Unit 3
Area of study 2
Outcome 2

The mechanisms responsible for the acute
responses to exercise in the cardiovascular,
respiratory and muscular system.
Words in red are to be defined in your glossary
 Physiological
changes to accommodate
energy requirements. There is an increased
demand for O² and energy substrates, the
Cardio-vascular, respiratory and muscular
systems respond to meet these needs.
 Initial responses to exercise of the 3 systems
are called ACUTE RESPONSES.
 The level of response is dependent on the
intensity and type of exercise.
 When
energy requirements are increased
during the transition from rest to exercise
the delivery of oxygen and fuels to the
working muscles for ATP (Adenosine
triphosphate) resynthesis is increased.
 Cardiovascular
system: to transport and
deliver oxygen to the skeletal muscles
 Respiratory
 Muscular
system: to take in oxygen
system: to uptake and utilise the
available oxygen
Acute responses to exercise are designed to
facilitate an increase in the availability of
oxygen and the removal of carbon dioxide.
These include:
 Increased respiratory rate (breathing rate)
 Increased tidal volume
 Increased ventilation
 Increased oxygen uptake
 Copy
Table 4.1 page 99
Define the above words using your textbook
 At
rest, ventilation varies from person to
person.
 Varies dependent on body size and gender
from 4-15l
 Increases significantly during exercise from
15-30 times greater than at rest
 This increase in ventilation is a result of an
increase in TV and/or RR

V (L/min) = TV (l) X RR (breath/min)
 At
a submaximal exercise intensity,
ventilation increases rapidly at the start,
then more slowly until it reached plateau.
(at about 4-5min into exercise)
 During light to mod exercise, ventilation and
oxygen consumption is linear
 Max intensity, ventilation increases until
exercise stops
 At high intensities, TC plateaus and any
further increase in ventilation is due to
further increases in RR
 When
ventilation is no longer increasing
linearly with the increase in exercise
intensity, this is called the ventilatory
threshold.
 At
the end of exercise and during recovery
ventilation remains elevated for some time
during recovery and returns to resting levels
at a slow rate compared to the energy levels
of the muscles which decrease immediately.
 Gas
exchange occurs in the lungs at the
alveolar-capillary interface and in the muscle
at the tissue-capillary interface through
DIFFUSION.
 Diffusion of gases always occurs from an area
of high pressure to an area of low pressure.
In the lungs:
 Oxygen concentration is high, so oxygen diffuses
from the alveoli into the bloodstream
 Carbon dioxide levels in the blood are high so
carbon dioxide moves from the blood into the
alveoli via a diffusion path.
1.
2.
Calculate the average person’s minute
ventilation using an average Tidal Volume
of 500mL and Respiratory Rate of 12
breathes per minute.
Using your prior knowledge of the
respiratory system, explain the mechanics
of inspiration (inhalation) and expiration
(exhalation), and how gases diffuse into
and out of the lungs and blood vessels. (Use
page 100 of your Nelson text book)
 Complete
peak performance
 Warm-up 1b, 2, 6,
 Training – 1, 2, 3,
 Game on – 4,
 Table
on Acute Respiratory Adaptations
 The
CV system needs to deliver greater
amounts of oxygen and energy substrates to
the working muscles.
 Focus is to get more blood to the working
muscles to meed this need and speed up the
removal of carbon dioxide and waste
products.
 Brain
storm the acute responses of the
cardiovascular system that take place when
exercising.
 Increased
heart rate
 Increased stroke volume
 Increased cardiac output
 Increased blood pressure
 Redistribution of blood flow to working
muscles
 Increased arteriovenous difference
DEFINE THE RED TERMS
 Copy
Table 4.2 page 102 Nelson text book

Heart rate: Is the number of times the heart
contracts or beats per minute (bpm).

When resting: heart rate usually 70 bpm

During exercise: heart rate increases
The increase in heart rate increases oxygen
delivery to the working muscles and aids in the
removal of waste products from the muscles and
body. The greater the increase in intensity the
greater the increase in heart rate
Example:
light or low intensity= 100-140 bpm
Moderate intensity=140-160
High intensity=(maximum) point of exhaustion
 Calculated
by subtracting the age of the
individual from 220
 (Maximum
 Calculate
heart rate 220-age in years)
your own heart rate
Example:
220-17=203bpm
 Is
the amount of blood ejected from the left
ventricle with each beat (contraction) of the
heart
Answer the following Question in your work book: At what intensity of
exercise does stroke volume reach maximum levels? Explain your answer.
 Cardiac
output (Q): is the amount of blood
ejected from the left ventricle of the heart
per minute.
(Already in glossary)
It is the product of HR multiplied by SV
Cardiac output (Q)= Heart rate (HR) x Stroke
Volume (SV)
So (Q) predictably increases during exercise
Exam Question 2011
Question 9
Cardiac output is the combination of two
factors.
a. List the two factors. Do not use
abbreviations in your answer.
2 marks
b.
Describe the relationship between cardiac
output and oxygen uptake, and the role of
the two factors listed in part a., when
moving from resting state to exercising.
3 marks
Exam Question 2010
Question 6 c.
For a given cardiac output, an elite athlete 10kilometre runner will generally have a lower
resting heart rate than an untrained person
of the same age, weight and sex.
c. Explain why this is the case by discussing the
relationship between the cardiac parameters
associated with this adaption.
3 marks
 Complete
handout
‘ Acute cardiovascular responses to exercise’
 Page
103 nelson text book
 Increased
blood pressure: is the pressure
exerted by the blood against the arterial
walls as it is forced through the circulatory
system by the action of the heart.
 Two


components:
Systolic blood pressure: is the blood pressure recorded
as blood is ejected during the contraction phase of the
heart cycle. It is the higher of the two blood-pressure
values.
Diastolic blood pressure: is the blood pressure
recorded during the relaxation phase of the heart
cycle. It is the lower of the two blood pressure values.
Answer the following question in your work books: What is the normal
blood pressure values at rest?
 Systolic
blood pressure will increase when
exercise intensity increases due to the
increasing pressure on the artery walls. This
may reach up to levels as high as 180-200
mm hg.
 Diastolic blood pressure changes little during
exercise. If increased more than 10 mm hg
this is considered abnormal. The minimal
change is accounted for by the decrease in
the peripheral resistance.
 During
exercise venous return in increases by
3 mechanisms: the muscle pump, respiratory
pump and vasoconstriction
Activity: Summarise the 3 mechanism stated
above pg 105
Question: What is the difference between Vasodilation and
vasoconstriction? Explain how these processes result in the increased
blood flow and oxygen delivery to working muscles
 During
aerobic exercise, blood volume
decreases
 Size of the decrease is dependent on the
intensity of exercise, environmental factors
such as temperature, and level of hydration
of the individual
 Under
resting condition there is only about
15-20 per cent of total blood flow that is
directed to the skeletal muscles.
The remaining 80-85 per cent is distributed to
the other organs (heart, liver kidney,
intestines and the brain)
Under exercise this is reversed.
Vasoconstriction in arterioles supplying
inactive muscles, and vasodilation for active
muscles.
Rest 5000 ml
Muscles, 20%
other, 7%
Brain, 14%
Skin, 6%
Heart, 4%
Liver, 27%
Kidneys, 22%
other
Brain
Heart
Kidneys
Liver
Skin
Muscles
Exercise
Brain, 4%
Other, 3%
Kidneys , 1%
Heart, 4%
Liver, 2%
Skin, 2%
Muscles, 84%
Other
Brain
Heart
Kidneys
Liver
Skin
Muscles
•
•
•
•
Is a measure of the difference in
concentration of oxygen in the arterial blood
and the concentration of oxygen in the
venous blood.
measured in millilitres per 100 millilitres of
blood.
At rest arteries contain an oxygen
consumption of 20 millilitres per 100
millilitres of blood (200 millilitres of oxygen
per litre of blood
At rest veins contain about 15 millilitres per
100 millilitres of blood.
 Arteriovenous
oxygen difference at rest is
about 5 millilitres per 100 millilitres of blood
a-VO²diff= 20ml
100ml
_
15ml
100ml
a-VO²diff= 5ml
100ml
The amount of oxygen extracted from the
arterial blood at rest is therefore about 25
percent.
 During
exercise= working muscles use more
oxygen from the blood that passes through.
It is about 75 percent
a-VO²diff increases and can be as high as 15-18
millilitres per 100 millilitres of blood
 Complete
Changes
the handout Acute Cardiovascular



Warm-up – 1a, 3, 4, 5, 6,
Training – 4, 5, 10,
Game on – 3, 6.
 During
exercise the amount of force
developed by working muscle increases. This
is done by the brain increasing the number of
motor units recruited, or it can increase the
frequency of messages sent to activate the
motor unit.
Define the following words:
 Adenosine triphosphate (ATP)
 Adenosine
diphosphate (ADP)
 Phosphatecreatine
(PC)
 Is
the immediate source for all muscular
contractions.
 Supply is relatively short
 When used up muscles must then relay on
energy substrates to fuel metabolism.
 Glycogen is used in both anaerobic and
aerobic respiration to produce ATP.
 During
exercise PC donates a phosphate to
ADP to resynthesise ATP.
 ATP, PC and muscle glycogen levels all
decrease as does intramuscular triglyceride
concentration.
 Glycogen decreases more rapidly with
endurance activities compared to highintensity sprint activities.
 As
exercise begins, and during maximal
exercise, lactate is produced as a waste
product from the creation of energy
anaerobocally
 Therefore lactate levels in the muscles and
the blood increase significantly.
 When oxygen supply equals oxygen demand,
lactate does not accumulate.
 Lactate will continue to accumulate at
intensities above the lactate inflection point
(define pg 109).
 When
ATP is metabolised (recreated using a
fuel) in the muscle, heat is produced. With
an increase in the rate of reactions, this
results in an increase in heat which causes
the body temperature to increase.
 The body accommodates this by sweating.
 Complete
Acute Muscular responses to
exercise
Complete lab pg 112
Peak Performance
Warm –up – 1c, 7, 8, 9, 10
Training – 6, 7, 8, 9,
Game on – 1, 5,
All multiple choice.