Biology OCR, B2

What are the symptoms of an infectious disease caused by?
damage done to cells by microorganism or the toxins they produce
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Why can microorganism reproduce quickly in the human body?
It's conditions are ideal: It's warm, with plenty of nutrients and moisture
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How can white blood cells destroy microorganisms?
they are part of the body's immune system and either engulf and digest microorganisms or produce antibodies
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How can antibodies recognise microorganisms?
by the antigens microorganims carry on their surface, different microorganisms have different antigens and therefore a different antibody is needed to recognise each different type of microorganism
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What causes natural immunity?
once the body has made the antibody to recognise a particular microorganism, memory cells an make that antibody again very quickly and therefore protecting against that particular microorganism in the future
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How do vaccinations provide protection from microorganisms?
by establishing memory cells that produce antibodies quickly on re-infection
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What do vaccines contain?
a weakened/ dead strain of the disease-causing microorganism
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Why is it important to vaccinate a high percentage of the future population?
to prevent epidemics of infectious disease and the more people that are vaccinated, the risk of coming into contact with an infected person is small
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Why can vaccines and drugs never be completely risk free?
individuals have varying degrees of side effects because of genetic differences
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What are antibiotics?
a type of antimicrobial that are effective against bacteria but not viruses
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What might happen to bacteria and fungi over a long period of time?
they may become resistant to antimicrobials
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How can this resistance be created?
random mutations in the genes of the microorganisms allow new strains to develop and reproduce to pass on their resistance
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How can we reduce antibiotic resistance?
only use antibiotics when necessary and always complete the course
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How are new drugs and vaccines first tested for safety?
using animals and human cells grown in a laboratory
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Who are human trials tested on?
a healthy volunteer to test for safety and on a person with the illness to test for effectiveness and safety
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What is the importance of long-term trials?
to ensure there are no harmful side effects and to make sure that the treatment continues to be effective
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What is the role of the heart?
the heart is a double pump that pumps blood to provide the cells with nutrients and oxygen and remove waste
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Why do heart muscle cells need their own blood supply?
the need a blood supply from the coronary artery to function properly
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What is the structure of arteries?
carry blood away from the heart and has a thick, elastic, muscular wall to cope with high blood pressure
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What is the structure of veins?
carry blood towards the heart from the organs and has a thin wall because of low blood pressure. Have pocket valves to stop blood flowing in wrong direction
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What is the structure of capillaries?
narrow vessels that carry blood between the arteries and veins. Walls are a single layer of cells and substances can be exchanged between blood and body cells
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What do blood pressure measurements record?
the pressure of the blood on the walls of the artery
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How is blood pressure measured?
given as two numbers, the higher number is when the heart is contracting and the lower number is when the heart is relaxed
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Why is the 'normal' for measurements given within a range?
individuals vary
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What causes a heart attack?
when fatty deposits in the blood vessels supplying the heart muscle, preventing the flow of blood
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What is heart disease caused by?
lifestyle and genetic factors
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What lifestyle factors increase the risk of heart attack?
poor diet, stress, cigarette smoking and misuse of drugs
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What maintains a constant internal environment?
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How does homeostasis work?
receptors detect a change in the environment, processing centres receive information and coordinate a response, effectors produce the response
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What is negative feedback?
where one system is the reverse to another in order to maintain a steady state
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How are water levels controlled?
balancing gains from drinks, food and respiration and losses through sweating, breathing and excretion
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What organ plays a vital role in maintaining water balance?
the kidneys
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How is negative feedback used when water levels are too high?
Receptors in the hypothalamus detect a change, less ADH is secreted into the blood, kidneys become less permeable so less water is reabsorbed, bladder fills with a large quantity of dilute urine (vice versa if water levels are too low)
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What effect does alcohol have on water levels?
more dilute urine is produced because of ADH suppression, which can lead to dehydration
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What effect does Ecstasy have on water levels?
less dilute urine is produced because of and increased ADH production
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Other cards in this set

Card 2


Why can microorganism reproduce quickly in the human body?


It's conditions are ideal: It's warm, with plenty of nutrients and moisture

Card 3


How can white blood cells destroy microorganisms?


Preview of the front of card 3

Card 4


How can antibodies recognise microorganisms?


Preview of the front of card 4

Card 5


What causes natural immunity?


Preview of the front of card 5
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