Transcript B1 Revision Hx

Arteries
carry blood
away from
the heart
to the
body.
Low BP…
- Tissues don’t get all of the
oxygen and food needed.
- Faint, dizzy, poor
circulation
Systolic – contract – large number.
Average – 135/85mmHg
Diastolic – relax – small number.
Measured by… strength,
speed, agility, flexibility and
stamina.
Stamina – cardiovascular
efficiency – how well the
heart supplies the muscles
with blood.
Veins carry
blood back
to the
heart.
Pressure decreases as it
moves through the system.
Fit – How well you can perform
physical tasks.
To reach the whole body.
Healthy – Being free from
illness and disease.
High BP…
Pumped under pressure by the
- Stress, smoking, poor diet,
heart.
overweight.
Health and
Blood
- Blood vessels burst,
Blood Pressure
Fitness
strokes, kidney damage,
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brain damage
Smoking
Increases blood pressure…
Carbon monoxide… combines
with haemoglobin in RBC and
reduces the amount of oxygen
carried. Heart beats faster
to make up for this.
Nicotine… stimulant which
increases the heart rate
Heart Disease
A disease that effects the heart.
Risks… diets high in fat and salt.
•
•
•
Saturated fats cause excess cholesterol to build up in the
arteries. You need some cholesterol to make cell
membranes.
This causes plaques which narrow arteries.
This restricts the flow of blood which can lead to a heart
attack.
Salt… Too much causes high blood
pressure. This can damage
arteries. This can cause plaques to
build up, block the artery, restrict
blood flow and lead to a heart
attack.
Thrombosis… this is a
blood clot. If it blocks
an artery, particularly
in the heart, the heart
muscles loses blood
supply. This causes a
heart attack.
Nutrient
Used for
Made of
Extras
Carbohydrate
Energy
Simple sugars, e.g. - glucose
Stored in the liver as glycogen or
converted to fats.
Fats
Energy and insulation
Fatty acids and glycerol
Stored under the skin and around
organs as adipose tissue.
Proteins
Growth and repair. Energy in
emergencies
Amino acids
Don’t get stored.
Proteins from meat and fish are
first class proteins – contain
amino acids the body cant make.
Plant proteins are second class
and don’t contain all essential
amino acids.
Vitamins and minerals
Keep the body healthy, e.g. – vit C
to prevent scurvy, iron to help
make haemoglobin
Chemical compounds
Fibre
Makes you poo – keeps a healthy
digestive system
Indigestible food stuffs
Water
Hydration
Hydrogen and oxygen
Supplies essential
nutrients.
Balanced Diet
Children and teens
need more protein as
they are growing.
Older people need
more calcium to
protect against bone
diseases.
Girls need more iron
due to menstruation.
Active people need
more protein for
their muscles and
carbs for energy..
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Protein…
• Too little protein
causes
kwashiorkor.
• This happens in
developing
countries due to
overpopulation,
lack of money,
poor agriculture,
war etc.
• EAR – Estimated
daily requirement
• EAR = 0.6 x
body mass (kg)
• EAR varies with
age and whether
your pregnant or
not.
BMI (Body Mass Index)
BMI
Helps to show if people
under
18.5
are overweight or
between
18.5
and
underweight. Not always
24.9
reliable. Athletes have a
between 25 and
lot of muscles which
29.9
weighs more than fats so
between
30 and
they have a high BMI
39.9
even though they are
over 40
healthy.
BMI = Body mass (kg)
----------(Height)2
Why do people
have different
diets?
Personal –
vegetarians, vegans.
meaning
underweight
normal
overweight
obese
very obese
Religion – Hindus
don’t eat beef as
they think cows are
sacred.
Medical – Some
people have allergies
and intolerances.
Malaria…
• Caused by protozoan (parasite)
• Protozoan lives off other organisms, these are the
host
• Carried by mosquitos – vector
• Reduce malaria by draining stagnant water or
spraying it with insecticide, put fish in the water
to eat the larvae, people protect themselves by
using mosquito nets and repellents.
Healthy lifestyle and diet
can help reduce chance of
Pathogen
Disease
cancer, e.g. – don’t smoke,
bacteria
cholera
more fibre and less
viruses
influenza (flu)
sun/sunbeds..
fungi
athlete’s foot
protozoa
malaria
Benign – Not normally
dangerous, cells don’t spread,
slow dividing.
Malignant – Rapid division
and growth, cells spread,
dangerous.
When cells divide out
of control.
Caused by pathogens
Non-Infectious Diseases:
Not caused by pathogens and so are not infectious. For example:
• scurvy is caused by vitamin C deficiency
• anaemia is caused by iron deficiency
• diabetes and cancer are disorders of the body.
Some disorders are inherited, such as red-green colour vision
deficiency.
Plus, when you
cut yourself,
blood clots to
form a scab to
prevent
pathogens
entering the
body
Infectious Disease
Cancer
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Immunisation – Helps prevent infections
White Blood Cells – Help destroy pathogens that
have entered the body and are dividing rapidly. They
have 3 attacks…
• Engulfing the pathogen and digesting it
• Producing antitoxins that the pathogen produces
• Producing antibodies…
WBC sees the pathogen and produces
specifically shaped antibodies to fit it.
The antibodies fit the pathogens, cause
them to clump and the WBC digests them.
Active Immunity – Immune system makes its own antibodies either by being ill or by immunisation.
Passive Immunity – You use antibodies made by another organism, e.g. – breast milk.
Advantages of Immunisation – protection, stops the spread.
Disadvantages of Immunisation – short term side effects, e.g. – swelling, cant have them if you are
ill, people think it can cause other disorders such as autism.
Antibiotic resistance:
Over time, bacteria can become resistant to certain antibiotics. MRSA is methicillin-resistant
Staphylococcus aureus. It is very dangerous because it is resistant to most antibiotics. To slow down
or stop the development of other strains of resistant bacteria, we should:
• avoid the unnecessary use of antibiotics
• always complete the full course.
Drug testing:
• Drugs are substances that cause changes to the body.
• Antibiotics are drugs that kill bacteria, but not viruses.
• Antivirals are drugs that prevent viruses reproducing.
New medical drugs have to be tested to ensure that they work, and are safe, before they can be prescribed. There are three main stages of testing…
• The drugs are tested using computer models and human cells grown in a laboratory. Many substances fail this test because they damage cells or do
not seem to work.
• Drugs that pass the first stage are tested on animals. In the UK, new medicines have to undergo these tests. But it is illegal to test cosmetics and
tobacco products on animals. A typical test involves giving a known amount of a substance to the animals, then monitoring them carefully for any
side-effects.
• Drugs that have passed animal tests are used in clinical trials. They are tested on healthy volunteers to check that they are safe. Very low doses of
the drug are given to begin with. If there are no problems, further clinical trials are done to find the optimum dose for the drug.
Clinical trials are not without risk. Sometimes severe and unexpected side-effects occur. Most substances do not pass all of the tests and trials, so
drug development is expensive and takes a long time.
Double blind trials:
It is important to be certain that a drug really does have positive effects, rather than people feeling better simply because they expect to feel
better if they take a medicine. This is called the ‘placebo effect’. Double blind trials aim to minimise the placebo effect. Some patients are given the
drug while others are given a placebo. A placebo is designed to appear exactly the same as the drug itself, but it does not actually contain any of the
drug. The doctors and patients are not told who have received the drug and who have received the placebo until the trial is over.
Drugs
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Alter the way the body works…
• Recreational – take a drug for fun for a high
• Medicinal – Prescribed/bought to help the body/illness
Addicted – You need a drug
Tolerance – Your body is used to it so you need a
higher dose for the same high
Withdrawal – The symptoms you experience when
coming off a drug addiction
Rehabilitation – The help and support to get over a
drug addiction
Stimulants and depressants affect the synapses
between neurones in the nervous system:
• stimulants cause more neurotransmitter molecules
to diffuse across the synapse
• depressants stop the next neurone sending nerve
impulses – they bind to the receptor molecules it
needs to respond to the neurotransmitter molecules.
type of drug
effect on the body
example
depressant
slows down brain activity
hallucinogen
alters what we see and hear LSD
painkiller
blocks nerve impulses
performance enhancer
improves muscle development anabolic steroids
stimulant
increases brain activity
Class A
•
•
•
Max 7 years in prison
and fine for
possession
Life in prison for
supplying
E.g. heroin,
methadone, cocaine
ecstasy, LSD, magic
mushrooms
Class B
•
•
•
Max 5 years in prison
and a fine for
possession
14 years in prison for
supplying
E.g. – amphetamines
barbiturates, cannabis
alcohol, solvents, temazepam
aspirin, paracetamol
nicotine, caffeine, ecstasy
Class C
•
•
•
Max 2 years in prison
and a fine for
possession
14 years in prison for
supplying
E.g. – anabolic steroids,
valium, tamazepam
Collects in the lungs and is full of toxic
chemicals called carcinogens. This can cause
cancerous tumours to develop leading to lung
caner
Smoking causes low blood oxygen in the mother
and lack of oxygen to the developing baby.
Low birth weight
babies
Reduces the ability of RBC to carry oxygen. Can
lead to heart disease and if the heart has a lack
of oxygen this can cause a heart attack
Tar
Cilia in the trachea, bronchi and bronchioles
become damaged. Excess mucus cant be shifted
so it sticks to the air passages giving a terrible
cough.
Smokers
Cough
Carbon
Monoxide
Makes cigarettes addictive
and speeds up the heart rate
Nicotine
Smoking
Emphysema
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The lungs become damaged, particularly the
alveoli. They lose the elasticity and not as much
oxygen can pass into the RBCs.
Alcohol
Depressant – slows down your
nervous system.
Makes you feel less inhibited which
can be positive for socialising.
Can also cause negative effects…
• Impaired judgement
• Poor balance
• Poor coordination
• Slurred speech
• Blurred vision
• sleepiness
You should not drive, fly a plane or
operate heavy machinery when
drunk.
Is a poison so it is therefor broken
down by enzymes in the liver.
Doctors recommend no
more than…
• 21 units per week
for a man
• 14 units per week
for a woman
Some of the products of alcohol
are toxic so if you drink too
much over a long period you can
damage your liver cells –
cirrhosis.
The liver becomes scarred and
therefore cant clean the blood
properly.
Dangerous substances build up
in the blood and can cause
serious problems for the body.
The effector carries out the appropriate
response.
The effector (normally a muscle or gland)
receives the message.
CNS decides what to do and sends a
message along the motor neurone.
Message sent to CNS (central nervous
system (brain and spinal cord)).
Message sent along the sensory neurone.
Organ
Receptor
Eye
Light
Ear
Hearing and
balance
Tongue
Chemical
Nose
Chemical
Skin
Heat,
temperature
and pressure
Normally found in sense organs
Detect stimuli in your environment
Receptors
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Reflex actions – conscious
brain not involved
Electrical insulator
to help the impulse
pass
To connect with
other neurones
Signal passes down
here
They are very long to speed
up the impulse.
Neurones are nerve cells. They carry information as tiny
electrical signals. There are three different types of
neurones, each with a slightly different function:
• sensory neurones carry signals from receptors to the
spinal cord and brain
• relay neurones carry messages from one part of the
CNS to another
• motor neurones carry signals from the CNS to
effectors
•
•
•
•
•
Neurones don’t touch and the
gap is a synapse
The impulse causes a
neurotransmitter to be released
and diffuse across the gap
This bind to the receptor
molecules
This causes a new signal to be
generated in the next neurone
The signal carries on
part
Cornea
description
function
Front part of the tough outer coat, the sclera. It refracts light - bends it as it
is convex and transparent.
enters the eye
Iris
Pigmented - decides the colour of your eyes - so
light cannot pass through. Its muscles contract controls how much light enters
and relax to alter the size of its central hole or the pupil
pupil.
Lens
Transparent, bi-convex, flexible disc behind the
iris attached by the suspensory ligaments to the focuses light onto the retina
ciliary muscles.
Retina
The lining of the back of eye containing two types
of photoreceptor cells - rods - sensitive to dim
light and black and white, cones - sensitive to
contains the light receptors
colour. A small area called the fovea in the middle
of the retina has many more cones than rods.
Optic nerve
Bundle of sensory neurones at back of eye.
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Light passes through the eyeball to the retina. It is refracted (its rays
are bent) by the cornea and lens, so that the light is brought to a focus
on the retina.
To look at close objects…
• Ciliary muscle contracts
• Suspensory ligament slackens
• Lens is more rounded so light is refracted more
To look at distant objects…
• Ciliary muscle relaxes
• Suspensory ligament pull tight
• Lens is more narrow and thin so less light refracted
Binocular vision
Because our eyes sit side by side, each eye captures a slightly different
view. This is called binocular vision. When signals from the two eyes reach
the brain, they are superimposed and processed into a single picture with
depth. As a result, we get a 3D picture and are able to judge distances
well.
Most birds and lizards have monocular vision - their eyes are on each side
of their head. This gives them a greater field of view, which is useful for
spotting predators. However, they have poor depth perception.
carries impulses from the eye
to the brain
Red/green colour blindness – Lack of receptors in
retina – cant distinguish between red and green.
Short-sight
Someone with short-sight can see near objects clearly, but can't focus
properly on distant objects. This is caused by the eyeball being
elongated, so that the distance between the lens and the retina is too
great. It can be corrected by placing a concave lens in front of the eye.
Long-sight
Someone with long-sight can see distant objects clearly, but can't focus
properly on near objects. This is because the lens focuses the sharpest
image behind the retina, instead of on it. This defect is often agerelated, and due to a loss of elasticity in the lens. It is corrected by
putting a convex lens in front of the eye.
Negative feedback is a
mechanism the body uses to
keep all these things
automatically steady
We need to maintain things
such as CO2, water and body
temperature.
Keeping conditions in the body
stable so you can function
Controlled by thermoregulatory
centre in the brain. Receptors in the
skin provide information.
Needs to be kept at 37oC so our enzymes
work properly.
Temperature Control
Maintaining a constant internal
environment
Controlling blood sugar
glucose level
effect on
pancreas
too high
insulin secreted
into the blood
liver converts
glucose into
glycogen
insulin not
secreted into
the blood
liver does not
convert glucose
into glycogen
too low
effect on liver
Homeostasis
Hyperthermia – exposed to high temperatures causing
dehydration and heat stroke. Can kill.
Hypothermia – exposed to low temperatures. Can Kill.
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effect on
glucose level
goes down
Insulin, a hormone secreted by the pancreas, controls blood sugar levels in the
body. It travels from the pancreas to the liver in the bloodstream. As with other
responses controlled by hormones, the response is slower but longer lasting than
if it had been controlled by the nervous system.
Type 1 diabetes
goes up
Who it mainly
affects
Type 2 diabetes
Adults, normally over
the age of 40 (there
Children and
is a greater risk in
teenagers. Adults
those who have poor
under the age of 40. diets and/or are
overweight).
How it works
The body no longer
The pancreas stops
responds to its insulin.
making enough insulin.
How it is controlled
Injections of insulin
for life and an
appropriate diet.
Exercise and
The amount of insulin appropriate diet.
needed depends on
diet and activity
In a shoot, the shaded side contains more auxin. This means that the shaded side grows longer,
causing the shoot to bend towards the light. The diagram shows the typical results seen when
growing oat seedlings in a box, with a light at one side.
Results and explanation
Seedlings
The tips have been removed. No auxin is produced
and the shoots do not grow longer.
A
The tips have been covered so light cannot reach
them. Auxin is in the same concentration on both
sides of the shoots, so they grow longer evenly on
both sides.
B
Shoots and roots respond differently to high concentrations of auxins:
• cells in shoots grow more
• cells in roots grow less.
Auxins can move through a
plant dissolved in water.
part of plant
shoot
root
Use of Plant Hormones
One side of the tips are in more light than the
other side. Auxin is in a greater concentration on
the shaded side, causing the cells there to grow
longer than the cells on the light side.
C
Tropisms
Plants need light and water for photosynthesis. They
have developed responses called tropisms to help make
sure they grow towards sources of light and water.
There are two main types of tropisms:
light
gravity
• positive tropisms – the plant grows towards the
stimulus
positive phototropism (grow
negative geotropism (grow
•
negative tropisms – the plant grows away from the
towards the light)
against the force of gravity)
stimulus.
Phototropism
is a tropism where the stimulus is light. A
positive geotropism (grow in
negative phototropism (grow
geotropism
is
a tropism where the stimulus is gravity.
the direction of the force of
away from the light)
The roots and shoots of a plant respond differently to
gravity)
the same stimuli. The table summarises these
differences.
Controlled in tips and roots
Plant Growth
by a plant hormone called
auxin.
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Use
Explanation
Weedkillers
Selective weedkillers attack some plants and not others. Contains a
growth hormone that causes plants to grow too quickly and die.
Rooting Powder
Dip a cutting in rooting powder to rapidly produce roots so it can be
planted and grow. Helps with cloning plants.
Ripening
Fruits are sprayed with hormones to either delay or speed up ripening so
they are ready to sell.
Dormancy
A hormone called gibberellin can help seeds become dormant out of
season.
Variation is caused by…
• Genes being mixed up when sex cells (sperms and
eggs) are made
• Genes coming from both parents during
fertilisation
• Changes in genes called mutations
•
•
•
•
•
•
Nucleus houses genetic material
Most animal cells have 46 chromosomes or 23 pairs
in the nucleus
Chromosomes carry different genes which code for
our features
Genes are made of DNA
DNA is made of base pairs wound in a double helix
We have different versions of the same gene
called alleles
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Environmental and inherited characteristics:
Some characteristics of an individual are caused by the environment.
For example, the language we use or whether we have scars are
environmental characteristics.
Other characteristics are inherited…the shape of the earlobes, eye
colour, nose shape.
Some characteristics - including intelligence, body mass and height - are
the result of both environmental and inherited factors. But there is
debate about the relative importance of these two types of factor in
some human characteristics, such as intelligence, health and sporting
ability.
Gender determination
Female gametes (eggs) contain X
chromosomes, while male gametes
(sperm) contain either X chromosomes
or Y chromosomes. This genetic
diagram shows that equal numbers of
male and female offspring should be
produced.
Alleles:
• Different versions of the same gene
• Mostly have 2 of each gene – 1 from each parent
• If the alleles are different you have instructions for 2 different
versions of the characteristic
• The version of the characteristic that appears is caused by the
dominant allele
• The other allele is recessive
• Recessive alleles are only shown if there are not dominant alleles
Example for blue eyes…
• BB = Homozygous Dominant
• Bb = Heterozygous
• Bb = Homozygous Recessive
Cystic Fibrosis
Huntington’s Disease
Cystic fibrosis is an inherited disorder caused by a recessive allele.
Symptoms:
• Thick sticky mucus in the airways and pancreas
• Poor digestion
• Terrible cough
• Prone to infections
This genetic diagram shows the
possible outcomes when both
parents are heterozygous for
the faulty allele. There is a one
in four chance of the offspring
being homozygous for the faulty
allele, and so having cystic
fibrosis.
Huntington’s disease is an inherited disorder caused by a dominant
allele. It normally appears during middle age.
Symptoms:
• Tremors
• Clumsiness
• Mood changes
• Memory loss
• Inability to concentrate
In this example
(represented on a
Punnett square), one
parent - the mother carries one copy of
the Huntington’s allele
and has the disorder.
B1 – Understanding Ourselves The father does not
carry the Huntington’s
allele, so he does not
This genetic diagram shows
have the disorder.
the possible outcomes when
There is a 1 in 2 or 50
only one parent carries the
per cent chance of the
faulty allele. There is no
couple producing a
chance of the offspring
child with the
being homozygous for the
disorder.
faulty allele and therefore
having cystic fibrosis.
Genetic testing
Scientists are now able to test adults and unborn babies for alleles that can cause
genetic disorders. However, the scientific information produced raises many issues
that science cannot address. For example, should a couple with a one in four risk of
having a child with cystic fibrosis take the gamble, or decide not to have any
children at all? If a woman becomes pregnant with a child that is going to have
cystic fibrosis, should she have the child, or choose to have an abortion? These are
questions about values that science cannot answer. Different people will have
different views.