OLLOWING ORDERS · Just as tightrope-walkers need to keep their balance, organisms need to keep...

Just as tightrope-walkers need to keep their balance, organisms need to keep their internal environment constant and stable. Inside their bodies, the activities of their cells and systems need to be coordinated. How do plants and animals achieve this? Let’s find out!

Let’s also journey through your own nervous and endocrine systems and discover why you act and feel the way that you do!

99F O L L O W I N G O R D E R S

Explain how animals use their senses to detect and respond to their environment.

Explain coordination and control systems in humans and flowering plants.

Describe technologies that intervene in life processes and discuss their impact on science.

Why is a wrinkly brain a good thing to have?

Which part of your brain controls coughing and

vomiting?

Which types of intelligence do you most commonly

use?

What do you have in common with all of the matter in the universe?

What do jellyfish in your swimsuit have in common with chemical warfare?

Which hormone gives you ‘butterflies’ in your stomach?

Which types of chemical make plants ‘dance’ with the moon and the sun?

How does a plant know when it’s time to flower?

When can men produce milk?

K E Y Q U E S T I O N S

F O L L O W I N G O R D E R S 211

Thinking aboutThinking aboutFollowing orders

1. Word associationsWhen you see or hear a word, you make associations in your mind using what you

know about that word. Consider the words below:• nerve • reflex action• hormone • receptor• coordination • stimulus(a) Write down all the associations that immediately

come to mind about each one. Share your ideas with a partner, then report to the class.

(b) Did you notice any trends in the word associations made by other groups in the class? What were the similarities and differences? To find out, you could collect the data, group it, and present the findings for the class noticeboard. For example, you could use a table format like the one below:

Comment on why is it useful to include a column with percentages of students in your table.

(c) Use your data to make conclusions such as:‘Most students thought that....’‘Very few students associated...’You could revisit this activity when you have completed this topic.

2. What do you know about animals and plants?

Your teacher may divide the class into two groups for this activity.

Group 1: Take part in a debate or discussion about the differences between the ways animals and plants respond to events in their environments.Group 2: Take part in a debate or discussion about the differences between the ways humans and other animals respond to events in their environments.

During each debate or discussion, the other half of the class may act as the audience. The audience may contribute points or ask questions after the main debate or discussion has taken place.

Were there any major findings from the groups? Were there any major questions that require further investigation? If so, write them down in your workbooks, or on a poster for the noticeboard. You may address these questions during and after your study of this topic.

Word AssociationNo. of

studentsPercentage of students

WORK

WORK

3. Fast and slow responsesAt any moment, you are responding to what is happening around you. Sometimes you hardly notice this, and most times you don’t notice this at all. Consider the three different responses described in the box below and answer the questions that follow.

(a) Of the three responses, which will take i(i) the longest time?(ii) the shortest time?

(b) Explain your answers, using the knowledge you have about the human body. Share your ideas in a class discussion.

IMAGINE THAT:1. A quick puzzleA mobile has lost a piece and is hanging crooked. When a fly lands on the mobile, it becomes balanced again. Given the masses in the diagram, what is the mass of the fly?Response: Solving the puzzle

2. Ouch!You sit down on a chair and feel a sharp object.Response: Removing yourself from the chair

3. Feeling flatYou have been in three classes before lunch. You had very little breakfast and you feel that you have no energy. Your friend Janine, who ‘knows everything’, tells you that you have low blood sugar and must eat your lunch so that your blood sugar level can get back to normal. The bell rings, and you rush to the canteen to get lunch.Response: Getting your blood sugar back to normal

1.5 g

1.2 g

2.0 g

9.19.1

212 C O R E S C I E N C E 3

Have you ever wondered whatthe recipe for life is? Whichingredients would you blendtogether to make up a living thing?How could this mixtureresult in life?

Life — what is it?Many of the mysteries of life are being explored. Scientists andtechnologists have developed a huge range of different instrumentsand techniques to discover more information about life. This hashelped our knowledge and understanding of the structure of livingthings and how they work. Experimentation has also helped us findout more about the chemical processes occurring in cells that keepliving things alive. Metabolism is the way that cells undergo theseprocesses.

Different types of scientist study the ingredients of life in dif-ferent ways. Biologists may be interested in the cells that make upthe organism and how those cells help the organism to grow andmaintain itself. Chemists may see the organism as an amazinglycomplicated combination of atoms and molecules that are involvedin millions of chemical reactions every second. Physicists and engi-neers, however, may see organisms as incredibly sophisticated,self-controlling and self-repairing machines.

Much was learnt about the human body from the dissection of dead criminals. This painting by Rembrandt shows the dissection of Aris Kindt, who was hanged for stealing clothes. Anatomists can be seen examining the flexor muscles of his hand.

The recipe for life


Ingredients of lifeOrganisms, like all matter in theuniverse, are made up of atoms(see page 214). In the humanbody, approximately 65 per centare oxygen atoms, 18 per centare carbon, 10 per cent arehydrogen and 7 per cent areother types of atom. The tabledirectly below lists some of the

different types of atoms, orelements, in the human body,maize (a plant) and yeast.

Collections of atoms in organ-isms make up molecules. Mostmolecules contain more than onetype of element and are thesmallest units of compounds. Alllife on Earth is made up of

organic (carbon-containing) mol-ecules, such as glucose (C6H12O6),which contains 24 atoms. Glucosebelongs to the group of com-pounds called carbohydrates.Water, proteins, carbohydrates,minerals and lipids are some ofthe compounds that make upliving things. The lower table onthe left lists some of the com-pounds that make up the humanbody, maize and yeast.

Organelles are made up ofmillions of molecules. Eachorganelle, like different posi-tions in a hockey game, has ajob to do, as it contributes to thelife processes of a cell. Mito-chondria are an example oforganelles found in cells. Insidethese sausage-shaped organ-elles, the chemical energy inglucose is transformed intoenergy that the cell can use.

Experiments in the 1950s,

that tried to reproduce the

conditions on Earth during

its early history, used energy

similar to that found in

lightning and ultraviolet

radiation. The experiments

produced the chemicals

necessary for life. The

scientists were amazed to

find carbon compounds like

carbohydrates, amino acids,

(the building blocks for

proteins) and nitrogenous

bases (which make up the

DNA molecule), in their

‘primordial soup mix’.

Source: adapted from Australian Academy of Science, Biological Science: The Web of Life, part 1, 3rd edn, Australian Academy of Science, Canberra, 1986 (p. 215)

Source: adapted from Australian Academy of Science, Biological Science: The Web of Life, part 1, 3rd edn, Australian Academy of Science, Canberra, 1986 (p. 219)

Some of the most common elements found in three different organisms

Element Symbol

Approximate % (by mass) of the human

body

Approximate % (by mass)

of maize

Approximate % (by mass)

of yeast

oxygen O 65 75 72

carbon C 18 13 14

hydrogen H 10 10 10

nitrogen N 3.3 0.45 2.4

calcium Ca 1.5 0.07 0.01

phosphorus P 1.0 0.06 0.5

potassium K 0.35 0.28 0.6

sulfur S 0.25 0.05 0.005

sodium Na 0.24 trace 0.05

Some of the most common substances (compounds) found in three different organisms

Substance

Approximate % (by mass) of the human

body

Approximate % (by mass) of

maize

Approximate % (by mass) of

yeast

protein 15.0 2.5 13.0

fat 18.0 1.0 1.0

carbohydrate 0.1 8.0 11.0

water 60.0 86.0 70.0

minerals 4.5 1.5 2.5

others 2.4 1.0 2.5


The building blocks of life

All matter in the universe is made up of atoms.

A group of atoms is called a molecule.

An organelle is made up of thousands of molecules.

Cells are the basic building blocks of all living things.

The central nervous system consists of the brain and the spinal cord.

connecting nerves (peripheral nervous system)

Groups of cells that carry out a specialised job are called tissues. The smooth muscle in your body is a tissue.

Organs like the human brain are made up of different kinds of tissues.

Several organs working together make up a system, such as the central nervous system and peripheral nervous system.


Cells, like bricks in a house,are the basic building blocks ofall living things. Multicellularorganisms are made up of dif-ferent types of cells, each withdifferent jobs to do. Althoughthese cells may have similar basicstructures, they may differ in anumber of ways, such as size,shape and the number and kindsof organelles that they contain.These differences will depend on

the main job of the particulartype of cell.

Groups of similar cells that carryout a specialised job are calledtissues. Muscle tissue containscells with many mitochondria sothat its energy requirements can bemet. In order to function properly,the activities of cells in tissuesneed to be coordinated.

Organs are made up of one ormore different kinds of tissue

and carry out one or more mainfunctions. The human brain is anexample of an organ.

Several organs workingtogether make up a system. Inhumans, the brain and spinal cordmake up the central nervoussystem. Some systems, like ournervous and endocrine systems,work together to control andcoordinate our bodies’ activitiesefficiently.

Using dataUse the tables on page 213 to answer the following questions.1. Which element is found in the largest percentage

in each organism?2. Which organism has the highest percentage of

phosphorus?3. State the percentage of nitrogen in each organism.4. Which element is present in the same percentage

in each organism?5. (a) Construct a graph that shows the percentage of

C, H, O, N and P for each of the organisms. Be careful to select the type of graph that shows the data most clearly.

(b) Describe the difference between the percentages of these elements in the three organisms.

6. Identify the organisms which have the highest percentage of:(a) protein(b) fat(c) carbohydrate(d) water.

7. For each organism, state the:(a) water content(b) mineral content(c) carbohydrate content.

8. Describe any patterns that you see emerging from the tables.

Remember1. What is metabolism and why is it necessary?2. Describe the ways different types of scientists

may study the ingredients of life.3. What do organisms have in common with other

matter in the universe?4. What type of molecule is common to all life

on Earth?5. Describe the relationship between atoms,

molecules, elements, compounds and organelles.

6. In what ways can cells be different from each other? Why do cells differ?

7. What are the differences between cells, tissues, organs and systems?

Investigate1. Research some of the different theories about how

life began. Display your information in the form of a newspaper article.

2. What do cells need to live? What causes them to die? What happens to them when they die?

3. Your skin and cheek cells do not live forever. Different cells live for different periods of time. Find out the life span of at least four different types of cell and draw a histogram to show your information. Suggest reasons for the differences in the life spans.

4. Construct a table like the one below. Complete it (using other references) to include a specific plant cell and a specific animal cell.

Create and imagine1. Write a creative essay beginning with: ‘The

surface was covered in a watery mix ofpotassium, magnesium and calcium. Suddenly a bolt of lightning flashed through the atmosphere rich in . . .’.

2. Design your own organism. Draw labelled diagrams of the cells, tissues, organs and systems of your organism. Describe how they work together so that the organism’s needs are met.

3. Select a human system (e.g. nervous, endocrine, digestive, gas exchange or reproductive) and build a working model to show how it functions.

Organism Cell Tissue Organ System

plant

animal

Activities

9.29.2


Whether you are rollerblading, catching a ball,slicing carrots or breathing, you need to be in con-trol. Without control, your wellbeing can be at risk.

Like other organisms, you have to be able toobtain food, remove wastes, detect what is goingon in your surroundings and respond in ways thatensure your survival. Coordination describeshow the various systems in living things worktogether so that they function effectively.

What a nerve!Your nervous system has an important role in thecoordination and control of your body. It is com-posed of the central nervous system (the brainand spinal cord) and the peripheral nervoussystem (the nerves that connect the central ner-vous system to the rest of the body). Specialnerve endings in your skin called receptors candetect stimuli. Stimuli may be heat, cold, pres-sure, pain or some other sensation from theinside or outside of your body. Information aboutthe stimuli in the form of electrical impulses(nerve signals) passes rapidly from the receptorsand along the peripheral nervous system to thecentral nervous system. These electrical impulsestravel through the nervous system via neurons(also known as nerve cells) Neurons groupedtogether form a nerve.

There are three different types of neuron: sen-sory neurons, which carry the impulse generatedby the stimulus to the central nervous system;interneurons, which then carry the impulsethrough the central nervous system; and motorneurons, which take the impulse from the centralnervous system to effectors such as muscles or

The structure of a neuronA neuron is a long cell with three main parts:• A dendrite, which is a group of fine branches that

receive messages from receptors and other neurons and convey nerve signals to the cell body

• A cell body containing a nucleus which supplies energy and nutrients for the activity of the neuron

• An axon, which is a long structure through which the nerve impulses pass from the cell body. There are axon branches at the end of the axon. The axon is electrically insulated by a sheath or covering of the substance myelin.

Nerve impulses travel along a neuron in one direction only — from dendrite to axon branch.

glands. The response from these effectors dependson the original stimulus. For example, if you putyour hand on the hotplate of your stove, the recep-tors in the skin on your hand will immediatelysend a signal via your sensory and motor neuronsto the effectors in your arm muscles. The responsefrom the effectors tells your arm muscles to moveyour hand away from the hotplate.

The gaps between the neurons, called syn-apses, have to be crossed by the impulse. Chem-ical compounds called neurotransmitters areproduced in little pockets at the end of a neuron’saxon. They carry the impulse across the synapseto the next neuron. The message is then con-verted back into an electrical impulse, which con-tinues down that axon until it reaches the nextsynapse or finishes its travels at the effector.

Neurotransmitters passing along the synapse to the next neuron

‘Sending’neuronaxon of

‘sending’ neuron

mitochondrionreleased neurotransmitters

neurotransmitterpackages

synapse‘Receiving’ neuron

Fast control

Sensoryneuron

axon branch

nerve cell body

dendrite

Motor neuron

synapse

nerve cell body

axon axon

Nerve signalarrives at the effector.

Interneuron

Myelin sheathinsulates the axon.

path ofnerve signal

dendrite

Receptor in theskin producesa nerve signal.

axonbranch

Relationship between the sensory neuron, interneuron and motor neuron


Watch out!Have you ever had sand thrown in your eyes or touched somethingtoo hot? Sometimes you don’t have time to think about how youwill react to a situation. Some actions need to be carried out veryquickly. These reactions may require only a few neurons. Thepathway shown below is known as a reflex arc. No consciousthought is required for this type of action. The impulse follows adirect route from the receptor to the effector with an interconnectinglink in the spinal cord. Additional impulses are sent to the appro-priate part of the brain to keep it ‘informed’ of what happened. Thereflex arc can be described in terms of a stimulus-response model.The stimulus may be the heat from a candle and our response maybe to move away from the candle quickly.

(a) This response involves a reflex arc.

(b) Diagram of the reflex arc

Think about itMore complex actions involve many interconnecting neurons andspecialised parts of the brain. The messages pass into and along thespinal cord to be interpreted. When thinking takes place, we canmake decisions about which responses are needed. Impulses are thensent along appropriate motor neurons to the effectors. This is calleda conscious response. Many learned actions can become automaticif the same pathways are used often enough. Skill development andcontrol in playing musical instruments and sport, for example,depend on practice during which the same pathways are used often.

spinal cord

connecting neuronsmotorneurons

sensory receptors

muscle

sensoryneurons

interneurons

actionor

stimulus sensoryneurons

sensoryreceptors

centralnervoussystem

effector(muscle or

gland)motorneurons

Controlling the inside

It is important that we keep ourinternal conditions, such as tem-perature, carbon dioxide andglucose level, steady. The bal-ancing of these conditions is oftenachieved by negative feedbackmechanisms, which can involvethe nervous system. For example,if an increase in blood pressure isdetected, our bodies eventuallyrespond in such a way that resultsin the blood pressure beingreduced. This type of responsecounteracts the initial change.

Remember1. Distinguish between:

(a) a receptor and an effector(b) a sensory neuron, an

interneuron and a motor neuron

(c) a neuron and a nerve.2. Use a diagram to describe how

impulses are transmitted between sensory and motor neurons.

3. What is a stimulus-response model?

4. Give an example of a negative feedback mechanism in the human body.

ThinkDraw a concept map that links the bolded terms on this spread.

Investigate1. What is the difference between

grey and white matter?2. Research and report on the

nervous system of an animal and a nervous system disorder.

Create1. Make models of the different

neurons using balloons, string or cotton, straws and tape.

2. In a group, act out a simple reflex arc and a conscious response.

Activities

A bundle of nerves

A reflex action

9.39.3


Beware of toxic ticks, stingingtrees, nasty nettles or jellyfish inyour swimsuit! Many plants andanimals have ways of repellingattackers or paralysing theirprey.

Pests and poisons

How do they do it? The blue-ringed octopus, paralysis tick,tiger snake and other animalsand plants produce cocktails ofpoisons which block theproduction and action of neuro-transmitters at synapses. Thepoison from a red-back spider,for example, stops the action ofthe neurotransmitters. Interferingwith the neurotransmitters’ job ofcarrying the message to the nextneuron can cause spasms andparalysis.

Many plants, such as nettles,produce chemicals which ‘sting’by strong stimulation of the painreceptors in the skin. Messagesare sent rapidly to the brain,which interprets them as pain.Other plants like chrysan-themums produce insecticidessuch as pyrethrums. These targetthe nervous system of insectsresulting in their death. The com-mercial production of such ‘natu-ral pesticides’ is a large industryand is regarded as environmen-tally friendly because natural pes-ticides replace the use of moreharmful chemicals.

Nerve nastiesSimilar chemicals have been used as agents of human warfare.These chemicals specifically target the nervous system. Nerve gas,for example, contains a substance which prevents neurotransmittersfunctioning properly at the synapses. The neurotransmittersaccumulate, causing the nervous system to lose control. Such chaoscan result in death.

Safe disposal of stockpiles of unused chemical weapons is a majorproblem. In 1993 the International Chemical Weapons Conventionwas signed by 165 countries, including Australia. In signing theconvention, these countries agreed to stop production, developmentand stockpiling of chemical weapons and to destroy any suchweapons in their possession. Several countries, however, are knownto be continuing with their chemical weapons programs.

During the Gulf Wars, troops took anti-nerve-gas pillsas a precaution against a nerve-gas attack. The pills con-tained a drug designed to protect the peripheralnervous system from nerve agents. To keep thenumerous biting insects at bay, insecti-cides were sprayed on clothes, sleepingbags and tents.

Chemical warfare

Poisonous pests

Not aliens or humans from a futuristic world, but soldiers wearing protective masks and clothing against nerve gases and chemical warfare


Mysterious mattersAn assortment of unexplained symptoms were suffered by about30 000 of the 700 000 American troops who served in the Gulf Warin 1991. These symptoms have been linked to chemicals used toprotect the troops, such as the insecticide mists sprayed at night tokill malaria-carrying mosquitoes and other insects that carrydisease. However, these findings are inconclusive and the cause ofthis syndrome remains a mystery.

A species of blue-green algae that accumulates in dams and rivers each summer has been found to contain a deadly nerve toxin which causes paralysis.

Note: Some veterans reported more than one set of symptoms.

Gulf War sickness

Symptoms

Percentage of veterans

affected

Major

Impaired thought processes, depression, insomnia, slurred speech

2.0

Confusion, disorientation, dizziness, impotence

3.5

Muscle pain and weakness, fatigue, numbness in hands and feet

3.6

Minor

Claustrophobia, trouble controlling hands

1.8

Fever, swollen glands

2.6

Numbness of the face, lack of bladder control, general weakness

1.5

Unrelated or no health problems

Unrelated health problems

19.1

No health problems 11.6

Number of veterans contacted

606.0

Number of responses 249.0

Remember1. Describe one way that animals

can cause paralysis.2. Describe how some plants

defend themselves against:(a) humans(b) insects.

Think1. How does blocking the

production and action of neurotransmitters cause paralysis?

2. What could be the effect of toxins on aquatic food chains?

3. Suggest ways in which chemicals that affect the nervous system may be ‘mopped up’.

4. What do insecticides do?5. Suggest why nerve gas is used

in warfare.

Using dataUse the information in the table on the left to draw a bar graph showing the percentage of veterans suffering the various symptoms.(a) What percentage of the

veterans contacted responded to the survey?

(b) Do you consider the information obtained adequate for making reliable conclusions? Explain.

Investigate1. Conduct a survey of

insecticides at your local nursery or supermarket. Construct a table to record:(a) the names of commercial

brands of insecticides and their action

(b) the target organisms(c) the active chemical

ingredients(d) information given about

safety precautions.2. A pesticide called 1080 is used

to kill foxes. Research the chemical nature of 1080 and find out if it harms native wildlife.

3. Researchers of the Gulf War syndrome have carried out experiments on chickens to find out the cause of the syndrome. They exposed the chickens to separate doses of the chemicals and found the chemicals to be harmless. However, when some of the chickens were exposed to a combination of two or three of the chemicals, they began to shake and stumble. Nerve damage was visible when a post-mortem was carried out and levels of some enzymes were lower than normal.(a) What conclusions could be

drawn from these results? Explain.

(b) Do you think the researchers were justified in carrying out experiments on chickens? List arguments for and against.

4. Working in groups of four, make a list of about ten different poisonous or venomous Australian plants and animals. Each person is to research and report on at least one. As a group, negotiate the aspects to include in the report. Present your findings as a poster to accompany a taped commentary.

Activities

9.49.4


Resembling a piece of softcheese and weighing the sameas a large grapefruit, your brain,like the air traffic control roomin an airport, is the controlcentre for all of your body’sfunctions. It is responsible foryour intelligence, creativity, per-ceptions, reactions, emotionsand memories. Whether it’sremembering the taste of choco-late, working out a crosswordpuzzle, controlling your heart-beat or monitoring the glucosein your blood, your brain is atthe wheel, steering your systemsso that your body continues tofunction effectively.

Dissecting the brain

Your brain has three mainstructural parts. These are thecerebrum, the cerebellum andthe brain stem. The cerebrummakes up about 90 per cent ofthe brain’s volume. It is dividedinto two wrinkled halves,which are responsible for com-plex thoughts. These halves areoften referred to as the left andright cerebral hemispheres. Ifyou were to lay the surface ofthese hemispheres out, itwould cover the top of anoffice desk. This large surfacearea provides space for themany highly complex andsophisticated nerve connectionsin your brain. Each hemisphereis specialised to handle dif-ferent tasks.

The cerebellum is mainlyresponsible for the coordinationof complex muscle movementslike balancing, pouring a drinkor riding a bike.

The brain stem is locatedbetween the spinal cord and thecerebrum. It is mainly con-cerned with the control of yourheartbeat, breathing and bloodpressure. Some parts of thebrain stem are responsible foryour emotions and feelings,while other parts deal withmemories. Basic motivationssuch as hunger are also gener-ated in this part of the brain.The brain stem also acts as arelay centre, sending messagesbetween the spinal cord and thecerebrum.

Ouch!Have you ever bumped intosomething? Sensory memoryprovides you with an awarenessof where you are in relation toobjects and the space aroundyou. Sensory memory lasts onlya few seconds and dependsonly on vision. This informationis stored in the outside layer ofthe cerebrum called the cer-ebral cortex. For example,imagine you are staying thenight at a friend’s house. Whenyou turn off the light, youshould be able to find your wayto the bed easily because thelayout of the room will remainimprinted on your cerebralcortex long enough for you toget into bed. The particular areainvolved in the cerebral cortexfor this type of memory is calledthe visual-spatial scratchpad. Ithelps you to stop bumping intothings.

Telling talesAsk for a friend’s phonenumber. How long could youremember it without writing it

down? For us to remembersomething, we have to be ableto record the experience andstore it in an appropriate part ofthe brain. If we are unableto retrieve or pull out thatinformation, we have forgottenit. Before writing became acommon form of communi-cation, messengers had to mem-orise long passages withoutomitting details. Druids andbards were renowned for beingable to recite the histories oftribes and families and theevents of many generations.

9.1

A STAB IN THE DARK?• Stand about two metres away

from a partner.• Point at each other so that

your forefingers are lined up together.

• Your partner is to ‘freeze’ in position.

• Close your eyes, but keep a ‘mental picture’ of your partner’s position.

• Lower your arm.• After three seconds, with your

eyes still closed, point at where your partner’s finger should be.

1. How accurate were you?2. Repeat the activity to find out

how the accuracy of pointing changes over time by keeping your eyes closed for increased periods of time.

3. Record your results in a table and then draw a conclusion based on your data.

Brain power


Research on falling in love suggests there are three distinct stages: lust, attraction and attachment. Scientists are currently investigating the hypothesis that attraction is caused by a group of neurotransmitters in the brain called monoamines (such as serotonin and dopamine) and that these chemicals cause many of the symptoms associated with infatuation. If their hypothesis is supported, could this lead to the production of ‘magic love potions’?

pituitary gland

corpus callosum — a bridge of 100 million nerve fibres that link the two cerebral hemispheres

spinal cord

brain stem

cerebellum

pineal gland

cerebrum — the surface of the cerebrum is the cerebral cortex

hypothalamus

The human brain. Have you used yours today?

Impulses from the skin are received here.

The cerebrum is made up of two hemispheres and is responsible for complex thought.

Impulses from the eyes are received here.

The cerebellumis responsible for coordinating complex muscle movements.

The medulla in the brain stem controls breathing and heartbeat, maintains blood pressure and body temperature and controls coughing and vomiting.

Impulses from ears are received here.

This area controls speaking.

left cerebral hemisphere

right cerebral hemisphere

ventriclecerebral cortex

This area controls muscle action.


To stay or go away?Do you remember your first day at school? How about the eighthday of school? While the memory of your first day at school maybe remembered for the rest of your life, unless something signifi-cant happened on the eighth day, you have probably forgotten it.Why do you remember one day, and not the others? Scientists arestill trying to solve this question, but they suggest that it hassomething to do with the way that the information is stored andretrieved.

Short-term memory processes information that you have justreceived. This type of memory, however, has a very limited timespan. Long-term memory processes information that has beenselected for ‘storage’ over time. A part of the brain stem called thehippocampus transfers information from short-term memory tolong-term memory and back again.

It is currently thought that memories exist as patterns of connec-tions at synapses between the neurons of the brain. To store aparticular memory, nerve signals travel along a specific pathwaythrough certain synapses. Each time this memory is remembered,nerve signals are re-activated to again travel along this pathway.

Strong left or right?Learning and memory are linked. The way that you approach thelearning of different tasks and information can be influenced byhow you use the left and right cerebral hemispheres. Somepeople will use one side of their brain for a particular activity insome situations. Others feel more ‘comfortable’ using one side ofthe brain for a particular activity in all situations. The table belowshows the different ways the left and right hemispheres processinformation.

Left mode and right mode indicators

The left hemisphere: The right hemisphere:

processes language, numbers and symbols

processes pictures and images

likes to tell how likes to show how

responds to being told what to do responds to being shown what to do

solves problems sequentially solves problems with hunches

prefers talking and writing prefers essay tests

reads articles first sees pictures first

follows instructions step by step plays it by ‘ear’

is punctual and organised is intuitive

is a mismatcher (looks for differences)

is a matcher (looks for similarities)

controls feelings is free with feelings

follows directions is creative

Mind mappingMind maps are a way of creatingmemory (i.e. learning) in a waysimilar to that of the brain by pre-senting information in a visual andconnected form. Mind maps con-tain information in a predigestedform which the memory can mosteasily assimilate and access.

Why use them?Mind maps appeal to the rightside of the brain which processescolours, relationships, picturesand symbols. Using mind mapscan increase your understandingof information and boost yourrecall of it dramatically.

Create your own mind map about your favourite hobby. How? By:

• writing the topic or key idea in the centre of the paper

• adding branches to hold key sub-topics

• adding detail to branches• personalising the map for the

right side of the brain with symbols, pictures and colours.

The following points are tips to remember when creating your mind map.• Use curved lines — they are

easier to write on.• Draw connecting lines like

branches.• Use unlined paper and place it

horizontally.• Relax and use your imagination

to create your map.• Use nouns, verbs and adjectives.• Use upper case for key words

and lower case for those that branch out.

• Use at least three colours to decorate your map.

• Use your own codes, arrows and symbols.

MAPPING OUT


A mind map

Remember1. In a table, name the three main structural parts of

the brain and describe some of their main functions.2. Describe the difference between sensory memory,

short-term memory and long-term memory.3. What do scientists think synapses have to do with

memory?4. How can mind mapping help you remember

information?

Think1. Copy out the table on page 222. Use a five ‘x’

grading scale (x = not very comfortable with this type of action and xxxxx = very comfortable with this type of action) to grade each of the different actions in the table. Did you have more ‘x’s in the left or right hemisphere column? This gives you an indication of which areas you feel you are most comfortable with in your learning.

2. The koala’s brain size in relation to its body is smaller than that of other mammals. Its diet of gum leaves is not a very rich source of energy. What is a possible relationship between the two pieces of information?

3. Analgesics such as paracetamol and aspirin acton the brain to deaden the sensation of pain. What are the advantages and disadvantagesof this?

4. Suggest the biological advantages of the suggested stages of love. How might they assist in the survival of a species?

Create1. Develop a mind map that summarises the

information about the brain that you have just learnt.

2. Develop a mind map of all the previous information in this chapter.

Activities

Brain control

9.59.5


Intelligent toolboxDid you know that there is more than one typeof intelligence? Models are a useful way ofunderstanding intelligence. (Remember that amodel is limited as it is not identical with thesubject it is trying to explain.) One model of

intelligence suggests that there are seven ways of‘knowing’. If you ‘know’ and think about theways that you go about knowing and thinking,you can find your strengths and concentrate onactivities that maximise your learning.

Multiple intelligence toolbox

IntrapersonalRelates to inner states of being

thinking strategies

focusing andconcentration

skills

self-reflectionand metacognition

(thinking about thinking)

‘know thy self’procedures

JohnLennon

DalaiLama

InterpersonalThrough person-to-person

relationships andcommunication

collaborationskills

sensing others’motives; intuition

person-to-personcommunication

groupprojects

RoveMcManus

OprahWinfrey

Musical/RhythmicRecognition of tonal patternse.g. environmental sounds,

rhythm and beats

humming singing

musiccomposition/

creation

musicalperformances

Alex Lloyd

DanielJohns

DeltaGoodrem

PeterSculthorpe

Body/KinaestheticRelates to physical

movement and motionmime physical

exercise

drama role-playing

NicoleKidman

PatrickJohnson

Logical/Mathematical

Often called ‘scientific learning’

numbersequences

abstract symbols and

formulas

problemsolving

patterngames

AlbertEinstein

PeterDoherty

AdamSpencer

Visual/SpatialRelies on sight and

being able tovisualise an object

patterns,designs

colourscheme

pictures mind mapping

JamieDurie

ColletteDinnigan

Verbal/LinguisticRelates to written wordsand spoken language

poetry reading

storytelling debate

J.K.Rowling AndrewDenton

Multiple Intelligences Toolbox

Multiple Intelligences Toolbox


UNPACKING THE TOOLBOX

• Draw up a table with two columns headed ‘Behaviour statement’ and ‘Type of intelligence’.

• Read through the ‘Knowing behaviours’ in the table below, and select and record those statements which apply to you in the ‘Behaviour statement’ column of the table you have drawn up.

• Use the multiple intelligence toolbox illustration on the left to determine which type of intelligence matches the types of knowing that you have just selected. Record this in your ‘Type of intelligence’ column.

1. Describe the pattern of your ‘multiple intelligences’. Which were the most and the least common?

2. Did you have any problems in deciding on which statements to select? Explain.

3. Which types of factor do you think might affect the types of intelligence that people use?

4. Suggest other statements that could be used to test for each type of intelligence.

5. Can you think of any types of intelligence not in the illustration on the left?

‘Knowing’ behaviours

1. I can hear words in my head before I read, speak, or write them down.

2. I get more out of listening to the news on the radio than I do from watching it on television.

3. I enjoy entertaining others with tongue twisters, nonsense rhymes or puns.

4. I frequently beat my friends in chess, checkers or other strategy games.

5. I am very curious about how things work.

6. I feel more comfortable when something has been measured, categorised, analysed or counted.

7. I often see clear visual images when I close my eyes.

8. I can easily solve jigsaw puzzles, mazes and other visual puzzles.

9. I can easily find my way around unfamiliar territory.

10. I regularly engage in at least one sport or physical activity.

11. I frequently use hand gestures or other forms of body language when conversing.

12. I need to touch things in order to learn more about them.

13. I sing and hum a lot during the day.

14. I can recognise and remember songs and music easily.

15. I can easily keep time with a piece of music.

16. I feel comfortable in the midst of a crowd.

17. I usually seek out the help of others to solve problems.

18. I enjoy the challenge of teaching another person what I know how to do.

19. I think a lot about myself and why I am the way I am.

20. I consider myself to be strong-willed or fiercely independent.

21. I frequently have intuitions about things that turn out to be true.

9.69.6


Whether it’s birds singing songs,spiders spinning webs, dogsscratching itches or studentsasking questions, doing the rightthing at the right time can be anadvantage. How do we knowwhat to do and when to do it?

The behaviour of an animaldescribes what that animal does.Nearly all the behaviour dis-played by animals is in responseto stimuli in their environment.For example, a kangaroo willseek shelter when it is very hotand a snail will withdraw into itsshell in dry conditions. Behav-iour tends to help animals sur-vive by assisting them inobtaining food, protecting them-selves and other animals, andreproducing.

Programming for successMany kinds of animal behaviour do not have to be learnt — theyare innate or inborn. A spider, for example, does not have to learnhow to spin its web. Innate behaviour is controlled by the pro-gramming of the nervous system and is inherited. It can be simple,such as in a reflex action, or more complex.

There are several types of innate behaviour, including courtship,communication, group organisation, migration and competition.Courtship refers to the rituals of mating. The courtship behaviourof birds programs prospective mates to recognise and respond onlyto the mating rituals of their own species. Communication behav-iours allow organisms to transfer information, such as the locationof food and the borders of territories. Group organisation definesthe roles that each organism plays in its own society. Bees in a hive,for example, have a distinct hierarchy of a queen bee, who lays allthe eggs; female worker bees, who collect pollen and nectar; anddrones, who mate with the queen bee. Migration behaviours governthe movement of large numbers of animals, usually over largedistances. Many types of animal, including fish and birds, migrateannually because of climate changes. Competition refers to theinnate ability of animals to compete for food, shelter and mates.

Changing for the better

Animals, including humans, canchange behaviour as a result ofother experiences. This is calledlearned behaviour and can takeplace in a number of ways. Foranimals to be able to learn, theyhave to be programmed with theability. Therefore, the abilityitself is innate.

There are a number of learnedbehaviours, including con-ditioning, imprinting, trial anderror, habituation and insightlearning. Conditioning occurswhen an organism associates onestimulus with another, such as youthinking of food when the schoollunch bell rings. Imprinting is abehaviour that occurs when anorganism forms an attachment tosomething in its environmentshortly after birth, such asthe attachment a newly hatchedduckling forms with its mother.

Getting it right

Some of the types of behaviour

THECOMPLEXITY OF

BEHAVIOUR

THECOMPLEXITY OF

BEHAVIOUR

CompetitionInnate behaviour of competing with

others for resources

Insight learningLearned behaviour of

applying past experiences to new problems (without

trial and error)

MigrationInnate behaviour governing the movements of

large numbers of animals over long distances

ImprintingLearned behaviour of

forming an attachment to something shortly

after birth

ConditioningLearned behaviour of associating one

stimulus with another

Trial and errorLearned behaviour of repeating a task and learning from

mistakes

HabituationLearned

behaviour of becoming

accustomed to a repeated

stimulus

CourtshipInnate behaviour

governing the rituals

of mating

CommunicationInnate behaviour of

transferring information

Group organisationInnate behaviour of creating a group

hierarchy


Rewarding the positive

How do you feel when you geta ‘pat on the back’ or congratu-lated for something you did? Areyou likely to do it again? Anewly hatched chicken pecks atnearly everything, but it soonlearns what is food and what isnot. Through trial and errorand reinforcement, which canbe positive or negative, usefulkinds of behaviour are learnt.

Getting used to it

Your brain can sometimes pickand choose what stimuli it willrespond to. If you tap gently onthe shell of a moving snail, it willwithdraw into its shell. If yourepeat the procedure, it will even-tually ignore the tap. The snail hasbecome familiar with the stimulusand there are no nasty conse-quences. This decreased responseto repeated stimulus is calledhabituation.

Insight and getting it right

The ability to reason and solveproblems is a type of learningwhich chimpanzees, dolphinsand humans often use. Gettingyourself out of awkward situ-ations can often require con-siderable thought, sometimesinvolving past experiences togive you some clues about theapproach that you will take. Theability to use past experiencesto solve new problems is calledinsight learning. The ‘Think’questions in the ‘Activities’ sec-tions of this book exercise thisability.

DOES PRACTICE MAKE PERFECT?Drawing on your own experience, predict what your answers to the questions in this experiment may be. Then carry out the experiment.YOU WILL NEEDretort stand, bosshead and clampsa partner plane mirrorstopwatch pencilA4 paper cardboard

• Draw a figure of eight or a star to fit the sheet of paper and another line following the shape about 5 mm inside the outline.

• Set up the equipment as shown in the diagram below. Use the clamps to hold the mirror in place.

• Position yourself so that you can look into the mirror and see the figure of eight or star diagram. Draw a line between the double lines of your diagram while your partner times you. If you touch a line, you must go back to the start while the timing

continues. Remember to look only at the diagram’s reflection in the mirror. Don’t look at it directly.

• Repeat the procedure at least five times, timing each attempt separately.

1. Record your results in a table as you proceed. Draw a bar graph of the results with the number of attempts on the horizontal axis and the times taken on the vertical axis.

2. Analyse your results. Was there any difference between the times of successive attempts?

3. Predict what might happen if you were to repeat the experiment another ten times.

4. What conclusions can you make from this experiment? How reliable are your conclusions? Explain. How could the reliability of your findings be increased?

planemirror

foldedcardboard

9.2

RememberUsing examples, describe the difference between learned and innate behaviour.

Think1. What are some advantages of:

(a) insight learning?(b) trial and error learning?(c) habituation?

2. List things you have learnt through trial and error. Compare your list with others

and comment on any interesting findings.

Investigate1. Gather information about how

ants follow a trail, and how and why birds migrate.

2. Find out some of the innate behaviours of babies. Why might they be useful to a baby?

3. Dogs often ‘know’ when you are about to take them for a walk or feed them. How do you think they ‘know’ this?

Activities

9.79.7


Feeling excited? ‘Butterflies’ in your stomach?Have you ever wondered about the changestaking place in your body and what causes them?

Helpful hormonesThe nervous system is not the only means of con-trolling and coordinating activities in your body.The endocrine system uses chemical messengerscalled hormones. They are produced in yourendocrine glands and are released directly intoyour bloodstream. Although hormones are carriedto all parts of your body, only particular cells aretargeted. It is a little like radio signals which aresent out in all directions, but picked up only byradios attuned to a particular signal. These targetcells are attuned to the hormones carried throughyour body and respond in a particular way.

Hormones control and regulate functions likemetabolism, growth, development and sexualreproduction. Like the nervous system, the endo-crine system detects a change in a variable andoften acts using a negative feedback mechanism tocounteract the initial change. The endocrine systemalso works with the nervous system to regulateyour body’s responses to stress. The effects of theendocrine system are usually slower and generallylonger lasting than those of the nervous system.

pineal gland

hypothalamus gland

thyroid gland

pituitar

Some of the main glands of the endocrine system. Note: In females, ovaries are located in the lower abdomen.

pancreas

testes(in males)

adrenal glands

Gland

Type of hormone(s) produced

Hormone’sfunction/effect

pituitary gland (called the ‘master gland’ because it controls many other endocrine glands)

many hormones including: follicle stimulating hormone (FSH) and luteinising hormone (LH)

growth hormone

prolactin

stimulates ovaries to produce ova and stimulates testes to produce sperm

affects cell growth

stimulates breasts to produce milk

hypothalamus many hormones

connects the nervous system with the endocrine system; controls body temperature, growth, sex drive, thirst, hunger and pleasure and pain sensations

pineal gland melatonin controls body rhythms like sleeping and waking

thyroid gland thyroxine controls rate of chemical activity in cells and regulates growth

adrenal glands

adrenaline and others

raises blood pressure, heart rate, breathing rate and supply of blood to muscles

pancreas insulin

glucagon

decreases blood glucose level

increases blood glucose level

parathyroid glands

parahormone maintains level of calcium in the blood

ovaries (females)

oestrogen and progesterone

controls development of breasts; prepares uterus for zygote and controls menstrual cycle

testes (males) testosterone controls body hair, deepening of voice and sexual urges

Slow control


Superhuman feats?‘Butterflies’ in your stomach are the effects of a hormone calledadrenaline. When you experience some kind of fright or stress,the adrenal gland releases adrenaline into your bloodstream. Not allparts of your body will be affected by its presence in the blood-stream. Adrenaline may cause your face to turn pale, your heart tobeat faster and your muscular actions and energy ‘levels’ toincrease. This prepares your body to escape from, or fight yourway out of, a dangerous situation. Adrenaline is often referred to asthe ‘flight or fight’ hormone.

Sweet controlInsulin, a hormone produced by your pancreas, acts on target cellsin the liver. After you have eaten a lot of sugary food, your bloodglucose (or blood sugar) level rises. The rise is detected by cells inthe pancreas. The pancreas then secretes insulin which travels throughthe bloodstream to the liver. Specific target cells respond by absorbingglucose from your blood and converting it to glycogen, which maythen be stored. This has the effect of lowering the amount of glucosein your blood. Another hormone, glucagon, also produced by yourpancreas, has the opposite effect and raises your blood glucose levels.

Puberty bluesOestrogen, progesterone and testosterone are sex hormoneswhich can be responsible for other types of change. Duringpuberty, many changes take place and sometimes it may seem thatyou lose control of what is happening to your body. Voices can‘break’ and uncontrollable blushing can occur. Your body shapechanges and sometimes arms and legs don’t always do what youwant them to! Even emotions can be unpredictable.

From blushes to flushesSometime during ‘middle age’, hormones controlling a woman’sfertility and menstrual cycle stop being produced. This can affectchemical activities in her body and her emotions. In some womenthe effect is minimal. Hormone replacement therapy (HRT) may beused to treat more severe symptoms such as hot flushes, headachesand irritability. However, recent evidence has shown that HRT mayhave some harmful side effects.

Following World War II, many starving men in concentration camps were discovered lactating (producing milk). The glands in men and women produce similar hormones but in very different amounts. Hormones are constantly being made and being broken down, mostly by the liver. In the starving men the liver had shrunk enormously and was barely able to break down even the small amounts of hormones their bodies produced. So the level of some hormones actually rose to a point where breasts grew and milk was produced.

Remember1. What are hormones and where

are they produced?2. Are all parts of the body

affected by a particular hormone? Explain.

3. List some functions that hormones control and regulate.

4. Why is adrenaline referred to as the ‘flight or fight’ hormone?

5. Insulin and glucagon both help regulate your blood glucose level. How are they different?

6. Which hormones cause many of the changes that take place during puberty?

Think1. Collate the information

provided in this section to make a ‘mind map’ of the endocrine system.

2. Discuss some advantages and disadvantages of the effects of adrenaline in modern-day living.

3. Assess the risks and benefits of hormone replacement therapy for treating the symptoms of menopause in women.

Investigate and createIn a group create a ‘Hormonal Pursuit’ game.• Game board: Creatively sketch

and label a ‘map’ of the endocrine and circulatory systems on an outline of a human body drawn on a large sheet of card or paper.

• Question cards: Research the endocrine system, glands and specific hormones. Use the information to make up question cards. Place these on the game board.

• Rules, dice and roll: Make a creative dice, dial or other ‘moving’ system. Decide on and document your game rules. Play your game and then another group’s game.

• Brain drain: Make a list of the strengths and weaknesses of each game. How could they be improved? Draw a mind map to summarise what you have learnt about the endocrine system.

Activities

9.89.8


Have you ever watched a plantmove? They do, and most grace-fully too. If you watch plants overa length of time, or using time-lapse photography, you can seehow they ‘dance’ with the sunand the moon. These ‘dances’may be choreographed byhormones or by their internal bio-logical clocks (see Core Science 2,second edition, page 90).

Not nervous?Plants do not have a nervoussystem! Instead, the way plantsgrow, develop and respond totheir internal and externalenvironments is usually coordi-nated by plant hormones. Planthormones are mainly producedin the growing tips of roots andshoots, in buds and in devel-oping fruits. Only very smallquantities are needed for aneffect. The same hormone mayproduce different responses indifferent parts of the plant.

Plant hormones are generallydivided into five main groups:auxins, cytokinins, gibberellins,abscisic acid and ethylene. Insome cases a number of thesehormones work together to pro-duce a response. The illustrationon the right shows where theseplant hormones are producedand their effects.

Bent on lightWhen light shines on the tips ofa plant’s shoots, auxins areproduced and released. Theseauxins travel down the plantand cause the cells on the sideopposite the light to growlonger than those on the otherside. This causes the stem tobend towards the light.

Hormone journeys

Auxins cause plants to grow towards the light.

Auxins move down towards the root tip.

Auxins and gibberellin promote the formation of woody tissues.

Gibberellin and cytokinins move up to the shoot and leaves.

Gibberellin and cytokinins are made in the roots.

A factor made in the root tip controls the root’s downward growth.

abcission zone

Ethylene and abscisicacid made in old leaves promotes the development of a zone (the abcission zone) where the leaf will break off.

Abscisic acid made in the leaf closes stomata and reduces water loss.

root growth in balance.

equalelongation

increasedelongation

shoot bends towards lightauxin moves to

shaded sideshoot grows straight

auxin

Plant movesCell reproduction below the shoot tip is controlled by gibberellin.

Auxin and gibberellin, produced in young leaves and buds, move to the stem to control stem growth.

Ethylene ripens mature fruits.

Cytokinins made in young fruit stimulate their growth.


Is it time yet?Like us, plants have internal bio-logical clocks and may havedifferent patterns of movement ina 24-hour cycle. The leaves ofsome plants, for example, may behorizontal during the day andthen drop into a ‘sleeping’ pos-ition at night. If you were to placethese plants in 24 hours of day-light or darkness, they would stillcontinue their ‘sleeping’ move-ments because the sleep patternof these plants is internallycontrolled. Such a 24-hour cycleis referred to as a circadianrhythm or cycle. The opening andclosing of flowers is anotherexample of a plant’s activitiesthat involves a circadian rhythm.Unlike a plant’s movementtowards light, these kinds of move-ments are independent of thedirection of the stimulus.

The timing of flowering ofmany plants is controlled by thelength of uninterrupted dark-ness. Long-day plants floweronly when the period of daylighthours is greater than a certaincritical minimum (or when dark-

ness is less than a critical value).Short-day plants flower onlywhen exposed to daylight for aperiod less than a certain criticalmaximum number of hours (orwhen darkness is greater than acritical value). Gladioli, cabbageand hibiscus are long-day plants,

while daffodils, rice and chrysan-themums are short-day plants.Day-neutral plants, such aspotatoes and tomatoes, do notdepend on day length to flower.Currently, hormones are alsothought to play a role in deter-mining when plants flower.

Remember1. If plants do not have a nervous system, what

coordinates their life cycle?2. List the five groups of plant hormones and the main

locations in plants where these hormones are produced.

3. Describe how hormones allow a plant to grow towards light.

4. What is a circadian rhythm? Give an example.5. Which two factors are thought to control the timing

of flowering?6. Give examples of (a) long-day, (b) short-day and

(c) day-neutral plants.

Think1. Which types of plant do you think would flower in

winter and summer?

2. By knowing the effects of plant hormones, horticulturists are able to control the timing of the flowering of plants and the ripening of fruits. Why do you think they do this?

Investigate1. Why would gardeners put bulbs of some kinds of

plants (e.g. tulips) in a refrigerator before planting?2. Find out more about the Dutch biologist Friedrich

Went (1863–1935) and his research that led to the isolation of the auxin that causes plants to bend towards light.

3. Research one of the following hormones: auxins, ethylene, abscisic acid or gibberellins. Summarise your information in a poem, poster or newspaper article.

4. Find out which group of plant hormones is responsible for the ‘carpets of colour’ created by trees losing their leaves during autumn.

Activities

Getting into circadian rhythm: a flower performs its daily dance © Biozone International Ltd/Richard Allan

5.00 pm 7.00 pm

7.30 am 9.30 am

11.00 am


9.9

G E T T I N G B A C K I N C O N T R O LSometimes people get very nos-talgic about living in the pastbut there are many advantagesto living in the present. Julie Hillwould certainly agree eventhough one of the features oftoday — the motor car — wasthe cause of her problem in thefirst place.

A car accident severed herspinal cord, leaving her with nosensation or muscular controlbelow the waist. The passage ofnerve impulses to and from herbrain was impossible as thepathways were damaged.

Julie Hill’s spinal cord was severed in a car accident. Modern technology has given her artificial nerve impulses.

At the press of a button

After a complex pioneeringoperation, Julie can now standand sit at the press of a button.Electrodes were attached to 12nerves that ran from the base ofher spine to her legs. The elec-trodes were linked by wires toa small computerised receiverplaced in her chest cavity. Bypressing a button on a smallcomputer attached to her waist,Julie can send pre-programmedradio signals to the implantedreceiver which then triggersresponses in her leg muscles.The system acts rather like acomplicated jump lead, con-necting the nerve pathways oneither side of the damagedspinal cord.

The electrode system that allows Julie to stand and sit

1. Press button oncomputer attachedto waistband

2. Signal from computer sent to implanted receiver, which then sends signal to electrodes at base of spine

receiver

controlcomputer

3. Electrode connects nerves in spine to nerves in legs, allowing the nerve signal to complete its journey to leg muscles

Restoring control

Being able to stand and sit usingher own muscles not only givesJulie a feeling of being in controlbut improves her muscle tone,strength and blood flow. Julie hasmanaged to walk some steps, butresearchers are cautious aboutthe potential of these technol-ogies. Walking involves manynerve fibres or axons and syn-chronising the contraction andrelaxation of dozens of muscles.The electrode which stimulatedthe muscle enabling Julie tostraighten her knee also causesher body to bend sharply. Theresearchers are trying to find outwhich muscle is causing theproblem by anaesthetising dif-ferent ones in turn.

After spinal injury, a personhas no control of the sphinctermuscle which holds urine in thebladder, nor of the musclewhich helps squeeze out theurine. Restoration of bladdercontrol, which is possible insome cases, gives a sense ofindependence and dignity to aperson. It also is importantbecause bladder infection is amajor cause of disease anddeath among paralysed people.

Coming to grips

Bio-engineers work to solveproblems like paralysis by tryingto copy the body’s own muscularcontrols. The enormous com-plexity of the nervous system


makes this very difficult. Julie’soperation is an importantadvancement in the developmentof functional electrical stimu-lation (FES) systems to helppatients with spinal cord andother nerve injuries.

In certain cases, a part of thebody that is not paralysed can beused to control the current inelectrodes linked to paralysedparts. A tiny platinum cuff thatcan be attached to a sensorynerve in the palm of the hand isbeing developed in Denmark.The cuff allows the movement ofa shoulder to be used in control-ling the grip of a hand. Theproblem is in adjusting thedegree of grip required in dif-ferent situations — the grip mustnot be too loose or too tight. Sen-sory feedback, using nerves onthe other side of the damage,automatically adjusts the strengthof the grip to avoid crushing ordropping objects.

Making smilesIsn’t smiling wonderful? It creates warm responses in people, andbabies soon learn how to do it. How would you feel if youcouldn’t show expressions on your face? Try keeping a ‘straight’face for a day.

Moebius syndrome is a rarecondition in which the facial nervefails to develop. The cause isunknown. As the facial nerve con-trols about 40 muscles involvedin forming expressions, sufferers,such as Yvette Machado in thephotograph on the right, areunable to smile, purse their lips ormove any part of their face.Speech, swallowing and eating arevery difficult. Another nerve,which controls eye movements, isalso affected, so Yvette had to turnher head instead of her eyes.

Yvette underwent two lengthy operations at Melbourne’s RoyalChildren’s Hospital. In each operation, muscles, blood vessels andvery fine nerves were removed from her thighs and incorporated ina ‘facelift’. The fine nerves and other tissues grew in place, eventuallyenabling Yvette to start to learn to smile. She will have to work hardto develop a reflex (an automatic response) for looking happy.

Yvette Machado

Investigate1. Draw a map to show the location

and type of disability access available at your school. Do the same for your local shopping centre. Are there any places it would be impossible for a disabled person to get to? Find out from your local council what regulations there are relating to disability access to parks and public and commercial buildings.

Standard disability parking and access signs

2. Find out more about some other bio-engineering successes and present your findings in a poster.

3. What would you have to do to your home if a member of your family had to spend the rest of his or her life in a wheelchair? Work out the cost of new items that would have to be purchased and alterations that would need to be made to your house. Find out what services would be available to assist you.

4. Collect a media file of articles related to bio-engineering.

5. Compile a report on the 2004 Paralympics. Include the major events, the winners and any other items of interest to you. Consider writing to one ofthe sponsors to say how much their sponsorship is valued and why.

6. Find out more about a day in the life of an occupational therapist.

7. What is the difference between bio-engineering and bionic engineering?

Imagine1. Imagine you have lost the use of

both of your legs and one arm due to damage to your spinal cord in a diving accident. You have a little control in the other arm. Describe your day. How would you manage physically? What do you think your thoughts and feelings would be? How would you want others to treat you?

2. Imagine you are a bio-engineer. Select a task or job your body performs and find out how it is achieved. Design a way of enhancing it by using your own creative ideas on bio-engineering, so that you could become ‘super human’ at that task.

CreateDesign and make a ‘machine’ or ‘instrument’ that could be used by a person with a particular physical disability.

DISABLEDPERSONSPARKING

ONLY ACCESS ATSIDE OF

BUILDING

Activities

it all togetherPutting Putting it all together


Word list

cerebellum

brain

molecules

tissues

organs

interneurons

synapse

negative feedback mechanism

cerebrum

peripheral

plant hormones

endocrine

cells

motor neurons

mind maps

spinal cord

brain stem

coordination

sensory neurons

hormones

Copy and complete the statements below to compile a summary of this unit. The missing words can be found in the word list below.

1. Organisms are made up of atoms. Collections of atoms make up . Organelles are made up of many molecules. are the basic building blocks of all living things. Groups of similar cells that carry out a specialised job are called . Organs are made up of one or more different kinds of tissue and carry out one or more main functions. Several

working together make up a system.

2. describes how the various systems in living things work together so that they may function effectively.

3. The human nervous system is composed of the central nervous system (the brain and

) and the nervous system (the nerves that connect the central nervous system to the rest of the body).

4. carry the information from the receptors, carry the information through the central nervous system and take the information to the effectors.

5. Neurotransmitters are chemicals which pass the information across the to the next neuron.

6. In a , the response leads to the

removal of the need for a continued response.

7. The human has three main structural parts. These are the cerebrum, the cerebellum and the brain stem.

8. The is responsible for complex thoughts, the for the coordination of complex muscle movements and the for the control of heartbeat, breathing and blood pressure.

9. appeal to the right cerebral hemisphere which processes colours, relationships, pictures and symbols.

10. Chemical messengers called are produced in your endocrine glands and released directly into your bloodstream.

11. are mainly produced in the growing tips of roots and shoots, in buds and in developing fruits.

12. The effects of the system are slower but longer lasting than those of the nervous system.

Summing upSumming up


1. Underline the incorrect term in each sentence. Replace it with the correct term and then find the correct term in the word puzzle. Write definitions of the incorrect words you replaced.(a) The neuron carries hormones to target cells.(b) The master gland of the endocrine system is the

adrenal gland.(c) The brain and spinal cord make up the

peripheral nervous system.(d) Organelles carry messages across synapses.(e) Each molecule has tissues which carry out

particular functions.(f) Reflex actions and negative feedback

mechanisms are examples of learned behaviour.

(g) Hormones are constantly being broken down, largely by the brain.

2. Construct a table to summarise the differences between the nervous and endocrine systems. Make sure you include the name of the information each system produces, how that information is carried throughout the body, and the speed and length of each system’s response.

3. Draw a mind map with ‘coordination’ as the central idea. Begin your branching out with the headings ‘Nervous system’ and ‘Endocrine system’, and then let your mind map fill the page with a summary of the key ideas of this chapter. Remember to include lots of colours and symbols.

4. Match the numbers on the diagrams below to the following labels.dendrite cerebrum sensory neuronsadrenal glands pancreas nerve cell bodycerebellum effector axonpituitary gland brain stem motor neurons

G A P I T U I T A R Y

Z E V N O B L I C N B S

O C F A E N L I N E E R K P X

L R G P U T O V N L R A I O N

Q G C N R I O E A N V I N B F

V Y B L O O D R T P E N J C Y

S N I D T I S C E N T R A L

R G A R I T S M

O R G A N R L

D A N Z E

I S D A

M Y M

I E

T

T

E

R

S

interneurons

actionor

responsestimulus

sensoryreceptors

centralnervoussystem

4. 5.

6.

7.8.

9.

10.

11.

1.

2.

3.

12.

Looking back

Extension ExtensionHarnessing hormones


Seemingly inexplicable observations have ledscientists to investigate hormones.

Observations made in the days of gas streetlamps caused scientists to think about the treesdownwind of the lamps that shed their leaves.Experiments led to the discovery that the gas usedin the lamps, ethylene, was responsible. Further

research showed that ethylene was a plant hor-mone which promotes a plant’s ability to shedleaves.

Such investigations have increased our under-standing and allow us to put some hormones towork. The mind map below shows the many usesof hormones.

Think and investigate1. Find out what other effects ethylene may have on

plants.2. Discover more about the hormones used to

increase milk or food production (such as lactation in cows and goats or growth in cows, sheep or chickens). Gather information on the advantages and disadvantages of these hormones. Use the information in a class debate on ‘Hormones should be used to increase food production for humans’.

3. Find out and report on the hormones that could be ‘harnessed’ or used to the advantage of humans. Present your information in an advertising brochure.

4. A synthetic chemical called pyrethrin is increasingly being used in sheep dip. It breaks down within a few days, but during that time it can kill many types of invertebrates in the waterways.(a) Why are sheep dipped?(b) How could sheep dip reach waterways?(c) Suggest implications for the deaths of

invertebrates on other organisms.

Activities


Reflection Reflection

1. Revisiting your ideasRead through your own notes and any class findings from the ‘Thinking about’ activities at the start of this chapter (see page 211). Have you changed your views or ideas about responses made by humans and plants? Write a few paragraphs to describe these changes.

2. Stopping in timeImagine that you are driving along a road, and a person runs in front of you. Will you stop in time?

The person in front of your car is detected by receptors in your eyes. The image is transferred to your central nervous system. A signal comes back to your leg muscles instructing them to push hard on the brakes. The distance travelled from the time you see the person to the time that you apply the brakes is called the reaction distance. The distance travelled from the time you brake to the time you stop is called the braking distance. The total distance travelled is called the stopping distance, and is the sum of the two:

The faster your car is travelling, the greater the stopping distance. The reaction time (the time you take to react) is, on average, about 0.75 seconds.

Work on the following questions with a partner, then present your views in a class discussion. Collect the main points made during the discussion to make a poster for the class noticeboard.

stopping distance = reaction

distance + braking distance

(a) Is the reaction distance, braking distance or both affected by the speed of the car? Provide an explanation for your answer.

(b) Which one factor remains fairly constant in the time taken to cover the stopping distance?

(c) What factors, other than the speed of the car, affect the stopping distance? Make a list of these factors.

(d) Is your reaction a reflex (involuntary) or voluntary action? Explain your answer, including a diagram of the pathway in the nervous system.

WALKING THE LINE• Working in pairs, find an

open space in the playground and use chalk to draw a straight line 10 to 20 metres long.

• Take turns walking along the line, putting one foot closely in front of the other.

• Wearing a blindfold, take turns to walk along the line again. Stop when you think you have walked along the whole line. (Your partner should write down any observations in his or her workbook as you do this.)

• At the end of the walk, remove the blindfold and note the position where the walker finished.

• Discuss the sensations felt by the walker when blindfolded, and the observations made by the other student.

1. Using all the understandings you have gained during your study of this topic, explain the differences between walking with and without sight along the line.

2. Imagine that the line ran alongside the edge of a cliff that drops straight down to the sea far below. In this case, how would you feel while walking along the line (with or without a blindfold)? Would you expect any hormones to be involved in your response to this situation?

OLLOWING ORDERS · Just as tightrope-walkers need to keep their balance, organisms need to keep...

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