RESPIRATORY SYSTEM
Introduction

The Respiratory System performs 3 main processes which are linked
via the heart and vascular system
1. Pulmonary Ventilation – breathing air into and out of the
lungs
2. External Respiration – exchange of O2 and CO2 between
lungs and blood
3. Internal Respiration – exchange of O2 and CO2 between
blood and muscle tissue
Structure of the Respiratory System

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Lobes of the lungs (right lung has 3 lobe and left lung has 2 lobes)
Air enters Oral Cavity and Nasal Cavity and travels down the
Trachea, passing the Pharynx and Larynx
Air reaches the left and right bronchus which branch into smaller
bronchioles eventually reaching the alveoli ducts and into alveoli
sacs which are surrounded by capillaries for gaseous exchange
Alveoli increase the efficiency of gaseous exchange by:
o Forming a vast surface area (about half the size of a Tennis
court)
o Having a single-layer of thin epithelial cells
The lungs have a pulmonary pleura which is a double walled sacs
consisting of two membranes filled with pleural fluid, to help reduce
friction between the ribs and lungs during breathing. The outer layer
attaches to the ribs and the inner layer to the lungs. This ensures the
lungs move with the chest during breathing
Respiration at Rest
INSPIRATION
Diaphragm contracts – active
External intercostals contract – active
Diaphragm flattens/pushed down
Ribs/Sternum moves up and out
Thoracic cavity volume increases
Lung air pressure decreases below
atmospheric air
Air rushes into the lungs
EXPIRATION
Diaphragm relaxes – passive
External intercostals relax – passive
Diaphragm pushed upward
Ribs/Sternum moves in and down
Thoracic cavity volume decreases
Lung air pressure increases above
atmospheric air
Air rushes out of the lungs
Mechanics of Respiration during Exercise


The rate and depth of breathing needs to increase during exercise to
allow more O2 into the lungs to meet the demands of exercise
Below is a table which shows the mechanics of respiration during
exercise:
1
INSPIRATION
Diaphragm contracts
External intercostals contract
Sternocleidomastoid contracts
Scalenes contract
Pectoralis minor contracts
EXPIRATION
Diaphragm relaxes
External intercostals relax
Internal intercostals contract
(active)
Rectus abdominus/Obliques
contract (active)
Diaphragm pushed up harder with
more force
Ribs/Sternum pulled in and down
Greater decrease in thoracic cavity
volume
Higher air pressure in lungs
More air pushed out of the lungs
Diaphragm flattens with more force
Increased lifting of ribs and sternum
Increased thoracic cavity volume
Lower air pressure in lungs
More air rushes into lungs
Respiratory Volumes at Rest



Tidal Volume (TV) – The volume of air inspired or expired per breath
(about 500ml at rest)
Frequency (f) – The number of breaths per minute (about 12-15 at
rest)
Minute Ventilation (VE) – The volume of air inspired or expired in one
minute (or TV x f = about 7500ml/min or 7.5 L/min)
o VE
= TV x f
o
= 500 ml x 15
o
= 7500 ml/min
o
= 7.5 L/min
Lung Volume Changes during Exercise
LUNG VOLUME
Tidal Volume
Frequency
Minute Ventilation
NOTE:



RESTING
VOLUME
500ml
12-15
6-7.5 L/min
CHANGE DUE TO
EXERCISE
Increases up to 3-4 L
Increases between 40-60
Increases up to 120 L/min in smaller
individuals and up to 180+ L/min in
larger aerobic trained athletes
f = rate of breathing
TV = depth of breathing
At lower intensities an increase in TV and f will increase VE
However, during maximal work, it is an increase in the rate of breathing
(f) which increases VE further
This is due to the fact that it is not efficient to increase TV towards
maximal values due to the time it takes
2
Gaseous Exchange
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



This is the exchange of CO2 and O2 in the lungs (external respiration)
and tissues (internal respiration)
It relies on the process of diffusion. Which is the movement of gases
from areas of high pressure to areas of low pressure
The difference between high and low pressure is called the diffusion
gradient. The bigger the gradient, the greater the diffusion
Partial Pressure (PP) of a gas is the pressure it exerts within a mixture
of gases
Although you do not need to know the exact pressures; you are
required to know where these PP are higher or lower (to
understand which direction the gases are moving) during internal
and external respiration
External Respiration
Movement
Why O2?
Why CO2?


O2 in alveoli diffuses to blood
CO2 in blood diffuses to alveoli
PP of O2 in alveoli higher than the PP
of O2 in the blood so O2 diffuses into
the blood
PP of CO2 in blood higher than the PP
of CO2 in alveoli so CO2 diffuses into
alveoli
Internal Respiration
O2 in blood diffuses into tissues
CO2 in tissues diffuses into blood
PP of O2 in blood is higher than PP of
O2 in tissues so O2 diffuses into the
Myoglobin within tissues
PP of CO2 in tissues is higher than PP
of CO2 in blood so CO2 diffuses into
the capillary blood
External (Alveoli) Respiration – Air entering lungs has a high PP of
O2 and low PP of CO2 compared with deoxygenated blood in
capillaries which has a low PP of O2 and high PP of CO2. This causes
two pressure gradients and cause diffusion
o O2 from alveoli diffuses into the blood in the capillaries
o CO2 from the blood in the capillaries diffuses into the alveoli
Internal (Tissue) Respiration – Capillary blood (around muscle cells)
has a high PP of O2 and low PP of CO2 compared with muscle/tissue
cells which has a low PP of O2 and high PP of CO2 (due to O2 being
used for energy production and giving CO2 off as a by-product). Again
this causes two pressure gradients and cause diffusion
o O2 is diffused from the haemoglobin (in the red blood cells) in
the capillary blood to the myoglobin within the muscle tissue.
Which both stores and transports the O2 to the mitochondria
where it is used for energy production
o CO2 diffuses from the muscle cells into the capillary blood
Exercise Changes to Gaseous Exchange

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Both internal and external respiration increases during exercise in
order to increase the supply of O2 to the working muscles
Oxygen-Haemoglobin Dissociation Curve informs us of the amount
of Haemoglobin saturated with O2.
Haemoglobin fully loaded with O2 is termed saturated or associated
O2 unloading from haemoglobin is called dissociation
Below is the oxygen-haemoglobin dissociation curve at rest
3
100
Volume of O2
Unloaded to
80_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Tissue
% O2
Saturation of
Haemoglobin 60
10
40
5
ml O2/
100ml
blood
20
0
0
0
20
40
60
80
Muscle Tissue PPO2 (mmHg)
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
100
Lungs
The higher the PPO2 , the higher the % of O2 saturation to
haemoglobin (Hb)
The higher PPO2 in lungs results in almost 100% saturation, compared
with a lower PPO2 in the tissues which results in only about 75%
saturation
25% of the O2 has dissociated from Hb into the tissues/muscles
The association of O2 and Hb takes place in the lungs to maintain
efficient supply of O2 to working muscles during exercise
Blood then carries O2 to the muscle capillaries where it can dissociate
and unload O2 to the muscle tissue to provide energy for work
Therefore, during exercise, the oxygen-haemoglobin dissociation curve
shifts to the right which represents a greater dissociation of O2. Which
means more O2 is unloading from the Hb in the blood to the muscle
tissue (see graph below of the curve shifting to the right)
100
Volume of O2
Unloaded to
80_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Tissue
% O2
Saturation of
Haemoglobin 60
Body temperature
37/38°
pH 7.4
10
40
5
20
CURVE
SHIFTING
RIGHT
0
0
0
20
40
60
Muscle Tissue PPO2 (mmHg)
4
80
100
Lungs
ml O2/
100ml
blood
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
External Respiration. During exercise, skeletal muscles are using
more O2 to provide energy, which means more CO2 is produced
Venous blood returning to the lungs from the right ventricle has a
higher PPCO2 and lower PPO2.
Alveolar air has a high PPO2 and a low PPCO2
This increases the diffusion gradient between alveoli-capillary
membrane which increases speed and amount of gaseous exchange
The high PPO2 in alveoli and low PPO2 in capillaries ensures
haemoglobin is almost fully saturated with O2 (see table below)
O2 and CO2 will diffuse across until the PP are equal
Partial
Pressure
Alveolar Air
O2
CO2
100 (high)
40 (low)

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
Capillary
Blood
(around
alveoli)
40 (low)
46 (high)
Diffusion
Gradient
60
6
Internal Respiration. Greater O2 dissociation in muscle tissue during
exercise is needed in order to increase the supply of O2 to the working
muscles
Four factors all have the effect of shifting the dissociation curve to the
right (increase the dissociation of O2 from Hb in blood capillaries to the
muscle tissue):
o Increase in blood and muscle temperature
o Decrease in PPO2 within muscles, increasing O2 diffusion
gradient
o Increase in PPCO2, increasing CO2 diffusion gradient
o BOHR EFFECT – increase in acidity (lower pH)
All of these factors increase the dissociation of O2 with Hb, which
increases the supply of O2 to the working muscles and therefore
delays fatigue and increases the possible intensity/duration of
performance
Partial
Pressure
Alveolar Air
O2 resting
O2 during
exercise
CO2 resting
CO2 during
exercise

Direction of
Diffusion
(High to Low
PP)
→
←
Capillary
Blood
(around
alveoli)
40
<5
Diffusion
Gradient
100
100
Direction of
Diffusion
(High to Low
PP)
→
→
40
40
←
←
46
80
6
40
60
95
Below is a comparison of dissociation curve at rest (a), and during
exercise (b) with specific values
5
(a)
100
% O2
80_ _ _ _ _ _ _ _ _
Saturation of
Haemoglobin 60
40
Body temperature
37/38°
pH 7.4
PPCO2 40mmHg
20
0
0
20
40
60
80
100
Muscle Tissue PPO2 (mmHg)
(b)
100
% O2
80
Saturation of
Haemoglobin 60
Body temperature
39°
pH 7.2 (Bohr effect)
PPCO2 40-50mmHg
40
---------------20
0
0
20
40
60
80
100
Muscle Tissue PPO2 5–40 (mmHg)
e.g. showing 30mmHg = approx 30% saturation
Ventilatory Response to Light, Moderate and Heavy Exercise


The diagram below shows the Pulmonary Ventilation (or Minute
Ventilation = VE) response from resting to sub-maximal and maximal
exercise intensities
Ventilatory response to exercise mirrors that of the heart (except that it
is the Respiratory Control Centre = RCC that controls the respiratory
muscles that increase or decrease breathing)
6
Start
Exercise
4
1200
Stop
600
Pulmonary
Ventilation
(L/min)
500
5
80
60
40
2
3
c
1
6
b
a
20
0
-2
-1
0
1
2
Time (mins)
3
4
5
6
7
a
b
c
=
=
=
Light Exercise
Moderate Exercise
Heavy Exercise
1
=
2
=
3
=
4
=
5
=
6
=
Anticipatory Rise prior to exercise as Adrenalin is released
which stimulates the RCC
Rapid rise in VE at start of exercise due to neural stimulation of
RCC by muscle/joint proprioreceptors
Slow increase – in sub-maximal exercise due to continued
stimulation of the RCC by proprioreceptors and chemoreceptors.
OR Plateau which represents a steady state where the
demands of O2 by working muscles are being met by O2
supply
Continued but slower increase in VE towards maximal values
during maximal work, as chemoreceptors detect an increase in
CO2 and lactic acid accumulation
Rapid decrease in VE once exercise stops due to decrease in
chemoreceptor stimulation and decrease in proprioreceptor
detection
Slower decrease towards resting VE values. The harder the
intensity, the longer it will take to return to resting levels (due to
removing by-products like lactic acid)
7
Control of Breathing

The Respiratory Control Centre (RCC) regulates pulmonary
respiration (breathing) and is found in the medulla oblongata and
responds in conjunction with the CCC and VCC
Nervous/Neural Control.
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Respiratory muscles are under involuntary neural control
The RCC has two areas; the inspiratory and expiratory centres,
which are responsible for stimulation of the respiratory muscles at rest
and during exercise
AT REST
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
The inspiratory centre is responsible for the rhythmic cycle of
breathing to produce a rate of 12-15 breaths a minute
o The inspiratory centre sends impulses to the respiratory muscles
via:
 Phrenic Nerves to the diaphragm
 Intercostal Nerves to the external intercostals
o When stimulated, these muscles contract and increase the
volume of the thoracic cavity, causing inspiration (active)
o When their stimulation stops, muscles relax and decreases the
volume of the thoracic cavity, causing expiration (passive)
The expiratory centre is inactive during resting breathing as expiration
is passive
DURING EXERCISE



The inspiratory centre:
o Increases stimulation of the diaphragm and external intercostals
o Stimulates additional inspiratory muscles for inspiration (the
sternocleidomastoids, scalenes and pectoralis minor), which
increase the force of contraction and depth of inspiration
The expiratory centre:
o Stimulates the expiratory muscles (internal intercostals,
rectus abdominus and obliques), causing a forced expiration
which reduces the duration of inspiration
The inspiratory centre immediately stimulates the inspiratory muscles
to inspire. The net effect of the above is that as exercise intensity
increases, the depth of breathing decreases and the rate of breathing
increases
8
Factors Influencing the Neural Control of Breathing


The main receptors that send information to the RCC during exercise
are:
o Chemoreceptors within the medulla and carotid arteries send
information to the inspiratory centre on:
 Increase in PPCO2
 Decrease in PPO2
 Decrease in pH (increase in acidity)
o Proprio-receptors located in the muscles and joints send
information to the inspiratory centre on motor movement of the
working muscles
o Thermoreceptors send information to the inspiratory centre on
increase in blood temperature
o Baroreceptors or stretch receptors in the lungs send
information to the expiratory centre on the extent of lung inflation
during inspiration
Only the Baroreceptors stimulate the expiratory centre to actively
expire. This reduces the duration of inspiration and therefore increases
the rate of breathing
Effects of Altitude on the Respiratory System
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Exposure to high altitude has a significant effect upon the performance
by affecting the normal process of respiration
At high altitude (above 1500m) the PPO2 in the atmospheric air is
significantly reduced (Hypoxic), which decreases the efficiency of the
respiratory process
The following table shows the changes in PP with changes in altitude
ALTITUDE (m)
9000
4000
3000
2000
1000
0 (Sea Level)

BAROMETRIC
PRESSURE (mmHg)
231
462
526
596
674
760
PPO2
59
97
110
125
141
159
Altitude Training can be used as an Ergogenic (anything that improves
performance) Training Aid
Primary Effects of Altitude on the Respiratory System
 Decreased PPO2 in alveoli = Hypoxia due to decrease in PPO2 in
atmospheric air
 Decreased PPO2 causes a reduction in the diffusion gradient
 Decrease in O2 and Hb association during external respiration
 Resulting in decreased O2 transport in the blood
9
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
Causing a reduction in O2 available to muscles – due to a reduction in
diffusion gradient and O2 exchanged during internal respiration
Net effect – decreases VO2 max/aerobic capacity which decreases
aerobic performance and increases the onset of muscular fatigue
Other Effects of Altitude on the Respiratory System
 Colder air increases water loss as air warms/moistens in the lungs
leading to dehydration
 Decrease in muscles O2 chemoreceptors stimulating respiratory centre
to increase breathing rate = hyperventilation
 Long-term effect – decreased PPO2 increases Hb and RBC production
which increases external respiration and O2 transport
Altitude Training

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

The main reason for Altitude Training is that due to the Hypoxic
conditions the body adapts by increasing the release of Erythropoietin
(EPO) which stimulates an increase in RBC production and an
increase in capillarisation
Therefore, when returning to sea level, O2 carrying capacity (VO2
max) is increased and will subsequently increase aerobic-based
performance
Most research suggests that there is no significant benefit for training
at altitude than at sea level
High altitudes prevent athletes from training at the same intensity as
they can at sea level due to the Hypoxic air
Any adaptations that do occur are not significant and are short lived; so
there is only an advantage for a few days after returning to sea level
Respiratory Adaptations to Physical Activity


The overall effect of training on the Respiratory System is an increase
in its efficiency to supply O2 to the working muscles during higher
intensities of physical activity
Below are the specific respiratory adaptations that improve this
efficiency (for Respiratory Structures, Breathing Mechanisms,
Respiratory Volumes and Diffusion):
Respiratory Structures
 Increased alveoli, increasing the surface area for diffusion
 Increased elasticity of respiratory structures (lungs, alveoli, pleura)
 Increased longevity (prolonged existence) of respiratory structure
efficiency
Breathing Mechanisms
 Increased efficiency/economy of respiratory muscles reduces the O2
costs of the respiratory muscles, reducing respiratory fatigue
 Increase in strength, power and endurance of respiratory muscles
10
Respiratory Volumes
 In general the lung volumes and capacities change little with training, at
rest and during sub-maximal activity
 However, TV can increase during maximal exercise
 Respiratory frequency decreases at rest/sub-maximal activity but can
increase during maximal work
 Maximal VE can significantly increase from around 120 L/min in an
untrained athlete to 150L/min following training
 180-200+ in elite athletes, due to an increase in TV and f at maximal
exercise
Diffusion
 Diffusion unchanged at rest and sub-maximal exercise
 Increase in pulmonary diffusion during maximal exercise
 Increased VO2 difference (arterial-venous oxygen difference) at
maximal activity (less O2 in venous blood representing increased
delivery and extraction of O2 to active muscles)
Outcomes of Altitude Training


The overall effect of all the above efficiency improvements is that VO2
max (maximal oxygen consumption) and the lactate threshold (the start
of anaerobic work) increase, both of which will improve performance.
The main performance benefits are:
o Aerobic performance during higher/maximal work rates is both
increased and prolonged
o More effect with aerobic endurance activity that is dependent
upon O2, although it will delay the anaerobic threshold and
therefore delay fatigue during anaerobic activity
o Reduces the effort of sub-maximal work, therefore increasing
duration of performance
o A more efficient and healthy respiratory system encourages and
promotes a lifelong involvement in an active/healthy lifestyle
Respiratory System and an Active Lifestyle
Asthma and an Active Lifestyle

You need to be able to evaluate critically the following factors in
relation to asthma:
o Awareness of symptoms to be able to detect its presence
o Awareness of tests to measure its severity
o Understand what conditions trigger its symptoms
o Understand its effects on physical activity/performance
o Understand the treatments to help its management
11
Symptoms
 Asthma is characterised by a reversible narrowing of airways; with
common symptoms of:
o Hyperirritability of airways, coughing, wheezing, breathlessness
or mucus production
 Asthma occurs in response to a trigger or allergen
Measurement
 Asthma is measured by breathing into a spirometer and measuring the
exhaled volume of air
 If the individual improves their expiratory volumes after inhaling
bronchodilator treatments, they are considered to have asthma
 The International Olympic Committee (IOC) now requires medical
evidence of asthma and accepts a 15% improvement in forced
expiration in 1 second, within 10 minutes of using a bronchodilator
treatment
 There are challenges to this rule due to variations in triggers. E.g.
exercising above 85% intensity for 6 minutes to allow airways to dry,
hyperventilating for 6 minutes, and inhalation of triggers to induce the
asthmatic response
Triggers
 The main trigger is the drying of the respiratory airways, normally due
to water loss from the airway surfaces. This causes an inflammatory
response, and triggers the constriction/narrowing of airways termed
bronchoconstriction
 Bronchoconstriction is often brought on shortly after exercise or some
hours after
 The link between exercise and asthmatic symptoms is termed exercise
induced asthma (EIA)
 Other common allergens inducing asthma are:
o Exhaust fumes, air pollutants, dust, hair and pollens
 EIA is more common in cold weather sports, as cold air is dryer than
warm air and therefore is more likely in winter when the respiratory
airways are processing ice-cold air
 Ice surface sports like ice hockey and skating act as triggers due to the
ice resurfacing machine pollutants and chlorine in water triggers
swimming-related asthma
Performance Effects
 Asthma and related respiratory problems are increasingly common in
athletes, particularly elite aerobic athletes
 However, the respiratory system can limit performance in people with
asthma
12
Management of Asthma
 Medical Treatments
o Normally treated by inhaled medications (bronchodilators) –
which are ‘reliever’ (coded blue) medication which relax muscles
around the airways, and are normally taken before exercise or in
response to symptoms
o Corticosteroids are ‘preventer’ (non-blue) medication which
suppress the chronic inflammation and improve the pre-exercise
lung function and reduce the sensitivity of the airway structures.
A daily dose for mild asthma is the normal treatment
 Non-Medical Treatments
o A warm-up, at least 10-30 mins at 50-60% max HR provides a
‘refractory period’ for up to 2 hours, after which exercise is
possible without triggering EIA
o Dietary modification of reducing salt and increasing fish oils and
(antioxidant) vitamins C and E have also shown to help reduce
the inflammatory response to EIA
o Caffeine is also a bronchodilator, but the IOC limit on caffeine is
12mg/ml
Inspiratory Muscle Training (IMT)
 Increased respiratory effort is a major principle symptom of
breathlessness; hence, there is a strong relationship between the
strength of the respiratory muscle and the sense of respiratory effort
 IMT cannot cure asthma, but it has shown to increase airflow and
alleviate (ease) breathlessness. Therefore, the benefit to asthmatic
athletes may be greater in terms of performance as well as control of
the symptoms
 For competitive athletes, when asthma is short of the IOC criteria for
pharmacological treatments, non-pharmacological approaches may be
the only way of minimising the negative impact of EIA on an athlete’s
ability to fulfil their potential
 IMT therefore, reduces the use of medication and improves quality of
life
 ‘POWERbreathe’ is now available on prescription and show that IMT is
now a well established drug-free method of managing asthma
 The more obvious management strategies are simply to stop the
conditions that act as triggers in the first place. For example:
o Refrain from endurance training when suffering respiratory
infections
o Avoid exercise in cold/dry air conditions
o Or if unavoidable, minimise the effects by wearing a mask to
cover the nose and mouth to enable exhaled air to help raise the
temperature of the air inhaled
13
Smoking and an Active Lifestyle

You need to be able to evaluate critically the effects of smoking on the
respiratory system with reference to a lifelong involvement in an
active/healthy lifestyle
Health Effects
 Impairs natural development in teenagers
 Impairs lung function and diffusion rates
 Increased damage and likelihood of respiratory diseases, infections
and symptoms outlined below
o Asthma
o Irritates/damages respiratory structures (cilia, alveoli,
bronchioles, trachea and larynx)
o Narrows/constricts respiratory airways
o Emphysema (diseased elasticity of respiratory structures)
o COPD (Chronic Obstructive Pulmonary Disease)
o Cancers of respiratory structures
o Shortness of breathe, coughing and wheezing, mucus/phlegm in
the lungs
Performance Effects
 Smoking decreases the efficiency of the respiratory system to take in
(VO2 max) and supply oxygen to our working muscles
 It also works against the positive long-term adaptations made from
being involved in physical activity
 Smoking therefore, impairs performance at all levels
 Smoking mostly affects endurance-based exercise, especially high
intensity maximal activity like triathlon
 It also reduces respiratory health in general, so even something as
simple as walking will be impaired
14
EXAM QUESTIONS
JANUARY 2002
2
b)
At rest and during physical activity the performer varies the
volume of gas exchanged in the lungs.
(i)
Give typical minute ventilation values in either L/min or
ml/min for a 20 year old fit athlete at rest and during
maximal exercise.
Rest ……………………………………………………………………
Maximal ………………………………………………………………
(ii)
Describe how neural control enables the athlete to
increase lung volumes. Why is this beneficial to
performance?
MAY 2002
1
b)
Explain how the structure of the lungs enables efficient
exchange of gases.
(3 marks)
2
b)
During a marathon the performer must increase the volume of
gas exchanged in the lungs and at the muscles.
(i)
Describe the changes in the mechanics of breathing
(inspiration and expiration) which allow the performer to
exchange larger volumes of gas.
(3 marks)
(ii)
Explain how gas is exchanged between the blood and the
muscle tissues during exercise. Why is this beneficial to
performance?
(5 marks)
JANUARY 2003
2
a)
During prolonged physical activity the performer needs to take in
more oxygen and remove carbon dioxide.
(i)
Explain how oxygen is exchanged at the alveoli during
exercise. Why is this beneficial to performance?
(4 marks)
MAY 2003
1
b)
Identify the changes you would expect to see in the following
three lung volumes, from resting to exercise conditions, e.g.
during aerobic activity.
 Tidal Volume
 Inspiratory Reserve Volume
 Expiratory Reserve Volume
(3 marks)
15
c)
Why would endurance performance decrease when performing
at altitude?
(2 marks)
JANUARY 2004
2
a)
During prolonged aerobic activity a performer needs to
exchange greater amounts of oxygen and carbon dioxide.
(i)
Describe how the mechanics of breathing change to allow
more oxygen to be inspired during exercise. (3 marks)
(ii)
Explain how the performer is able to exchange greater
volumes of oxygen and carbon dioxide between the lungs
and the blood during exercise.
(4 marks)
MAY 2004
2
a)
Exercise results in an increase in the volume of gas exchanged
in the lungs.
Define Tidal Volume and describe how a performer is able to
increase lung volumes during exercise using neural control.
(4 marks)
b)
(iii)
Describe how more oxygen is diffused into the muscles
during exercise.
(4 marks)
JANUARY 2005
2
a)
During aerobic performance a large amount of carbon dioxide is
produced at the muscles.
(i)
How is carbon dioxide diffused from the muscle tissue
into the blood during exercise?
(3 marks)
(v)
Describe how the mechanics of breathing alter during
exercise to expire greater volumes of carbon dioxide.
(3 marks)
MAY 2005
1
d)
During endurance activities at altitude there may be a reduction
in performance.
Why do the changes in air pressure at altitude reduce
performance?
(4 marks)
16
2
d)
Minute ventilation is defined as the volume of air inspired or
expired in one minute.
Sketch a graph below to show the minute ventilation of a
swimmer completing a 20 minute sub maximal swim. Show
minute ventilation:



Prior to the swim
During the swim
For a 10 minute recovery period
(4 marks)
120
100
80
Minute
Ventilation
(L/min)
60
40
20
0
Rest
Swim
Time (minutes)
17
Recovery
JANUARY 2006
1
d)
Figure 2 shows a spirometer trace of lung volumes of a
performer at rest.
Inspiratory Reserve
Volume
Lung
Volumes
(litres)
Vital Capacity
3.4
A
3.0
Expiratory Reserve
Volume
1.5
Functional Residual
Capacity
Residual Volume
Figure 2
2
b)
(i)
Name and define the lung volume labelled A.
(2 marks)
(ii)
What change would you expect in lung volume A as the
performer starts to exercise?
(1 mark)
Figure 3 shows oxygen diffusing into the blood stream and being
transported in the blood to the working muscles.
Alveoli of lung
Capillary
O² O²
O²
O²
O²
Figure 3
18
to working muscles
via heart
(i)
Explain how gas exchange is increased at the lungs to
ensure that a greater amount of oxygen is diffused into
the blood during exercise.
(4 marks)
(ii)
How is oxygen transported in the blood to the working
muscles?
(2 marks)
(iv)
Describe the mechanisms of breathing which allow a long
distance runner to breathe in (inspiration) greater
volumes of oxygen during a sub-maximal training run.
(3 marks)
(v)
Explain how the respiratory centre uses neural control to
produce changes in the mechanics of breathing.
(2 marks)
MAY 2006
1
a)
JANUARY 2007
1
c)
Stroke volume is an important factor during aerobic
performance.
Define stroke volume and give a maximal value for an aerobic
athlete.
(2 marks)
d)
2
a)
Lung volumes can be a good indicator of aerobic fitness.
(i)
Define minute ventilation and give an average value
during maximal exercise.
(2 marks)
(ii)
What happens to the inspiratory reserve volume as an
athlete moves from rest to exercise?
(1 mark)
(iii)
How is oxygen exchange increased at the muscle tissues
(gas diffusion) during a five mile training run? Why is this
beneficial to performance?
(5 marks)
(iv)
Identify two mechanisms of venous return which enable
the athlete to deliver deoxygenated blood back to the
heart during a five mile training run.
(2 marks)
(v)
Describe how the mechanics of breathing ensure carbon
dioxide is expired during the training run.
(3 marks)
19
MAY 2007
2
a)
With reference to the mechanics of breathing, describe how a
cyclist is able to inspire greater amounts of oxygen during a 10
mile training ride.
(2 marks)
d)
Describe how carbon dioxide is diffused from the blood into the
alveoli during the training ride.
(3 marks)
e)
Give reasons why the cyclist’s performance would decrease
when performing at altitude.
(2 marks)
JANUARY 2008
2
a)
Fig. 2 shows the lung volumes of a performer at rest.
Total
Lung
Volume
(dm³)
A
Tidal Volume
B
Residual Volume
0
Time
Fig. 2
b)
(i)
Name the two lung volumes marked A and B. (2 marks)
(ii)
Describe tidal volume. What would you expect to happen
to tidal volume during exercise?
(2 marks)
Fig. 3 shows the dissociation curve. During exercise this curve
moves to the right.
20
100
90
%
80
Saturation
of
70
Haemoglobin
With
60
Oxygen
50
40
30
20
10
0
0
20
40
60
80
100
Oxygen Partial Pressure (mm Hg)
120
Fig. 3
Explain what physiological factors cause the curve in Fig. 3 to
move.
(4 marks)
MAY 2008
2
c)
During exercise minute ventilation increases.
Identify the neural factors which influence the depth of
inspiration of the performer.
(4 marks)
d)
During exercise a performer requires large amounts of oxygen
to be transported to the muscles.
(ii)
Explain the process of carbon dioxide diffusion at the
muscle tissue.
(3 marks)
21