infective organs

Question 1

what is a pathogen?

Answer 1

its anything that causes diseases

Question 2

what does a pathogen cause?

Answer 2

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

Question 3

what are the characteristics of a virus?

Answer 3

• theyre small

- theyre made up of genetic material

Question 4

what is the structure of a virus?

Answer 4

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

Question 5

what is the life cycle of a virus?

Answer 5

• 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

Question 6

what does the host have to control to stop a virus infecting itself?

Answer 6

• the virus particles (virions)
• the virus infected cells
• viral toxins

Question 7

what is measles?

Answer 7

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

Question 8

what is coronavirus?

Answer 8

its a viral infection caused by (SARS)-CoV-2

Question 9

what is the structure of (SARS)-CoV-2?

Answer 9

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

Question 10

what is transmission of (SARS)-CoV-2 caused by?

Answer 10

• its mainly caused by respiritory droplets, direct human contact and fecal-oral route may also occur

Question 11

what does (SARS)-CoV-2 affect?

Answer 11

• 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

Question 12

what are bacteria?

Answer 12

theyre microspopic organisms that can be free-living or parasitic

Question 13

what are the three main shapes of bacteria?

Answer 13

• rod
• spherical
• spiral

Question 14

what is more complex: viruses or bacteria?

Answer 14

bacteria

Question 15

what are some of the structures bacteria have?

Answer 15

• cell wall
• a capsule around the cell wall
• outside structures i.e flagellum and/or pilli
• BUT the structure depends on the species

Question 16

what is salmonella?

Answer 16

its a bacteria which is gram-negative and intracellular

theres over 2500 types (serovars)

Question 17

how is salmonella transmitted?

Answer 17

by faecal-oral route and 94% of cases are from contaminated food

Question 18

what are the symptoms of salmonella?

Answer 18

diarreal disease

Question 19

what is TB and how is it transmitted?

Answer 19

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

Question 20

why is TB such a concern?

Answer 20

as its multi-drug resistant (MDR TB) and is a significant threat to global health

Question 21

is there a vaccine against TB?

Answer 21

yes, theres the BCG vaccine which people are vaccinated with a weakened strength of TB bacteria

Question 22

what are the symptoms of TB?

Answer 22

• fever, night sweats and weight loss

Question 23

what are fungi?

Answer 23

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

Question 24

how are fungi spores dispersed?

Answer 24

by the wind or animals

Question 25

what is candidiasis and who is at risk of it and what are the symptoms of it?

Answer 25

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

Question 26

what are the different forms candidiasis can take?

Answer 26

- oropharyngeal - oesophageal - systemic - nappy rash

Question 27

what must the immune response control in candidiasis?

Answer 27

- budding yeast cells psudo hyphae - hyphae

Question 28

what must the immune response control in candidiasis?

Answer 28

- budding yeast cells - psudo hyphae - hyphae

Question 29

what is systemic candidiasis?

Answer 29

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

Question 30

what are parasitic infections?

Answer 30

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

Question 31

what examples of parasitic infections?

Answer 31

malaria - trophozites 1-2 microns | helminths- tape worm 15m long

Question 32

how do intracellular parasite and intracellular parasite?

Answer 32

intracellular- kill

Question 33

how are intracellular parasites and intracellular parasites killed? [what examples do you know?]

Answer 33

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]

Question 34

what are gastrointestinal nematodes? | can you name any different types?

Answer 34

theyre also known as round worms, and are a parasite | there are many different types: ascaris, tichuis, hook worms: nector and anacylostoma, enterobius, toxocara

Question 35

what are the symptoms caused by round worms?

Answer 35

- diarrhoea - blood in faeces - passing the worm in faeces - mild > severe stomach pain - nausea - vomiting - weight loss

Question 36

what is the life cycle of ascaris?

Answer 36

- 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

Question 37

what do hook worms cause?

Answer 37

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