Cardiovascular System 2.2

2.2

Cardiovascular

System

Assessment Statements

2.2.8 Explain cardiovascular drift.

2.2.9 Define the terms systolic and diastolic blood pressure.

2.2.10 Analyse systolic and diastolic blood pressure data at rest and during
exercise.

2.2.11 Discuss how systolic and diastolic blood pressure respond to dynamic
and static exercise.

2.2.12 Compare the distribution of blood at rest and the redistribution of
blood during exercise.

2.2.13 Describe the cardiovascular adaptations resulting from endurance
exercise training.

2.2.14 Explain maximal oxygen consumption.

2.2.15 Discuss the variability of maximal oxygen consumption in selected
groups.

2.2.16 Discuss the variability of maximal oxygen consumption with different
modes of exercise.

2

Starter-Group Thought

How does the heart change as a result of
training?

3

Cardiovascular Drift

⦁Cardiovascular drift is the upward drift of heart
rate over time, coupled with a progressive
decline in stroke volume and continued
maintenance of cardiac output.

⦁Occurs while exercise intensity remains
constant (endurance activates)

⦁Characterized by an increase in HR and
decrease in arterial pressure and stroke volume

⦁This decrease in stroke volume is due to a
decrease in venous return

4

Cardiovascular Drift

⦁Connected to an increase in core temperature and
body water losses

⦁When there’s an increase in core body temp., the HR increases.
The body responds by increasing skin blood flow to control
temp. rise (homeostasis!)

⦁This creates “competition” between working muscles (need
large amounts of blood flow) and skin blood flow

5

Explanation of cardiovascular drift

6

Explain Cardiovascular Drift

An increase of body temperature results in a lower
venous return to the heart, a small decrease in blood
volume from sweating. A reduction in stroke volume
causes the heart rate to increase to maintain cardiac
output.

This results in an increase in blood viscosity (the
thickness of blood)

7

“

8

Describe how cardiovascular drift
occurs during a marathon. (5)

⦁Blood pressure readings are given in two
numbers: max amount your heart exerts while
beating and amount of pressure in your arteries
between beats

⦁Measured in blood vessels (artery)

⦁Determined by cardiac output and resistance
to flow of blood in vessels

⦁Resistance to flow affected by diameter of
blood vessels

⦁Narrower vessels (vasoconstriction)

⦁Wider vessels (vasodilation)
11

Blood Pressure

⦁Stiffness of the aorta is the most important
cause of elevated pulse pressure.
⦁Stiffness due to high BP or fatty deposits
damaging walls of arteries, leaving them
less elastic (atherosclerosis).

⦁Treating high BP often reduces pulse pressure!

12

Blood Pressure

⦁Systolic: the force
exerted by blood on
arterial walls during
ventricular contraction.

⦁Top number

13

Systolic and diastolic blood pressure

⦁Diastolic: the force
exerted by blood on
arterial walls during
ventricular relaxation.

⦁Bottom number

What is the definition of systolic
blood pressure?

A. The force exerted by

blood on arterial walls
during ventricular
contraction

Measuring Blood Pressure

⦁We record blood pressure as: Systolic
BP/Diastolic BP

⦁The average blood pressure reading should be
120/80 mmHg

16

17

Measuring Blood Pressure

⦁The pressure in the cuff is
increased until the blood
flow stops, and then the
flow gradually returns as
the cuff is slowly deflated.

⦁This enables you to
measure the blood
pressure when the artery
is closed by pressure from
the cuff, and when the
artery is fully open.

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19

Analyze Systolic and Diastolic blood

pressure data during exercise and at rest

20

Systolic & Diastolic Pressure response to

static and dynamic exercise

⦁Dynamic Exercise (isotonic): Increases systolic
pressure in the first few minutes and then levels
off; diastolic pressure remains relatively
unchanged

⦁Push-ups, curl-ups, bicep curls, squats

⦁Static Exercise (isometric): Can increase blood
pressure dramatically – Muscular
force/contraction compresses peripheral
arteries increasing the resistance to blood flow

⦁Planks, wall-sits, side planks

21

Systolic & Diastolic Pressure response to

static and dynamic exercise

⦁Static = muscles create higher pressure on blood
vessels

⦁Causes an increase in systolic and diastolic
pressure because the muscles exert a
continuous pressure on the vascular system

⦁Dynamic = creates lower pressure on blood vessels

22

23

24

Describe the Blood Pressure Trend

25

Briefly explain the terms ‘cardiac
output’ and ‘stroke volume’, and
the relationship between them. (3
marks)

Explain how running versus static
exercise (such as holding a plank
position) affect systolic and
diastolic blood pressure levels. (4)

Compare the distribution of blood at
rest and the redistribution of blood
during exercise

When you decide to workout:

⦁The nervous system (ANS) prepares body to secrete
hormones to signal dilation of blood vessels in heart and
working muscles

⦁More training= systems act faster and more efficiently to
redistribute blood

⦁Blood redistribution takes a couple of minutes

⦁Stopping or starting slows the effects

⦁Ever started quickly and felt out of breathe...?

⦁Ever stopped abruptly and felt dizzy...? Blood pools in working
muscles from sudden reduction of muscle contractions to
return blood to the heart

30

Compare the distribution of blood at
rest and the redistribution of blood
during exercise

When you decide to workout:

⦁Number of capillaries in muscles increases with training

⦁Blood becomes thinner and flows better

⦁Flow of blood through capillaries is crucial for maximum
exertion

⦁# of RBCs slightly increases

⦁Adaptation to aerobic training allows for more water and
dissolved proteins to be added to the plasma volume to thin
blood

⦁Results in an increase in total plasma volume and decrease
in concentration of RBCs

⦁Vasodilation of the arterioles in the working muscles

⦁Vasoconstriction of the arterioles in internal organs

31

Compare the distribution of blood at
rest and the redistribution of blood
during exercise

⦁At rest the blood is distributed to the working internal
organs

⦁During exercise the blood is distributed to the working
muscles (80-85%)

⦁It takes little pressure to force the blood through veins
because they offer little resistance to blood flow. Their
diameters are large and vein walls are so thin they can hold
large volumes of blood.

⦁During exercise increased muscle contraction results in
increased flow of blood through the veins and into the heart,
thereby increasing cardiac output.

32

33

Analyze the distribution of blood
during maximal exercise. (6)

Cardiovascular Adaptations
resulting from endurance training

⦁During prolonged sub-maximal exercise (performed to
calculate maximal performance) at a fixed intensity,
cardiac output is maintained at same level

⦁This is due to the demand remaining constant with
stroke volume and heart rate at values higher than rest

⦁Capillarization increases (increase in density of
capillaries)

⦁Resting heart rate decreases as a result of aerobic
training. This is due largely to an increase in stroke
volume.

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37

Cardiovascular Adaptations
resulting from endurance training

⦁Stroke volume increases due to an increased cardiac
hypertrophy (muscle size)/left ventricular volume from
aerobic training.

⦁Therefore, for every heartbeat, a trained athlete can
pump more blood from the heart to the working
muscles.

⦁The maximum arteriovenous oxygen difference of a
trained athlete usually exceeds that of an untrained
person. The training effect may be due to adaptations in
the mitochondria, increased myoglobin content of
muscles, or improved muscle capillarization.

38

Outline two cardiovascular
adaptations following
steady-state endurance training.
(2)

Maximal Oxygen Consumption

⦁The most commonly used indication of an individual’s
aerobic fitness is the maximal oxygen uptake (VO2 max)
which is the maximum rate an individual can take in and use
oxygen.

⦁VO2 is calculated by measuring the volume of air being
exhaled at progressively increasing intensities of exercise. As
the oxygen demands increase, so does VO2

⦁VO2 max represents the maximum aerobic capacity of an
individual. At this point, the person will stop exercising
because they will no longer be able to continue.

41

Maximal Oxygen Consumption

⦁Arterio-venous oxygen difference (a- vO2 diff) is the
difference in the oxygen content of the blood between the
arterial blood and the venous blood. It indicates of how
much oxygen is removed from the blood in capillaries as the
blood circulates in the body. It is measured in (mL O2/100
mL blood)

⦁

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Variability of Maximal Oxygen

Consumption

⦁Endurance athletes have high
VO2max scores

⦁Gender: due to size, absolute
VO2max are lower in women

⦁Age: VO2max increases during
childhood and adolescence and
peaks in early 20s for men and
mid-teens for women.

⦁In adulthood, for both
genders, VO2max
declines 1% each yr.

⦁Exercise: highest values are in
cross-country skiers- place
more O2 demand on upper and
lower body and postural
muscles.

45

Why do some sports have a
higher vO2 Max?

46

Identify the group
with the higher
VO2max values.

Discuss expected changes
to systolic and diastolic
blood pressure between
rest and during prolonged
cycling.