Health, Disease, and Pathogens Flashcards
What is Health?
Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.
What is disease?
Disease is a condition where part of an organism doesn’t function properly.
What is communicable disease?
Communicable diseases (caused by pathogens) can be spread from one organism to the next.
What are non-communicable diseases?
Non-communicable diseases (caused by injury, genetics or lifestyle) cannot be spread from one organism to another.
What are pathogens?
Pathogens are organisms which cause disease. They include bacteria, fungi, protists and viruses. They can be spread in air, water, food animal vectors, needles and sexual activity.
What are two examples of a virus?
Ebola and HIV (An STI)
Ebola is spread from contact with an infected person’s bodily fluids such as sweat, saliva, and blood. Wear full-body suits to prevent coming in contact.
HIV is spread through sexual activity as it is an STI. It can be spread through blood, breast milk, semen and vaginal fluids. To treat it, use contraception, take medicine and just not have sex.
What are two examples of a bacteria?
Tuberculosis and Chlamydia (STI)
Tuberculosis spreads through the air when infected individuals cough. Infected people should avoid crowded public spaces, practise good hygiene and sleep alone.
Chlamydia is spread through sexual intercourse as it is an STI. The spread of Chlamydia can be reduced by wearing a condom when having sex, screening individuals so they can be treated for the infection or avoiding sexual contact.
What is one example of a protist?
Malaria is a disease caused by a protist.
Mosquitoes act as animal vectors (carriers) -they pass on the protist to humans but don’t get the disease themselves.
Mosquito nets and insect repellent can be used to prevent mosquitoes carrying the pathogen from biting people.
What is one example of a fungi?
Chalara causes ash die-back disease in trees.
The fungus is carried through the air by the wind. (It also spreads when diseased ash trees are moved between areas.)
Transmission can be reduced by removing young, infected ash trees and replanting with different species or by restricting the import or
movement of ash trees.
What is herd immunity?
The protection given to a population against an outbreak of a specific disease when a very high percentage of the population have been vaccinated against it.
What are the two types of defences the body has against pathogens?
Physical barriers: They block the disease from going inside.
Examples include hair, skin etc…
Chemical barriers: They destroy disease chemically.
Examples include enzymes, saliva, lysozyme (in tears) and stomach acid, which produce hydrochloric acid and kill most pathogens.
Describe the process of the lytic pathway for viruses:
- The virus attaches to a specific host cell and
injects its genetic material into the cell. - The virus uses host cell machinery (e.g.
ribosomes) to replicate its genetic material and
produce the components of new viruses. - The viral components assemble into new
viruses! - The host cell splits open (lyses), releasing the
new viruses, which infect more cells.
Describe the process of lysogenic pathways for viruses:
- Viral genetic material is incorporated into the
genome (DNA) of the host cell. E.g. HIV does
this when it infects white blood cells. - The viral genetic material gets replicated
along with the host DNA every time the host
cell divides - but the virus is dormant
(inactive) and no new viruses are made. - Eventually, a trigger (e.g. stress) causes the
viral genetic material to leave the genome and
enter the lytic pathway, making new viruses.
What are some of the physical and chemical barriers for plants against pathogens?
. Physical barriers: plants have a waxy cuticle and thick cell walls
. Chemical defences: plants produce chemicals to defend themselves
from attached microbes (and animals) such as antiseptics and poison. Things like nicotine and caffeine produced by plants are poison to insects but we use them for cigarettes and coffee.
What are some plant chemicals that are used as drugs?
Quinine: comes from the bark of the cinchona tree. For years it was the main treatment for malaria (a protist parasite spread by mosquitoes acting as an animal vector)
Aspirin: is used to relieve pain and fever. It was developed from a
chemical found in the bark and leaves of willow trees.
Digoxin: Foxglove plants produce a chemical called digoxin.
This toxin can affect the human heart rate and it has been used as an herbal medicine for hundreds of years.
