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Transcript
CARDIOVASCULAR AND CONTROL OF BLOOD
SUPPLY
CARDIOVASCULAR SYSTEM
AEROBIC
-
A process taking place in the presence of Oxygen
ANAEROBIC
-
A process taking place in the absence of Oxygen
AEROBIC
SYSTEM
-
Provides energy for prolonged work and consists
of 3 body systems: the heart, vascular system and
respiratory system
AEROBIC
CAPACITY
-
The ability to supply and use Oxygen to provide
the energy for prolonged periods (limited by the
efficiency of the 3 systems)
OXYGENATED
-
Blood saturated/loaded with Oxygen
DEOXYGENATED -
Blood depleted of Oxygen
Structure and Function of the Heart
The Heart’s structure includes the following:








Septum – separates the left and right side
Valves that control forward motion of blood flow through the Heart and
prevents backflow of blood within the Heart chambers
o Atrioventricular (AV) Valves
 Bicuspid – separates the left Atrium and left Ventricle
 Tricuspid – separates the right Atrium and right Ventricle
o Semi-Lunar (SL) Valves
 Pulmonary Valve – exits the right Ventricle into the
Pulmonary Artery
 Aortic Valve – exits the left Ventricle into the Aorta
Superior and Inferior Vena cavae – deoxygenated blood from the
body to the Heart
Pulmonary Artery – deoxygenated blood from right ventricle to the
lungs
Pulmonary Veins – oxygenated blood from the lungs to the left atrium
Aorta – oxygenated blood from the left ventricle to the whole body
Coronary Arteries – left and right branches from the Aorta encircle
and supply the Heart muscle with oxygen and glucose
Coronary Veins – drain deoxygenated blood directly back into the
right atrium via the coronary sinus
1
Conduction System
 The electric impulse responsible for stimulating the heart to contract is
called the Cardiac Impulse
 The heart is said to be Myogenic as it generates its own electrical
impulse
 The Cardiac Impulse is initiated by the sino-atrial (SA) Node (also
known as the Pacemaker) which is found in the posterior wall of the
right atrium
 The impulse travels through the atria and cause them to contract
 The ventricles are not stimulated yet as they are insulated from the
atria
 The impulse reaches the Atrioventricular (AV) Node in the right
atrium which passes the impulse down the Bundle of His found in the
septum
 This then splits down the left and right reaching the ventricle walls via a
network of Purkinje Fibres which cause the ventricles to contract
Cardiac Cycle
 This is one heartbeat which lasts 0.8 seconds and repeated about 72
times a minute
 It is split into 2 phases:
o Diastole lasting 0.5 seconds (the Relaxation Phase)
o Systole lasting 0.3 seconds (the Contraction Phase)
 The Cardiac Cycle follows these events:
DIASTOLE
Both Atria fill with blood. AV Valves closed
Atrial blood pressure rises above Ventricular pressure
Atrial blood pressure forces AV Valves open and blood passively passes into both
ventricles. SL Valves closed
SYSTOLE
Both atria contract actively forcing the remaining atrial blood into the ventricles. SL
Valves remain closed
Both ventricles contract. Increasing ventricular pressure
SL Valves open. AV Valves closed
Blood then travels to the Lungs and the whole Body
Diastole begins. SL Valves close to prevent backflow of blood
2
Describe the link between the Cardiac Cycle and the Conduction System
Resting Heart Rate – Volumes and Definitions
HEART RATE
-
-
-
STROKE VOLUME -
-
CARDIAC OUTPUT -
The number of times the Heart ventricles beats in
one minute. The average resting HR is 72 beats
per minute (bpm). The maximum HR is calculated
by subtracting your age from 220.
Low resting HR may indicate a high level of
aerobic/endurance fitness. Highly trained athletes
can have a resting HR as low as 28 bpm
A resting HR below 60 bpm is termed bradycardia
(or slow HR), due to increase in Stroke Volume
due to an increase size of the heart muscle (called
hypertrophy)
The volume of blood ejected from the ventricles
every beat
This is the difference in volume of blood in the
ventricles before and after the ventricles contract
The following terms are used to measure SV:
End-diastolic volume (EDV) – volume of
blood in ventricles at the end of relaxation
phase (before contraction)
End-systolic volume (ESV) – volume of
blood in ventricles at the end of contraction
phase (before contraction)
Resting EDV is about 130ml; resting ESV is about
60ml. Therefore, resting SV is about 70ml
The volume of blood ejected by the heart
ventricles in one minute (can also be called Q)
The resting value is about 5 litres per minute
(L/min)
Q
=
SV
x
HR
(L/min)
(ml per beat)
(beats per min)
Heart Rate Response to Exercise
STROKE VOLUME RESPONSE TO
EXERCISE


As an athlete starts running, their SV increases
linearly as their running speed/intensity increases
(only up to 40-60% of max running speed). SV will
then reach a plateau
SV is determined by the heart’s ability to fill and empty each beat.
Ability of heart to fill is dependent on:
o Venous return – SV increases due to an increase in blood
returning to the heart
o The ventricles are able to stretch further
3



Ability of heart to empty is dependent on:
o Greater EDV provides a greater stretch on the heart walls
o A greater stretch increases the force of ventricular systole
(contraction of ventricles)
These increase ventricular contractility (capacity of the ventricles to
contract) which almost completely empties the blood from the
ventricles
During exercise EDV = 130ml; ESV = 10ml; therefore SV = 120ml
HEART RATE






-
HR will change before, during and after exercise
depending on the exercise being taken
HR will increase above resting values before exercise takes place. This
is called the anticipatory rise which is the early release of adrenaline
which stimulates the SA node to increase HR
HR increases as exercise intensity increases but slows down just
before maximal HR values
HR decreases as exercise intensity decreases
HR reaches a plateau during sub-maximal work, which represents the
optimal steady state HR for meeting the demand for oxygen at that
specific intensity of work
HR decreases rapidly after exercise stops due to a decrease in
demand for oxygen by the working muscles
A more gradual decrease in HR towards resting levels, but still
elevated to allow the body to recover – this is oxygen debt (additional
oxygen consumption during recovery, above that usually required when
at rest)
CARDIAC OUTPUT (Q)



Increases directly in line with exercise intensity from resting values of 5
L/min to maximal values of 20-40 L/min in highly trained endurance
athletes
Q primarily increases to supply the increase in demand for oxygen from
our working muscles
When exercise intensity exceeds 40-60% of an athlete’s maximal
exercise intensity, SV begins to plateau. Any further increase in Q is a
result of an increase in HR
Here is a summary of HR, SV and Q values related to exercise intensity:
Value
SV
HR
Q
Resting
60 - 80ml
80 - 110ml
70 - 72bpm
5 L/min
EXERCISE INTENSITY
Sub-maximal
Maximal
80 - 100ml untrained 100 - 120 untrained
160 - 200ml trained
160 - 200 trained
Up to 100 -130ml
220 minus your age
Up to 10 L/min
20 - 40 L/min
4
Heart Rate Regulation and Control
CARDIAC CONTROL CENTRE (CCC)





This is found in the medulla oblongata in the brain
It is primarily responsible for regulating the heart and is controlled by
the autonomic nervous system (ANS)
This means that it is under involuntary control and consists of sensory
nerves (nerves that transmit information to the Central Nervous
System – from receptors to the CCC) and motor nerves (nerves that
stimulate muscle tissue causing motor movement)
Sympathetic nerves increase HR whilst Parasympathetic nerves
decrease HR
Each cardiac cycle is controlled by the initiation of the SA node. The
CCC initiates the sympathetic or parasympathetic nervous systems to
stimulate the SA node to either increase or decrease HR
FACTORS AFFECTING
THE CCC
-
There are 3 main factors affecting the CCC
Neural Control
Hormonal Control
Intrinsic Control
NEURAL CONTROL
-
Proprio-receptors in muscles, tendons and
joints inform the CCC that motor
(movement) activity has increased
Chemoreceptors detect chemical changes
in the aorta and carotid arteries and inform
the CCC that lactic acid and CO2 levels
have increased and O2 and pH levels have
decreased
Baroreceptors detect stretch within blood
vessel walls, in aorta and carotid arteries
and inform the CCC that blood pressure has
increased
-
-


The CCC responds to the above neural information by stimulating the
SA node via the sympathetic cardiac accelerator nerve to increase
HR and SV
When exercise stops, all above neural factors are reversed gradually
and the CCC increases stimulation via the parasympathetic vagus
nerve for the SA node to decrease HR
HORMONAL CONTROL
-
Before and during exercise, adrenalin is
released within the blood stream. Adrenalin
stimulates the SA node to increases both
HR and strength of ventricular contraction
(which increases SV)
5
INTRINSIC CONTROL

-
DURING EXERCISE -
-

AFTER EXERCISE -
There are a number of intrinsic/internal
factors that affect HR control during and
after exercise
Temperature increases, which increases
the speed of nerve impulses, which in turn
increases HR
Venous return (blood returning to the
heart) increases HR which directly
increases EDV and therefore SV (Starling’s
Law – SV dependent upon venous return
= any increase in VR causes an increase
in SV and Q)
Temperature decreases and HR decreases
Venous return decreases, which in turn
decreases SV (Starling’s Law)
6
CONTROL OF BLOOD SUPPLY
Circulatory Networks
SYSTEMIC
CIRCULATION
-
Oxygenated blood from the left ventricle to the
body tissues and deoxygenated blood back to the
right atrium
PULMONARY
CIRCULATION
-
Deoxygenated blood from the right ventricle to the
lungs and oxygenated blood back to the left
atrium



Arteries are the largest blood vessels, as they get further away from
the heart they reduce in size to become arterioles and finally into
capillaries (one cell thick to allow gaseous exchange)
Capillaries then flow into larger venules and then into even larger
veins before entering the right atrium from either the superior vena
cava (from the upper body) or inferior vena cava from the lower body
Arteries normally carry oxygenated blood and veins normally carry
deoxygenated blood – this is true with the exception of the
Pulmonary Artery (carries deoxygenated blood) and the Pulmonary
Vein (carries oxygenated blood)
Blood Vessel Structure
BLOOD VESSELS 




Arteries transport oxygenated blood away from the
heart and towards tissue/muscles
Veins transport deoxygenated blood back to the
heart
Capillaries bring blood directly into contact with the
tissues where O2 and CO2 are exchanged
All blood vessels have 3 layers (apart from single-walled capillaries)
Arteries and arterioles have a large middle layer of smooth muscle
(involuntary muscle within blood vessel walls) to allow them to
vasodilate (widening of arteries) and vasoconstrict (narrowing of
arteries) to regulate blood flow
Arterioles have a ring of smooth muscle surrounding the entrance to
the capillary networks to control blood flow. These are pre-capillary
sphincters, they vasodilate and vasoconstrict to regulate blood flow
Larger veins have pocket valves to prevent backflow of blood and
direct blood back to the heart
Venules and veins have a thinner muscular layer allowing them to
venodilate (widening of veins) and venoconstrict (narrowing of veins)
and a thicker outer layer to help support the blood that sits within each
pocket valve
7
Venous Return (VR)

This is the transport of blood from the capillaries through venules, veins
and back to the heart
STARLING’S LAW -
-
This states that stroke volume is dependent upon
venous return. If VR increases, SV increases. If
VR decreases then SV decreases. If SV
increases or decreases, so does Q. Therefore, VR
will determine SV and Q
At rest VR is sufficient to maintain SV and Q to
supply the demand for O2. During exercise the
pressure of blood in the veins is too low to
maintain VR and then SV and Q decrease.
Therefore the body needs additional mechanisms
to help blood return to the heart against gravity to
increase VR and so SV
Venous Return Mechanisms

Pocket Valves
-

Muscle Pump
-

Respiratory Pump -

Smooth Muscle
-

Gravity
-
Prevent backflow of blood and direct it back
to the heart
Veins are situated between skeletal muscle
which help push blood back to the heart
when they contract and relax
Pressure changes in the thorax and
abdomen during exercise. The increase in
pressure in the abdomen, squeezes large
veins in that area and forcing blood back to
the heart
Contraction and relaxation of smooth
muscle in the middle layer of veins helps
push blood back to the heart
Blood from the upper body is aided by
gravity as it descends to the heart
Blood Pooling




VR requires a force to push the blood back to the heart. If there is
insufficient force then the blood will sit in the pocket valves in the veins.
This is Blood Pooling
At rest gravity, pocket valves and smooth muscle are enough to
maintain VR at rest, but not during or immediately after exercise
Therefore, the skeletal and respiratory pumps are needed to maintain
VR during exercise and immediately after exercise
In order for this to happen, an active cool down must take place to
maintain these two pumps and help maintain VR and redistribute Q to
prevent blood pooling
8
Venous Return’s Impact on the Quality of Performance
Venous Return (VR) is important to performance as it determines SV and Q. If
SV/Q decreases, oxygen transport to the working muscles decreases, which
reduces the ability to contract/work aerobically. The impact on performance is
that exercise intensity has to be reduced or muscles will have to work
anaerobically, which will result in muscle fatigue.
A good VR in anaerobic activities will speed up recovery and therefore allow
performers to work anaerobically for longer.
Distribution of Cardiac Output at Rest and during Exercise


The process of redistributing Q is called the vascular shunt
mechanism
Below is a table of the distribution of Q and then where and how it is
redistributed during exercise:
TISSUE
Liver
Kidneys
Brain
Heart
Muscle
Skin
Other
Total


Distribution of Q during light, moderate and maximal exercise
REST
LIGHT
MODERATE
MAXIMAL
(%)
(ml)
(%)
(ml)
(%)
(ml)
(%)
(ml)
27
1350
12
1100
3
600
1
300
22
1100
10
900
3
600
1
250
14
700
8
750
4
750
3
750
4
200
4
350
4
750
4
1000
20
1000
47
4500
71
12500
88
22000
6
300
15
1500
12
1900
2
600
7
350
4
400
3
500
1
100
100 5000 100 9500 100 17600 100
25000
At Rest:
o Only 15-20% resting Q is supplied to working muscles
o Remaining Q (80-85%) supplies body organs
During Exercise:
o Increased Q (80-85%) supplied to working muscles as exercise
intensity increases
o Decreasing % of Q supplied to body organs
o Blood supply to the brain is maintained
o Increased blood supply to the skin surface during light work, but
decreased as exercise intensity increases
Vasomotor Control Centre

The vascular shunt mechanism redistributes Q during rest and exercise
and is controlled by the Vasomotor Control Centre (VCC) found in
the medulla oblongata
9




It stimulates the sympathetic nervous system to either vasodilate or
vasoconstrict the pre-capillary sphincters and arterioles supplying
muscles and organs
VCC receives information from:
o Chemoreceptors in muscles, aorta and carotid arteries which
inform VCC that latic acid and CO2 levels have increased and
O2 and pH levels have decreased
o Baroreceptors in aorta and carotid arteries which inform VCC
that systolic blood pressure has increased/decreased
Organs (during exercise) – The VCC controls blood flow by
increasing sympathetic stimulation which vasoconstricts arterioles and
pre-capillary sphincters which decreases blood flow to non-essential
organs
Muscles (during exercise) – The VCC controls blood flow by
decreasing sympathetic stimulation which vasodilates arterioles and
pre-capillary sphincters which increases blood flow to the capillaries to
the working muscles
Oxygen and Carbon Dioxide Transport
Oxygen Transport
-
97% transported within the protein
haemoglobin in red blood cells
(RBC). When combined together
they make oxyhaemoglobin (HbO2)
3% within blood plasma
-
Haemoglobin has a high affinity for oxygen and will carry it when available,
but give it to tissue’s that have low concentrations of oxygen. Each
Haemoglobin molecule can carry four molecules of oxygen.
Carbon Dioxide Transport
70% combined with water in RBC’s
as carbonic acid
23% combined with haemoglobin as
carbaminohaemoglobin (HbCO2)
7% dissolved in plasma
-
Effective Transportation of Carbon Dioxide and Oxygen within the
Vascular system aids Participation in Physical Activity
Efficient transportation of Oxygen and Carbon Dioxide aids participation in the
following ways:




Prolongs the duration of anaerobic and especially aerobic activity
Delays anaerobic threshold, which
Increases the possible intensity/work rate for the activity
Speeds up recovery during and after exercise
10
Smoking Affects the Transportation of Oxygen
Cigarette smoke contains Carbon Monoxide (CO). Haemoglobin has a higher
affinity (240+ times) to CO and therefore combines with CO in preference to
O2. This reduces the HbO2 association in the lungs and therefore the
performer’s maximal uptake. As a result, less O2 is supplied to the working
muscles and the lactate threshold decreases which both decrease optimal
performance.
Warm-Up – Effects on Vascular System






Gradual increase in blood flow/Q due to vascular shunt mechanism
Vasoconstriction of arterioles/pre-capillary sphincters to organs,
decreasing blood flow to the organs and thereby increasing blood flow
to the working muscles
Vasodilation of muscle arteriole/pre-capillary sphincters, which
increases the blood flow delivery to the working muscles
Increased body/muscle temperature causing a more rapid increase in
transport of the enzymes required for energy systems and muscle
contraction
Increase in body/muscle temperature
o Decreases blood viscosity which improves blood flow to
working muscles
o Increases the release of oxygen from haemoglobin
Decrease in OBLA (Onset of Blood Lactate Accumulation) due to early
anaerobic work when a warm up is not carried out
Cool-Down – Effects on Vascular System




Keeps metabolic activity elevated which gradually decreases HR and
respiration
Maintains respiratory and muscle pumps (prevents blood pooling in
veins; and maintains venous return)
Maintains blood flow to maintain blood pressure
Keeps capillaries dilated to flush muscles with oxygenated blood, which
increases removal of lactic acid and CO2
Blood Pressure



Blood Pressure is caused by the contractive force of the ventricles
forcing blood through the arteries
Definition – The pressure exerted by blood against the (arterial) blood
vessel walls
Blood Pressure (BP) is normally expressed as below:
Systolic
Diastolic
11



Systolic blood pressure represents the highest arterial pressure and
reflects ventricular systole. Diastolic blood pressure represents the
lowest arterial pressure and reflects ventricular diastole
Resting Values – The average resting BP is 120mmHg (in the
aorta)
80mmHg
(mmHg = millimetres of Mercury)
BP is also expressed as “blood flow (Q) X resistance”. Therefore, if
Q is increased, so is blood pressure.
RESISTANCE -
-
-
BP MEASUREMENT -
This is the friction of the blood cells as they travel
against the vessel wall which is termed
VISCOSITY (fluid friction).
BP will decrease when arteries dilate (widening)
and BP will increase when arteries constrict
(narrowing).
This controls the redistribution of blood via the
vascular shunt mechanism
BP is measured using the sphygmomanometer
BP Changes that Occur During Physical Activity and Hypertension
BP changes for lots of reasons; but generally BP:
 Decreases when we are asleep
 Increases temporarily during stress
 Increases with age
 Increases in hot temperature
 Decreases in cold temperature
BP During Exercise (Endurance training)
SYSTOLIC - Systolic BP increases in line with exercise intensity and will
plateau or steady-state during sub-maximal exercise (about 140160), but may decrease gradually if this sub-maximal intensity is
prolonged
As exercise intensity increases, systolic BP continues to
increases in line with intensity, from 120mmHg to above
200mmHg during exhaustive exercise intensity. Systolic BP of
240-250 have been reported in elite athletes at maximum
exercise intensity
DIASTOLIC - Diastolic BP changes little during sub-maximal exercise,
irrespective of intensity. During gross muscle activities like
rowing and running, localised muscular diastolic BP may fall to
around 60-70mmHg. Diastolic BP may increase a little (max
12% or >10mmHg) as exercise intensity reaches maximum
levels
12
Isometric/Resistance Training





Lifting heavy weights during strength/resistance training involves
isometric work
|during isometric work, blood vessels are blocked due to sustained
static muscle contractions which restricts the blood flow through arterial
and venous blood vessels; thus increasing vascular resistance
This can cause an increase in systolic and diastolic BP as blood flow
builds up behind this area of restriction, and BP can exceed
480/350mmHg
The Valsalva manoeuvre often occurs during this type of exercise
(when an athlete attempts to breathe out while the mouth and nose are
closed). This type of exercise is not recommended for individuals
already prescribed as hypertensive
Resting BP after resistance training tends not to change, but may
decrease
Post-Exercise Recovery



Systolic BP decreases temporarily below pre-exercise levels for up to
12 hours
Diastolic BP also remains low, often below normal resting levels and
can remain low for hours afterwards
This may have an important application in promoting a healthy lifestyle
in that it may help lower BP, as exercising more regularly can reduce
BP on a daily basis and this is more significant in individuals who are
already hypertensive
Long-Term Changes
Any reasons behind long-term adaptations to BP are still not fully understood;
but are likely to be due to changes in:
 CV adaptations
 Diet
 Smoking
 Weight
 Stress
The following points are relevant:






Mixed views that resting BP may decrease with continued endurance
training
Resting BP is generally lowered in people already with mild or
moderate hypertension
Endurance training can reduce the risk of developing high BP
BP changes little during sub-maximal or maximal work rates
Although resistance/isometric training significantly increases both
systolic and diastolic BP; it does not increase resting BP
Little or no changes to those who are already max hypertensive
13
BP Changes during Hypertension
HIGH Blood Pressure Symptoms: Stressed, Sedentary, Bloated, Weak,
Fainting
Systolic-Diastolic
Category
210 – 120
Stage 4 (very severe) High Blood
Pressure
180 – 110
Stage 3 (severe) High Blood Pressure
160 – 100
Stage 2 (moderate) High Blood
Pressure
140 – 90
Stage 1 (mild) High Blood Pressure
130/139 - 85/89
High Normal
<130-<85
NORMAL Blood Pressure
110 – 75
Low Normal
90 – 60
BORDERLINE LOW
60 – 40
TOO LOW Blood Pressure
50 – 33
DANGER Blood Pressure
LOW Blood Pressure Symptoms: Weak, Tired, Dizzy, Fainting, Coma
Table:








Blood Pressure Norms
This table is often misinterpreted in that high BP is more often viewed
negatively as hypertension and is associated with an unhealthy lifestyle
Hypertension is only present if a high BP is prolonged/long term
Hypertension is not short term temporary high BP, like that induced by
stress, but long term, enduring high BP
Treatment is normally provided if BP exceeds 140mmHg over
90mmHg, but 160 over 95 is more commonly regarded as real
hypertension
Hypertension interrupts the control system for maintaining a normal low
BP and if not treated makes hypertension worse and can lead to some
harmful effects:
o Increased workload on heart (increased resistance to expel
blood)
o Increasing/accelerating atherosclerosis (hardening of arterial
walls = less elastic)
o Increasing/accelerating arteriosclerosis (narrowing of arterial
walls)
o Arterial damage (above) increases the risk of a stroke and
congestive (weakening) heart failure
Although there is mixed evidence, it is generally suggested that
exercise can reduce the risk of developing high BP – and in some
cases can bring down BP in people that already have mild to moderate
hypertension
An active lifestyle can prevent high BP indirectly by reducing the risk of
obesity – which increases the chance of hypertension
Exercise has also been strongly linked with reductions in stress, which
may help to keep blood pressure at moderate levels
14
Impact of Different Types of Physical Activity on the CV System
Arteriosclerosis





This relates to a loss in elasticity, thickening/hardening of the arteries
Which reduces the arteries efficiency to vasodilate/vasoconstrict
Our arteries harden as part of the natural aging process
Smoking increases this process and if you start to smoke younger, it
will start earlier
Blood clots are also two to four times more likely
Atherosclerosis



This is a form of Arteriosclerosis that affects changes in the lining of the
arteries
Cholesterol and fat deposits accumulate within arterial walls forming
fatty plaque which leads to progressive narrowing of the lumen, which
increases the chance of blood clots forming
This can restrict blood flow and lead to high BP (hypertension)
Angina



Angina is a partial blockage of the coronary artery causing intense
chest pain which occurs when there is an inadequate oxygen/blood
supply to the heart muscle wall
Both Arteriosclerosis and Atherosclerosis in coronary arteries deprive
areas of the heart of oxygen/blood
This can occur during rest, anxiety, but more especially during physical
effort/exercise, when the heart requires more oxygen than the coronary
arteries can provide due to blockages
Heart Attack



This is a more severe/sudden or total restriction of oxygen/blood supply
to part of the heart muscle wall, usually causing permanent damage
It is most like due to blood clots from larger coronary arteries that get
stuck in smaller ones and block them
Death can occur if the damaged area is large enough to prevent the
remaining heart muscle wall from supplying sufficient cardiac output to
the body
Impact on Coronary Heart Disease (CHD) of lifelong involvement in an
active lifestyle


The World Health Organisation endorses the view that the risk of CHD
is 2-3 times more likely in inactive sedentary individuals than that of
those physically active
Inactivity is a major risk factor for CHD, almost doubling the risk of a
fatal heart attack
15


Research suggests there is a ‘cause-and-effect’ relationship between
inactivity and CHD
Lifelong involvement in an active lifestyle will maintain significant
protection from CHD
Risk Factor
1–
Physical/activity
(mins/wk)
Above 60% HR
Max
2 – Blood
Pressure
(mmHg)
Systolic
Diastolic
3 – Smoking
(cigs per day)
4 – Blood Lipids
Cholesterol
(mg/dl)
Triglycerides
(mg/dl)
5 – Obesity
(BMI)
Table:
1
V Low
2
Low
Level of Risk
3
Moderate
120
90
30
0
0
<110
<70
0
120
76
5
130-140
82-88
10-20
156-160
94-100
30-40
>170
>106
>50
<180
<200
220-240
260-280
>300
<50
<100
<130
<200
<300
>25-27
27-30
30 - <35
35 - <40
>40
4
High
5
V High
Primary Risk Factors
Calculation of BMI
Example
1.
Height squared:
2.
Weight divided by
height squared:
3.
BMI:
1.88 x 1.88 = 3.53
952 / 3.53 = 26.9
27 (overweight)
CHD – How to Reduce the Risk
Physical activity can protect us from CHD in the following ways:



Improve heart-hypertrophy pumping capacity and circulation;
vascularisation; increase capacity/size of coronary circulation
Decrease blood fibrinogen; decrease blood clotting and decreases
blood viscosity, improving blood flow to the coronary circulation
Decrease blood lipids (triglyceride/cholesterol) which can be deposited
on arterial walls leading to atherosclerosis and arteriosclerosis
16





Decrease Low Density Lipoproteins (LDL) – high in blood
lipids/cholesterol which are deposited on vessel walls leading to
atherosclerosis and arteriosclerosis
Increase High Density Lipoproteins (HDL) – low in blood
lipids/cholesterol and act as scavengers removing cholesterol from
arterial walls
Lower BP and reduce the risk of developing hypertension
Reduce obesity controlling body weight which helps against
hypertension and controls of diabetes
Alleviate tension/stress helping reduce hypertension
Other Factors
There are factors apart from exercise that help reduce CHD, they are:



Stopping smoking reduces the speeding up of arteriosclerosis
Regular physical activity
Proper nutrition/diet, which reduces weight/obesity, blood lipids,
glucose and body fat
Recommendations for Physical Activity
We know that physical activity reduces CHD, but what level of physical activity
is recommended to help achieve this protection?
The level of activity required is generally low – walking, low intensity
jogging/cycling provides adequate protection against CHD, although higher
intensity exercise will provide even greater protection
17
EXAM QUESTIONS
MAY 2002
2
a)
An 18 year old swimmer uses maximum effort to complete 100
meters front crawl in a personal best time of 60 seconds. The
swimmer’s heart rate is recorded using a heart rate monitor.
(i)
Sketch a graph to show the swimmer’s heart rate trace
during the following three stages; prior to the race; during
the race; for ten minutes after the race.
(5 marks)
200
Heart
Rate
(beats/ 150
min)
100
50
0
Prior to Race
(ii)
During Race
Time
10 min After Race
Why is a warm up beneficial to the vascular system of a
swimmer?
(2 marks)
JANUARY 2003
1
e)
It is often recommended that a performer cools down following
physical activity.
State three effects that a cool down will have on the vascular
system of the performer.
(3 marks)
2
a)
(ii)
b)
During and after exercise the performer’s heart rate will increase
and decrease.
Describe how neural control regulates a performer’s heart rate.
(3 marks)
Describe how oxygen and carbon dioxide are transported
in the blood.
(4 marks)
18
c)
Endurance (aerobic) performance is dependent upon the heart
supplying blood to the muscles.
Describe the flow of blood through the heart during the cardiac
cycle (Diastole and Systole Phases).
(4 marks)
MAY 2003
2
a)
The measurement of heart rtes during training can provide
valuable information to the athlete and the teacher/coach.
(i)
Sketch a graph on the plan below to show the heart rate
of an athlete who completes a 30 minute aerobic training
run. Show heart rate prior to the training run, during the
run and 10 minutes after the run.
(4 marks)
200
Heart 150
Rate
(beats
per
minute) 100
50
Rest
Training Run
Time
Recovery
(ii)
Describe how hormonal control is used to alter heart rate
during the training run.
(2 marks)
(iii)
Draw and label a diagram to show how the two circulatory
networks (systemic and pulmonary) transport the blood
around the body during the training run.
(4 marks)
(iv)
Describe the mechanisms of venous return that ensure
enough blood is returned to the heart during the training
run.
(2 marks)
(v)
Why should the performer warm up before the training
run?
(3 marks)
19
JANUARY 2004
1
2
c)
During aerobic exercise the performer requires the heart to
pump more blood to the working muscles.
(i)
Define Stroke Volume and give a value for maximal
Stroke Volume during exercise.
(2 marks)
(ii)
Explain how a performer is able to increase stroke
volume during exercise.
(3 marks)
b)
The cardiac cycle explains how the heart pumps blood to the
working muscles.
Describe how the conduction system of the heart controls the
cardiac cycle in the diastole and systole stages.
(4 marks)
c)
Describe the changes that occur in the distribution of cardiac
output as a performer moves from rest to exercise. Explain how
the vasomotor centre controls this distribution.
(4 marks)
MAY 2004
1
b)
The graph below shows a heart rate sketch of a 17-year-old
cyclist before a maximal effort sprint race.
250
200
Heart
Rate
(beats/ 150
min)
100
50
0
Rest
(i)
Sprint Race
Recovery
Time
Define the term heart rate and explain why the heart rate
of the cyclist increases prior to exercise.
(3 marks)
20
(ii)
2
b)
Complete the graph above to show the changes in heart
rate you would expect during the sprint race and in the
following 10 minute recovery period.
(2 marks)
During exercise more oxygenated blood is required by the
muscles.
c)
(i)
Define cardiac output and give a maximum value for a fit
17-year-old endurance performer.
(2 marks)
(ii)
Explain how oxygen is transported in the blood to the
working muscle tissue.
(2 marks)
Following the release of oxygen at the tissues the blood is
returned to the heart (venous return)
(i)
Identify two mechanisms that aid venous return during
exercise.
(2 marks)
(ii)
Give one reason why a good venous return helps an
endurance performer.
(1 mark)
JANUARY 2005
1
b)
Following a training session a coach will require the performer to
complete a cool down.
How would a cool down aid the vascular system?
(2 marks)
c)
Sketch a graph showing the changes you would expect in
cardiac output:
 At rest
 During a 30 minute sub-maximal training run
 For a 10 minute recovery period
(4 marks)
25
20
Cardiac
Output 15
(L/min)
10
5
0
Rest
Exercise
Recovery
Time (mins)
21
2
a)
(ii)
Describe the passage of deoxygenated blood through the
systemic and pulmonary networks which allows carbon
dioxide to be removed during aerobic performance.
(4 marks)
(iii)
Identify two ways in which carbon dioxide is carried in the
blood during aerobic performance.
(2 marks)
(iv)
Why does an increase in carbon dioxide during exercise
increase heart rate? How does this happen? (3 marks)
MAY 2005
1
c)
It is recommended that a performer completes a warm up prior
to exercise.
Give two effects of a warm up on the vascular system,
(2 marks)
2
a)
During exercise more oxygen must be supplied to the working
muscles.
Describe the passage of oxygenated blood through the
pulmonary and systemic networks from the lungs to the working
muscles.
(4 marks)
b)
Cardiac Output is a determining factor during endurance
activities.
Describe how cardiac output is increased during endurance
activities.
(4 marks)
c)
Explain the conduction system of the heart.
(3 marks)
JANUARY 2006
1
b)
A cool down has a number of effects on the vascular system
which aid the performer. One effect is the prevention of blood
pooling. Identify two other effects.
(2 marks)
2
a)
Large amounts of blood need to be circulated around the body
during prolonged aerobic exercise.
(i)
Identify the mechanisms of venous return that ensure a
sufficient supply of blood is returned to the heart during
exercise.
(3 marks)
(ii)
An increase in venous return leads to an increase in heart
rate. Explain how this is achieved by intrinsic control.
(2 marks)
22
(iii)
Describe how the blood travels through the heart in the
following stages of the cardiac cycle.
(3 marks)
 Diastole
 Atrial Systole
 Ventricular Systole
(iv)
Whilst exercising a greater volume of blood is ejected
during ventricular systole. Why is this beneficial to
performance?
(1 mark)
MAY 2006
1
d)
2
a)
One change to the vascular system during a warm up is the
ability of the haemoglobin to release oxygen quickly. Identify
two other changes to the vascular system during a warm up.
(2 marks)
A long distance runner completes a 60 minute sub-maximal
training run.
(i)
Complete the graph below to show the changes in heart
rate in the following three stages:
 Before the run
 During the run
 For a ten minute recovery phase
(4 marks)
200
Heart
Rate
(beats
per
min)
150
100
50
0
Prior the
Run
Training Run
Time (minutes)
23
Recovery
Phase
(ii)
Explain how the cardiac control centre (neural control)
increases the heart rate.
(3 marks)
(iii)
During the training run blood needs to be diverted away
from non-essential organs to the working muscles.
Explain how the vasomotor centre controls this
distribution.
(3 marks)
JANUARY 2007
2
a)
(i)
Describe how the conduction system of the heart controls
the cardiac cycle to ensure enough blood is ejected from
the heart during a five mile training run of a marathon
runner.
(3 marks)
(ii)
Identify two ways in which oxygen is transported in the
blood during the training run.
(2 marks)
During the pull up exercise carbon dioxide is transported
to the lungs. Identify two ways in which carbon dioxide is
carried in the blood during this exercise.
(2 marks)
MAY 2007
1
a)
(ii)
2
b)
Draw a graph to show how a cyclist’s cardiac output changes in
the following phases of an aerobic training session. (4 marks)
 Prior to Exercise
 Exercise Session
 Recovery Period
25
20
Cardiac
Output
(L/min)
15
10
5
0
Prior to
Exercise
Exercise
Time (minutes)
24
Recovery
Period
c)
Draw and label a diagram to show how blood flows through the
pulmonary and systemic networks of the cyclist’s body during
the training ride.
(4 marks)
JANUARY 2008
1
b)
It is recommended that an athlete completes a cool down after
exercise.
Describe three ways in which an active cool down affects the
vascular system of the athlete.
(3 marks)
2
c)
Describe how intrinsic control affects the cardiac output of a
performer during exercise.
(4 marks)
d)
Describe how the conduction system of the heart controls the
cardiac cycle.
(3 marks)
25
MAY 2008
1
c)
Complete the flow diagram outlining the flow of the blood
through the pulmonary circulatory system during exercise.
(4 marks)
Right Atrium
Right Ventricle
Lungs
Left Atrium
Left Ventricle
2
a)
Sketch a graph to show the heart rate changes of a sprinter in
the following phases of a race.
(4 marks)
 Prior to exercise
 During the race
 Recovery period
26
200
Heart
Rate
(beats
per
min)
150
100
50
0
Prior to
Exercise
During the Race
Recovery
Time (minutes)
b)
An increase in heart rate during exercise is a result of intrinsic,
neural and hormonal responses.
Describe the hormonal factors which affect heart rate during
exercise.
(2 marks)
d)
During exercise a performer requires large amounts of oxygen
to be transported to the muscles.
(i)
Explain how oxygen is transported in the blood. (2 marks)
27