its multi-drug resistant (MDR TB) and is a significant threat to global health
is there a vaccine against TB?
yes, theres the BCG vaccine which people are vaccinated with a weakened strength of TB bacteria
what are the symptoms of TB?
- fever, night sweats and weight loss
what are fungi?
theyre larger pathogens which you can see with the naked eye but their spores are microscopic
the spores germinate to produce a pycelium- hyphae grow out in the medium used for growth
how are fungi spores dispersed?
by the wind or animals
what is candidiasis and who is at risk of it and what are the symptoms of it?
its an infection caused by the fungus Candida Albicans
its an opportunistic infection which occurs because the patient is immunosuppressed
its a part of the normal flora found on mucosal surfaces like mouth and genitals
patients with HIV, cancer, diabetes and transplants are at risk
- the clinician symptoms depend on the site of infection
what are the different forms candidiasis can take?
- oropharyngeal
- oesophageal
- systemic
- nappy rash
what must the immune response control in candidiasis?
- budding yeast cells
psudo hyphae - hyphae
what must the immune response control in candidiasis?
- budding yeast cells
- psudo hyphae
- hyphae
what is systemic candidiasis?
its a fungal infection with 30-50% mortality when left untreated
in 10% of cases, it causes macronodular skin lesions
10-28% of cases have candidal endophthalmitis (inflammation in the eye)
septic shock (hypotension, tachichardia, tachpynea) may also occur
disseminated candidiasis - 40-60% blood cultures may be negative
what are parasitic infections?
its an infection caused when the immune system cant control the parasite
theyre multi/unicellular infections which can be intra/extracellular
they occur in different locations
what examples of parasitic infections?
malaria - trophozites 1-2 microns
helminths- tape worm 15m long
how do intracellular parasite and intracellular parasite?
intracellular- kill
how are intracellular parasites and intracellular parasites killed?
[what examples do you know?]
intracellular- killed by activating the infected cell [leishmania parasite inside macrophages] or by eliminating the infected cell [use cytotoxic T lymphocyte e.g. toxoplasma]
extracellular - too big for cells to kill the whole organism so need to damage the parasite[ gut parasite- expelled by the accumulation of fluid in the gut and production of diarrhoea, tissue parasite- damage and break down]
both ways require co-operation between a range of immune cells and other mechanisms]
what are gastrointestinal nematodes?
can you name any different types?
theyre also known as round worms, and are a parasite
there are many different types: ascaris, tichuis, hook worms: nector and anacylostoma, enterobius, toxocara
what are the symptoms caused by round worms?
- diarrhoea
- blood in faeces
- passing the worm in faeces
- mild > severe stomach pain
- nausea
- vomiting
- weight loss
what is the life cycle of ascaris?
- the host is infected by 2nd stage larva in eggs
- the eggs hatch in the gut
- the larva migrate though the tissues into the lungs
- it passes up the trachea and is then swallowed
what do hook worms cause?
theyre a parasite that infect 576-740 million people
they cause physical and intellectual development changes in children
- they affect the economic development of communities
