and

breathe.

smoking

amounts

and drugs.

illegal.

and drugs.

and

antagonistic move

Quick Quiz 1 The Quick Quiz is to see how much you already know about a subject. It also gives you some idea

of the things you will soon be learning about. Record your answers in the answers column. Shade

in or tick the ones you get right.

9Ba A Model Life

What do we mean by fitness?

Background reading Being fit means different things for different individuals and the level of fitness depends on age,

gender and amount of physical activity. Fitness is the ability to perform daily activities with ease and

without getting tired. Being fit and being healthy are NOT the same thing. An athlete may be very fit

but medically unhealthy, for example if he or she suffers from a disease such as diabetes.

Models come in all shapes and sizes but invariably those most often seen are those that are ‘fit’. As

such, many models spend a lot of time making sure that they keep their bodies in shape and stay fit.

However, ‘being fit’ is a very loose term and so, in science, it is broken down into different

components that can be measured. Fitness is usually judged using four criteria: stamina, suppleness,

strength and speed. These are often called the four S-factors.

Stamina is really cardiovascular or aerobic fitness and is important in reducing the risk of heart

disease. It improves the condition of the heart, lungs and blood and enables muscles to release energy

from glucose more efficiently. Sports that require stamina include swimming, cycling, running,

power walking, football, hockey and squash. Stamina forms the basis of overall fitness and is the

most beneficial to health.

Suppleness or flexibility is the ability of muscles and joints to allow a full range of movement.

Warming up and cooling down exercises are important to develop suppleness. Gymnasts and dancers

have to be very supple.

Strength refers to a muscle’s ability to lift a heavy object or carry out strenuous tasks. The harder an

exercise is the stronger the muscle needs to be.

Speed relates to how quickly individual muscles can contract in fast movements such as sprinting,

throwing and jumping. Overall fitness also involves the brain coordinating muscle activity and

maintaining balance.

When athletes train to improve their fitness they begin by developing all four components. They then

train to further develop those components relevant to their sport. Regular exercise increases a

person’s basal metabolic rate (BMR) – the minimum amount of energy needed to support the vital

functions of the heart, digestive system, brain activity and respiration in a resting person (an

approximate average value being 4.6 kJ/min). Athletes therefore eat a diet rich in carbohydrates to

provide glucose for respiration. The carbohydrate is stored as glycogen in muscles and the liver.

When glucose is required the glycogen polymer is broken down into glucose again. (Look back at

your notes on respiration from last year - Unit 8B.)

Regular vigorous exercise leads to several changes in the circulatory system. The resting heart rate

decreases because the heart becomes bigger and stronger, and so produces a larger stroke volume.

This is the volume of blood pumped out at each beat. Fewer beats are therefore needed to pump the

same volume of blood as before. This also explains why the heart rate of fit people returns to normal

more quickly after exercise. The total volume of blood can also increase by up to 25%. As this is

mainly due to more plasma, rather than cells, the effect is that the blood becomes thinner and so can

flow through the capillaries more easily. An important change is that the number of capillaries

between the muscle fibres increases. This therefore means that the reactants and products of

respiration can be transported to and from the muscle cells much more quickly.

Key terms to Learn and USE Word Pronunciation Meaning

aerobic respiration Process that releases energy from food. Needs oxygen from

the air. Carbon dioxide is produced as

a waste gas.

breathing rate The number of breaths taken in one minute.

breathing system Made up of the trachea, bronchi and lungs. Gets oxygen

into the blood and takes carbon dioxide out of the body.

Also called the respiratory system.

circulatory system Organ system containing the heart and blood

vessels.

criteria cry-teer-ee-a Set of rules that are used to judge how good or poor

something is. Singular = criterion.

digestive system The group of organs that carries out digestion.

heartbeat rate The number of times the heart beats in one minute.

organ system Collection of organs working together to do an

important job.

respiratory system Another name for the breathing system.

social behaviour How an animal communicates with or reacts to other

animals of the same species.

1) Look at photo A. What is the link that the advertiser is trying to get you to make?

...............................................................................................................................................................

2)

a) What change in your behaviour do advertisers want you to make?

.........................................................................................................................................................

b) Suggest one way in which this might be a good thing.

.........................................................................................................................................................

3) What sort of model would you choose to advertise the following?

a) Nappies ............................................................................................................................................

b) a sunshine holiday ...........................................................................................................................

c) toy cars ............................................................................................................................................

d) milkshakes to replace meals, for people going on a diet.................................................................

e) a weightlifting exercise machine .....................................................................................................

4)

a) How do you think exercise machines are scientifically tested? Think of as many ways as you

can.

.........................................................................................................................................................

.........................................................................................................................................................

.........................................................................................................................................................

b) What are the benefits of buying an exercise machine?

.........................................................................................................................................................

c) What are the drawbacks? ................................................................................................................

.........................................................................................................................................................

d) Use your answers to parts b and c to evaluate exercise machines. That means you need to say

whether exercise machines are worthwhile or not.

.........................................................................................................................................................

.........................................................................................................................................................

.........................................................................................................................................................

9Ba Fighting fit

Describe how exercise affects the pulse rate and breathing rate.

Recall which organ systems work together to release energy from food.

Explain how muscles release energy from food.

Describe some ways in which fitness can be assessed.

1)

a) Look at the photos of models A–C. Which model do you think is the fittest?

.........................................................................................................................................................

b) Why do you think this?

.........................................................................................................................................................

2) Look at this list of sports: archery cricket fishing hill walking volleyball.

Which sport do you think requires:

a) the most stamina? ............................................................................................................................

b) the least stamina? ............................................................................................................................

3) What exercises does Simon do to increase his performance in each S-factor?

S .........................................................................................................................................................

S .........................................................................................................................................................

S .........................................................................................................................................................

S .........................................................................................................................................................

4)

a) Look at photo B. Which S-factor would this model score highest in? ...........................................

b) Which S-factor would you score highest in? .................................................................................

5) Describe two criteria used to evaluate fitness programmes.

.........................................................................................................................................................

.........................................................................................................................................................

6) Here is a list of organ systems:

circulatory system - breathing system - digestive system - nervous system - locomotor system

(skeleton, muscles and joints).

Which system does each part of Simon’s training programme help?

Stretching ..............................................................................................................................................

Sprint intervals ......................................................................................................................................

Running .................................................................................................................................................

Weights .................................................................................................................................................

7) For each organ labelled in photo E, write down the organ system it is part of.

Lungs.....................................................................................................................................................

Heart ......................................................................................................................................................

Small intestine .......................................................................................................................................

Muscles .................................................................................................................................................

8) How does knowing about the effects of exercise help people to make decisions about looking

after their bodies?

.........................................................................................................................................................

.........................................................................................................................................................

When you are __________________ you are able to do all the activities that your lifestyle

demands. Fitness can be divided into four S - __________________:

__________________, strength, speed and stamina (how __________________ you can

do an exercise for).

Some people are __________________ than others. To __________________ how fit

someone is, scientists have developed some rules or __________________. How fast you

can run can be used as a __________________ to judge your fitness and to see if a

__________________ training programme is working.

When you exercise you need more __________________ and so your body needs more

__________________ and oxygen for __________________ respiration to release energy.

Your __________________ (or respiratory) system gets oxygen into your blood (and

removes carbon __________________). Your __________________ system gets glucose

into the blood.

The word __________________ for aerobic respiration is:

glucose + __________________ __________________ + carbon dioxide

Your __________________ system carries glucose and oxygen to the cells that need it.

The heart beats __________________ when you exercise to get more glucose and oxygen

to your cells.

aerobic breathing circulatory criteria criterion

digestive dioxide energy equation factors faster fit

fitness fitter glucose light long measure oxide

oxygen slower sucrose suppleness water

9Bb Easy Breathing

Describe what happens when you breathe.

Background reading The structure of the respiratory system and gas exchange was covered last year in Topic 8Bd. Be

careful not confuse the terms breathing, ventilation and respiration.

Breathing is when the diaphragm and intercostal muscles between the ribs change the volume of the

thorax.

Ventilation is the movement of air into and out of the lungs as a result of breathing.

Respiration is a chemical reaction that occurs inside all living cells to release energy from glucose.

During inhalation (breathing in) the intercostal muscles contract and shorten, pulling the ribcage

upwards and outwards. The diaphragm also flattens. These changes increase the volume of the thorax

making the pressure inside less than the air pressure outside. Air is therefore forced into the lungs,

inflating them, until the internal and external pressures are equal. During exhalation (breathing out)

the intercostal muscles relax and become longer, so the ribcage falls back down to its resting

position. The diaphragm relaxes to become dome-shaped. This decreases the volume of the thorax,

increasing the internal pressure so air is forced out of the lungs and they deflate.

Asthma attacks are caused by allergic reactions, infection and emotional stress. The muscles in the

walls of the tubes in the lungs (bronchi and bronchioles) contract, making the tubes much narrower

and, therefore, making it difficult to breathe. Substances in inhalers help these muscles to relax.

Cystic fibrosis (CF) is a genetic disease that causes large amounts of sticky mucus to build up in the

lungs, often becoming infected and reducing the surface area available for gas exchange.

Breathing can stop under some conditions (e.g. following an accident). Mouth-to-mouth resuscitation

can be used to keep a supply of oxygen going to the brain (providing the heart is still working). This

resuscitation method is commonly called ‘the kiss of life’ or artificial respiration. In medical dramas

on TV you might have seen heard the term ‘sats’. This is short for ‘saturation of oxygen’ and refers

to the amount of oxygen carried in the blood.

Cancer is caused by chemicals (called carcinogens) found in the tar of cigarette smoke. The most

common cancers associated with smoking are lung, mouth, throat, stomach and bladder.

Bronchitis can be caused by chemicals in the tar that irritate the delicate linings of the tubes leading

from the trachea into the lungs. The tubes become red and swollen and, since the cilia (hairs that

normally sweep out dirt and mucus from the lungs) have been stopped from working by the tar and

heat from the smoke, the swelling becomes worse. The mucus often becomes infected with bacteria.

A smoker’s cough occurs as a direct result of the cilia not working. The mucus cannot be swept out

of the lungs and so the smoker must cough it up.

Emphysema occurs when chemicals in the smoke damage the lung tissue in the air sacs. Large holes

appear in the lungs, which may fill with fluid, making breathing difficult. Heart disease is caused by

fatty deposits narrowing the arteries that feed the heart muscle. Nicotine appears to speed up this

process, meaning that cells in the heart muscle do not get enough oxygen, cease to work efficiently

and even die.

Key terms to learn and USE Word Pronunciation Meaning

lung cancer A disease when cells in the lungs start to divide and grow

uncontrollably.

mucus A sticky fluid produced by your body to trap

particles.

nicotine nick-O-teen Poisonous, addictive drug found in cigarettes.

night-blindness Deficiency disease caused by a lack of vitamin A. You

cannot see very well in dim light.

nutrient A part of your food that is used as a raw material

(fat, carbohydrate, protein, vitamins, minerals).

premature A baby that is born too early and small is said to be

premature.

rickets Deficiency disease caused by a lack of calcium. It causes

weak and poorly shaped bones.

scurvy skur-vee Deficiency disease caused by a lack of vitamin C. The

gums bleed and cuts take a long time to heal.

stroke When the nerve tissue in the brain starts to die

because too little blood is getting to it.

tar A poisonous, black, sticky substance found in

cigarette smoke.

ventilation The movement of air into and out of the lungs.

recreational drug reck-ree-ay-shun-al A drug used for its mind-altering effect rather then as a

medicine.

side-effect Harmful or unpleasant effects caused by drugs.

solvent A liquid used to dissolve things.

solvent abuse Sniffing solvents used in glue and other things.

stimulant stim-you-lant Drug that increases the speed at which nerves carry

messages, e.g. caffeine.

1) What sort of model would you select to advertise a decongestant?

.........................................................................................................................................................

2) Explain why using the medicine in photo B will help you breathe more easily.

.........................................................................................................................................................

.........................................................................................................................................................

3) Explain the meanings of:

a) Breathing .........................................................................................................................................

b) Gas exchange ..................................................................................................................................

c) Ventilation .......................................................................................................................................

4) When you inhale do your lungs get bigger or smaller? ........................................................................

5) How do the muscles and diaphragm cause you to exhale? ...................................................................

.........................................................................................................................................................

.........................................................................................................................................................

6) Diagram D shows a model of the breathing system. When the rubber sheet is pulled down, the

volume inside the jar increases and air is forced into the balloons.

a) What happens when the rubber sheet is let go? ..............................................................................

.........................................................................................................................................................

.........................................................................................................................................................

b) What part does the rubber sheet represent?.....................................................................................

.........................................................................................................................................................

.........................................................................................................................................................

Getting oxygen into your blood and removing carbon dioxide is called gas

__________________. It happens in your __________________ . __________________ is

the process in which muscles make your lungs bigger and smaller, so that air flows into and

out of your lungs (a process called _________________).

When you breathe in, your __________________ moves down and becomes flatter. When

you breathe __________________, it rises again.

To help keep your lungs clean, the tubes that lead to them are covered in ciliated

__________________ cells. These have hairs (called __________________) on them.

__________________, produced by other cells, traps dirt and __________________ and

the cilia sweep the mucus out of the tubes.

breathing cilia diaphragm epithelial exchange hairs in

lungs microbes mucus out respiration swapping ventilation

9 Bb Smoke signals

Recall some effects of smoking on the body.

1) List three chemicals in cigarette smoke and describe their dangers.

a) .........................................................................................................................................................

.........................................................................................................................................................

b) .........................................................................................................................................................

.........................................................................................................................................................

c) .........................................................................................................................................................

.........................................................................................................................................................

2)

a) Describe the overall trend shown in chart C. ..................................................................................

.........................................................................................................................................................

.........................................................................................................................................................

b) What do you think is responsible for this trend?.............................................................................

.........................................................................................................................................................

c) Tom has an opinion:

‘The number of people quitting smoking has not changed for a long time.’

How would you use evidence from the chart to support his statement?

.........................................................................................................................................................

.........................................................................................................................................................

.........................................................................................................................................................

d) Describe the repeating pattern in the chart. .....................................................................................

.........................................................................................................................................................

e) Why do you think this pattern occurs? ............................................................................................

.........................................................................................................................................................

f) Do you think the advertising ban or the BHF adverts had more impact?

Use the chart to support your argument.

.........................................................................................................................................................

.........................................................................................................................................................

Tobacco smoke contains:

tar, which can cause __________________

__________________, which is addictive and makes __________________

narrower

carbon __________________ which stops __________________ blood cells

carrying oxygen.

Smoking can cause __________________ to build up in arteries and block them. This can

cause a __________________ (when blood stops flowing to part of the brain) or a

__________________ attack (when blood stops flowing to part of the heart muscle).

arteries cancer dioxide fat heart

monoxide nicotine red stroke white

9Bb Striking a balance

Describe some effects of an unbalanced diet.

Explain the importance of eating the right amounts of nutrients.

Background reading You studied the uses of the different food groups needed in a balanced diet last year in Unit 8A. I

highly recommend you listen to the podcast on the VLE page for this unit. It’s a radio 4 programme

for adults so the language might be hard work at times, but what they have to say about the

implications of what we eat is frightening.

It is important to remember that malnutrition can result from a diet that is either deficient in one or

more nutrients or has an excess of one or more nutrients. The most common example of the latter is

when the diet contains too much in the way of energy-providing nutrients, which can eventually

result in obesity. Being obese increases the risk of heart disease, high blood pressure, various cancers

and joint problems. The podcast on the VLE (section 9B) is well worth listening to about the dangers

of eating too much of the wrong type of fat in your diet. It’s your body – so it’s worth knowing what

sort of fuel it takes, and what sort of problems you will have if you don’t !

With the increasing use (and abuse) of vitamin and mineral supplements more people are actually

developing symptoms of their excess.

Deficiency diseases are the result of a shortage of a particular nutrient in the diet. A shortage of

protein results in a muscle-wasting disease called kwashiorkor. Vitamins are compounds needed in

small amounts. They are divided into two groups – fat-soluble vitamins and water-soluble ones. The

former are vitamins A, D, E and K and all the rest are water-soluble. The fat-soluble ones can easily

be stored in fat in the body. Some of the water soluble ones (e.g. vitamin C) can also be stored to

some extent.

The elements carbon, hydrogen and oxygen are provided in most foods. Nitrogen is provided in

proteins. Trace elements (e.g. calcium and iron) are those that, although vital, are needed in much

smaller quantities. These trace elements are taken in the form of chemical compounds that make up

an organism used as part of our food. What we tend to refer to as minerals are really mineral salts –

that is, compounds that contain important trace elements. Calcium phosphate is a mineral salt. We

tend to call this ‘calcium’ or ‘phosphorus’ depending on the context!

1) Why do you think many models suffer from anorexia?

.........................................................................................................................................................

2)

a) Why do you think children are more likely than adults to be poisoned by vitamin and mineral

pills?

.........................................................................................................................................................

.........................................................................................................................................................

b) Suggest ways in which these poisonings could be prevented. ........................................................

.........................................................................................................................................................

3) Vitamin and mineral pills were invented in the 1930s.

a) Why do you think companies started to sell them? ........................................................................

.........................................................................................................................................................

b) What are the benefits and drawbacks of this scientific advance?

i) Benefits .....................................................................................................................................

...................................................................................................................................................

ii) Drawbacks.................................................................................................................................

...................................................................................................................................................

4) A child’s liver is badly damaged.

a) Suggest how not eating the correct balance of nutrients can cause this..........................................

.........................................................................................................................................................

b) What could be done to save the child? ............................................................................................

.........................................................................................................................................................

A __________________ disease is caused by a lack of a nutrient.

_______ Recommended

daily amount

for 14 year

olds

Deficiency disease __________________

protein 42.1 g (boys)

41.2 g (girls)

__________________ swollen tummy, liver

damage

calcium 1 g (boys)

0.8 g (girls)

__________________ weak bones with odd

shapes

Nutrient Recommended

daily amount for

14 year olds

Deficiency

__________

Symptoms

iron 11.3 mg (boys)

14.8 mg (girls)

_______________

___

tiredness and shortness

of breath

vitamin A 600 µg _______________

___

unable to see in dim

light

________ 35 mg scurvy bleeding gums

anaemia deficiency disease kwashiorkor night-blindness nutrient

rickets scurvy symptoms vitamin B vitamin C vitamin K

9Bb Focus on: Diet Controversies

How evidence about dieting can be misleading

1) Write three bullet points to give advice to people looking for a diet.

i) ...................................................................................................................................................

ii) ...................................................................................................................................................

iii) ...................................................................................................................................................

2) Vitamins A, D, E and K are fat-soluble.

a) What do you think fat-soluble means? ............................................................................................

b) Suggest a problem with going on a very low-fat diet. ....................................................................

.........................................................................................................................................................

3) Make up some figures to illustrate how a percentage can be used to hide a real figure. Carefully

show your working.

.........................................................................................................................................................

.........................................................................................................................................................

.........................................................................................................................................................

4) How would you collect evidence to show that a diet plan works?

.........................................................................................................................................................

.........................................................................................................................................................

5) Why are people tempted to give misleading evidence when marketing diet plans?

.........................................................................................................................................................

.........................................................................................................................................................

6) Explain why many diet plans use lots of scientific words. ...................................................................

.........................................................................................................................................................

7) In the Slim-Fast® diet you replace one meal a day with a special milkshake. What are the benefits

and drawbacks of this diet?

a) Benefits ...........................................................................................................................................

.........................................................................................................................................................

b) Drawbacks .......................................................................................................................................

.........................................................................................................................................................

9Bc Drink and Drugs

Explain what addiction is and recall some addictive drugs.

Classify drugs as medicines or recreational, legal or illegal.

Recall some of the effects and side-effects of different drugs.

Explain what stimulants and depressants are.

Background reading Even in moderation, alcohol (ethanol) is linked to an increased risk of cancer of the breast, colon,

rectum, mouth, pharynx and oesophagus (gullet). Smoking further increases the risk. Alcohol is also

linked to high blood pressure and gastric ulcers. Liver disease and a depletion of its stored vitamins

and minerals are caused by excess alcohol consumption. There are also social and psychological

implications of alcohol abuse. It is estimated that it costs the NHS £6 billion a year to treat alcohol-

related illnesses. One person in 25 is dependent on alcohol and this is thought to have genetic causes.

Approximately 40% of all violent crime is attributed to alcohol. Women are at greater risk of

alcohol-related illnesses than men, partly because they are generally smaller and also because they

have a higher proportion of body fat, so the alcohol absorbed is not diluted as much as in men. This is

why the recommended weekly consumption is less for women than men. In the UK, 1 unit is 7.9 g or

10 cm3 of pure alcohol, but this changes from country to country. For example, in the USA, 1 unit is

14 g of alcohol. Each gram of alcohol provides 29 kJ of energy. These are often described as ‘empty

calories’ because they do not provide the body with any useful nutrients, but they can lead to an

increase in body mass.

Alcohol is a diuretic – it increases the loss of water from the body leading to dehydration. This is the

main cause of the symptoms of a hangover. It also inhibits the conversion of liver glycogen to

glucose, which can cause ‘shakes’ and light-headedness.

People who drink alcohol should make sure that they eat some carbohydrate and drink plenty of

water.

Drugs are often classified into different groups but there is some overlap between the different

categories. For example, some illegal drugs such as amphetamines are also prescription drugs; over-

the-counter drugs such as nicotine can also be recreational and addictive drugs.

It is worth remembering that many of these drugs were originally developed as medicines. Heroin,

for example, was a registered trademark of the German drugs company Bayer, until it was forced to

give this up (along with aspirin) at the Treaty of Versailles in 1919. It was originally developed as a

painkiller and is still used in hospitals in the UK under the name of diamorphine.

Key terms to learn and USE Word Pronunciation Meaning

addictive If something makes you feel that you need to have it, it is

said to be addictive.

caffeine caff-een A stimulant that increases the speed at which nerves carry

impulses. Found in coffee, tea and cola drinks.

cannabis A drug that can cause memory loss.

cocaine cO-cane Very powerful and harmful stimulant that causes

blocked arteries and mental problems.

depressant Drug that decreases the speed at which nerves carry

impulses, e.g. alcohol.

drug Substance that affects the way your body works.

ecstasy A stimulant that can cause depression, mental illness and

even death.

heroin A very dangerous depressant drug. Causes vomiting and

severe headaches.

impulse Electrical signal carried by a nerve cell.

medicine med-iss-in A drug that helps the body to ease the symptoms of

a disease or cure the disease.

neuron nyour-on A cell that carries signals round the body.

recreational drug reck-ree-ay-shun-al A drug used for its mind-altering effect rather then as a

medicine.

side-effect Harmful or unpleasant effects caused by drugs.

solvent A liquid used to dissolve things.

solvent abuse Sniffing solvents used in glue and other things.

stimulant stim-you-lant Drug that increases the speed at which nerves carry

messages, e.g. caffeine.

1)

a) Use photo A to make two lists – one of drugs and one of other substances.

i) Drugs .........................................................................................................................................

ii) Other substances .......................................................................................................................

b) Divide your list of drugs into further groups. Explain your reasoning.

.........................................................................................................................................................

.........................................................................................................................................................

2) Look at photo A again.

a) Which of the substances do you think are harmful? .......................................................................

b) Which can you buy at any age?.......................................................................................................

c) Which are only legal to buy above a certain age? ...........................................................................

d) Which are illegal? ...........................................................................................................................

3) What do stimulants do? .........................................................................................................................

.........................................................................................................................................................

4) Why do people continue using cocaine even after it starts to harm them? ...........................................

.........................................................................................................................................................

5) Why do you think people should not drink and drive? .........................................................................

.........................................................................................................................................................

6) A man drank a pint of beer and a measure of whisky.

a) How many units of alcohol did he drink? .......................................................................................

b) How long would it take his liver to break this down?.....................................................................

7) If he drank this amount every day, how many units above the recommended weekly amount

would he drink?.....................................................................................................................................

.........................................................................................................................................................

Complete the table

Name of drug Stimulant or depressant? Side-effects

Alcohol depressant deficiency diseases, liver damage

caffeine stimulant stomach problems (or other effects from pupils’ own

experience, e.g. jitters)

cannabis depressant memory loss, lung damage

Cocaine stimulant blocked arteries

Ecstasy stimulant mental illness, kidney problems

Heroin depressant collapsed veins, vomiting and severe headaches

nicotine stimulant lung damage, blocked arteries

solvents depressants brain damage, stop heart and lungs working

__________________ are substances that change the way your body works.

Some drugs are:

medicines (e.g. __________________) – they are used to treat disease symptoms

__________________ (e.g. nicotine) – people use them because they enjoy the

effects.

Some drugs are:

illegal (e.g. __________________) – you are not allowed to buy or use them

__________________ (e.g. __________________) – they increase the activity of

your nervous system.

Some drugs are:

__________________ (e.g. alcohol) – they decrease the activity of your nervous

system

__________________ (e.g. nicotine) – they make you feel like you can’t cope

without them.

addictive aspirin banned caffeine depressants

drugs heroin impulse recreational stimulants

9Bd Muscles & Bones

Recall the functions of the skeleton.

Identify some common joints.

Describe how muscles work.

Explain how antagonistic pairs of muscles move bones in some joints.

Background reading There are three types of muscle. Skeletal muscle makes up about 40% of the wet mass of a man’s

body and about 23% of a woman’s (about 70% of the body is water). There are over 600 skeletal

muscles which are under our direct control and which enable us to move larger joints. This type of

muscle is, therefore, sometimes called voluntary muscle. It consists of striped fibres that run parallel

to one another. The muscles are attached to bones by fibrous cords of a substance called collagen, the

cords being the tendons. We will be learning about only the voluntary muscle is in this unit. Briefly,

there are two other types of muscle, both of which come under the control of the subconscious.

Smooth muscle (so called because its fibres are not striped) is found associated with internal organs.

It contracts slowly and smoothly.

Cardiac muscle is only found in the heart. It is striped like skeletal muscle, but like smooth muscle it

is not under conscious control. It also never tires.

In a joint, the bones are held in place by ligaments (ligaments connect bones to other bones). These

often constrict the action of the joint, allowing the bones to move only in certain directions Flexible

joints come in various forms; the two of major importance are the hinge, and the ball and socket

joints. Hinge joints (such as found in the elbow or knee) only allow movement in one plane, like the

hinge of a door. Ball and socket joints (such as found in the shoulder and hip) allow movement in all

planes. The end of one bone rotates within an enclosing cup formed by another bone.

Other joints include pivot joints, which allow rotation only. This type of joint is found where the

skull meets the ‘backbone’, and it allows rotation about a fixed point. Saddle joints allow movement

in one plane – backwards and forwards, and sideways – but with no rotation. There is a saddle joint at

the base of the thumb. Gliding joints are found between the vertebrae where two fairly flat bones can

slide over one another to some degree. The wrist joint is a condyloid joint in which a slightly convex

surface fits into a slightly concave, elliptical indent.

Skeletal muscles are controlled by nerve impulses that travel from the brain and through the spinal

cord. Many joints (and all those mentioned above) contain a fluid (synovial fluid) to allow easy

movement of the bones and to protect their ends from wearing away. Such joints are called synovial

joints. The fluid is kept within the joint and is secreted by the synovial membrane. Some adolescents

suffer from what is often referred to as ‘water on the knee’ or Osgood-Schlatter’s disease, when part

of one of the bones in the knee joint grows faster than the other bones, causing extra fluid to collect

beneath the knee cap and, consequently, some pain.

Muscles, when stimulated by a nerve, contract. When the stimulation is no longer present, they relax.

Therefore, muscles cannot push (only pull) and thus they usually exist in antagonistic pairs (one

muscle pulls the joint in one direction and another pulls in the opposite direction). There are many of

these pairs throughout the body, for example, the biceps and triceps, found in the upper arm. The

biceps muscle is at the front of the arm and when it contracts it causes the forearm to be raised

(forearm flexion – a decrease in the angle around the joint). During forearm flexion the triceps (at the

back of the upper arm) relaxes. When the forearm is moved downwards (forearm extension – an

increase in the angle around the joint) the biceps relaxes and the triceps contracts. The biceps muscles

are, in fact, bigger than the triceps since they need to pull things up against the force of gravity. In an

adult human there are 206 bones which are used to support the body (e.g. the ‘backbone’ – actually a

series of 26 bones called vertebrae), to protect delicate organs (e.g. the skull) and to allow movement

(via joints operated by muscles).

Bone is NOT dead material. It is very much alive and contains a blood supply and nerves, and can act

as a store of mineral salts. The chief mineral salt component of bone is calcium phosphate. This is

deposited around living cells called osteocytes, forming bone. The outside of a bone is usually dense

and hard, whereas further in it is spongy, helping to make it lightweight. The middles of many larger

bones are hollow and are filled with bone marrow (a tissue, responsible for the production of blood

cells). Once formed, many bones continue to change shape even in adults. Calcium phosphate is

continually reabsorbed from the bones and re-deposited again. This process is controlled by

hormones and means that the skeleton continues to change shape and develop in order to best serve

the needs of the individual at a particular time. For instance, the stresses on the bones of a manual

labourer cause the bones to develop more ridges, thus increasing the surface area for muscle

attachment. Bone that is never stressed tends to break down and this is a problem for astronauts who

spend long periods of time in the ‘weightless’ conditions of space.

Regular exercise is essential for strong bones. Bone structure can also be weakened by a lack of

calcium, vitamin A or vitamin D in

the diet. Older women may suffer

from brittle bones (osteoporosis). It

is thought that the sex hormone

oestrogen plays a role in bone

absorption and deposition. The

levels of this hormone fall after the

menopause and this is thought to

lead to more bone being absorbed

than is deposited, giving an

increased chance of bone fracture.

This condition can often be helped

by using hormone replacement

therapy (HRT) – but HRT is

thought to increase the risk of some

cancers.

Sporting injuries include pulled

muscles, in which muscle fibres

become stretched or torn, although

more often than not this happens in

the tendon rather than the muscle

itself. Common names for some

forms of tendon damage are

‘housemaid’s knee’ and ‘tennis

elbow’. Haematomas often are

mistakenly called ‘pulled muscles’.

In fact, the pain caused by

contraction of the muscle is due to

a blood clot in the muscle, formed

following rupture of a blood vessel.

In a sprain one of the ligaments is

torn. Dislocations occur when the

positions of the bones within a joint

are altered. A fracture is the more

correct term for a broken bone.

Key terms to learn and USE Word Pronunciation Meaning

antagonistic pair ant-tag-on-iss-tick Two muscles that work a joint by pulling in opposite

directions, e.g. biceps and triceps.

biceps bye-seps Muscle at the front of the upper arm that can

contract and move the lower arm upwards.

contract When a muscle becomes fatter and shorter.

joint Part of the body where bones are moved by

muscles.

relax When a muscle stops contracting and becomes

thinner and longer, it relaxes.

skeleton All the bones in the body of a vertebrate.

skull Collection of bones that protect your brain.

triceps try-seps Muscle at the back of the upper arm that can

contract and move the lower arm downwards.

vertebra Your ‘backbone’ is made of many bones called

vertebrae.

1)

a) How would you describe Simon’s body to an advertiser? ..............................................................

.........................................................................................................................................................

b) Suggest a product you think Simon could advertise. ......................................................................

2) Which bones protect the heart and lungs? ............................................................................................

3) The nervous system contains the brain and spinal cord. Your spinal cord runs down your back

and contains many important nerves. Which bones protect:

a) your brain? ......................................................................................................................................

b) your spinal cord? .............................................................................................................................

4) What does your body use to make bones move? ..................................................................................

5) The diagrams show the names that doctors give to different sorts of break. What sort of break is

shown in X-ray C? ................................................................................................................................

6) When the biceps muscle contracts, what happens to the triceps? .........................................................

7) Why do muscles work in antagonistic pairs? ........................................................................................

.........................................................................................................................................................

8) Look at drawing F. It shows some other muscles in the body. You don’t need to remember their

names!

a) Write down all the antagonistic pairs you can see. .........................................................................

.........................................................................................................................................................

.........................................................................................................................................................

.........................................................................................................................................................

b) If you point your toes to the ground, which muscle contracts? ......................................................

c) If you raise your toes, which muscle contracts? .............................................................................

The bones of your __________________ can have one or more of three main functions:

support (e.g. your __________________ supports your upper body)

protection (e.g. your __________________ protects your brain)

movement (muscles move bones at _________________).

Your bones are __________________ and can grow and change shape.

Muscles cannot __________________, they can only __________________. So, they are

found in __________________ pairs.

One muscle in the pair can __________________ (get shorter and fatter) to pull the bone in

one direction and the other muscle in the pair can __________________ the bone the other

way. When one muscle is pulling, the other one in the pair _________________.

agonistic antagonistic alive backbone constrict

contract joints neck pull pull push push

relaxes skeleton skull sternum

9Bd Pictures of Health

How advertising can be misleading

1) Do you think that H.G. Wells was right? Explain your reasoning. ......................................................

.........................................................................................................................................................

2) What things should people remember when they look at adverts? Write a list. ...................................

.........................................................................................................................................................

.........................................................................................................................................................

.........................................................................................................................................................

3) Briefly state how you can keep the following organ systems healthy:

a) digestive system ..............................................................................................................................

.........................................................................................................................................................

b) breathing system..............................................................................................................................

.........................................................................................................................................................

c) circulatory system ...........................................................................................................................

.........................................................................................................................................................

d) nervous system ................................................................................................................................

.........................................................................................................................................................

e) locomotor system (your muscles and bones). .................................................................................

4)

a) In which organ system do you think the specialised cell in drawing C is found?

.........................................................................................................................................................

b) What do these cells do? ...................................................................................................................

and

breathe.

smoking

amounts

and drugs.

illegal.

and drugs.

and

antagonistic move

Quick Quiz 2

Where do you need to target your revision for the end of unit test ?

Being fit means that your body can cope with the activities that you need to do. To stay fit you

should eat a balanced diet, exercise regularly, avoid smoking and avoid alcohol and drug abuse.

If you follow these rules your heart will stay healthy and you will be less likely to suffer from high blood

pressure and other circulatory problems like heart disease (when heart muscle cells start to

die).

During exercise, muscle cells need more energy. Energy is released from a sugar called glucose through the

process of aerobic respiration. This is the word equation:

oxygen + glucose → carbon dioxide + water

For respiration to take place the following organ systems are needed:

• The respiratory (or breathing) system supplies the oxygen and removes the carbon dioxide.

• The digestive system provides the glucose.

• The circulatory system carries the glucose and oxygen to the muscle cells, and carries the carbon

dioxide away to the lungs.

When you exercise, your breathing rate (number of breaths in one minute) and your pulse rate (number

of times your heart beats in one minute) increase. This is because your cells need more oxygen and glucose

for respiration.

Breathing is carried out by two sets of muscles, the diaphragm and the rib muscles (found

between the ribs). These change the volume of the chest. Breathing ventilates (moves air into and out of) the

lungs.

• Diaphragm contacts and moves downwards. • Diaphragm relaxes and moves upwards.

• Rib muscles contract and lift ribs up and

outwards.

• Rib muscles relax and move ribs down and

inwards.

• The volume of the chest inreases. • The volume of the chest decreases.

• Air flows into the lungs. • Air flows out of the lungs.

9B Summary

heart

carbon red

Drugs are chemicals that affect how the body works. Cigarettes contain a drug called nicotine, which is

addictive (you feel that you cannot do without it). The chemicals in cigarette smoke are harmful.

Medicines are drugs that can help people who are suffering from diseases (e.g. antibiotics).

Recreational drugs are legal drugs that people take because they like the effect that they have on their body

(e.g. caffeine in coffee and alcohol). Some are illegal drugs (e.g. heroin and ecstasy) because they can be

very harmful.

Drugs that slow down the nervous system are called depressants. Alcohol is a depressant. It alters behaviour and

slows reaction time. Drugs that speed up the nervous system are called stimulants (e.g. caffeine). Misuse of any

drug can be harmful, especially to the liver.

A balanced diet is essential to health. A shortage of a particular nutrient can cause a deficiency disease.

Eating too much of a particular substance can also cause problems.

Skeleton and muscles

Your skeleton:

• protects some organs (e.g. the ribs protect the lungs)

• supports your body (e.g. your ‘backbone’ holds you up straight)

• allows you to move (using muscles at your joints).

Muscles cannot push and so joints need pairs of muscles (antagonistic pairs) to pull in opposite directions.

One muscle contracts and gets shorter and fatter to pull a bone. At the same time,

the other muscle in the pair relaxes and gets longer and thinner. Exercise strengthens bones and

muscles.

.

9B Summary (continued)