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AQA GCSE Biology ­ Unit 1 summary notes
11.1 Internal Control
The Nervous System
The nervous system enables humans to react to their surroundings and coordinate their
behaviour.
Information from receptors passes along cells (called neurones) in nerves to the brain.
Nerve impulses are electrical signals that travel along neurones.
Nerve impulses travel at high speed.
Receptors detect stimuli which include light, sound, changes in position, chemicals, touch,
pressure, pain and temperature.…read more

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AQA GCSE Biology ­ Unit 1 summary notes
Reflexes
A reflex is a rapid automatic response to a stimulus, which does not involve conscious
control.
Functions:
Protection from dangerous stimuli.
Eg hand withdrawal from a hot object.
Maintenance of body processes
eg. Heart rate and breathing
Muscle coordination and posture
Eg knee jerk
A reflex arc is the route taken by a nerve impulse from receptor to effector via the central
nervous system to bring about a reflex action.
This involves:
1. A receptor
2.…read more

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AQA GCSE Biology ­ Unit 1 summary notes
Hormones
Many processes within the body are coordinated by chemical substances called hormones.
Hormones are secreted by glands and are transported to their target organs by the
bloodstream.
Hormones regulate the functions of many organs and cells.…read more

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AQA GCSE Biology ­ Unit 1 summary notes
Multiple births ­ some babies may die.
People do not like embryos to be used for research.
Oral contraceptives
Contain hormones that inhibit FSH production so that no eggs mature.
Benefits:
It can reduce population growth in the developed world.
Concerns:
Health problems ­ eg some increase the risk of blood clots.
Religious objections to preventing conception.
Homeostasis
The maintenance of a constant internal environment.…read more

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AQA GCSE Biology ­ Unit 1 summary notes
Higher concentration of ions than in body fluids
Water is drawn into the gut ­ this dehydrates you not sensible in a sports drink!
Page 6…read more

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AQA GCSE Biology ­ Unit 1 summary notes
11.2 Healthy lifestyles
Balanced Diet
A healthy diet contains the right balance of different foods.
A healthy diet contains the right amount of energy.
It will provide carbohydrates for energy.
It will provide fat for energy and insulation.
It will provide protein for growth and repair.
It will provide vitamins and minerals to help our bodies function well.
It will provide fibre to ensure food moves through our digestive systems efficiently.…read more

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AQA GCSE Biology ­ Unit 1 summary notes
In the developed world too much food and too little exercise are leading to high levels of
obesity.
Some diseases linked to excess weight:
arthritis (worn joints)
diabetes (high blood sugar)
high blood pressure
heart disease.
Malnourishment
A person is malnourished if their diet is not balanced.
This may lead to a person being too fat or too thin.
It may also lead to deficiency diseases.…read more

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AQA GCSE Biology ­ Unit 1 summary notes
11.3 Drugs
Drug Abuse
Drugs can be beneficial but may harm the body.
Many drugs derived from natural substances have been known to indigenous peoples for
many years.
Some people use drugs recreationally.
Some of these recreational drugs are more harmful than others.
Some of these drugs are legal, some illegal.
What do abused drugs do?
Drugs change the chemical processes in people's bodies.
Drugs work by affecting synapses.
Some drugs make them work faster (eg, caffeine).…read more

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AQA GCSE Biology ­ Unit 1 summary notes
11.4 Infectious Disease
Pathogens
Microorganisms that cause infectious disease are called pathogens.
Bacteria
Bacteria are very small singlecelled organisms.
Not all cause disease.
Pathogenic bacteria reproduce rapidly inside the body and may produce poisons (toxins)
which make us feel ill.
Example: E.coli produces toxins that cause fever symptoms when we have food poisoning.
Viruses
Viruses are much smaller than bacteria.
All viruses are pathogens.…read more

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