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B1a: Human Biology
B1a: 1 Coordination and Control

-Hormones are chemicals that help control and coordinate many of the processes in your body
-They are made by special glands and then secreted into the bloodstream to be carried to their
target organs in the body
-They can act…

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How a synapse works
-A synapse is a junction between two nerve endings.
-When an electrical impulse arrive at the junction bwteween two neurones, chemicals are released
which cross the synapse and arrive at receptor sites n the next neurone. This stars up an electrical
impulse in the next neurone…

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Pros Cons

The pills have helped reduce family sizes in the The pill can cause health problems/side effects
developed world =less poverty as not so much such as headaches and weight gain but even
money needing to be spent on food etc things as extreme as strokes and heat attacks…

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The metabolic rate
-The metabolic rate is the rate at which chemical reactions take place in the cells of the body
-The metabolic rate varies from person to person, meaning they will need different amounts of
energy in their diets
-The proportion of muscle to fat in your body affects…

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These foods contain high proportions of fat and/or salt which have a real impact on your health, and
make you overweight

-Cholesterol is as substance made in the liver and found in the blood
-It is needed to make hormones/cell membranes deal with stress
-The amount/type of fat you…

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Why use drugs?
-To help them cope with everyday life
Excitement/escape from life or group pressure

Drug Abuse
-People take drugs for a reason often to make them feel good about themselves/peer pressure if
they are young
-Many recreational drugs are addictive and do serious harm to your health

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Alcohol and society
Alcohol not only puts yourself at risk but affects those around you as well, as alcoholics can become
very violent and do things they regret doing later
Drink driving is very common, particularly in youths, and this is a cause of many road accidents
involving youths. Sadly…

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Lung Cancer and Smoking
-Timeline of Evidence building up against smoking

1908: Sale of cigarettes to children under sixteen banned
1912-The first suggestion of a link between lung cancer and smoking
1914-18 Smoking increased dramatically due to soldiers smoking in the War
1930s-Britain has highest smoking rate
1951-Link found between…

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-Average size -1m
-Colonies can be seen with naked eye
-Single celled organism made up of cytoplasm surrounded by cell wall and membrane-NO NUCLEUS
so DNA free in cytoplasm
-Binary fission to reproduce
-Produce toxins that cause symptoms of disease
3 types-cocci, spiral and rods
-Some useful: In foods e.g.…

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-Hairs-sebum produced-antiseptic to kill microbes
-Eyes-tear glands produce tears containing antiseptic that kills microbes and blinking spreads this
around the eye
-Stomach-HCL produced which destroys microorganisms taken in through mouth
-Skin-water-proof barrier preventing microorganisms reaching the vulnerable tissues underneath

Immune Response
-White blood cells-Phagocytes--Engulf and destroy pathogens
-Attracted to chemicals…


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