9.2 Constructed Fluid Systems - WordPress.com...creating a low-pressure area above the paper, so the paper rises. low pressure high pressure Figure 9.12 The force of the water spray

Pressure in fluids at rest and fluids in motion can produce a force to operate

mechanical devices. Hydraulic systems create pressure that moves through a liquid

such as oil or water. Hydraulic systems can greatly multiply force. In pneumatic

systems, an enclosed gas such as air transmits a force, causing motion.

On August 29, 2005, Hurricane Katrina struck the United Statesdevastating the coastal areas of Louisiana, Mississippi, and Alabama.The winds of 233 km/h caused immense damage, but the worst wasyet to come in the days following.

Hurricane Katrina struck an area of the U.S. coast where manypeople live below sea level. The city of New Orleans, for example, hasareas that are up to 3 m below the level of the nearby ocean. The cityis normally kept dry by a series of levees (also known as dikes) thatsurround the city. Levees are large walls of stone and earth that holdback the water. In addition to the levees, the city maintains massivepumping stations that remove water from the “bowl” that NewOrleans sits in.

Unfortunately, huge waves caused by Hurricane Katrina brokethrough the levee system. When the levees broke, the pumps couldnot remove water from the flooded city fast enough. Eventually thepumps failed completely when electrical power was lost in the region.Could some of the devastation of New Orleans caused by HurricaneKatrina have been prevented by using stronger water pumps or bydesigning different fluid systems? How can we use pressure to makefluids go where we want them to go?

Constructed Fluid Systems9.2

Key Termshydraulicshydraulic systemshydraulic multiplication pneumaticspneumatic systems

324 MHR • Unit 3 Fluids and Dynamics

Figure 9.10 Hurricane Katrina caused severe damage and loss of life.

Did You Know?

Dikes are used in some areas ofBritish Columbia to protect theland from flooding. For example,dikes are needed on someislands of the Fraser River deltathat average just 1 m above sea level.

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Chapter 9 There are both natural and constructed fluid systems. • MHR 325

Spray Ball 9-6

In this activity, you will observe evidence of howpressure is exerted when a fluid is enclosed.

Safety

• Be careful not to poke yourself with the pin or scissors.

Materials • pushpin

• racquetball

• scissors

• syringe

• water

What to Do1. Use the pushpin to poke about 10 holes evenly

spread around the racquetball.

2. Use one end of the scissors to enlarge one of theholes for the tip of the syringe to tightly fit into.

3. Fill the syringe with water and stick the tip of thesyringe into the racquetball. Holding the syringeupright, squeeze the water into the racquetball.Repeat until the racquetball is full.

4. When the ball is full, fill the syringe again and stickthe tip into the hole. Hold the ball over a sink orlarge tub, and squeeze the water into the ballvigorously.

5. Clean up and put away the equipment you haveused.

What Did You Find Out? 1. Why did the water spray out of the ball?

2. How can you explain the pattern of spray from theball?

3. How would you describe the pressure at each ofthe pinhole locations you made? Explain.

Find Out ACTIVITY

Teacher Demonstration

apply brake

Figure 9.11 The forcefrom a fluid at rest can beused to stop vehicles.

Did You Know?

Pascal observed that thepressure in a fluid depends onthe depth of the fluid and notthe shape of a fluid’s container.

Fluids at RestBlaise Pascal, a French physician, studied fluid systems in the 1600s.He observed that when pressure is applied at one point to a fluid inan enclosed system, that pressure is transmitted equally through the entire system.

Every time you squeeze a tube of toothpaste you demonstratePascal’s principle. The pressure that your fingers exert at the bottomof the tube is transmitted through the toothpaste and forces the pasteout at the top. Likewise, if you squeeze one end of an inflated balloon, the other end of the balloon expands.

Squeezing an enclosed fluid creates static pressure. The fluid is now capable of applying a force, even though it is not moving. For example, pressing the brakes in a car compresses the fluid in the brake lines which causes the brake pads to push against the wheels, stopping the car.

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You might be surprised to know that ballpoint pens do not work upside down or inspace. Ballpoint pens needgravity to make the ink flow.The Fisher Space Pen® solvesthe problem by forcing the inkout under pressure. Find outmore about how the Fisher Space Pen® works. Start your search atwww.bcscience8.ca.

internet connect

Fluids in MotionA fluid in motion has dynamicpressure, which is energy that can be used directly to perform tasks(Figure 9.12). Dynamic pressure canalso be used indirectly to performtasks. Daniel Bernoulli, a Swissscientist, observed in the 1700s thatas the speed of a fluid increases, thepressure exerted perpendicular to themotion decreases. For example, airtravels faster over the top of anairplane wing, creating an area of lowpressure above the wing. Therelatively greater pressure below thewing pushes the airplane upward.This effect is demonstrated with apiece of paper in Figure 9.13.

Hydraulic SystemsHydraulics is the study of pressure in liquids. Hydraulic systems aredevices that create pressure that moves through a liquid such as oil orwater. Recall that liquids are not compressible under typical pressures.When pressure is applied to a liquid that is continuous and enclosed ina pipe or tube, the force is transmitted along the liquid. In otherwords, you could apply pressure to water in a pipe at one location andthe force could perform a task in another location. The force of thewater spraying out of the hose in Figure 9.12 is the result of pressureapplied to water in a pipe many miles away.

ageoverghaper,

Figure 9.13 The airabove the sheet of paperis moving faster than theair below the paper,creating a low-pressurearea above the paper, sothe paper rises.

low pressure

high pressure

Figure 9.12 The force of the waterspray can be changed by openingand narrowing the nozzle on thegarden hose.

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Hydraulic Fluid TransportationWhere does the water that pours from your tapscome from? How does it get to your home? If youlive in a rural area, your water might come from awell. Figure 9.14 shows water being drawn from awell by a pump. The pump forces water through apipe into a pressure tank. As more and more waterenters the tank, it pressurizes the small amount ofair in the tank. When the appropriate pressure isreached, the pressure tank sends an electrical signalto turn the pump off. The pressure tank transmitswater under pressure through the entire system, sowhenever you open a tap, water flows out of itunder pressure.

If you live in a town or a city, your waterprobably travels much farther to reach you. Thewater first moves through a water treatment plantwhere it is made safe to drink. Then it must gothrough large pumps to give it enough pressure toreach the many far-reaching branches of the system.

Pumps are an important part of hydraulicsystems. In the case of water supplies, the watersource may be actually lower in elevation thanwhere the water is being used. Water will only flowdownward, unless it is placed under pressure toflow against gravity. A pump can be used to raise ormove fluids. There are many different types ofpumps, but they all work to create areas of low andhigh pressure to move water along a pipe. A simpleexample is a piston pump shown in Figure 9.15.

pressureTank

wellcap

water level

pump


9.15B The piston reverses its direction,placing the water under pressure. The valve letting water into the system closes,preventing water going back to the source.

9.15C As the piston pushes forward,a valve leading to the plumbing systemopens and water is forced into it underpressure.

Figure 9.15A Water is drawn up intothe pump as the piston creates an areaof low pressure.

Figure 9.14 Static pressure ofwater in pipes causes the waterparticles to push against the insidewalls of the pipes.

internet connect

There are hundreds ofdifferent pumps for the manyapplications of moving fluids.Find out more about pumpdesigns. Start your search atwww.bcscience8.ca.

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ValvesAnother important part of a hydraulic system is a valve. A valve is adevice for controlling the passage of fluid through a pipe. As shown inFigure 9.16, when a water valve is closed, it stops the flow of water.When the valve is opened, the water can flow through. Valves thatallow fluids to flow in only one direction are called check valves.

Hydraulic MultiplicationNot only can hydraulic systems operate mechanical devices from adistance, they can also greatly multiply the force exerted by a liquid.

In hydraulic multiplication anincompressible fluid increases andtransmits a force from one pointto another. Figure 9.17 showshow pushing on the small pistonof a hydraulic system (A) canresult in a force that is 10 timesgreater on the large piston (B).This method is used to hoistvehicles for repair. Only a smallelectric motor is needed to push a small piston, and it lifts a whole car.

Reading Check

1. Which type of fluid is used in hydraulics? 2. How do hydraulic systems allow you to perform a task at a

distance? 3. Why might a pump be needed in a hydraulic system?4. How are valves used in hydraulic systems?

Figure 9.17 Hydraulic multiplication greatly increases force over a relatively small distance.

valveclosed

water

handle

valveopen

tap

Figure 9.16 Valves control the flow of fluids.

force: 5000 Narea of piston : 0.5 m2

pressure: 10 kPa

force: 50 000 Narea of piston : 5 m2

pressure: 10 kPa

A

B

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Syringe System9-7

In this activity, you can observe evidence of hydraulicmultiplication.

Be sure to follow the directions about how to connect thesyringes.

Safety• Never point the tubing or syringe toward anyone

when applying force to the system.

Materials • two different sizes of syringes• short piece of plastic tubing• water

What to Do 1. Connect the plastic tubing to the tip of the

large syringe.

2. Dip the open end of the tubing in the water. Pullon the plunger to fill the large syringe and tubingwith as much water as possible.

3. Push the plunger of the small syringe all the wayin. Connect the small syringe to the free end of thetubing. Try to minimize the amount of air in thesystem.

4. Once the syringes are securely connected to thetubing, press gently on the plunger of the largesyringe. Observe what happens.

5. Press gently on the plunger of the small syringe.Observe what happens.

6. Clean up and put away the equipment you haveused.

What Did You Find Out?1. What happened when you applied a force to the

plunger of the large syringe?

2. What happened when you applied a force to theplunger of the small syringe?

3. What evidence of hydraulic multiplication did you observe?

4. Explain how your syringe hydraulic system couldbe used to multiply force.

Find Out ACTIVITY

Problems in Hydraulic SystemsMoving liquids from place to place is morechallenging than simply connecting pieces of pipeand then pumping a fluid through them. Engineersmust plan pipe systems carefully to avoid a lot oftwists and turns that would increase resistance toflow. Pipes must also be connected carefully to avoidleakage. The pressure in a system is affected by thesize of the pipe (see Figure 9.18) and by howsmooth the insides of the pipes are. Fluid particleslose energy as they brush past each other inconfined spaces and as they bump into the walls ofthe pipelines. Build-up of sludge, corrosion, andmineral deposits all interfere with water flow.

[CAstuusidiff

Figure 9.18 If you have ever tried to drink a thick milkshakewith a thin straw, you can appreciate why it is important tohave the proper pipe size in a hydraulic system.

C

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Pneumatic SystemsPneumatics is the use of gas (usually air) in an enclosed system underpressure. Pneumatic systems are similar to hydraulic systems, exceptgases are used instead of liquids. In pneumatic systems, an enclosedgas transmits a force, causing motion. The operation of mostpneumatic systems is based on the fact that gases can be compressed.Therefore, compressors—devices that compress air—are needed. Airpressure builds up in a compressor. As the pressure is released, the airparticles move apart suddenly, creating a strong, steady force for ashort time that can perform powerful tasks. Many tools usepneumatics, from large tampers used to pack down dirt and gravelwhen building a road to tiny precision drills used by dentists.

Pneumatic systems can also be used in combination with hydraulicmultiplication. Heavy trucks and buses rely on pneumatic brakes (alsocalled air brakes) to stop quickly and smoothly. Large vehicles requirethe application of more force to operate their brakes. Because the forcethat a human leg can deliver is limited, compressed air is used to applythe force. As you can see by the diagrammed system in Figure 9.19,these brakes make good use of the advantages of hydraulics andpneumatics:• Highly compressed air delivers great force to the braking system.• Pipes and tubes deliver the force to many places at once.• Hydraulic multipliers in the wheels increase the force that stops

the vehicle.

hydraulicwheelcylinders

compressor

air lines

reservoir

booster unit

airlines

booster unit hydraulic mastercylinder

hydraulic line

hydraulicwheelcylinders

hydraulic line

brakepedal

Figure 9.19 Hydraulic-pneumatic braking systems are effective at stopping large trucks.

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The term “vacuum” is oftenused to describe an areawhere pressure is very low.There is no atmosphere inouter space, so it is avacuum. Humans cannotsurvive in a vacuum, soastronauts must beprotected from exposure tothe vacuum of space. Findout more about the effectsof a vacuum on the humanbody and how astronautsare protected from it. Startyour research atwww.bcscience8.ca.


Reading Check

1. How can hydraulic multiplication be used?2. What are some challenges to designing an effective

hydraulic system? 3. What is the difference between a hydraulic system and a

pneumatic system?4. How does a vacuum cleaner work?

exhaustport

dust bag

filter

area of low pressure

intake port

rotating brush

fan

electricmotor

Problems in Pneumatic SystemsPneumatic systems rely on movement of air or another gas. When thatmovement is blocked, the pneumatic system does not work as well. Agood example is a typical home vacuum cleaner. A vacuum cleaner hasa motor that spins a fan at high speed. The fan creates an area of lowpressure inside the vacuum cleaner. Recall that fluids move from anarea of high pressure to an area of low pressure. When the air pressurein the vacuum is reduced, the higher pressure air from the roomrushes into the vacuum (Figure 9.20).

The air that rushes into the vacuum exhausts into the room through a filter, trapping the dirt inside the vacuum. If the filter is not cleaned regularly, the flow of air out of the vacuum is blocked. If the air cannot escape, the air pressure rises inside the vacuum. Rising air pressure inside defeats the purpose of the vacuum, as there is no longer a strong pressure difference to force air into it. The vacuum filter needs to be cleaned or replaced regularly.

Figure 9.20 Dirt is carriedwith high-pressure air intothe vacuum cleaner.

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Checking Concepts 1. Why are oil and natural gas pipelines

made with as few sharp turns as possible? 2. Why do you think oil and natural gas

companies must regularly clean and inspectthe inside of their pipelines?

3. Portable sprayers are fairly simple to use. The liquid you wish to spray is added, andthen the sprayer is sealed. A handle at thetop doubles as a pump. By pumping thehandle, air is added to the tank.(a) Explain how a portable sprayer is an

example of both dynamic and staticpressure.

(b) What causes the liquid inside the tank to spray out?

4. Fountains push water high up into the airagainst the force of gravity. How is thisaccomplished?

5. Draw a diagram of a hydraulic multiplicationsystem that could be used to hoist a car. Addan explanation of how it would work.

Understanding Key Ideas 6. While you are cleaning between the cushions

of a sofa with a vacuum cleaner hose, a pieceof cardboard gets stuck against the end ofthe hose. You pull off the cardboard, butyou are surprised that it takes quite a bit ofeffort to do so. Using what you have learnedabout pressure, explain why it is difficult toremove the cardboard.

7. Some aquarium owners add check valves tothe tubes that supply air to their fish tanks.This is a safety measure to prevent waterflowing back through the air tubes if the airpump stops. Explain, using a diagram, howthe check valve would work in this situation.

8. A defective syringe has two small equallysized pinholes; one near the tip of thesyringe and one near the middle of the tube.To observe the leaks, a student fills thesyringe with water, covers the tip of thesyringe, and presses the plunger. Out ofwhich of the two pinholes would water spraythe farthest? Explain.

Most passenger vehicles have liquid in their braking systems. When a mechanicworks on brakes to repair them, sometimesthe mechanic must replace the brake fluid.During this process, air sometimes gets into the brake lines. When the repair iscompleted, the mechanic very carefullyremoves all the air from the brake lines.Why is it so important to remove all the air from the brake lines?

Pause and Reflect


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The circulatory system is an example of a natural fluid system. The heart pumps

blood through the circulatory system. The force of the blood on the walls of the

blood vessels is called blood pressure. Breathing is partly the result of changes

in air pressure. Clogged passageways affect natural systems as well as constructed

systems.

Natural fluid systems exist around us in the atmosphere, deep insideEarth, and in the oceans. As we learn more about the processes thatgovern complex fluid systems like the oceans and the atmosphere, we can more accurately forecast day-to-day weather. We can betterpredict changes in climate that are caused by human activities.Understanding fluid systems also allows us to develop new models forforecasting extreme weather events such as hurricanes (see Figure 9.21).

Natural Fluid Systems9.3

Key Termsbarometercirculatory systemdiaphragmrespiratory systemsphygmomanometer


Figure 9.21 Hurricanes, such as Hurricane Katrina shown here, are natural fluid systems.

Volcanoes represent a type of natural hydraulic system.Magma (molten rock) flowsinto active volcanoes. Whenthat flow becomes blocked,the pressure caused by thebuild-up of magma can cause the volcano to explode.Find out more aboutvolcanoes. Start your search at www.bcscience8.ca.

internet connect

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In this activity, you will construct a barometer, which isan instrument used for monitoring air pressure. You canobserve evidence of atmospheric pressure increasingand decreasing.

Materials • 250 mL beaker• modelling clay• transparent straw• food colouring• water• clear tape• index card• pencil

What to Do 1. Put 100 mL of cold water into the beaker.

Add a few drops of food colouring to the water.

2. Place the straw in the coloured water, making sureit does not touch the bottom of the beaker. Tapethe straw to the inside of the beaker.

3. Slowly suck the water about halfway up into the straw. Do not to suck any water into yourmouth. Pinch the top of the straw to hold the water in place. Place a small ball of clay on the top of the straw.

4. Tape an index card to the back of the beakerbehind the straw. Make a pencil mark on the indexcard to show the level of the water in the straw.Label the mark with the date.

5. Place your barometer in a location where thetemperature will be fairly constant.

6. Check your barometer once a day for three days.Each time make a mark to show the water level inthe straw. Label the mark with the date.

What Did You Find Out?1. If atmospheric pressure increases, will the water go

up or down inside the straw? Why?

2. If atmospheric pressure decreases, will the water goup or down inside the straw? Why?

3. Why is it important that your barometer be placedin an area where temperature does not change?

4. How did the atmospheric pressure change overyour three-day observation period?

Straw Barometer 9-8 Find Out ACTIVITY

Fluid Systems in HumansLiving things rely on fluids and fluid systems for most of their functions. Pressure plays animportant role in keeping fluids moving in livingthings. Your body is an excellent example of anatural fluid system. On average, the human body is about 66 percent water. Every day yourbody loses about 2.3 L of water, even more if you exercise (Figure 9.22). Water plays manyimportant roles in your body; it helps you absorbfood, transport nutrients, and remove wastes, and it also helps protectyour tissues. The correct amount of water in your system is also vitalfor maintaining proper blood pressure. Too much or too little watercan interfere with proper blood circulation.

Figure 9.22 Having the rightbalance of fluids in your body isimportant. When you lose fluids,they have to be replaced.

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The Circulatory SystemAs you learned in Unit 1, one of the most efficient natural hydraulicsystems is the human circulatory system. The circulatory systemtransports blood around the body. Blood vessels are like pipelines thatcarry the blood to all parts of the body. At the centre of thecirculatory system is a powerful and amazing pump, the heart. Theconstant beating of the heart keeps the blood moving throughout theblood vessels (see Figure 9.23).

Blood PressureIf you fill a balloon with water and then push on it, the pressure moves through the water in all directions. Your circulatory system is like a water balloon. When your heart pumps blood through thecirculatory system, the pressure of the push moves through the blood. The force of the blood on the walls of the blood vessels iscalled blood pressure.

Special nerve cells in the walls of some arteries sense changes in blood pressure. When pressure is higher or lower than normal,messages are sent to your brain by these nerve cells to raise or lowerblood pressure—by speeding up or slowing the heart rate for example.

When you take your pulse, you can feel the waves of pressure. This rise and fall of pressure occurs with each heartbeat. Normalresting pulse rates are 60 to 100 heartbeats per minute for adults, and 80 to 100 beats per minute for children. A typical blood pressurereading for an adolescent is 120/75 mm Hg. The first number is ameasure of the pressure caused when blood is pushed out of the heart.The second number is a measure of the pressure that occurs as theheart relaxes and refills with blood.

Blood pressure is measured using a device called asphygmomanometer. A sphygmomanometer measures blood pressureby applying enough pressure to an artery in your arm to briefly stopthe flow of blood. The doctor listens carefully with a stethoscope asthe pressure of the sphygmomanometer is released. When she hearsthe normal flow of blood return, the pressure is determined (seeFigure 9.24).

Section 2.3 has moreinformation about thecirculatory system.

Connection

toward heart

valve open; blood passes through

skeletal muscle contracts, squeezing vein

skeletal muscle relaxes

valve closed; keeps blood from flowing back

vein

Figure 9.23 When themuscles surrounding the veinscontract, they squeeze theblood forward under pressure.

Figure 9.24 Your blood pressure istaken as part of a regular checkup.

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Disorders of Blood CirculationBlood pressure is an indicator of your general health. Abnormal blood pressure readings can give a doctor strong clues as to what may be causing certain problems, and can be a warning of problemsthat could occur in the future if the blood pressure is not broughtback to normal.

Arteries that are clogged with deposits can increase bloodpressure. Recall from Section 9.2 that when deposits form along the pipes in a hydraulic system, the flow of fluid is reduced orblocked. Smoking can cause the blood vessels to contract, therebyincreasing blood pressure. When blood pressure is higher than normalmost of the time, the heart must work harder to keep blood flowing.Arteries are normally elastic and springy, but high blood pressure canharden them and even make them burst (see Figure 9.25).

Reading Check

1. How are blood vessels like pipelines?2. How is your circulatory system like a water balloon?3. What does each of the numbers of a blood pressure reading

measure?4. What are two causes of high blood pressure?5. What are two causes of low blood pressure?

Figure 9.25 AHigh blood pressure: too much forceon the walls of arteries can damagethe arteries

Figure 9.25 BNormal blood pressure

Figure 9.25 C Low blood pressure: not enoughblood flow could be an indication ofheart problems, or low water levelsin the body

Did You Know?

It is important for all mammalsto keep blood flowing to thebrain to remain conscious. Thisis probably most difficult for an extremely tall animal, like the giraffe. A giraffe’s body hasto maintain a very high bloodpressure to stay conscious as itraises its head 4 m after having a drink of water.

Design Your Own Investigation9-9 on page 340

Suggested Activity

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Inhale Exhale


The Respiratory System Recall from Unit 1 that the respiratory system is the set of organs andpathways involved in breathing. Breathing is partly the result ofchanges in air pressure. Recall that under normal conditions, a gasmoves from an area of high pressure to an area of low pressure. Whenyou inhale, the chest cavity expands to create an area of low pressure inthe lungs (Figure 9.26). Air rushes from the higher pressure outsideyour body to the lower pressure in your lungs. The chest cavity is madebigger by the movements of two sets of muscles:• the muscles between the ribs, which move the rib cage up and out• the diaphragm, a sheet of muscle in the lower chest that moves

downward as you breathe inWhen you are finished inhaling, the pressure outside the body

and inside the lungs is exactly the same. As you exhale, the chest cavity contracts, the diaphragm muscle moves up, and air is pushed out of the lungs.

Your lungs inhale and exhale about 500 mL of air with an averagebreath. This increases to 2000 mL of air per breath when you dostrenuous activity.

Section 2.3 has moreinformation about therespiratory system.

Connection

(A) Inhale: When the chest cavityexpands, an area of low pressure iscreated. Higher-pressure air from theatmosphere rushes into the lungs.

Did You Know?

Free diving is diving deepunderwater without taking anyexternal sources of air, just byholding your breath. The worldfree-diving record of 160 m wasset by Tanya Streeter in 2002. Inorder to get that deep fastenough, she descended with ametal sled at about 3 m/s, andused an air-filled balloon for thetrip back up. The record divekept her underwater for 3 minand 38 s.

(B) Exhale: When the chest cavitycontracts the air in the lungs issqueezed, so the pressure increases.This makes air rush out of the lungs.

Figure 9.26 The red arrows show the movement of muscles that changes the volume ofthe chest.

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Disorders of BreathingClogged or swollen passageways affect natural systems as well asconstructed systems. Bacteria, viruses, and other micro-organisms can cause infections, such as colds, pneumonia, or bronchitis. Theinfections can cause swelling within the respiratory system making itdifficult to breathe. Breathing in smoke, polluted air, coal dust, orasbestos can all be harmful to your respiratory system.

Asthma is a disease of the respiratory system that interferes with the normal flow of air into the lungs. The causes of asthma areuncertain, but it is well known that asthma attacks can be triggered by many things, including cold air, dust, exercise, and stress. Theattacks cause the pathway to the lungs to narrow, making it difficultto breathe (Figure 9.27). An inhaler is often used to delivermedication to the lungs (Figure 9.28).

Figure 9.28 Asthmamedications can assist inreturning the airways to normal.

Reading Check

1. When is the air pressure in the lungs less than the air pressureoutside the body?

2. When is the air pressure in the lungs greater than the air pressureoutside the body?

3. What is the function of the diaphragm?4. What are two causes of swelling within the respiratory system?5. What happens in an asthma attack?

About 1 child in every 2500 is born with the disease cystic fibrosis (CF). One of the symptoms of CF is theproduction of very thick mucusby the lungs, which can clogthe airways and make itdifficult to breathe. Find outmore about the symptoms and treatments for CF.Begin your search atwww.bcscience8.ca.

Word Connect

The combining form pneumois from a Greek word meaningair or lungs. Pneumo is foundin the word pneumonia, adisease of the lungs. Pneumois also used to form the word“pneumatics.”

Figure 9.27 Asthma affects the respiratory pathway.

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Checking Concepts1. Explain why the human circulatory system

can be thought of as a natural hydraulicsystem.

2. Explain why the human respiratory systemcan be thought of as a natural pneumaticsystem.

3. Explain how the motion of your diaphragmcauses you to inhale.

4. Angioplasty is a procedure where doctorsinsert a tiny balloon into a patient’s narrow,blocked artery on the outside of the heart,then expand the balloon. This forces theartery into a more open position. Why doyou think doctors would use such aprocedure?

5. Cardiopulmonary resuscitation (CPR) is anemergency procedure used to keep a personalive after his or her heart has stopped. Oneof the movements of CPR involvesrepeatedly pressing on the person’s chest.How do you think applying pressure tosomeone’s chest helps the person surviveheart stoppage?

Understanding Key Concepts6. After lying down, many people feel a

momentary feeling of dizziness if they stand up too quickly. Dizziness can becaused by a lack of blood flow to the brain. Explain why this temporary dizzinessoccurs. Include the words “pressure” and“pump” in your explanation.

7. Feelings of nervousness or excitement cancause hiccups. Hiccups occur when yourdiaphragm becomes irritated and pushesupward in a very quick jerky motion. (a) How might this jerk upward of the

diaphragm affect the pressure in thelungs?

(b) How does this movement of thediaphragm affect your breathing?


In this section, you have learned about the dangers of high blood pressure and other disorders of the circulatory system.How important do you think lifestyle choices concerning diet and exercise are to the health of your circulatory system?Write a short paragraph that states youropinion on this issue.

Pause and Reflect

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Prepare Your Own SummaryIn this chapter, you have compared natural and constructed fluid systems. Create your own summary of the key ideas from thischapter. You may include graphic organizers or illustrations with your notes. (See ScienceSkill 10 for help with using graphic organizers.)Use the following headings to organize yournotes:1. Fluids Under Pressure2. Buoyancy3. Hydraulics4. Fluids in Natural Systems5. Disorders of Natural Fluid Systems

Checking Concepts1. Draw a diagram of a closed container of

air and water, and use it to explain whathappens to each when pressure is applied to the container.

2. Use the example of a popped balloon toexplain how gases travel between areas ofhigh and low pressure.

3. Draw a cross section of a swimming pooland use it to describe how water pressurechanges with depth.

4. (a) What are the differences betweenhydraulics and pneumatics?

(b) How are the terms related?5. How does the concept of hydraulic

multiplication apply to lifesaving tools used by fire departments?

6. What is the function of a check valve?7. Why are pumps needed in municipal water

systems?8. State three things that can reduce the flow

of fluid in a pipe.

Understanding Key Ideas9. A railway worker uses hot water and steam

to clean the inside of a tanker car thatcarries chemicals mixed with water. Whenthe worker finishes the job, he seals thetanker car and goes home. When he arrivesfor work the next day, he finds the tankercar has imploded. Explain why thisoccurred.

10. How could pressure differences in Earth’satmosphere contribute to winds?

11. Assuming that you could survive in outerspace without a space suit, would it bepossible to drink using a straw? Explainwhy or why not.

12. In 1850, Wilhelm Bauer designed asubmarine. It was used successfully once,but on the second attempt it sank in about15 m of water. When Bauer and his submates tried to escape, they couldnot open the hatch. The submarine had a small leak, and after six hours it wasnearly full of water. With only a tinyamount of air left, the men tried the hatch again. It opened easily, and theyescaped and survived. Explain why the mencould not initially open the hatch, and whyit was easy to open the hatch once thesubmarine filled with water.

C h a p t e r

9

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13. An inflation needle on the end of a bicycle pump is commonly used to inflatesports balls.(a) Describe how a bicycle pump produces

compressed air.(b) Why is it much harder to press the

pump if there is an inflation needle added to the end of the hose?

(c) When the needle is removed from the rubber valve in a soccer ball afterinflation, the air stays inside the ball.Explain what type of valve this mustbe. Draw a diagram that illustrates howyou think it works.

14. Many functions of a military aircraft arecontrolled by a hydraulics system. Wingflaps, landing gear, gun turrets, and bombbay doors are just a few of the systems thatget their power from a hydraulic pumpthat is driven by the airplane engine. Usingthe example of an airplane and a diagram,explain how a single pump can transmitforce to many different areas all over theaircraft.

15. Building contractors sometimes usepowerful hydraulics to lift up a house so that repairs can be made to thefoundation. Using a diagram, explain how hydraulic multiplication can be usedto lift a house.

By creating better barometers and usingthem to take careful measurements ofatmospheric pressure, meteorologists havebeen able to improve their weatherforecasting. This is an example of anapplication of technology that improves ourlives. How has the improvement of pressure-measuring technology helped to make oureveryday lives safer?

Pause and Reflect

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Unit 3 Summary • MHR 347

Key Terms• condensation• density• evaporation• expansion • mass• melting• solidification• sublimation• volume

Key Terms• adhesion• cohesion• force• friction• gravitation • magnetic• pressure• viscosity• weight

Key Terms• convection• hydraulics• pneumatics

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9.2 Constructed Fluid Systems - WordPress.com...creating a low-pressure area above the paper, so the paper rises. low pressure high pressure Figure 9.12 The force of the water spray