4.1 Flashcards
Pathogen
A microorganism that can cause disease
Name types of pathogen
Virus
Bacteria
Fungi
Protoctista
Bacteria
Organism that can reproduce every twenty minutes
They can cause disease by damaging cells or releasing toxins in the host body
Virus
Organisms that invade cells and take over their genetic machinery
They can make copies of itself causing the host cell to burst open and spread the virus
eg. flu, cold,measles
Fungi
Can cause disease in plants and animals
They release spores which can cause redness and irritation
Protoctista
Organisms that cause harm by entering host cells and feeding on the contents as they grow
Describe callose deposition
- Plants produces callose
- During stress, callose gets deposited between plant cell walls and plasma membranes
- This makes it harder for pathogens to enter cells and limits the spread of viruses
How are communicable diseases spread?
Directly or indirectly
Direct transmission
Passing a pathogen from host to host with no intermediate
Indirect transmission
Passing a pathogen from host to host via a vector or intermediate
Examples of direct transmission
Droplet infection Sexual intercourse Touching Faecal - oral transmission Transmission by spores
Give examples of non specific animal defences against pathogens
Skin Mucous membranes Blood clotting Inflammation Wound repair Expulsion reflexes
How does skin act as a defence?
Acts as a physical barrier by blocking pathogens
Acts as a chemical barrier by producing chemicals that are antimicrobial
How does mucous membranes act as a defence?
Protects body openings that are exposed to the environment by secreting mucus
How does inflammation act as a defence?
Causes swelling and isolates any pathogens that entered the damaged area
How does wound repair act as a defence?
The skin can repair itself to reform a barrier against pathogen entry
How do expulsive reflexes act as a defence?
They’re automatic.
For example, coughing and sneezing are attempts to expel foreign objects such as pathogens when they irritate our nostrils or throat
Why are primary defences non-specific?
They work in the same way for all pathogens