Mantaining a balance - summary slides.pdf

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KISS Resources for the NSW Syllabus.

Biology 9.2 Maintaining a Balance PhotoMastercopyright 2014 KEEP IT SIMPLE SCIENCEwww.keepitsimplescience.com.au

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KEEP IT SIMPLE SCIENCEPhotoMaster Format

Maintaining a BalanceBiology HSC Course Topic 1

Topic Outline

Topic Bio 9.2Senior Science Subject

NSW Syllabus Content reference

3. InternalTransport

2. TemperatureRegulation

4. Excretion

& Water

Balance1. Enzymes &Homeostasis

What is this topic about?To keep it as simple as possible, (K.I.S.S. Principle) this topic covers:

1. ENZYMES & HOMEOSTASISWhat are enzymes? Functions & characteristics. Factors that affect enzyme

activity... temperature, pH & substrate concentration.Negative feedback control systems. What is Homeostasis?

2. TEMPERATURE REGULATION IN LIVING THINGSThe hypothalamus & effector organs in mammals.

Temperature regulation in endotherms, exotherms & plants.

3. INTERNAL TRANSPORT SYSTEMSBlood & blood vessels. What the blood carries. Gas transport.

Transport in plants... xylem & phloem.

4. EXCRETION & WATER BALANCE

Importance of water for homeostasis.Kidney & nephron structure & function. Water balance in insects &mammals. Water conservation in plants.

Blood & Blood Vessels

Substances Transported

Transport in Plants

Kidney Structure& Function

Water Balance inInsects, Mammals

& Plants

Maintaininga Balance

Functions & Characteristicsof Enzymes

Factors which affectenzyme activity

Concept ofNegative Feedback

Hypothalamus &Effector Organs

TemperatureRange of Life

Temperature Regulation inEctotherms, Endotherms & PlantsINSPECTION COPY

for schools only


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Metabolism is ChemistryEverything that happens inside a living thing isreally a matter of cell chemistry... metabolism.For example...

For your body to grow, cells must divide and addmore membranes, cytoplasm and organelles. Thisinvolves the chemical construction of new DNAmolecules, new phospholipids for membranes andso on.

All these chemical reactions require energy.Energy is delivered by the ATP molecule, itself theproduct of a series of chemical reactions in themitochondria... cellular respiration.

All of these reactions are metabolism: the sumtotal of all the thousands of chemical reactionsgoing on constantly in all the billions of cells in

your body.

EnzymesEvery reaction requires a catalyst... a chemicalwhich speeds the reaction up and makes it happen,without being changed in the process.

In living cells there is a catalyst for every differentreaction. Biological catalysts are called enzymes.

Enzymes are protein molecules.

Each has a particular 3-dimensional shape, which

fits its substrate perfectly.

Enzymes are highly specific. This meansthat each enzyme will only catalyse oneparticular reaction, and no other.

Enzymes only work effectively in a relativelynarrow range of temperature and pH (acidity).

The Importance of ShapeMany of the properties of enzymes are related totheir precise 3-dimensional shape.

The shape of the enzyme fits the substrate

molecule(s) as closely as a key fits a lock.

This is why enzymes are substrate-specific...only one particular enzyme can fit each substrate

molecule. Each chemical reaction requires adifferent enzyme.

Changes in temperature and pH (acidity) can causethe shape of the enzyme to change. If it changes itsshape even slightly, it might not fit the substrateproperly any more, so the reaction cannot run asquickly and efficiently. This is why enzymes arefound to work best at particular optimumtemperature and pH values.

1. Enzymes & Homeostasis

Various

Different

Substrate

Molecules

Onlythisonefits

Enzyme shapeat optimum pH

andtemperature

Shape changesslightly at

different pH ortemp.

Substrate...

...no longerfits enzyme

Polymerisation

Polypeptide chain

Productreleased fromenzyme

Substratemolecules are chemically

attracted tothe enzymesactive site

Protein, with precise 3-D shape...

Substrate moleculesbrought together andreact with each other

Amino acid molecules

Twists& folds

...becomesan ENZYME

molecule

Enzymes

Active Site

has a shape

to fit the

substrate(s)

exactly ENZYME ENZYME ENZYME can reactwith more substrate

Enzymemolecule

From Amino Acids to Enzyme, to Metabolic ControlNSPECTION COPYfor schools only


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The pH ScaleThe acidity or alkalinity of any solution is measured on

a numerical scale known as pH.

On the pH scale, anything which is neutral(neither acid nor alkaline) has a pH = 7.

The inside environment of a cell, and most parts of an organisms body, is always very close to pH 7...i.e. neutral. An exception is in the stomach where conditions are strongly acidic. (approx. pH 2)

Optimum TemperatureNot all enzymes will peak at the same temperature, or haveexactly the same shape graph. In mammals, most enzymeswill peak at around the animals normal body temperature,and often work only within a narrow range of temperatures.

An enzyme from a plant may show a much broader graph,indicating that it will work, at least partly, at a wider range oftemperatures.

An enzyme from a thermophilic bacteria from a hot volcanic

spring will show a totally different peak temperature,indicating that its metabolism will perform most efficiently attemperatures that would kill other organisms.

76 8543 119 10

Neutralincreasing

acidityincreasingalkalinity

Temperature

1/timetakenforrea

ction(rate)

You may have measured the rate of a chemicalreaction being catalysed by an enzyme, such as: the rate of milk clotting by junket tablets. the rate of digestion of some starch by amylase

the rate of decomposition of hydrogenperoxide by catalase enzyme.

Enzyme Activity GraphsYou will have done experimental work to measure the activity of an enzyme under different conditions of

temperature, pH and the concentration of the substrate chemical.

A common way to measure the rate of a reaction isto measure the time taken for a reaction to reachcompletion... the shorter the time taken, the fasterthe reaction. This why the reciprocal of time taken

(1/time) is used as the measure of rate of reaction.

The Effect of TemperatureWhen enzyme activity is measured at different temperatures, the results produce a graph as below.

ExplanationsAs temperature rises the rate increases because themolecules move faster and are more likely to collide andreact. All chemical reactions show this response.

However, beyond a certain optimum temperature, theenzymes 3-D shape begins to change. The substrate no

longer fits the active site so well, and the reaction slows. Ifthe temperature was lowered again, the enzyme shape, andreaction rate could be restored.

If the temperature reaches an extreme level, the distortion ofthe enzymes shape may result in total shut-down of thereaction. The enzyme may be permanently distorted out ofshape, and its activity cannot be restored. We say the enzymehas been denatured.

ExperimentalPoints

0 20 40 60 80 100

Temperature (oC)

ReactionRate

MammalEnzyme

PlantEnzyme

Thermophilicbacteriaenzyme


INSPECTION COPYfor schools only


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When the temperature is kept constantand the enzyme tested at various pHlevels, the results will produce a graph asshown.

Generally, all intra-cellular enzymes (i.e.those from within a cell) will show peakactivity at about pH = 7, very close toneutrality.

Generally in any chemical reaction occurring in solution therate of the reaction increases if the concentration of thereacting chemical(s) is increased. The explanation is simplythat if the molecules are more concentrated, then it becomesmore likely that they will collide and react with each other.

When an enzyme is involved, the situation is a little morecomplicated:

Initially the rate of the reaction increases as the substrateconcentration goes up, just as it does with any reaction.

Soon though, the graph begins to flatten out and level offbecause the enzyme molecules are saturated withsubstrate and cannot work any faster.

2 3 4 5 6 7 8 9 10pH

1/time(rate)EnzymeActivity

Substrate Concentration

ReactionRate

ReactionRate

Substrate Concentration

Extra enzymeadded

Initial Increase

in Rate

Levels out


The Effect of pHThe digestive enzyme pepsin from the stomach shows anoptimum pH about 2 or 3, allowing it to work best in theacidic environment.

The explanation forthe shape is as follows:

at the optimum pH the enzymes 3-D shape is ideal for thesubstrate, so reaction rate is maximum.

at any pH higher or lower than optimum, the enzymesshape begins to change. The substrate no longer fits, soactivity is less.

at extremes of pH, the enzyme can be denatured and showsno activity at all.

EnzymeActivity

1 2 3 4 5 6 7 8 9 10 11pH

Intra-cellularenzyme

Pepsin.(Stomachenzyme)The shape of the pH

graph is usuallysymmetrical on

either side of thepeak.

Effect of Substrate Concentration

If, at this point, you were to add moreenzyme then the reaction rate would onceagain go up. It would level off again asthe enzyme molecules were once againswamped and saturated with thesubstrate.



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Therefore, it follows that an organismsbody and cells must be maintained atstable temperature and pH levels close to

the optimum for the enzymes.

The process of maintaining a stable,internal environment is called

Homeostasis.

HomeostasisMetabolism is largely a matter of chemical reactions, and each

reaction is catalysed by an enzyme. Enzymes are very sensitive to temperature and pH.

As well as regulation of temperature andpH, homeostasis involves the regulation ofmany other factors such as:

water and salt balance in body fluids.

blood sugar levels.

oxygen and carbon dioxide levels.

Feedback MechanismsA feedback mechanism is a situation where the result of some action

feeds back into the system to control the next change to the system.

In a Positive Feedback system any changere-reinforces itself by causing more change in

the same direction.

For example, a fire growing bigger...

small fire producesheat

Heat ignitesmore fuel

Heat ignites

more fuel

Producesmore heat

Positive Feedback

always causes a

system to grow

out of control, or

shrink away to

nothing.

It never results in

stability.

In Negative Feedback any change causes thenext change to be in the opposite direction.

A good example is an oven thermostat control:

The result is that the temperature of the ovenremains fairly stable. It oscillates up and downa little, but always stays close to thetemperature the oven was set at.

Turn heaterOFF

Turn heaterON

If temperatureis too high

If temperatureis too low

Oven

cools

Oven

heats

up

NEGATIVEFEE

DBACKACTION

NEGATIVEFEE

DBACKACTION

Negative Feedback

causes a system to

maintain stability.

TemperatureSensor

(detector)

The key parts of a negative feedback system are:

a receptor, to measure the conditions.

a control centre, which decides how to respond

and

effectors, which carry out the commands of thecontrol centre and make the necessaryadjustments to the system.

In animals, it is the Nervous System which islargely responsible for carrying out the receptorand control centre functions necessary for manyaspects of homeostasis.

In mammals, which maintain fairly constant bodytemperatures, it is the Hypothalamus at the base ofthe brain which monitors blood temperature andsends out command messages for negativefeedback, rather like the oven thermostat system.

Homeostasis is always Negative Feedback control.This ensures that stable conditions are maintained so that enzymes are operating near optimum.

Fire growslarger

Fire growslarger


Complete Worksheets 1,2 & 3.



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Temperature Controlin Mammals

In a healthy human the internal core temperature ofthe body is about 37

oC and is maintained within

about 0.5oC at all times. If the body temperature goes

up, or down, by more than about 4oC it is a life-threatening situation.

Control of body temperature is achieved as shownin this schematic diagram:

Main Parts of the SystemThe Receptor and Control Centre is theHypothalamus at the base of the brain. Specialcells constantly monitor the temperature of bloodflowing by. If the temperature varies by even a

fraction of a degree, nerve messages are sent tothe effectors.

The Effectors include blood vessels, sweat glands,endocrine (hormone) glands, muscles and bodyhairs.

IF BODY TEMPERATUREIS TOO HIGH

IF BODY TEMPERATUREIS TOO LOW

COOLING MECHANISMSBlood vessels dilate.

Sweat glands activated.Hair lowered.

Metabolic rate reduced.

WARMING MECHANISMSBlood vessels constricted.Muscles begin shivering.

Hairs erected (goose bumps).Metabolic rate increased.

BODY TEMPERATURE REDUCES,

BLOOD COOLS

BODY TEMPERATURE INCREASES,

BLOOD WARMS

Nerve

Command

to

Effectors

Nerve

Command

to

Effectors

What the Effectors Do

Blood VesselsDilation (widening) of veins,

arteries and capillaries near the

skin allows more blood to flowout near the skin surface.

This allows more body heat toescape from the skin, thus

cooling the body.

Constriction (narrowing) ofblood vessels causes less

blood to flow near skin. Lessheat flows out to the skin to be

lost, somore body

heat isretained.

Body HairsEach hair on your body has atiny muscle at its base which

can cause the hair to stand uperect and give you goosebumps. This traps a layer of still

air against the skin and helpsinsulate and prevent heat loss.

If the hair follicle muscle isrelaxed the hair lies flat and

allows more heat loss.

2. Temperature Regulation

Hypothalamusmonitors blood

temperature

Cerebrum

Cereb

ellum

Blood

temp.

measu

red

Bloodte

mp.

measu

red

MusclesNerve signals can cause the skeletalmuscles to begin shivering. This

extra muscle activity generatesmore heat to warm the body.

Sweat Glands

When activated, the sweat glands secrete perspiration.The water evaporates from the skin, carrying away body

heat... this has a powerful cooling effect.

Hormonesare chemicals which control

various body functions.

The hormone thyroxine(produced by the thyroid gland in

the neck) controls the rate ofmetabolism. It is under the

control of the hypothalamus, via

another hormone from thepituitary gland.



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Extreme HeatThere are thermophilic bacteria (members of theArchaea) which live and thrive in volcanic hotsprings at temperatures up to 120

oC.

In terrestrial environments such as hot deserts, thetemperature can often reach 40

oC and sometimes

as high as 60oC. Many plants and animals are

adapted to survive these extremes, but few remainactive in this heat. Generally in deserts the animalsseek shelter and become inactive, while plantsshut down their metabolism and merely survive.

Cold Water EnvironmentsEven when ice forms on the surface, waterenvironments rarely fall below +4

oC, and are

remarkably stable in temperature. Life-forms donot need to cope with change, although mammalsor birds need serious insulation to stay warm. It isthe terrestrial environment that is more of achallenge.

In prolonged periods of cold weather, such aswinter in the Australian Alps, ectotherms cannotremain active.

Animals such as the CopperheadSnake and the Corroboree Frogseek shelter underground and

become dormant throughout thewinter.

In a process similar to thehibernation of bears, the animalsheartbeat and breathing slow down,their metabolism almost stops andtheir body temperature chills toonly just above freezing.

As long as they are more than about 50centimetres underground, the ground will notfreeze even though buried in snow for several

months. If they havent burrowed deeply enoughthey will freeze to death!

The Temperature Range of LifeHomeostasis allows an organism to maintain its cells at a temperature close to

the optimum for its enzymes. This allows its metabolism to run efficiently,despite changes in the temperature of the surrounding environment.

However, homeostasis has its limits, and no organism can remain active and thriving underthe full range of temperatures of the biosphere of the Earth. Different organisms have

adapted to survive in extreme cold, or in extreme heat, but never both.

Extreme ColdThere are many organisms which can surviveextreme cold, but few that remain active. Certaintypes of algae and photosynthetic bacteria arefound to live within the snow and ice near the polesand are still metabolically active at temperatures aslow as -10

oC.

Generally however, plants and animals cannot toleratetheir body temperature going below 0

oC, since ice

crystals forming in cells can destroy membranes andkill cells. Also, the chemical reactions of metabolismrun so slowly at low temperature, that life functions

are not possible.

Of course, many animals do live and survive in thecold because they can produce their own body heat(mammals and birds) and are equipped with bodyinsulation and homeostatic mechanisms to maintaintheir core temperature despite the cold environment.Perhaps the world champions are the EmperorPenguins which maintain core body temperaturesaround +33

oC throughout the Antarctic winter in air

temperatures as low as -50oC.

Temperature Control in EctothermsEctotherms are the cold-blooded animals, such as reptiles, amphibians, insects, fish, worms, etc.Cold-blooded is a misleading term and is best avoided, since these animals are NOT always cold,

but rather they rely on the outside environment for their body heat...they do not generate heat internally like a mammal or bird.

Ectotherms have a variety of adaptations, many ofthem behavioural, to regulate their bodytemperature and keep it within the range in whichthey can be active; generally 10-30

oC.

For example, the Blue-Tongue Lizard will lie ina sunny spot with itsbody flattened andturned side-on to theSun on a cool morning.This way it absorbsheat more quickly toget its bodytemperature highenough to becomeactive.

As the day becomes hotter, the lizard will turnfacing the Sun to absorb less heat, and seek shade

to avoid over-heating.

Bluey sun-baking




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Page 9

Inspection Copy for Schools only.

All endotherms rely heavily on having bodyinsulation... fur, feathers or blubber (fat). Humansrely mostly on technology to provide heaters,jackets, wetsuits, gloves, etc, to protect our fragilebodies from extremetemperatures.What do endothermic animals inthe wild do?

Firstly, they have all theresponses for homeostasisdescribed earlier... dilation orconstriction of blood vessels,shivering and sweating etc. Aswell as these, they may haveextra adaptations to helpregulate their temperature.

Temperature Control in EndothermsEndotherms are the animals which produce their own internal body heat

and maintain a constant body temperature... the birds and mammals.

In hot environments such as the Australiandeserts, mammals such as the Red Kangaroo orthe Bilby, have many adaptations to help themcool their bodies:

Large ears, with many blood

vessels, increases the surfacearea for heat loss.

They seek shade in the heat ofthe day.

Panting evaporates water fromthe mouth and throat, andcools the blood.

They may lick their forearms.The evaporation of saliva coolstheir body the same as

sweating.

In the desert, big ears are cool!

In the cold, endotherms go for thick fur coats (Wallaroo) or layers of fat (Australian Fur Seal).

Penguins, such as the Fairy Penguins along Australias southern coast, have a specialblood shunt in their legs. In warm conditions the shunt is closed and blood flows normally

to the feet. Since the feet are about the only part of their body not well insulated, in cold waterthey could lose a lot of body heat. So in cold water the flow of blood from body toward

the feet is shunted via a special vein with a valve in it, back into the body.The feet receive virtually no blood, and this conserves body heat.

Responses of Plants to Temperature ChangePlants cannot respond to temperature change by moving away or hiding.

To cope with temperature extremes they must have structural or physiological adaptations.

When it is hot and DRY, they have a problem.Desert plants tend to have very small leaves andthick, stocky shaped stems. This reduces thesurface area being hit by heat radiation from theSun, and helps prevent over-heating. The cactiplant group have taken the strategy to the limit...their leaves are spines, and stems are fat androunded. They are also light coloured to reflect alot of the radiant heat away. They have very fewstomates.

The sclerophyll plants ofAustralia (e.g. gum trees) alsohave small narrow leaves toreduce heat absorption fromthe Sun. Their other trick is toallow the leaves to droop. Thisallows them to catch light forphotosynthesis in the coolermorning when the Sun is low,but avoid absorbing heat whenthe Sun is overhead at midday.They have few stomates, and

close them in dry times.

To cope with seasonal cold weather, many plants(especially in the northern hemisphere) aredeciduous... they shed their leaves and basicallyshut down their metabolism for the winter, ratherlike an animal hibernating. Their leaves cannot beprotected from freezing, so the strategy is to losethe vulnerable parts, survive until next spring, thengrow new leaves.

Coping with heat is another story.

If there is plenty of wateravailable, such as in atropical jungle, then theplants cool themselves byallowing maximumevaporative cooling. Theleaves open their manystomates and allowtranspiration to occur. Theevaporation has a coolingeffect, in the same way thatsweating cools an animal.

Narrow,droopinggum tree

leaves


Complete Worksheets 4 & 5.



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BloodYou willhaveexaminedbloodunder amicroscopeand seensomethinglike this:

Blood is made of a liquid (plasma) withmillions of special blood cells carried in it.

Arteriescarry blood from the heart out to thebody tissues. The walls of an artery are relativelythick and muscular to withstand the high pressure inthe blood when the heart pumps.

Artery walls are very elastic, and when a pulse ofhigh pressure blood passes through, they expandoutwards and then contract again, helping to pushthe blood along. This rhythmic expanding andcontracting is what you can feel as your pulsewherever an artery is close to the skin, such as inyour wrist or throat.

3. Internal Transport Systems

Sketch of Blood Cells

RedCells

Shaped like a

donut with thehole closed over

nonucleus

large, irregular nucleus

There are about 600 redcells to 1 white cell

VEIN Cross-Section

Side view of VEINshowing a valve.

Blood can flow one way,but not back the other.

Relatively thin walls areoften squashed by

surrounding muscles.

RED BLOODCELLS

Size

7 mMost

white cellsare much

larger thanred cells

Internal Transport in MammalsAs with most animals, for internal transport mammals rely on their Circulatory System...the blood, heart and blood vessels; veins, arteries and capillaries. A basic knowledge of

how the system operates was covered in Preliminary Topic 2.

Thick, muscular walls

bloodflow


You need to be able to sketch diagramsof blood cells, and have an ideaof their relative sizes.

There are 2 general categories of these cells:Red Blood Cellscontain the red pigment haemoglobin, which carries oxygen.This is covered in more detail later in this topic.

White Blood Cellscome in a huge variety of types, but all are involved withdefence against disease. This is covered in a later topic.

Capillariesare the tiny blood vessels which form a network throughout the tissues so that everyliving cell is close to the blood supply. The walls of a capillary are only 1 cell thick, so diffusion of

substances from blood to cells (or cells to blood) is easily achieved.

The inside of a capillary is so small that red blood cells often travel through it in single file.

Blood VesselsAs the blood flows around the body it is always carried inside tubes, or vessels:

Veinscarry blood back from the body tissuesto the heart. The blood here is under lowerpressure and the walls of a vein are relatively thin.With little pressure to push blood forward, it is thecontraction of the surrounding muscles whichhelps push the blood along.

Some veins contain valves to prevent back-flow ofthe blood.



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Oxygen O2 is carried in the redblood cells by haemoglobin.

Carbon Dioxide CO2is partly carried by the haemoglobin

in red blood cells, but most of it iscarried in the blood plasma, in theform of bicarbonate ions (HCO3

-)

Water is carried as the liquidsolvent of blood plasma.

Salts, Sugars &Amino Acids

These are nutrients absorbed fromthe Digestive System. They aregenerally water soluble and arecarried dissolved in the blood plasma.

Lipids (Fats)absorbed from the digestive system are packaged in aprotein coat which makes the fat molecule miscible inwater. This means that, while not fully dissolved, themolecules can be dispersed in water and carried withoutjoining together into droplets of fat and separating fromthe water.

In this form they are carried dispersed in the bloodplasma.

Nitrogenous Wastessuch as urea, are water soluble and carried dissolved inthe blood plasma.

Prac Work: CO2 and Acidity

You will have carried out anexperiment to see the effect ofdissolved CO2 on the pH of water.

You might have chemically producedsome CO2 and bubbled it throughwater. Using a pH meter, or UniversalIndicator, you will have measured anychange in the pH of the water.

You would have found that the pHwent down... i.e. the water becamemore acidic.

Explanation and ChemistryCarbon dioxide reacts with water toform carbonic acid

CO2 + H2O H2CO3

Carbonic acid is a weak acid whichpartly ionises

H2CO3 H+

+ HCO3-

Substances Carried in the Blood

Hydrogen ionmakes water more acidic

Bicarbonate ion.This is how CO2 is

carried in the blood.

The Need to Remove Carbon DioxideCarbon dioxide doesnt just dissolve in water, it reacts to form a weak acid.

Its the hydrogen ions that createproblems. Hydrogen ions are acids andcan lower the pH of a cell or the blood.

At the concentrations produced by atypical cell, the hydrogen ions could easilylower the pH of the cytoplasm by 0.5 pHunit or more. This might not sound like

much, but it could be life-threatening.

Remember that enzymes are verysensitive to pH changes and quicklychange shape and lose their catalyticactivity. This would be disastrous for cellmetabolism.

To avoid this problem, CO2 is carriedaway in the blood as rapidly as it is

produced in the cells.

CO2 + H2O H2CO3 H+

+ HCO3-

carbonic hydrogen bicarbonateacid ion ion



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CHANGESINNUTRIENTS,

WATER&WASTES

ASTHEBLOODCIRCULATES

Nutrients &Nitrogenous Wastes

As the blood flows through capillaries in the

digestive system it picks up sugars, amino acids,salts, water, vitamins, etc that have beenabsorbed from the gut. (However, lipids are firstabsorbed into the lymphatic drains and enterthe blood much later)

This blood from the gut is collected in a veinwhich takes it directly to the liver. Here some ofthe nutrients may be absorbed from the blood forstorage or chemical processing (e.g. glucose isextracted from the blood and polymerised toform glycogen for storage in the liver). Also in theliver, large amounts of the waste chemical ureais added to the blood to be carried away for

excretion.

Later, as blood flows through capillaries in bodytissues such as muscle or bone, nutrients areabsorbed from the blood into the cells whichneed energy (glucose) and new chemical buildingblocks (amino acids, lipids).

Sooner or later, every bit of blood flows throughthe kidneys which extract the urea and excesssalts and water for excretion as urine.

Changes to the Blood as it CirculatesAs the blood circulates around the body its chemical composition

undergoes a number of changes...

Heart

Wastesinto

blood

Liver

Gut

Arteries

Veins

Nutrients move from blood into cells

DigestedNutrients

moveinto blood

Some Nutrientsinto storage

Wastes andexcess water & salts leave blood.

Excreted in urine.

Blood flow

in Lungs

Kidneys

Blood flow

in Body tissues

Respiratory Gases O2& CO2Gas exchange and transport is essential fordelivering oxygen to cells and removing CO2.

As blood passes through capillaries in bodytissues, oxygen is released from the haemoglobinmolecules and diffuses along the concentrationgradient into the body cells. There is always a

concentration gradient favouring this because thecells are constantly using up oxygen for cellularrespiration.

Meanwhile, the concentration of carbon dioxide ishigh because of its constant production by cellularrespiration, so it diffuses from the cells into theblood.

When the blood gets to the lungs the oppositeoccurs. Inside the alveoli (air sacs of the lungs) theair has a very high concentration of oxygen and isvery low in CO2. Therefore, oxygen diffuses into the

blood, while carbon dioxide diffuses from the bloodinto the air.

O2

O2

CO2

CO2

Oxygen

Air Blood

OxygenBlood Cells

Carbondioxide

Blood Air

Carbondioxide

Cells Blood

Heart

Arteries

Body tissues

Veins

Lungs

CHANGES IN OXYGEN ANDCARBON DIOXIDE

AS THE BLOOD CIRCULATES




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Blood is red because of the many redcells, and red cells are red becausethey are packed with the red-coloured,iron-containing protein haemoglobin.

In the lungs, where the oxygenconcentration is very high, someoxygen dissolves in the moisture lining the alveoli thendiffuses into the blood and dissolves in the plasma..

Oxygen is not very soluble in water, however, and if thats allthere was to the story, then our blood could never carryenough oxygen to supply our cells.

Haemoglobin molecules have a great attraction for oxygenmolecules and quickly grab any O2 molecules available.Because of this, our blood can carry thousands of times moreoxygen than would be possible by simply dissolving oxygen in

the blood plasma.

When the oxygenated blood gets to the body tissues thereverse happens.

Hb + O2 HbO2

abbreviation forHaemoglobin Oxyhaemoglobin

The concentration of O2 and CO2 in theblood is of great interest to doctorsmonitoring a patient, or an athlete intraining, or even to a pilot or mountain-climber at high altitude.

The most important measurement ispercentage oxygen saturation(%SpO2). A reading of 100 wouldmean that 100% of all haemoglobin in

an artery is totally saturated withoxygen. Readings between 95-100%indicate good health, fitness andadequate oxygen supplies.

Lower readings (e.g. 80%) couldindicate: respiratory or circulatory problems

in a patient. lack of fitness, or excessive exertion

in an athlete.

need for supplementary oxygen fora pilot or climber.

The Importance of Haemoglobin

The high concentration of dissolved CO2lowers the pH of the blood slightly. Thiscauses the haemoglobin proteins tochange shape slightly and release theoxygen molecules.

HbO2 Hb + O2

The oxygen diffuses into the cells, and thefreed haemoglobin molecules can pick upsome of the CO2 molecules and carry themback to the lungs.

Adaptive AdvantageHaemoglobin increases the oxygen-carrying ability of blood enormously. Itsuse in some ancient creatures primitivecirculation system gave that animal a huge

advantage to survive. With more oxygen, itcould move faster, grow faster and largerand breed more successfully.

Many animal types descended from thatancient success. Haemoglobin is a greatadaptation.

In years gone by, %SpO2 was measured bytaking blood samples and carrying outcomplex chemical testing. With moderntechnology, however, the readings are doneinstantly and non-invasively by a small,portable instrument clipped onto the end of afinger, ear lobe or foot.

The Oximeter works by sending red lightand infra-red beams through the flesh. The

amount of each light absorbed by thehaemoglobin gives a direct measurement of%SpO2, because haemoglobin with, orwithout,oxygenabsorbsthese lightbeamsdifferently.

Oxygen Saturation & Its Measurement

Foot-clamp Oximeter measures%SpO2 in a young patient



14/38




Perfluorocarbon-Based SubstitutesAnother area of research aims to develop a truly artificial blood substitute. The most promising basechemicals are the perfluorocarbon compounds. These can carry up to 5 times more oxygen than

blood and can be stored indefinitely at room temperature.They can be made totally sterile and disease-free.

At least 5 different products are being tested and trialled (USA),but none are yet approved for medical use. Trials in 2008 produced very negative results.

Artificial Blood?

Products of Blood DonationThe Australian Red Cross Blood Service collects about a million blood donations per

year. Most of this blood is used for people who need regular treatment withblood products for conditions such as leukemia. Only a very small amount is kept as whole blood for

emergency transfusions. Most donated blood is separated into about 20 different fractions or products,so each donation can treat many different patients.

The main blood products are:

Red Cell Concentratewhich contains about twice asmany red cells as normal, is used toboost the oxygen-carrying capacityof patients withanaemia or after blood loss, suchas might happen in a motoraccident.

Platelet Concentrateis given to patients who need extra

blood-clotting capability, such asleukemia sufferers, or followingsevere blood loss.

White Cell Concentrateis given to patients needing a boostto their immune system, perhapsfollowing a severe infection.

Plasmais the liquid part of the bloodand is often given in emergencyto boost the volume of bloodfollowing severe blood loss.

Cryoprecipitateis a fraction collected fromplasma and contains blood-clottingfactors. It is used to treatsevere bleeding.

Factor VIII and Monofixare extracts from plasma used totreat people who have haemophilia... aninherited, incurable disorder in whichthe blood will not clot properly.These blood products allow patientsto lead a relatively normal life.


Haemoglobin-Based Oxygen Carriersis one of the areas of current research.

Haemoglobin extracted from animal blood canbe purified and treated so that it is disease-free

and cannot cause any allergic or rejectionresponses in patients.

The products can be stored for years at roomtemperature, and promise to be highly effective

at carrying oxygen and releasing it into thetissues.

Currently undergoing clinical trials, but not yetapproved for medical use. Recent trials failed.

The Need for Artificial Blood

Fresh blood cannot be stored for long, andmany parts of the world lack the necessary

storage facilities.

Many blood products can set off immune-responses in long-term patients, even aftercorrect blood-typing. (Similar to rejection

of a transplanted organ)

Donated blood can carry diseases, such ashepatitis or HIV.

Many of these problems could be solved bythe use of an artificial blood which is easy

to store and can be made disease-free.



15/38





Xylem Tubes Carry WaterXylem tubes are dead, hollow cells, joined end-to-end forming a continuous tube from root toleaf. The xylem tubes transport water (and

dissolved minerals) generally upwards fromroots to leaves.

Transport Systems in Plants

Cohesion & AdhesionAnother factor which helps the process is calledcapillarity or the capillary effect. This is theway that water can climb up the walls of acontainer forming a meniscus in a test tube, for

example. This happens because water moleculesare not only attracted to each other (cohesion)but also to some other substances such as glassor the inside of a xylem tube. This attraction iscalled adhesion.

In very narrow tubes (capillaries) the water willclimb upwards against gravity because ofadhesion, and drag more molecules along bycohesion. This happens in xylem and helps liftwater upwards.

The veins in a leaf contain both the xylem &phloem tubes. Veins also act as ribs to helpkeep leaves in shape.

Active & Passive TransportNote that the flow of water in the xylem costs theplant nothing in energy terms... it is passivetransport.

In contrast, the other transport system in plants

is an active transport system... the plant mustconstantly supply energy to make it happen.

Photo at left: Scanning Electron Microscope (SEM)image of plant stem showing hollow xylem tubes.

Creative Commons Attribution-Share Alike 3.0 unported licence.Image by McKDandy at en.wikipedia.

Transpirationis theevaporation of water from theleaves. When the stomates areopen, water can constantlyevaporate, creating a tension, or

pull in the remaining water in theleaves.

Water molecules are quite stronglyattracted to each other and tend tocling tightly together. This force iscalled cohesion and is the reasonthat water tends to form droplets...little blobs of water that clingtogether.

So, when water evaporates fromleaves and creates a pull force,each water molecule pulls on thosebehind it because of the cohesion.Each molecule pulls others upwardand so the entire column of water ina xylem tube moves upwards toreplace the water lost bytranspiration. So water is pulledupwards by a combination oftranspiration and cohesion. Thisflow is called the transpiration

stream.

Hollow, dead cells, joinedend to-end forming a tube

Cell wallsre-inforcedwith ringsand spirals

of lignin

How do xylem tubes lift water upwards against the force of gravity?



16/38




PHLOEM CELLalive and filled with cytoplasm.

Flow of cytoplasm carries sugarsthrough each cell.

Sieve plate between cells.

Companion cellhas many

mitochondria toprovide ATP to the

phloem cell

Sugars areactively

transported inthe flow of

cytoplasm withinthe cells.

Translocation Works 2-Ways

While the xylem is a one-way flow system, thephloem system can carry food (especiallysugars) in either direction.

If a lot of photosynthesis is occurring, thephloem will carry sugar to storage sites inroots or stem.

If photosynthesis is not possible for anextended time, then the phloem willcarry sugars back from the storage

sites to feed the leaf cells, or supplya growing flower or fruit.

Phloem Tubes Carry Food NutrientsWhile the xylem tubes are formed from dead cells, the phloem are

living cells joined end-to-end. The ends of each cell are perforated (sieve plates)

so each cell is open into the next and they form a continuous tube.

The transportation of nutrients through thePhloem Tubes is called Translocation.


What Makes the Sap Flow?The flow of nutrients through the phloem iscaused by pressure differences between theSource tissues and the Destination.

The pressure difference is osmosic pressure,generated by active transport of sugars causingwater to flow into, or out of cells.

SOURCEHigher

Pressure

DESTINATIONLower Pressure

PHLOEM

TUBES

Translo

cation

Sugar is removed byactive transport, requiringenergy. Water flows out of

cells due to osmosis,lowering the pressure.

Sugar solutionflows due to

pressuredifferential

Translocation...

how it works

Sugar is carried into cellsby active transport,

requiring energy. Waterflows in due to osmosis,

raising the pressure.

The veins in a leaf are bundles of tubes with both xylem AND

phloem. There are also many strong fibres which add strength andhelp keep the leaf in shape so it gathers light without drooping.

After this page,

complete worksheets6, 7, 8, 9 & 10.



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Water is the Solvent of Life

All the chemical reactions of metabolismtake place in water solution, and thetransport of materials in cytoplasm, bloodor phloem takes place mainly in watersolution.

Water RegulatesTemperature

Water has a very high specific heatcapacity. This means it can absorb (orlose) relatively large quantities of energywith minimal temperature change. Thishelps stabilise the temperature of allliving things.

Water also has a very high heat ofvaporisation. This means that when itevaporates it absorbs huge amounts ofheat. This is why evaporation ofperspiration from the skin has such acooling effect.

4. Excretion & Water Balance

THE CONCENTRATION OF WATER &DISSOLVED SALTS MUST BE MAINTAINED

THIS IS ANOTHER EXAMPLE OFHOMEOSTASIS

IN MOST ANIMALSWATER BALANCE IS REGULATED

BY THE KIDNEYS

The Importance of WaterLife cannot exist without water. All living cells are at least 75% water.

The functions of water in living things include:

Water Supports &

Cushions Cells & OrgansMany plants and animals rely on water forbody support. Non-woody plants pumptheir cell vacuoles full of water to makecells tight and keep stems and leavesupright. Animals such as worms rely onthe hydraulic pressure of water in theirtissues to support their body and maintainits shape.

In vertebrate animals the water solutionsin the tissues helps to cushion organsagainst bumps and impacts. (e.g.cerebrospinal fluid around the brain)

Water is Involvedin Life Chemistry

Water is a reactant or product of manymetabolic reactions. The reactions ofphotosynthesis and cellular respiration arejust two of the many examples.

Homeostasis of Water & SaltsIts not just the water that is important, but its

concentration, and the concentration ofsubstances dissolved in it, such as salts.

If the concentrations are not kept at thecorrect levels, then osmosis may cause

problems. Cells could lose water anddehydrate, or gain too much water and bedamaged or even burst open by increasing

pressure within.

Bladder

Kidney

Ureter

Lungs

Heart

Liver

Stomach

Major Internal Organsin a Human




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Metabolic WastesThe many chemical reactions of metabolismsometimes produce chemicals which are toxic tocells, often because the chemical, when dissolvedin water, can change the pH and reduce enzyme

activity.

Therefore, it is essential that these wastes areremoved (excreted) as soon as possible. Themajor wastes are:

Carbon dioxideis produced by cellular respiration. As coveredpreviously, it will lower the pH (its acidic). It iscarried in the blood and excreted by the lungs.

The fish can get away with production ofhighly toxic ammonia. They can rely on

constant diffusion of ammonia from theblood in their gills into the waterenvironment which surrounds them.

In terrestrial environments, waste gasescan do exactly the same; thats howcarbon dioxide is excreted... by simplediffusion from the blood to the air in thelungs.

However, nitrogenous wastes are not

gaseous and need to be excreted in watersolution.

Kidneys Also Excrete Metabolic Wastes

Nitrogenous wastes(contain nitrogen)These wastes are produced mainly from themetabolism of proteins.

There are 3 main compounds that can beproduced:

Ammoniain most aquatic animals.

Uric acid in birds, reptiles & insects.

Ureain mammals and amphibians.

Excretion & Water Balance in FishFish produce the waste ammonia which is very alkaline and toxic. Luckily it is very soluble in water.Since they live surrounded by water, fish simply excrete ammonia from their gills by simple diffusion.

Their kidneys are used not so much for excretion, but for maintaining their water balance.Freshwater fish and saltwater fish have opposite problems with water balance.

SALTWATER FISH

Water loss from tissues by osmosis(mainly through gills)

Gills excrete Ammonia,Carbon Dioxide and

excess salt

Constantlydrink toreplacewater

(but getsalt, too)

Kidneys producesmall amounts ofurine to

save water

FRESHWATER FISH

Tissues gain water by osmosis(mainly through gills)

Kidneys produce a lotof dilute urine to

remove waterfrom body

Do not drink

Gills excrete Ammonia &Carbon Dioxide, andactively absorb salts

Excretion in Terrestrial Environments

Consequently, in land-living animalsnitrogenous wastes are produced not as

ammonia, but the less toxic compoundsurea (mammals) or uric acid (birds,reptiles, insects).

Excretion is via the kidneys. The simpleprocesses of diffusion and osmosis arenot adequate to achieve this.

For simple diffusion to achieve excretion itwould require huge amounts of water to beexcreted too, and no terrestrial animal can

afford to lose so much water, especially in adesert.

INSPECTION COPY for schools only


19/38





Each kidney contains about 1 million nephrons. Each nephron is acomplicated tangle of blood vessels and renal tubules (= smalltubes). What happens in a nephron is:

Filtrationremoves some of the water and many small dissolved molecules(including the waste urea) from the blood into the renal tubules. Thisoccurs because the walls of the glomerulus are leaky and theblood is under high pressure.

Reabsorptionthen occurs to move useful substances back into the blood.This is achieved by:Active Transportof sugar, amino acids & salts from the renaltubules back into the blood. This requires energy to be used totransport these chemicals across the cell membranes, against aconcentration gradient.Osmosisthen occurs, which causes water to flow from thetubules back into the blood. This is Passive Transport and coststhe body no energy.

Blood in

from artery.

Blood out

to vein

This blood

contains urea

This blood has had wastes removed, andwater balance adjusted for Homeostasis.

Glomerulusa coiled blood vessel

Bowmans Capsulea receiving cup to

collect the filtrateliquid from the

blood Blood CapillaryNetworkshown in

simplified form.

Renal Tubules

Urine

flows to

collecting

duct

then via

Ureter to

Bladder,

for

excretion.

THE NEPHRONof the KIDNEY

(simplified)

Filtrationoccurs

here

Filtration is the process in which somewater and many dissolved substances

(including sugar, salts & urea, BUT NOT anycells or blood proteins) leave the blood and

flow into the renal tubules.

Reabsorptionis the process in whichany useful substances (such as sugars &amino acids) are absorbed back into the

blood. Water & salts are also reabsorbed, butin varying quantities... the body is adjusting

water balance for Homeostasis

Urea is not reabsorbed back into the blood.Urea and some water continue along the tubule. This liquid is URINE.

Urine flows into the Ureter and is carried to the Bladder for storage.When the bladder becomes full, the urine is excreted via the Urethra.

Reabsorptionoccurs

here

Arterycarries bloodinto kidney.

Kidneyremoveswastes fromblood andadjustswater& salt balance.

Veincarries bloodout of kidney.

Uretercarriesurine tobladder.

Bladderstores urine.

Urethradrains urine from bladder.

How the Kidneys Work in Mammals

INSPECTION COPY

for schools only


20/38




The Kidneys & HomeostasisThe kidneys are not just used for excretion. As well, the kidneys can adjust the water balanceof the body by allowing more, or less, urine to be produced. In this way the kidneys are a vital

part of homeostasis.

Once again, the Hypothalamus is involved, but the control mechanism is by hormones... chemicals which are releasedinto the blood and exert a control function on some target organ. In this case the hormone is called Anti-Diuretic

Hormone (ADH) and the target organ is the kidney, specifically the nephron tubules.

WATER LEVEL INBODY TOO LOW

WATER LEVEL INBODY TOO HIGH

Pituitary Glandreleases more ADH

(Also nerve signals to braincause thirsty feeling so

you will want to drink)

Pituitary Glandreleases less ADH

(Also nerve signals to braincause feeling that you do

NOT want to drink)

BODY RETAINS MOREWATER, excretes less urine.Urine is more concentrated

BODY PASSES MOREWATER, excretes more urine.

Urine is more dilute.

NerveCommand

toPituitaryGland

NerveCommand

toPituitaryGland

ADH causes morereabsorption of waterfrom kidney tubules

Less ADH causes lessreabsorption of waterfrom kidney tubules.

Cerebrum

Cereb

ellum

Water

/Saltb

alanc

e

measu

red

Water

/Saltb

alanc

e

measu

red

Note the typical pattern of anegative feedback system

HYPOTHALAMUS&

PITUITARY GLAND

Practical WorkYou may have dissected a kidney in yourlaboratory work in class.

You need to be able to relate the grossstructure of the kidney to the structureand functioning of the nephrons.

This diagram may help you understandyour kidney dissection a little better.

DISSECTEDKIDNEY

Ureter carriesurine to bladder

Artery & Vein

Renal CortexDark red in colour due

to the many bloodcapillaries of the

nephrons

MedullaLighter in colour...less blood vessels.

Here manycollecting ducts

carry urine to theureter.


Kidney Structure & Nephrons



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Addisons Disease & HRT

Addisons Disease occurs when apersons adrenal glands do not produceenough aldosterone. Their nephrons

constantly fail to reabsorb salt and so theosmotic balance of the body ischronically out of order.

This leads to a variety of problems andmalfunctions throughout the bodyinvolving the heart, intestines and liver,and may cause psychological disordersas well.

This is a disease that can be sucessfuly

treated by Hormone ReplacementTherapy (HRT).

A person with Addisons Disease can betreated with appropriate doses of steroidhormones (usually cortisone) andalthough they cannot be totally cured,they can lead a normal, symptom-free lifeon HRT.

Sitting on top of the kidneysare the Adrenal Glandswhich produce a variety ofhormones. One of the adrenalhormones is Aldosteronewhich controls reabsorptionof salt from the nephrontubules.

If salt levels are too low, special cells inthe adrenal glands increase theproduction of aldosterone into thebloodstream. This causes the cells liningthe nephron tubules to actively transportmore sodium ions back into the blood.Chloride ions follow the sodium, and so

more salt is reabsorbed.

If salt levels are too high, the adrenalglands produce less aldosterone so lesssalt is reabsorbed, and the excess salt isexcreted in the urine.

Between ADH and aldosterone the bodymaintains a constant osmotic balance ofwater and dissolved salt... Homeostasis.

Adrenal

Gland

Water & Salt Balance Hormones

The hypothalamus monitors the blood flowing through it for the osmotic balance of waterand dissolved salt. If the body is even slightly dehydrated, more ADH is released by thepituitary gland and circulates in the blood stream.

The effect of ADH is to alter the permeability of the membranes lining the tubules of the

kidney nephrons. Increased ADH levels make the membranes more permeable to water,so more water is reabsorbed back into the blood. This means that less urine isproduced.If the body is over-hydrated, the production of ADH is reduced. This causes the tubulesto become less permeable to water so less is reabsorbed into the blood. The result ismore urine being produced.

ADH is the hormone controlling the water levels, but this is only part of the osmoticbalance story... the salt levels can be controlled too... see below.


Control of Salt Levels by Aldosterone



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If a persons kidneys cease functioning properly he/she can no longer remove toxicwastes such as urea from the blood, nor maintain homeostasis of water balance.In the case of complete kidney failure, this conditioncan be fatal within about 3 days without treatment.

Over the past 40 years or so, many people havebeen successfully treated by receiving a kidneytransplant. However, they may have to wait monthsor years to find a suitable organ donor.

Meanwhile, they need to be treated by RenalDialysis... the use of medical technology to remove

wastes from the blood artificially. Ineffect, a renal dialysis machine is anartificial kidney.

Dialyser CartridgeThe key component of a modern dialysis machine isa disposable dialyser cartridge.

The patients blood flows through the cartridge fromone end to the other inside thin dialysis tubes.

These tubes are made from a plastic which is semi-permeable.

The tubes are surroundedby a dialysing fluidwhich flows through thecartridge in the opposite

direction.

The dialysing fluidcontains water, salts,sugars, minerals etcexactly as in healthy blood plasma. Since

there is no concentration gradient for these chemicals they do not diffuse in or out ofthe blood. However, the wastes such as urea are in higher concentration in the blood,and so they diffuse from the blood into the dialysis liquid, which is later disposed of.

Similarities

Both processes removeurea and other wastes fromthe blood.

Both rely on movement ofdissolved substancesthrough semi-permeable

membranes.

Blood out

Blood flowsthroughdialysistubes

Dialysingfluid in

Blood in

Dialysingfluid out

Renal Dialysis

Dialyser cartridge

Dialyser cartridge

Comparison of Renal Dialysis with Natural Kidney FunctionDifferences

Kidney function involves the 2 steps of filtrationand reabsorption; dialysis involves only 1 step ofdiffusion of wastes from blood.

In a kidney, movement across membranes isachieved by both active transport and by passiveosmosis and diffusion; dialysis involves only

passive diffusion.

INSPECTION COPY

for schools only


23/38





The different conditions of each environmentdictate what an animal must do to to achievehomeostasis of its water balance. In eachenvironment there are different problems to beovercome, and the animals body organs mustrespond appropriately. Exactly how homeostasis isachieved will be reflected in the urine the animalproduces.

Comparison:Urine Productionin Different EnvironmentsMarine Fishproblem:constant loss of water by osmosis.urine:small amount, to conserve water.Urine does not contain wastes, since ammonia isexcreted from the gills.

Freshwater Fishproblem:constant gain of water by osmosis.urine:large volume, to remove water.Urine does not contain wastes, since ammonia isexcreted from the gills.

Terrestrial Mammalproblem:must excrete wastes in urine, but cannotafford to lose too much water, especially in dryAustralian ecosystems.urine:generally small volume, to conserve water.Urine is relatively highly concentrated in wastessuch as urea.

Water Balance in Australian Animals

Water Conservation &Excretion in Insects

All insects are small, and most are adapted forflight. This means they cannot afford to carry largeamounts of water in their bodies just for thepurpose of excreting urine. Their excretory systemmust be able to remove nitrogenous wastes, whilelosing only a minimum of water.

Firstly, their nitrogenous wastes are processedchemically into the form of uric acid, which has alow solubility in water. This means that, when theirurine is separated from the blood (filtration) andthen concentrated by reabsorption of water, theuric acid precipitates as a solid.

After further reabsorption of water, the insectsurine is a semi-solid paste, which is passed intothe rectum and excreted with their solid digestive

wastes.

MOUTH

MALPIGHIAN TUBES extend through insectsbody, collecting and concentrating urine.

Urine is emptied into the gut for excretion.

ANUS

Intestine

The Malpighian Tubes are theinsect equivalent of kidneys

Water Conservation & Excretion in Australian MammalsThey achieve this by:

having longer tubules intheir kidney nephrons,which allows for morereabsorption of water back

into the blood, thus lessurine is produced.

the cells lining thetubules are able to

actively transport urea from blood intothe urine. So, not only is urea notreabsorbed from the filtrate liquid, but isactively pumped from the blood.

The result is less water and more urea intheir urine.

Many Australian environments aredesert or semi-arid and waterconservation is vital for survival.Some adaptations for temperaturecontrol, while conserving water,were covered earlier in this topic.

Many Australian mammals haveexcretory systems that alsocontribute to water conservation,while managing to efficientlyremove their nitrogenous waste, urea.

The desert-living Red Kangaroo, theSpinifex Hopping Mouse, and even theKoala (which rarely drinks) all have the

ability to produce very small amounts ofhighly concentrated urine.



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The characteristics of Australias sclerophyll plants

were dealt with in the Preliminary Course topicEvolution of Australian Biota.

In summary, the sclerophyll plants include the gumtrees, banksias and acacias (wattles) and all shownumerous adaptations to conserve water in our aridclimate, such as:

Small, narrow, drooping leaves with thick, waxycuticles.

In dry times, gum trees shed many of their leavesso that there are less surfaces for evaporation.

Species such as Spinifex grass limit evaporationby having fine hairs all over their leaves. This trapsa layer of air near the leaf so that wind cannotincrease evaporation rates.

Generally, all Australian sclerophylls have fewerstomates on their leaves to limit the water loss fromtranspiration.

How Plants Cope With SaltMany of the Australian coastal estuaries are hometo Mangrove trees which have a number ofadaptations to cope with the salt water that coverstheir roots with every high tide.

To maintaintheirosmoticbalancethey mustbothconserve

water anddeal withhigh levelsof salt.

One of themostcommonspecies isthe GreyMangrove,Avicenniamarina, which has all the following adaptations:

Leaves with a thick, waxy cuticle and fine hairson the undersurface, all to minimise water loss.

Salt glands in the leaves which excrete aconcentrated salt brine onto the leaf surface. Thesalt gets washed away when it rains.

Salt is deposited in older leaves, so when theydrop off they carry a load of excess salt away.

Special tissues within their roots which allows

water to pass through, but reduces the passage ofsalt. This helps to reduce the salt intake.

Small & narrow toreduce Surface Areafor less evaporation

Droop downwards to avoid the heat ofmidday for less evaporation

Thick, waxycuticle

minimisesevaporation

Mangroves incoastal NSW

GUMLEAVES

EnantiostasisEnantiostasis is a special case of homeostasis.

It refers to the maintenence of metabolic and physiological functions, (i.e. homeostasis)despite significant variations in the surrounding environment.

An important example is an estuary,where river meets sea. Organisms areable to maintain their water and saltbalance, despite wild fluctuations inthe water and salt concentrationsaround them, every time the tideschange.

Examples of how they do this are:Crabs & yabbies burrow into the mud, where the saltconcentrations are more stable.

Oysters close their shell, to avoid extreme conditions theycannot cope with.

Estuary fish, like bream, switch their excretory systemsfrom water conservers when its salty, to water excreterswhen its fresh.


Water Conservation in Australian Plants

Complete Worksheets 11,12,13 & 14.



25/38





Fill in the blank spaces.The total of all the chemical reactions in anorganisms body is called a)........................................Each reaction requires a catalyst, which is achemical which b).................................... the reaction,

without being c)............................................... itself.

Biological catalysts are called d).................................These have the following properties:They are molecules of e)................................., whichare polymers of f)...................... .........................Each one has its own unique g).................................,which perfectly fits the molecule(s) of the reaction.These molecules are referred to as theh)..................................... Because each enzyme onlyfits its own particular h)..............................., they aresaid to be i)....................................................Enzymes will only work effectively in a narrowrange of j).................................. and k)....................This is because their l).................................. changesso that they no longer fit their substrate.

The pH scale is a numerical measurement ofm)........................ and n)........................................Things that are neutral have a pH= o)............. Acidshave pH values p).................... 7, while alkalis(bases) have pH q)..........................

3. Sketch a graph of Enzyme activity against pH.

4. Explain why the graphshows a peak ofoptimum activityat a certain pH.

5. Why does activity decline at pH values higher or lowerthan the optimum?

6. Sketch a graph of enzyme activity against substrateconcentration.

7. Explaina) why the graph rises

b) why the graphlevels off

1. Sketch the shape of a graph ofEnzyme Activity against Temperature.

2. Explain the shape of the graph;a) at temperatures below the optimum

b) at temperatures above the optimum.

Worksheet 1Enzymes & Homeostasis

Worksheet 2 Enzyme Activity Graphs

The pH inside living cells, and in most parts of anorganisms body is about r).............., but anexception is the s)............................... which is quitestrongly t).....................................

Homeostasis is the process of keeping anorganisms internal environment u)...........................The factors that need to be maintained includev).................................. and w)................ as well asx)............................. and salt balance,y).......................................... levels and oxygen andcarbon dioxide levels.

Homeostasis involves z)........................ feedback.The 3 parts of any feedback system are theaa)..........................., which measures or monitorsconditions, the ab)........................................ whichdecides how to respond and issues commands,and the ac).................................... which carry outthe commands.

In animals generally it is thead).......................................... system which islargely responsible for monitoring and control. Inmammals, homeostasis of body temperature iscontrolled by the ae)........................................... atthe base of the af).................................

Name....................................

Name....................................



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6.The effect on enzyme activity of increasing thesubstrate concentration is best described as:A. Activity rises to an optimum, then declines.B. Activity always continues to rise.

C. Activity declines as concentration increases.D. Activity rises, then levels off.

Longer Response QuestionsMark values given are suggestions only, and are to giveyou an idea of how detailed an answer is appropriate.Answer on reverse if insufficient space.

7. (4 marks)Discuss the importance of shape to thecharacteristics of an enzyme, with specificreference to:a) why each enzyme will usually only catalyse onlyone reaction.

b) why enzymes only work within fairly narrowranges of temperature and pH.

8. (8 marks)The following data was collected in an experimentin which the time taken for a chemical reactioncatalyzed by an enzyme, was measured at differenttemperatures.Temp (

oC) Time taken for reaction (min.)

5 4.010 2.015 1.020 0.225 2.530 10

a) Tabulate this data appropriately, adding a thirdcolumn for Reaction Rate and calculating valuesfor this.

b) Construct a graph of Temperature v Rate.

c) Is it likely that this is a human enzyme? Explain.

9. (5 marks)a) What is meant by Homeostasis

b) What is the link between the necessity forhomeostasis and enzymes?

c) Using a simple example, explain the concept of

negative feedback as a way to maintain stabilityof any system.

Worksheet 3Test Questions section 1

Multiple Choice1.Which of the following is NOT true about enzymes?Enzymes:-A. are catalysts which speed up chemical reactions.

B. are carbohydrate molecules of a special shape.C. only work within a narrow range of temperature.D. only works for one substrate... specific.

The graph shows the rate of an enzyme-catalysedreaction. Questions 2 and 3 refer to it.

2. Which part of this graph(A,B,C or D) corresponds tothe enzyme having the best3-dimentional shape to fit itssubstrate?

3.At point D on this graph, youcould describe the enzymeas:A. saturated with substrate.B. optimum shape.C. decomposed.D. denatured.

4.This graphcompares theperformanceof 2 enzymes

at different pHlevels.

It would be reasonable to conclude that:A. P is a stomach enzyme, Q is intra-cellular.B. P is from a plant cell, Q is from a mammalcell.C. Q performs better than P under allconditions.D. Both would have optimum activity at about 40

oC.

5.Which of the following is least likely to becontrolled by a negative feedback system?A. Body temperatureB. Blood sugar levelsC. Rate of digestion

D. Water & saltlevels.

Temperature

Ra

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Fill in the blank spaces.

Temperature regulation in mammals is

controlled by the a)..................................... at

the base of the brain. If body temperature istoo high it sends commands to the

b)..................................... organs to cool the

body. Cooling mechanisms include

c)............................ of blood vessels to allow

d)................... (more/less) blood to flow near

skin. Also, the e)............................ glands

may be activated, allowing f).........................

to flow. As it g).............................. from the

skin, it carries heat away. Metabolic rate

may be reduced, to reduce heat production.This is achieved by h).......................... which

are control chemicals. An example is

Thyroxine, produced by the

i)....................................... gland.

If the body is too cool, then the

hypothalamus commands various warming

mechanisms. Blood vessels can be

j).................................... to reduce blood flow

to k)...................... Body hairs arel).............................. to trap a layer of still air,

which acts to m).................................. better.

Nerve commands to muscles can cause

them to n)............................. which produces

extra heat. The metabolic rate can be raised

by hormones as well.

Animals which rely on the environment to

supply their body heat are called

o)........................................ Examples arep)............................, amphibians, fish etc. In

terrestrial environments they often seek or

avoid the heat of the q)................ in order to

regulate temperature. An Australian

example is the r)............................, which

often s)......................... in the morning to

warm up, and t)..................................... when

too hot. In cold winters, ectotherms cannot

get any heat from the environment and

many, such as the u).....................................survive by v)................................. for the

winter.

Animals which can regulate their bodytemperature are called w)..............................Examples are the x)......................... andy).................. They use all the homeostasis

techniques, plus rely on body insulationwith fur, z).................... or aa).....................

In extreme environments endotherms mayhave extra adaptations. In Australiandeserts many animals have largeab).................... to radiate heat away. Theydont have sweat glands because theycant afford to ac)..........................................but may lick their ad)............................... orpant to achieve some evaporative cooling.

In cold environments, thick fur or blubbergives ae)...................................... to retainbody heat. The penguins have a specialadaptation in the blood vessels to theirlegs. In cold water, the blood flow to thefeet is af).................. ......................................so that less heat is lost through theuninsulated feet.

Plants also have many adaptations to copewith temperature extremes. In coldclimates many plants areag).............................. which means theyah)............................................ in winter.

In hot climates with plenty of water, plantsopen their ai)............................ allowingevaporation to cool them. In dry climates,plants cannot afford the water loss, sothey stay cool without losing water. For

example, cacti have aj).......................-shaped leaves to reduce the surface areaabsorbing heat from direct sunlight. Theyare often ak)...........................-coloured toreflect heat radiation.

The Australian al)...................................plants mostly have am)..................................(shape) leaves to reduce surface area, andoften allow the leaves to an).........................(orientation) to avoid the Suns heat at

midday.

Worksheet 4Temperature Regulation Name....................................



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Multiple Choice1.The control centre for homeostasisinvolving the nerve system is the:

A. HypothalamusB. CerebrumC. CerebellumD. Pituitary gland

2.Which of the following is a response by aneffector organ which would be appropriatewhen the body is too warm?A. Muscles begin shivering.B. Blood vessels dilated.

C. Body hairs erected, forming goosebumps.D. Metabolic rate increased by a hormone.

3.Which statement is correct?A. Ectotherms such as fish, generate their

own body heat.B. Endotherms such as birds, rely on their

surroundings to supply their body heat.C. Ectotherms such as mammals,

generate their own body heat.D. Ectotherms such as reptiles, rely onthe surroundings to supply body heat.

4.A typical response of an ectotherm toover-heating is:A. sweating B. sun-bakingC. seeking shade D. shivering

5.

An important adaptation in Australianmammals to help keep cool in a desertenvironment is:

A. a lot of sweat glands in the skin.B. a stocky, thick-set shape to minimise

heat absorption.C. large ears to acts as heat radiators.D. thick fat layers to prevent heat gettinginto their body.

Longer Response Questions6. (8 marks)a) Discribe the role of the hypothalamus in theregulation of body temperature in a mammal.

b) Give an outline of how the blood vesselsfunction as effectors in the regulation of bodytemperature.

c) List 3 other effectors (apart from blood vessels)involved in temperature regulation.

7. (6 marks)a) Explain the difference between an ectotherm andan endotherm.

b) Using a named Australian example, outline howan ectotherm regulates its body temperature.

c) Using a named Australian example, outline 2adaptations of desert-living endotherm to keeptheir bodies cool.

8. (3 marks)Describe some adaptations of sclerophyll plantswhich help them minimise absorption of heat fromthe Sun.

Worksheet 5Test Questions section 2 Name....................................



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Blood is made up mainly of a liquid calleda).......................... and many blood cells.

The most numerous blood cells are theb)........................... which contain the proteinc)............................. responsible for carryingd).............................. gas. Most of the carbondioxide in blood is carried in the form ofe).................................... ions. These aremade when carbon dioxide reacts withf)................. forming g)........................ acid.

Most other substances carried in blood aredissolved in the h)................................. Thisincludes nutrients such as i).........................and j)................................., water and salts,and the nitrogenous waste k).........................Lipids (fats) are first wrapped in a coatingof l)............................ so they can bedispersed without separating.

There are 3 types of blood vessels: them)................................... have thick muscularwalls to withstand the high n)......................of the blood being pumped from theo)..................................

Worksheet 6Transport in Animals

p)................................ have thinner walls, andhave q)................... along their length toprevent blood r)..................... ............................Capillaries have walls which are

s).................................. thick and form a net-work throughout the bodys t).........................

As the blood flows around the intestines itpicks up u)..................................... It thenflows straight to the v)................................,where some nutrients are removed forw)....................... & ............................, andwastes such as x)..........................are added.These wastes are later removed from theblood by the y).................................. andexcreted with any excess z)........................ &

...................... as urine.

Meanwhile, when blood flows through thecapillaries of the lungs, aa)...........................gas is absorbed into the blood andab).............................. gas is released fromblood into air. When blood flows throughthe body tissues, nutrients move fromac)........................ to ad).................................as does ae)............................... gas, whileaf)..................................... gas moves the

other way.

Worksheet 7 Blood ChemistryAnswer the following questions.

1. Write 2 chemical equations to

summarise how carbon dioxide reactswith water.

2. Name the chemical form in which mostCO2 is carried in the blood.

3. With reference to one of the equations inQ1, explain why it is essential to quicklyremove CO2 from body tissues.

4. With reference to one of the equations inQ1, explain how the oxygen release fromblood cells to body tissues is facilitated.

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Worksheet 8Haemoglobin & Blood Products


Oxygen is carried by the a)...............-coloured, b).....................-containing protein

called c)....................................... It has agreat affinity for oxygen molecules, andeach molecule can absorb d)........

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Mantaining a balance - summary slides.pdf