B2 - Keeping Healthy Flashcards
What are symptoms of infectious disease caused by?
damage done to cells by microorganisms or the poisons (toxins) they produce
Why can viruses reproduce rapidly to form large numbers?
Viruses can only reproduce inside host cells, damaging them when they do so. Once inside, they take over the cell and make hundreds of thousands of copies of themselves. Eventually, the virus copies fill the whole host cell and it bursts open. The viruses then pass out through the bloodstream, the airways, or by other routes.
Why can bacteria reproduce so quickly?
In the correct conditions (with warmth, moisture, nutrients) bacteria can multiply rapidly. The human body can provide these conditions for bacteria to multiply, for example in a cut.
HOw often do bacteria divide?
Every 20 minutes
What are white blood cells?
part of the body’s immune system and can destroy
microorganisms by engulfing and digesting them or by producing antibodies
How do antibodies recognise microorganisms?
by the antigens that they carry on their surface, that different microorganisms have different antigens, and that a different antibody is therefore needed to recognise each different type of microorganism
Why does immunity occur?
once the body has made the antibody to recognise a particular microorganism, memory cells can make that antibody again very quickly, therefore protecting against that particular microorganism in the future (immunity).
What do vaccines do?
vaccinations provide protection from microorganisms by establishing memory cells that produce antibodies quickly on reinfection
What is inside vaccines?
A vaccine usually contains a safe form of a disease-causing microorganism
Why is it necessary to vaccinate large numbers of a population to prevent epidemics?
………..
Why can vaccines and drugs never be completely risk free?
since individuals have varying degrees of side effects to them due to genetic differences
What are antimicrobials?
chemicals called antimicrobials can be used to kill, or inhibit, bacteria, fungi and viruses
What are antibiotics effective against?
Bacteria and not viruses
over a period of time bacteria and fungi may become __________ to antimicrobials
resistant
Why do some microorganisms become less affected by antimicrobials?
random changes (mutations) in the genes of these microorganisms sometimes lead to varieties which are less affected by antimicrobials
What can we do to prevent antibiotic resistance?
only use antibiotics when necessary and always complete the course
How are new drugs and vaccines are first tested for safety and effectiveness?
using animals and human cells grown in the laboratory
Human trials may then be carried out on?
a. on healthy volunteers to test for safety
b. on people with the illness to test for safety and effectiveness
What is an open-label trial?
In an open-label trial the patient and doctor both know the treatment. This type of trial happens when there is no other treatment and the patients are so ill that doctors believe they will not recover from their illnesses
What are blind trials?
In a blind trial, the volunteers do not know which group they are in but the researchers do. The problem is the researchers may give away clues to the volunteers without realising it. This is called observer bias; it can make the results unreliable.
What are double-blind trials?
In a double-blind trial, the volunteers do not know which group they are in, and neither do the researchers, until the end of the trial. This removes the chance of bias and makes the results more reliable. But double-blind trials are more complex to set up.
