1 2 think about… 3.1 importance of regulating gas content in blood 3.2 control of breathing 3.3...

2

Think about…

3.1 Importance of regulating gas content in blood

3.2 Control of breathing

3.3 Control of heartbeat

3.4 Effects of exercise on breathing and cardiac output

Recall ‘Think about…’

Summary concept map

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cardiopulmonary resuscitation (心肺復蘇法 )

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The survival chance is higher if patients are treated by CPR within 6 minutes after breathing and heartbeat have stopped.

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CPR involves blowing exhaled air forcefully into the lungs and compressing the chest.

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They are done alternately in rhythm until breathing and pulse resume.

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Why does blowing exhaled air into thelungs of the patient help sustain life1

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What is the purpose of compressingthe chest2

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Which gas content in blood must be kept stable?

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oxygen content

carbon dioxide content

for respirationfor respiration

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oxygen content


• affects blood pH

• affects functioning of enzymes

• affects blood pH

• affects functioning of enzymes

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oxygen content

• how fast the gases are exchanged in the air sacs

• how fast blood is transported from the heart to the lungs and body cells

• how fast the gases are exchanged in the air sacs

• how fast blood is transported from the heart to the lungs and body cells

depend on

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oxygen content

controlling breathing and heartbeatcontrolling breathing and heartbeat

regulated by

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a To ensure there is a sufficient supply of oxygen to body cells for .

1 Importance of regulating the gas content in blood:

respiration


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b To maintain a stable blood pH for in cells to function properly.

1 Importance of regulating the gas content in blood:

enzymes


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2 By controlling andbreathing

The gas content in blood.

, the body can regulateheartbeat


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3.2 Control of breathing• under the involuntary control by the

medulla oblongata

backfront

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Which part of the medulla oblongata controls breathing?


respiratory centre contains chemoreceptors

detect changes in carbon dioxide content and oxygen

content in blood

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respiratory centre

chemoreceptors in:• carotid bodies• aortic bodies

stretch receptors in lungs

nerve impulses

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respiratory centre



nerve impulses to respiratory muscles to trigger inhalation

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respiratory centre


stimulated when the lungs inflate

Inhibitory nerve impulses

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respiratory centre



when there is no impulse, exhalation occurs

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respiratory centre



nerve impulses

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How does the respiratory centre control breathing?


• the basic rhythm is brought about by feedback mechanisms between the respiratory centre and stretch receptors

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respiratory centreinhalation exhalation

stretch receptors stimulated

neurones stimulated

neurones inhibited

stretch receptors no longer stimulated

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• one breath = inhalation + exhalation

measures how fast we breathe

• rate of breathing (呼吸速率 ) = number of breaths per minute


measures how deeply we breathe

• depth of breathing (呼吸深度 ) = volume of air that we breathe in

after an exhalation

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Effects of CO2 content in blood on breathing• respiratory centre responds to

changes in blood pH


• in blood:in body cells

(high CO2 conc)

in air sacs (low CO2 conc)

CO2 H2O H+ HCO3-

lowers blood pH

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respiratory centre (contains chemoreceptors)

normal CO2 content in blood

CO2 content in blood rises (blood pH falls)

chemoreceptors in aortic and carotid bodies

faster and stronger contraction of intercostal muscles and diaphragm muscles

rate and depth of breathing increase

CO2 content falls


29respiratory centre (contains chemoreceptors)

normal CO2 content in blood

CO2 content in blood falls (blood pH rises)chemoreceptors in aortic and carotid bodies

slower and weaker contraction of intercostal muscles and diaphragm muscles

rate and depth of breathing decrease

CO2 content rises


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1 The feedback mechanisms between the and the

in the lungs

respiratory centre

bring about the basic rhythm of breathing.

stretch receptors


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2 When carbon dioxide content in blood rises, blood pH . This is detected by the in the respiratory centre, the aortic and carotid bodies.

chemoreceptorsfalls


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2 nerve impulses


The receptors send to the respiratory centre. The centre causes the muscles andintercostaldiaphragmfaster and more strongly. This increases the rate and depth of breathing. The opposite occurs when carbon dioxide content in blood falls.

muscles to contract

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Which part of our body initiates heartbeat?• sinoatrial (SA) node (竇房結 )

Animation

a group of special cardiac muscles

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Which part of our body initiates heartbeat?

generates electrical impulses

• sinoatrial (SA) node (竇房結 )

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Which part of our body initiates heartbeat?

also called the pacemaker

• sinoatrial (SA) node (竇房結 )

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anterior vena cava

right atrium

posterior vena cava

aortapulmonary artery

pulmonary veins

left artrium

left ventricle

right ventricle

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pacemaker

• both atria contract at the same time

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• the ventricles contract after contraction of the atria

atrio-ventricular (AV) node

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What happens in a cardiac cycle? Animation

the sequence of events that take place in one heartbeat

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1 Atria contract (atrial systole)• electrical impulses spread from the pacemaker to the atria

atriaventricles

0 0.1s 0.4s 0.8s

relaxation / diastolecontraction / systole

• the atria contract

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atriaventricles

0 0.1s 0.4s 0.8s


• the ventricles are in a relaxed state• the semilunar valves are closed

1 Atria contract (atrial systole)

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2 Ventricles contract (ventricular systole)• the atria relax

atriaventricles

0 0.1s 0.4s 0.8s


• electrical impulses reach the ventricles and cause them to contract

• this occurs about 0.1 s after the atria started contracting

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2 Ventricles contract (ventricular systole)• time is allowed for the ventricles to fill

completely with blood before they contract

atriaventricles

0 0.1s 0.4s 0.8s


• the pressure inside the ventricles increases as they contract, the semilunar valves are forced to open

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2 Ventricles contract (ventricular systole)• the tricuspid and bicuspid valves are

forced to close

atriaventricles

0 0.1s 0.4s 0.8s


the first heart sound ‘lub’

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• both the atria and the ventricles are in a relaxed state

atriaventricles

0 0.1s 0.4s 0.8s


3 Atria and ventricles relax (diastole)

• the semilunar valves are closed

the second heart sound ‘dub’

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• blood from the venae cavae and the pulmonary veins flows into the atria and the cycle repeats

atriaventricles

0 0.1s 0.4s 0.8s


3 Atria and ventricles relax (diastole)

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What is cardiac output?• heart rate (心搏率 )

= number of heartbeats per minute

When a person is at rest, the heart rate is about 60 to 80 beats/min.

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• stroke volume (心搏量 ) = volume of blood pumped by each

When a person is at rest, the stroke volume is about 70 mL.

ventricle in one heartbeat

What is cardiac output?

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measures the performance of the heart as a pump

• cardiac output (心輸出量 ) = volume of blood pumped by each ventricle per minute

What is cardiac output?

=cardiac output (mL/min)

stroke volume (mL/beat)

x heart rate (beats/min)

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How does the body control cardiac output?

Nervous control

Hormonal control

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medulla oblongata

1 Nervous control

cardio-acceleratory centre

cardio-inhibitory centre

cardiovascular centre(心血管中樞 )

consists of

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1 Nervous control



pacemaker

sympathetic nerve (交感神

經 )

stimulated to increase cardiac output

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1 Nervous control



pacemaker

parasympathetic nerve (副交感神經 )

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1 Nervous control



pacemaker

vagus nerve (迷走神經 )

inhibited to decrease cardiac output

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cardio-vascular centre



detect changes in carbon dioxide

content and oxygen content in blood

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sensory nerve

stretch receptors in:• carotid arteries• aorta


detect changes in blood pressure

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sensory nerve



stimulated when blood pressure increases

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sensory nerve


sensory nerve

pacemakersympathetic nerve

vagus nerve


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cardio-inhibitory centre in medulla oblongata

normal blood pH / blood pressure


blood pH rises

blood pressure rises


stretch receptors in aorta and carotid arteries

vagus nerve

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• pacemaker is inhibited

• slower and weaker contraction of cardiac muscles


vagus nerve

• cardiac output decreases

• blood flow to lungs decreases

blood pH falls; blood pressure falls

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cardio-inhibitory centre in medulla oblongata

normal blood pH / blood pressure


blood pH rises

blood pressure rises



vagus nerve

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cardio-acceleratory centre in medulla oblongata

normal blood pH / blood pressure3.3 Control of heartbeat

blood pH falls

blood pressure falls



sympathetic nerve

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• pacemaker is stimulated

• faster and stronger contraction of cardiac muscles


• cardiac output increases

• blood flow to lungs increases

blood pH rises; blood pressure rises

sympathetic nerve

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cardio-acceleratory centre in medulla oblongata

normal blood pH / blood pressure3.3 Control of heartbeat

blood pH falls

blood pressure falls



sympathetic nerve

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2 Hormonal control When a person is under stress or

excited, adrenal gland secretes more adrenaline (腎上腺素 ).

kidney

adrenal gland

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2 Hormonal control When a person is under stress or

excited, adrenal gland secretes more adrenaline (腎上腺素 ).

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2 Hormonal control Adrenaline is transported around the

body by the circulation of blood.

blood vessel

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2 Hormonal control Adrenaline is transported around the

body by the circulation of blood.

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2 Hormonal control Adrenaline acts on cardiac muscles to

increase the cardiac output.

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2 Hormonal control• the cardiac output increases to prepare

the body for action in emergencies

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a The pacemaker generates

1 How the pacemaker initiates a heartbeat:

electrical impulses that causeboth atria to contract at the same time.

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b The impulses also travel to theatrioventricular node . The AV

node relays the impulses to the base of the .


ventricles

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bafter the atria started contracting.


The ventricles contract about 0.1s

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2 In a cardiac cycle:Time interval 0-0.1 s

AtriaVentriclesBlood flow Atria to ventricles

ContractRelax

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2 In a cardiac cycle:Time interval 0-0.1 s

Tricuspid and bicuspid valvesSemilunar valves

Open

Close

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2 In a cardiac cycle:Time interval 0.1-0.4 s

AtriaVentriclesBlood flow •Right ventricle to

pulmonary artery•Left ventricle to aorta

RelaxContract

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Close (gives 1st heart sound)Open

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AtriaVentriclesBlood flow •Venae cavae to

right atrium•Pulmonary veins to left atrium

RelaxRelax

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Close

Close (gives 2nd heart sound)

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a is the number of heartbeats per minute.

3 Heart rate


b is the volume of blood pumped by each ventricle in one heartbeat.

Stroke volume

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c is the volume of blood pumped by each ventricle per minute.

3 Cardiac output


=cardiac output (mL/min)

stroke volume (mL/beat)

x heart rate (beats/min

)

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a When the CO2 content in blood rises or blood pressure falls, the

4 Control of cardiac output:

cardiovascular centre sendsmore nerve impulses along thesympathetic nerve to thepacemaker to increase the cardiac output.

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b When the CO2 content in blood falls or blood pressure rises, the cardiovascular centre sends more


nerve impulses along thevagus nerve to the pacemaker

to the cardiac output.decrease

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c When a person is under stress or excited, the adrenal glands secrete more to increase the cardiac output.


adrenaline

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How does exercise affect the rate and depth of breathing?

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• during exercise, the energy requirement for vigorous muscular activity increases

more oxygen is needed to allow a higher rate of aerobic respiration

achieved by increasing both the rate and depth of breathing

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volu

me

of a

ir in

lung

s (c

m3)

time (s)5

1000

2000

10

3000

15

4000

200


at rest

during exercise

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• as we breathe faster and deeper, gas exchange occurs at a higher rate

blood flow

CO2

O2

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• as we breathe faster and deeper, gas exchange occurs at a higher rate

body can supply oxygen to muscle cells and remove carbon dioxide from them more rapidly

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• after exercise, the rate and depth of breathing remain at a high level for some time

provides more oxygen for the breakdown of lactic acid

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• the amount of oxygen required to remove all lactic acid after exercise is called oxygen debt (氧債 )

amou

nt o

f O2

brea

thed

in

timerest exercise recovery rest

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• the rate of breathing can be measured by counting the number of breaths within a certain period of time

• the depth of breathing can be measured by a breath volume kit, a data logger with a respiration rate sensor or a spirometer (肺量計 )

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3.1

Study of the changes in breathing before and after exercise using a breath volume kit

1 Sit down quietly for 2 minutes.

2 Get a classmate ready to do the timing and counting. Breathe through the mouthpiece of the breath volume kit for 20 seconds.


Video

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3.1

3 Record the number of breaths you take in that 20 seconds.

4 Force all of the air in the bag to the far end and record its volume.


5 Run on the spot for 3 minutes.

6 Repeat steps 2 to 4 to record the number of breaths and the volume of exhaled air in 20 seconds.

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3.2

Study of the changes in breathing before and after exercise using a data logger

Part 1: Computer set-up

1 Connect the data logger interface to the computer. Turn on the interface and the computer.


Video

2 Connect the low pressure sensor to the interface.

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3.2

3 Run the software and open the pre-configured file.

Part 2: Equipment set-up


1 Wrap around the chest of the test classmate with the respiration belt.

2 Connect the tube of the rubber bladder to the low pressure sensor.

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3.2

3 Close the valve of the squeeze bulb. Squeeze the bulb to inflate the rubber bladder.

Part 3: Data recording


1 Let the test classmate sit down quietly for 2 minutes.

2 Start recording his / her breathing rate before exercise (i.e. at rest).

3 Record data for 1 minute and then stop.

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3.2

4 Let the test classmate run on the spot and start recording his / her breathing rate during exercise at the same time.



6 Ask the test classmate to stop running and sit down. At the same time, start recording his / her breathing rate after exercise for 1 minute again.

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3.2

Part 4: Data analysis


1 Use the graph display function to display the data.

2 Calculate the minimum, maximum and mean breathing rate for each run by using the built-in functions of the software.

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How does exercise affect cardiac output?

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• during exercise, the cardiac output increases

facilitates the transport of oxygen to muscle cells and carbon dioxide to the lungs for removal

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exercise

cardiovascular centre stimulated

pacemaker generates more electrical impulses

cardiac muscles contract faster and more strongly

cardiac output increases

adrenal glands secrete more adrenaline

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• the heart rate can be measured by

- a data logger with a heart rate sensor

- measuring the pulse with a pulse sensor

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3.3

Study of the changes in heart rate before and after exercise using a data logger

Part 1: Computer set-up

1 Connect the data logger interface to the computer. Turn on the interface and the computer.


Video

2 Connect the heart rate sensor to the interface.

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3.3

3 Run the software and open the pre-configured file.

Part 2: Equipment set-up


1 Clip the ear clip of the heart rate sensor to the earlobe of the test classmate.

2 Connect the ear clip to the heart rate sensor.

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3.3

Part 3: Data recording


1 Let the test classmate sit down quietly for 2 minutes.

2 Start recording his / her heart rate before exercise (i.e. at rest).


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3.3

4 Let the test classmate run on the spot and start recording his / her heart rate during exercise at the same time.



6 Ask the test classmate to stop running and sit down. At the same time, start recording his / her heart rate after exercise for 1 minute again.

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3.3

Part 4: Data analysis


1 Use the graph display function to display the data.

2 Calculate the minimum, maximum and mean heart rate for each run by using the built-in functions of the software.

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a During exercise, both the rate and depth of breathing .

1increase


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b This allows the body to obtain1oxygen


for aerobic respirationin muscle cells and removecarbon dioxide from them at a

higher rate. They also provide oxygen to break downproduced during anaerobic respiration in the muscle cells.

lactic acid

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2


exercise

stimulated

generates

cardiac muscles contract faster and more strongly

cardiac output increases

adrenal glands secretecardiovascular centre

adrenalinepacemaker

more electrical impulses

more

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The increased cardiac output facilitates the transport of oxygen to muscle cells for respiration and the transport of carbon dioxide to the for removal.

3


aerobic

lungs

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Why does blowing exhaled air intothe lungs of the patient help sustain life?

1Exhaled air still contains 16% oxygen which helps maintain oxygenation of the blood.

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Why does blowing exhaled air intothe lungs of the patient help sustain life?

1Its high carbon dioxide content also helps stimulate the respiratory centre to trigger breathing in the patient.

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What is the purpose of compressingthe chest?2Compressing the chest helps maintain cardiac output to supply blood to the brain and other vital organs. This delays damage to tissues until further medical treatment is available.

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refers to

Gas content in blood

oxygen content

carbon dioxide content (blood pH)

regulated by controlling

breathing heartbeat

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receive nerve impulses from

controlled by

respiratory centre

breathing heartbeat

cardiac cycle

cardiovascular centre

controlled by

once in one

chemoreceptors

stretch receptors

and

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sends nerve impulses to

intercostal muscles and diaphragm muscles

to regulate

rate and depth of breathing

respiratory centre

119

rate and depth of breathing

cardiac output

exercise

increase during

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sends nerve impulses along

cardiac output

cardiovascular centre

adrenal glandspacemaker

sympathetic nerve vagus nerve

determinessecrete adrenaline to increase

1 2 think about… 3.1 importance of regulating gas content in blood 3.2 control of breathing 3.3...

Documents

blood slide

gas content

respiration slide

inhalation slide

fast blood

control of breathing

stable blood ph

control of heartbeat