B1 – Understanding Ourselves

Blood

Pumped under pressure by the heart.

Systolic – contract – large number.

Diastolic – relax – small number.To reach the whole body.

Pressure decreases as it moves through the system.

High BP…- Stress, smoking, poor

diet, overweight.- Blood vessels burst,

strokes, kidney damage, brain damage

Low BP…- Tissues don’t get all of

the oxygen and food needed.

- Faint, dizzy, poor circulation

Average – 135/85mmHgFit – How well you can perform physical tasks.

Healthy – Being free from illness and disease.

Health and Fitness

Measured by… strength, speed, agility, flexibility and stamina.

Stamina – cardiovascular efficiency – how well the heart supplies the muscles with blood.

Arteries carry blood away from the heart to the body.

Veins carry blood back to the heart.

Blood Pressure

Smoking

Carbon monoxide… combines with haemoglobin in RBC and reduces the amount of oxygen carried. Heart beats faster to make up for this.

Increases blood pressure…

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.

B1 – Understanding Ourselves

Balanced Diet

Supplies essential nutrients.

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

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..

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 meaning

under 18.5 underweightbetween 18.5 and

24.9 normal

between 25 and 29.9 overweight

between 30 and 39.9 obese

over 40 very obese

BMI = Body mass (kg) ----------- (Height)2

Why do people have

different diets?

Religion – Hindus don’t eat beef as they think cows are sacred.

Personal – vegetarians, vegans.

Medical – Some people have allergies and intolerances.

Helps to show if people are overweight or underweight. Not always reliable. Athletes have a lot of muscles which weighs more than fats so they have a high BMI even though they are healthy.

B1 – Understanding Ourselves

Infectious Disease

Caused by pathogens

Pathogen Diseasebacteria choleraviruses influenza (flu)fungi athlete’s foot

protozoa malaria

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.

CancerWhen cells divide out of control.

Benign – Not normally dangerous, cells don’t spread, slow dividing.Malignant – Rapid division and growth, cells spread, dangerous.

Healthy lifestyle and diet can help reduce chance of cancer, e.g. – don’t smoke, more fibre and less sun/sunbeds..

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

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.

Immunisation – Helps prevent infections

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.

B1 – Understanding Ourselves

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.

DrugsAlter the way the body works…• Recreational – take a drug for fun for a high• Medicinal – Prescribed/bought to help the

body/illnessAddicted – You need a drugTolerance – Your body is used to it so you need a higher dose for the same highWithdrawal – The symptoms you experience when coming off a drug addictionRehabilitation – The help and support to get over a drug addiction

type of drug effect on the body example

depressantslows down the heart and brain activity

alcohol, solvents, temazepam

hallucinogenalters what we see and hear LSD, cannabis

painkiller blocks nerve impulses aspirin, paracetamol

performance enhancerimproves muscle development anabolic steroids

stimulantincreases the heart rate and brain activity nicotine, caffeine, ecstasy

Thalidomide Deforms limbs in legs and arms (treats leprosy)

Pregnant women would take it as a sleeping pill and later morning sickness but gave birth to babies with deformed limbsClass A Class B Class C

• Max 7 years in prison and fine for possession

• Life in prison for supplying• E.g. heroin, methadone, cocaine

ecstasy, LSD, magic mushrooms

• Max 5 years in prison and a fine for possession

• 14 years in prison for supplying• E.g. – amphetamines barbiturates,

cannabis

• Max 2 years in prison and a fine for possession

• 14 years in prison for supplying• E.g. – anabolic steroids, valium,

tamazepam

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.

B1 – Understanding Ourselves

SmokingNicotineMakes cigarettes addictive and speeds up the heart rate

Carbon Monoxide

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

Collects in the lungs and is full of toxic chemicals called carcinogens. This can cause cancerous tumours to develop leading to lung caner

Smokers Cough

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.

Emphysema The lungs become damaged, particularly the

alveoli. They lose the elasticity and not as much oxygen can pass into the RBCs.

Low birth weight babies

Smoking causes low blood oxygen in the mother and lack of oxygen to the developing baby.

Alcohol

Depressant – slows down your nervous system.

Makes you feel less inhibited which can be positive for socialising.

Is a poison so it is therefor broken down by enzymes in the liver.

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.

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.

Doctors recommend no more than…• 21 units per

week for a man• 14 units per

week for a woman

ReceptorsDetect stimuli in your environment

Message sent along the sensory neurone.

Message sent to CNS (central nervous system (brain and spinal cord)).

CNS decides what to do and sends a message along the motor neurone.

The effector (normally a muscle or gland) receives the message.

The effector carries out the appropriate response.

Normally found in sense organs

Organ Receptor

Eye Light

Ear Hearing and balance

Tongue Chemical

Nose Chemical

Skin Heat, temperature and pressure

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.

B1 – Understanding Ourselves

Reflex actions – conscious brain not

involved

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

B1 – Understanding Ourselves

part description function

CorneaFront part of the tough outer coat, the sclera. It is convex and transparent.

refracts light - bends it as it enters the eye

Iris

Pigmented - decides the colour of your eyes - so light cannot pass through. Its muscles contract and relax to alter the size of its central hole or pupil.

controls how much light enters the pupil

LensTransparent, bi-convex, flexible disc behind the iris attached by the suspensory ligaments to the ciliary muscles.

focuses light onto the retina

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 colour. A small area called the fovea in the middle of the retina has many more cones than rods.

contains the light receptors

Optic nerve Bundle of sensory neurones at back of eye.carries impulses from the eye to the brain

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 moreTo look at distant objects…• Ciliary muscle relaxes• Suspensory ligament pull tight• Lens is more narrow and thin so less light refracted

Binocular visionBecause 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.

Short-sightSomeone 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-sightSomeone 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 age-related, and due to a loss of elasticity in the lens. It is corrected by putting a convex lens in front of the eye.

Red/green colour blindness – Lack of receptors in retina – cant distinguish between red and green.

B1 – Understanding Ourselves

Maintaining a constant internal environment

HomeostasisKeeping conditions in the body stable so you can function

We need to maintain things such as CO2, water and body temperature.

Negative feedback is a mechanism the body uses to keep all these things automatically steady

Temperature Control

Needs to be kept at 37oC so our enzymes work properly.

Controlled by thermoregulatory centre in the brain. Receptors in the skin provide information.

Hyperthermia – exposed to high temperatures causing dehydration and heat stroke. Can kill.Hypothermia – exposed to low temperatures. Can Kill.

Controlling blood sugar

glucose leveleffect on pancreas effect on liver

effect on glucose level

too highinsulin secreted into the blood

liver converts glucose into

glycogen goes down

too lowinsulin not

secreted into the blood

liver does not convert glucose into glycogen

goes up

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 Type 2 diabetes

Who it mainly affects

Children and teenagers. Adults under the age of 40.

Adults, normally over the age of 40 (there is a greater risk in those who have poor diets and/or are overweight).

How it worksThe pancreas stops making enough insulin.

The body no longer responds to its insulin.

How it is controlled

Injections of insulin for life and an appropriate diet.The amount of insulin needed depends on diet and activity

Exercise and appropriate diet.

B1 – Understanding Ourselves

Plant GrowthControlled in tips and roots by a plant hormone called auxin.

Auxins can move through a plant dissolved in water.

Shoots and roots respond differently to high concentrations of auxins:• cells in shoots grow more• cells in roots grow less.

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.

SeedlingsResults and explanation

AThe tips have been removed. No auxin is produced and the shoots do not grow longer.

B

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.

C

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.

TropismsPlants 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:• positive tropisms – the plant grows towards the

stimulus• negative tropisms – the plant grows away from

the stimulus.Phototropism is a tropism where the stimulus is light. A geotropism is a tropism where the stimulus is gravity. The roots and shoots of a plant respond differently to the same stimuli. The table summarises these differences.

part of plant light gravity

shootpositive phototropism (grow

towards the light)negative geotropism (grow against the force of gravity)

root negative phototropism (grow away from the light)

positive geotropism (grow in the direction of the force of

gravity)

Use of Plant Hormones

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.

B1 – Understanding Ourselves

• 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

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.

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

Gender determinationFemale 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 allelesExample for blue eyes…• BB = Homozygous Dominant• Bb = Heterozygous• Bb = Homozygous Recessive

B1 – Understanding Ourselves

Cystic Fibrosis

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.

This genetic diagram shows the possible outcomes when only one parent carries the faulty allele. There is no chance of the offspring being homozygous for the faulty allele and therefore having cystic fibrosis.

Huntington’s Disease

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. The father does not carry the Huntington’s allele, so he does not have the disorder. There is a 1 in 2 or 50 per cent chance of the couple producing a child with the disorder.

Genetic testingScientists 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.