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1
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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1
Why does blowing exhaled air into the
lungs of the patient help sustain life
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2
What is the purpose of compressing
the chest
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3.1 Importance of regulating
gas content in blood
Which gas content in blood
must be kept stable?
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3.1 Importance of regulating gas content in blood
oxygen
content
carbon dioxide
content
for respiration
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3.1 Importance of regulating gas content in blood
oxygen
content
carbon dioxide
content
• affects blood pH
• affects functioning of
enzymes
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3.1 Importance of regulating gas content in blood
oxygen
content
carbon dioxide
content
depend on
• how fast the gases are exchanged
in the air sacs
• how fast blood is transported from
the heart to the lungs and body cells
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3.1 Importance of regulating gas content in blood
oxygen
content
carbon dioxide
content
regulated by
controlling breathing and heartbeat
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3.1 Importance of regulating gas content in blood
1 Importance of regulating the gas
content in blood:
a To ensure there is a sufficient
supply of oxygen to body cells
for respiration .
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3.1 Importance of regulating gas content in blood
1 Importance of regulating the gas
content in blood:
b To maintain a stable blood pH
for enzymes in cells to function
properly.
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3.1 Importance of regulating gas content in blood
2 By controlling
breathing and
heartbeat , the body can regulate
The gas content in blood.
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3.2 Control of breathing
• under the involuntary control by the
medulla oblongata
front
back
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3.2 Control of breathing
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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3.2 Control of breathing
chemoreceptors in:
• carotid bodies
• aortic bodies
respiratory
centre
nerve impulses
stretch receptors
in lungs
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3.2 Control of breathing
chemoreceptors in:
• carotid bodies
• aortic bodies
respiratory
centre
nerve impulses to respiratory
muscles to trigger inhalation
stretch receptors
in lungs
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3.2 Control of breathing
respiratory
centre
stimulated when
the lungs inflate
Inhibitory nerve
impulses
stretch receptors
in lungs
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3.2 Control of breathing
chemoreceptors in:
• carotid bodies
• aortic bodies
respiratory
centre
when there is no impulse,
exhalation occurs
stretch receptors
in lungs
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3.2 Control of breathing
chemoreceptors in:
• carotid bodies
• aortic bodies
respiratory
centre
nerve impulses
stretch receptors
in lungs
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3.2 Control of breathing
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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3.2 Control of breathing
stretch
receptors
stimulated
inhalation
neurones
inhibited
respiratory
centre
neurones
stimulated
exhalation
stretch
receptors
no longer
stimulated
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3.2 Control of breathing
• one breath = inhalation + exhalation
• rate of breathing (呼吸速率)
= number of breaths per minute
 measures how fast we breathe
• depth of breathing (呼吸深度)
= volume of air that we breathe in
after an exhalation
 measures how deeply we breathe
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3.2 Control of breathing
Effects of CO2 content in blood
on breathing
• respiratory centre responds to
changes in blood pH
• in blood:
CO2
H2O
in body cells
(high CO2 conc)
in air sacs
(low CO2 conc)
H+
HCO3-
lowers
blood pH
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3.2 Control of breathing
respiratory centre
(contains chemoreceptors)
chemoreceptors
in aortic and
carotid bodies
CO2 content
in blood rises
(blood pH falls)
faster and stronger
contraction of intercostal
muscles and diaphragm
muscles
rate and depth of
breathing increase
CO2 content falls
normal CO2 content in blood
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3.2 Control of breathing
normal CO2 content in blood
CO2 content
in blood falls
(blood pH rises)
CO2 content rises
rate and depth of
breathing decrease
slower and weaker
chemoreceptors
contraction of intercostal
in aortic and
muscles and diaphragm
carotid bodies
muscles
respiratory centre
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(contains chemoreceptors)
3.2 Control of breathing
1 The feedback mechanisms between
the respiratory centre and the
stretch receptors in the lungs
bring about the basic rhythm of
breathing.
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3.2 Control of breathing
2 When carbon dioxide content in
blood rises, blood pH falls . This is
detected by the chemoreceptors
in the respiratory centre, the aortic
and carotid bodies.
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3.2 Control of breathing
2 The receptors send nerve impulses
to the respiratory centre. The centre
causes the intercostal muscles and
diaphragm muscles to contract
faster and more strongly. This
increases the rate and depth of
breathing. The opposite occurs when
carbon dioxide content in blood falls.
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3.3 Control of heartbeat
Which part of our body
initiates heartbeat?
Animation
• sinoatrial (SA) node (竇房結)
a group of special cardiac muscles
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3.3 Control of heartbeat
Which part of our body
initiates heartbeat?
• sinoatrial (SA) node (竇房結)
generates electrical impulses
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3.3 Control of heartbeat
Which part of our body
initiates heartbeat?
• sinoatrial (SA) node (竇房結)
also called the pacemaker
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3.3 Control of heartbeat
aorta
anterior
vena cava
pulmonary artery
pulmonary
veins
left artrium
right
atrium
left
ventricle
posterior
vena cava
right
ventricle36
3.3 Control of heartbeat
• both atria contract at the same time
pacemaker
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3.3 Control of heartbeat
• the ventricles contract after contraction
of the atria
atrioventricular
(AV) node
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3.3 Control of heartbeat
What happens in a
cardiac cycle?
Animation
the sequence of events that
take place in one heartbeat
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3.3 Control of heartbeat
1 Atria contract (atrial systole)
• electrical impulses spread from the
pacemaker to the atria
• the atria contract
atria
ventricles
0
relaxation / diastole
contraction / systole
0.1s
0.4s
40
0.8s
3.3 Control of heartbeat
1 Atria contract (atrial systole)
• the ventricles are in a relaxed state
• the semilunar valves are closed
atria
ventricles
0
relaxation / diastole
contraction / systole
0.1s
0.4s
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0.8s
3.3 Control of heartbeat
2 Ventricles contract (ventricular systole)
• the atria relax
• electrical impulses reach the ventricles
and cause them to contract
• this occurs about 0.1 s after
the atria started contracting
atria
ventricles
0
relaxation / diastole
contraction / systole
0.1s
0.4s
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0.8s
3.3 Control of heartbeat
2 Ventricles contract (ventricular systole)
• time is allowed for the ventricles to fill
completely with blood before they contract
• the pressure inside the
ventricles increases as they
contract, the semilunar
valves are forced to open
atria
ventricles
0
relaxation / diastole
contraction / systole
0.1s
0.4s
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0.8s
3.3 Control of heartbeat
2 Ventricles contract (ventricular systole)
• the tricuspid and bicuspid valves are
forced to close
 the first heart sound ‘lub’
atria
ventricles
0
relaxation / diastole
contraction / systole
0.1s
0.4s
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0.8s
3.3 Control of heartbeat
3 Atria and ventricles relax (diastole)
• both the atria and the ventricles are in a
relaxed state
• the semilunar valves are
closed
 the second heart sound
‘dub’
atria
ventricles
0
relaxation / diastole
contraction / systole
0.1s
0.4s
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0.8s
3.3 Control of heartbeat
3 Atria and ventricles relax (diastole)
• blood from the venae cavae and the
pulmonary veins flows into the atria
and the cycle repeats
atria
ventricles
0
relaxation / diastole
contraction / systole
0.1s
0.4s
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0.8s
3.3 Control of heartbeat
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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3.3 Control of heartbeat
What is cardiac output?
• stroke volume (心搏量)
= volume of blood pumped by each
ventricle in one heartbeat
When a person is at rest, the stroke
volume is about 70 mL.
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3.3 Control of heartbeat
What is cardiac output?
• cardiac output (心輸出量)
= volume of blood pumped by each
ventricle per minute
cardiac output
(mL/min)
=
stroke volume x heart rate
(mL/beat)
(beats/min)
 measures the performance of
the heart as a pump
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3.3 Control of heartbeat
How does the body control
cardiac output?
Nervous control
Hormonal control
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3.3 Control of heartbeat
1 Nervous control
medulla oblongata
cardiovascular centre
(心血管中樞)
consists of
cardio-acceleratory
cardio-inhibitory
centre
centre
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3.3 Control of heartbeat
1 Nervous control
pacemaker
sympathetic
nerve (交感神經)
stimulated to increase
cardiac output
cardio-acceleratory
centre
cardio-inhibitory
centre
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3.3 Control of heartbeat
1 Nervous control
pacemaker
parasympathetic
nerve (副交感神經)
cardio-acceleratory
centre
cardio-inhibitory
centre
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3.3 Control of heartbeat
1 Nervous control
pacemaker
inhibited to decrease
cardiac output
cardio-acceleratory
centre
vagus nerve
(迷走神經)
cardio-inhibitory
centre
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3.3 Control of heartbeat
detect changes in
carbon dioxide
content and oxygen
content in blood
cardiovascular
centre
chemoreceptors in:
• carotid bodies
• aortic bodies
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3.3 Control of heartbeat
sensory nerve
chemoreceptors
detect changes
in bloodin:
•
carotid
bodies
pressure
• aortic bodies
stretch receptors in:
• carotid arteries
• aorta
cardiovascular
centre
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3.3 Control of heartbeat
sensory nerve
chemoreceptors
stimulated
when blood in:
•
carotid
bodies
pressure
increases
• aortic bodies
stretch receptors in:
• carotid arteries
• aorta
cardiovascular
centre
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3.3 Control of heartbeat
sensory nerve
chemoreceptors in:
• carotid bodies
sensory
• aortic bodies
nerve
stretch receptors in:
• carotid arteries
• aorta
sympathetic nerve
cardiopacemaker
vagus nerve
vascular
centre
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3.3 Control of heartbeat
cardio-inhibitory centre
in medulla oblongata
chemoreceptors
in aortic and
carotid bodies
vagus
nerve
stretch receptors
in aorta and
carotid arteries
blood
blood pressure
pH rises
rises
normal blood pH / blood pressure
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vagus
nerve
3.3 Control of heartbeat
• pacemaker is inhibited
• slower and weaker contraction
of cardiac muscles
• cardiac output decreases
• blood flow to lungs decreases
blood pH falls;
blood pressure falls
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3.3 Control of heartbeat
cardio-inhibitory centre
in medulla oblongata
chemoreceptors
in aortic and
carotid bodies
vagus
nerve
stretch receptors
in aorta and
carotid arteries
blood
blood pressure
pH rises
rises
normal blood pH / blood pressure
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3.3 Control of heartbeat
normal blood pH / blood pressure
blood
pH falls
chemoreceptors
in aortic and
carotid bodies
blood pressure
falls
stretch receptors
in aorta and
carotid arteries
cardio-acceleratory centre
in medulla oblongata
sympathetic
nerve
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3.3 Control of heartbeat
blood pH rises;
blood pressure rises
• cardiac output increases
• blood flow to lungs increases
• pacemaker is stimulated
sympathetic • faster and stronger contraction
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nerve
of cardiac muscles
3.3 Control of heartbeat
normal blood pH / blood pressure
blood
pH falls
chemoreceptors
in aortic and
carotid bodies
blood pressure
falls
stretch receptors
in aorta and
carotid arteries
cardio-acceleratory centre
in medulla oblongata
sympathetic
nerve
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3.3 Control of heartbeat
2 Hormonal control
 When a person is under stress or
excited, adrenal gland secretes
more adrenaline (腎上腺素).
adrenal gland
kidney
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3.3 Control of heartbeat
2 Hormonal control
 When a person is under stress or
excited, adrenal gland secretes
more adrenaline (腎上腺素).
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3.3 Control of heartbeat
2 Hormonal control
 Adrenaline is transported around the
body by the circulation of blood.
blood vessel
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3.3 Control of heartbeat
2 Hormonal control
 Adrenaline is transported around the
body by the circulation of blood.
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3.3 Control of heartbeat
2 Hormonal control
 Adrenaline acts on cardiac muscles to
increase the cardiac output.
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3.3 Control of heartbeat
2 Hormonal control
• the cardiac output increases to prepare
the body for action in emergencies
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3.3 Control of heartbeat
1 How the pacemaker initiates a
heartbeat:
a The pacemaker generates
electrical impulses that cause
both atria to contract at the same
time.
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3.3 Control of heartbeat
1 How the pacemaker initiates a
heartbeat:
b The impulses also travel to the
atrioventricular node . The AV
node relays the impulses to the
base of the ventricles .
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3.3 Control of heartbeat
1 How the pacemaker initiates a
heartbeat:
b The ventricles contract about 0.1s
after the atria started contracting.
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3.3 Control of heartbeat
2 In a cardiac cycle:
Time interval
0-0.1 s
Atria
Contract
Ventricles
Relax
Blood flow
Atria to ventricles
74
3.3 Control of heartbeat
2 In a cardiac cycle:
Time interval
0-0.1 s
Tricuspid and Open
bicuspid valves
Close
Semilunar
valves
75
3.3 Control of heartbeat
2 In a cardiac cycle:
Time interval
0.1-0.4 s
Atria
Relax
Ventricles
Contract
•Right ventricle to
Blood flow
pulmonary artery
•Left ventricle to
aorta
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3.3 Control of heartbeat
2 In a cardiac cycle:
Time interval
0.1-0.4 s
Tricuspid and Close (gives 1st
bicuspid valves heart sound)
Open
Semilunar
valves
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3.3 Control of heartbeat
2 In a cardiac cycle:
Time interval
0.4-0.8 s
Atria
Relax
Ventricles
Relax
•Venae cavae to
Blood flow
right atrium
•Pulmonary veins to
left atrium
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3.3 Control of heartbeat
2 In a cardiac cycle:
Time interval
0.4-0.8 s
Tricuspid and Close
bicuspid valves
Close (gives 2nd
Semilunar
heart sound)
valves
79
3.3 Control of heartbeat
3a
b
Heart rate is the number of
heartbeats per minute.
Stroke volume is the volume of
blood pumped by each ventricle
in one heartbeat.
80
3.3 Control of heartbeat
3c
Cardiac output is the volume of
blood pumped by each ventricle
per minute.
cardiac output = stroke volume x heart rate
(mL/min)
(mL/beat)
(beats/min)
81
3.3 Control of heartbeat
4 Control of cardiac output:
a When the CO2 content in blood
rises or blood pressure falls, the
cardiovascular centre sends
more nerve impulses along the
sympathetic nerve to the
pacemaker to increase the
cardiac output.
82
3.3 Control of heartbeat
4 Control of cardiac output:
b When the CO2 content in blood
falls or blood pressure rises, the
cardiovascular centre sends more
nerve impulses along the
vagus nerve to the pacemaker
to decrease the cardiac output.
83
3.3 Control of heartbeat
4 Control of cardiac output:
c When a person is under stress or
excited, the adrenal glands
secrete more adrenaline to
increase the cardiac output.
84
3.4 Effects of exercise on
breathing and cardiac output
How does exercise affect the
rate and depth of breathing?
85
3.4 Effects of exercise on breathing and cardiac output
• 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
86
volume of air in lungs (cm3)
3.4 Effects of exercise on breathing and cardiac output
4000
during exercise
3000
2000
at rest
1000
0
5
10
time (s)
15
20
87
3.4 Effects of exercise on breathing and cardiac output
• as we breathe faster and deeper,
gas exchange occurs at a higher rate
blood flow
O2
CO2
88
3.4 Effects of exercise on breathing and cardiac output
• 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
89
3.4 Effects of exercise on breathing and cardiac output
• 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
90
3.4 Effects of exercise on breathing and cardiac output
amount of O2
breathed in
• the amount of oxygen required to
remove all lactic acid after exercise is
called oxygen debt (氧債)
rest exercise recovery
rest
time
91
3.4 Effects of exercise on breathing and cardiac output
• 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)
92
3.4 Effects of exercise on breathing and cardiac output
3.1
Video
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.
93
3.4 Effects of exercise on breathing and cardiac output
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.
94
3.4 Effects of exercise on breathing and cardiac output
3.2
Video
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.
2 Connect the low pressure sensor to
the interface.
95
3.4 Effects of exercise on breathing and cardiac output
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.
96
3.4 Effects of exercise on breathing and cardiac output
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.
97
3.4 Effects of exercise on breathing and cardiac output
3.2
4 Let the test classmate run on the spot and
start recording his / her breathing rate during
exercise at the same time.
5 Record data for 1 minute and then stop.
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.
98
3.4 Effects of exercise on breathing and cardiac output
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.
99
3.4 Effects of exercise on breathing and cardiac output
How does exercise affect
cardiac output?
100
3.4 Effects of exercise on breathing and cardiac output
• during exercise, the
cardiac output increases
 facilitates the transport of oxygen
to muscle cells and carbon dioxide
to the lungs for removal
101
3.4 Effects of exercise on breathing and cardiac output
exercise
cardiovascular centre
stimulated
pacemaker generates
more electrical impulses
adrenal glands secrete
more adrenaline
cardiac muscles contract faster and more strongly
cardiac output increases
102
3.4 Effects of exercise on breathing and cardiac output
• the heart rate can be measured by
- a data logger with a heart rate sensor
- measuring the pulse with a pulse sensor
103
3.4 Effects of exercise on breathing and cardiac output
3.3
Video
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.
2 Connect the heart rate sensor to the
interface.
104
3.4 Effects of exercise on breathing and cardiac output
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.
105
3.4 Effects of exercise on breathing and cardiac output
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).
3 Record data for 1 minute and then stop.
106
3.4 Effects of exercise on breathing and cardiac output
3.3
4 Let the test classmate run on the spot and
start recording his / her heart rate during
exercise at the same time.
5 Record data for 1 minute and then stop.
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.
107
3.4 Effects of exercise on breathing and cardiac output
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.
108
3.4 Effects of exercise on breathing and cardiac output
1a During exercise, both the rate and
depth of breathing increase .
109
3.4 Effects of exercise on breathing and cardiac output
1b This allows the body to obtain
oxygen for aerobic respiration
in muscle cells and remove
carbon dioxide from them at a
higher rate. They also provide
oxygen to break down lactic acid
produced during anaerobic
respiration in the muscle cells.
110
3.4 Effects of exercise on breathing and cardiac output
exercise
2
cardiovascular centre
adrenal glands secrete
stimulated
more adrenaline
pacemaker generates
more electrical impulses
cardiac muscles contract faster
and more strongly
cardiac output increases
111
3.4 Effects of exercise on breathing and cardiac output
3 The increased cardiac output
facilitates the transport of oxygen to
muscle cells for aerobic respiration
and the transport of carbon dioxide
to the lungs for removal.
112
1
Why does blowing exhaled air into
the lungs of the patient help sustain life?
Exhaled air still contains 16% oxygen
which helps maintain oxygenation of
the blood.
113
1
Why does blowing exhaled air into
the lungs of the patient help sustain life?
Its high carbon dioxide content also
helps stimulate the respiratory centre
to trigger breathing in the patient.
114
2
What is the purpose of compressing
the chest?
Compressing 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.
115
Gas content in blood
refers to
carbon dioxide
content (blood pH)
oxygen
content
regulated by controlling
breathing
heartbeat
116
breathing
controlled
by
heartbeat
controlled
by
once
in one
respiratory cardiovascular cardiac
centre
centre
cycle
receive nerve
impulses from
chemoreceptors
stretch
receptors
117
and
respiratory centre
sends nerve impulses to
intercostal muscles and
diaphragm muscles
to regulate
rate and depth of breathing
118
rate and depth
of breathing
cardiac
output
increase during
exercise
119
cardiovascular centre
sends nerve impulses along
sympathetic
nerve
pacemaker
determines
vagus nerve
adrenal glands
secrete adrenaline
to increase
cardiac output
120