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Responding to Change
Stimulus a change your body reacts to
e.g. bright light (stimulus) close eyes (reaction)
Hormones and the central nervous system control your bodys processes.
Hormones
Chemical
messengers
Made in
glands
Carried by
blood to
organs
Control
processes in
your body
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Central Nervous System
The central nervous system coordinates your responses (reactions) to stimuli
Brain
Spinal cord
Central
nervous
system
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Nervous System continued
Uses electrical impulses as messengers.
Neurones long cells that carry electrical impulses.
Receptors Cells in sense organs that detect a stimulus.
Sense organ full of receptors.
Sense organ Stimulus it detects
Eye Light
Ear Sound,
Position
Skin Touch,Pressure,
Pain,
Temperature
Nose and tongue Chemicals
Sensory neurone Takes electrical impulses to the central nervous system.
Motor neurone Takes electrical impulses from the central nervous system to the
effector organ.
Effector organ Muscle or gland that does something to respond to a stimulus.
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Example You see a cup and pick it up
Light from
cup
Eye sees cup Electrical
impulse goes
to CNS
Brain
coordinates
response
Electrical
impulse goes
from CNS to
effector
organ
Muscle
moves so
you can pick
up cup
Stimulus Receptor Sensory
neurone
Central
nervous
system
(CNS)
Motor
neurone
Effector
organ
(muscle)
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Example TV is too loud so you turn it down
Sound from
TV
Ear Electrical
impulse goes
to CNS
Brain
coordinates
response
Electrical
impulse goes
from CNS to
effector
organ
Muscle
contracts so
you can
press
remote
control
button.
Stimulus Receptor Sensory
neurone
Central
nervous
system
(CNS)
Motor
neurone
Effector
organ
(muscle)
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Reflex Actions
Automatic
Dont need to think about them
The brain is not involved
Reflex Arc
Receptor Sensory
neurone
Relay
neurone
Motor
neurone
Effector
organ
Detects
stimulus
Sends
impulse to
spinal
cord
In spinal
cord
sends
impulse to
motor
neurone
Sends
impulse to
effector
organ
Responds
(reacts)
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Example of a reflex action
Pulling your hand away from a hot pan without thinking about it.
1) StimulusHeat from
pan
2) Receptor
Skin
3) Sensory neurone
Impulse from receptor to
relay neurone
4) Relay
neurone in
spinal cord
5) Motor neurone
Impulse from relay neurone to
effector organ
6) Effector organ
muscle pulls hand away.
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A synapse a junction between neurones
= chemicals cross the gap
to set up an electrical
impulse in the next
neurone.
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The Menstrual Cycle
28 day cycle in women.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
The cycle is controlled by hormones called, FSH, Oestrogen and LH.
Hormones are released by the pituitary gland (in the brain) and the ovaries.
Hormone Released from What it does..
FSH Pituitary gland Makes an egg mature in the
ovary.Causes ovaries to produce
oestrogen
Oestrogen Ovaries Makes womb lining thicken
Makes pituitary gland make
LH instead of FSH
LH Pituitary gland Releases mature egg from
ovary
Day
Old egg and
womb lining
leave body as a
period.
New egg
released
from
ovary
If egg is not
fertilised
new period
starts
Womb lining thickens
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Controlling Fertility
Contraceptive Pill
Fertile
Can have babies
Infertile
Cant have babies
Prevents pregnancy
Contains oestrogen
Stops FSH production so
.. no mature eggs
Contraceptive pill
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Controlling Fertility (continued)
FSH as a drug
FSH is given to a woman who doesnt produce mature eggs She can then produce mature
eggs.
IVF Treatment
FSH
Mature eggs
The Woman is
given FSH
Mature eggsSperm
Eggs and sperm mixed in a dish
Fertilised eggs become embryos
Embryos put in womans uterus (womb)
to grow.
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Controlling Conditions
Internal Environment The conditions in your body
Homeostasis Keeping conditions inside you stable (unchanging)
What must be kept stable?
Temperature
Salt content =ion content
Watercontent
Sugar content
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Keeping Your Water Content Stable
Keeping Your Ion (Salt) Content Stable
Urine - Produced by the kidneys
- Kidneys control how much salt and water is lost.
Water in Water out
Drinks
Food
Breathing out
Sweat
Urine
Ions in Ions out
Drinks
Food
Sweat
Urine
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Keeping Your Temperature Stable
Body temperature = 37oC
If your temperature is too high or too low enzymes in your body wont work properly.
Warm Up
Cool Down
Keeping Your Blood Sugar Constant
You need sugar (glucose) for energy all the time.
Hormones from the pancreas stop the blood sugar getting too high or too low.
Shiver
Warm clothes
Sweat
Cool clothes
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Diet and Exercise
A healthy, balanced diet is:-
All in the right amounts
Malnourished An unbalanced diet makes you malnourished and ill.
How much energy do you need?
Need less energy Need more energy
Carbohydrates
Fat Protein
Vitamins
Minerals Fibre
+ + Energy
Water
Female Male
or
pregnant female
Little exercise Lots of exercise
Elderly Young
Hot weather Cold weather
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Metabolic Rate - The rate your body uses energy to carry out chemical reactions in your cells.
- Different people have different metabolic rates.
- You could think of it as how quickly your body uses up food.
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Weight Problems
Losing weight:-
Eat less food.
Exercise to use energy.
Diabetes
Obesity
Cause
Eat too much energy (food)
It is stored as fat
Very fat = obese
Health Problems
Arthritis High
blood
pressureHeart
disease
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Fast Food
Causes
high blood
pressure
Causes weight problems Causes lots of cholesterol
Fast Food
Contains lots of salt
Contains too much fat
Cooking
fat
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Cholesterol
Cholesterol
Made in the
liver
LDL cholesterol = bad cholesterol
causes heart disease
from eating saturated fats
Statins are
drugs that
reduce
cholesterol
HDL cholesterol = good cholesterol
reduces heart disease
from eating polyunsaturated
fats or monounsaturated
fats
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Drugs
Drugs change the way your mind or body works.
Legal drugs
o Caffeineo Alcoholo Nicotineo Medicines
Illegal drugs examples-
o Cocaineo Heroino Cannabis
Addiction Your body needs the drug more and more.
Withdrawal symptoms Addicts feel very ill if they stop taking the drug.
Medicines
From the doctor Legal Safe if used correctly
Recreational drugs
Used for pleasure Some are legal e.g. alcohol Some are illegal e.g. heroin
Drugs in sport
Used illegally e.g. to speed you up e.g. to build muscles
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Alcohol
Drink a little
Drink too muchAddictive
Brain and liver
damage (cirrhosis
of the liver)
Relaxes you Makes you cheerful
Shy Confident
Slow reactions
Poisonous
coma or death
AMBULANCE RIP
Loss of self control
Do stupid
things
Violence
drink
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Contains tar
smoke
Clogs
lungs
EmphysemaCoughs
Bronchitis
Causes
cancer
Miscarriage
or
low weight baby
Contains
carbon
monoxide
Legal
Feel calmAddictive
Heart
disease
Contains
nicotine
Smoking Stops blood
carrying
enough
oxygen
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Pathogens or Microorganisms
Pathogens are bacteria and viruses.
Pathogens reproduce inside your body and make toxins (poisons).
The toxins make you ill.
Pathogens cause infectious diseases the pathogen can be passed onto
someone else and make them ill too.
Doctor Semmelweiss
o He realised doctors were picking up pathogens from one patient andgiving them to the next patient so ..
o Doctors must wash their hands between patients.
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Defences Against Disease
Stop pathogens getting in:-
Mucus in the
breathing system
traps pathogens.
Skin stops pathogens
getting in.
Blood clots to form a
scab to stop
pathogens getting in.
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Defences Against Disease
White blood cells defend against disease.
Remember toxin = poison.
White blood cells
Ingest and destroypathogens
Produce antibodies to
destroy pathogens
Produce antitoxins to neutralise
(cancel out) the toxins.
Toxin
antitoxin
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Using Drugs to Treat Diseases
Painkillers
o They cant get rid of the diseaseo They stop you feeling pain, so you feel better.
Antibiotics
o Kill bacteria not viruses.o Penicillin is an antibiotic.
(viruses live inside our cells, so antibiotics cant reach them).
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Resistance to Antibiotics
Natural selection
Bacteria evolve into new types by mutating.
This process is called natural selection.
Antibiotic resistance = cant be killed by the antibiotic
Example:- MRSA bacteria cant be killed by antibiotics.
Bacteria
reproduce
and some
mutate
Mutation
makes a
new type
of bacteria
New
bacteria
are not
killed
All
bacteria
are
resistant
to an
antibiotic
Take an antibiotic XX
X
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Developing New Medicines
Why test new
medicines?
Are they toxic
(poisonous)?
Are they effective do
they treat the disease?
Are there side effects do
they cause other problems?
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Thalidomide (a drug)
ZZZZZ
Side effects
Babies born
with short,
deformed
arms and legs.
It was a sleeping pill Then it was used
to stop morning
sickness
Now
Treats leprosy
No longer given to
pregnant women
All drugs must be fully
tested.
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Immunity
Dead or inactive
(weak) pathogen.
Inject into
blood
White blood cells make
antibodies against the
pathogen
If the full strength pathogens get into your body
the white blood cells now know how to make the
antibodies quickly.
You dont get the disease. You are immune.
Vaccine