Health and Disease Flashcards
What are pathogens?
Microorganisms that cause communicable (infectious) diseases
How can pathogens be spread?
In the air, in water and by direct contact between individuals
What is the non-specific defence system designed to do?
Prevent pathogens from entering the body
Skin and cilia are physical defence barriers. Describe what they do.
Skin - a protective layer that pathogens can’t penetrate through
Cilia - tiny hairs covered in mucus which waft pathogens away from the lungs
Name two chemical barriers
Hydrochloric acid in the stomach (kills pathogens) and lysozyme enzymes in saliva and mucus (digest cell walls of bacteria)
White blood cells produce antibodies. What do they do?
Specific antibodies stick to the antigen on the pathogen and kill it. Antibodies remain in the blood for a long time, so they protect us from being infected by the same pathogen in the future
How does vaccination work?
It introduces small quantities of dead or inactive pathogens into the body, and white blood cells then produce antibodies against that pathogen to prevent future infections
What is the difference between bacterium and viruses?
Bacterium release toxins that make us feel ill. Viruses take over a host cell’s DNA, causing the cell to make toxins
Are fungi and protists eukaryotic or prokaryotic?
Eukaryotic
How does someone get aids?
HIV enters the blood and reproduces inside white blood cells, causing white blood cell destruction. This means the immune system can’t work properly
Describe the lytic cycle of a virus.
1) Virus enters the host cell and injects its DNA into it.
2) Virus DNA copies itself and causes new virus proteins to be made, using the organelles in the host cell.
3) DNA and virus proteins are packaged together to make new viruses. These are released to the cell, which destroys the host cell
Describe the lysogenic cycle of a virus
1) Provirus inserts it’s DNA into the chromosomes of a host cell
2) Replicates with the host cell every time it divides - remains dormant for a long time like this
3) At some stage, the provirus can become active and make new viruses in the lytic cycle
Why would a wire frame called a stent be inserted into an artery?
To widen the artery. If an artery becomes narrow, the drop in blood flow can cause damage to tissue
What does heart by-pass surgery involve?
A new blood vessel is inserted to s by-pass blocked by coronary arteries
How does a heart attack happen?
If blood supply to the heart muscles is reduced or stopped, the heart cells cannot get enough oxygen for respiration. This means that the cells die and the person has a heart attack
