Transcript Power point presentation cardiovascular

Cardiovascular System
Exercise physiology
State the composition of blood
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Composed of cells
 Erythrocytes (red blood cells)
 Leucocytes (white blood cells)
 Thrombocytes (platelets)
Plasma- liquid portion of blood
 Carries nutrients, electrolytes, proteins,
gases, waste and hormones.
Blood Facts
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Blood is a specialized type of connective tissue.
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It is heavier and more viscous than water and
accounts for about 8% of our total body weight.
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Healthy adult males have around 5-6 litres of
blood and females about 4-5 litres.
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Its color varies, depending upon the amount of
oxygen it is carrying, from dark red (oxygen poor)
to scarlet red (oxygen rich)
Acts as a regulator of temperature, the water
content in cells, and body pH.
Red Blood Cell

Erythrocytes (Red Blood Cells): contain an
oxygen-carrying pigment called haemoglobin,
which gives blood its red color.
They live for around 120 days, and are replaced
at the astonishing rate of 2 million per second.
White Blood Cells
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Leukocytes
exist in our bodies to combat infection and
inflammation. They do this by ingesting foreign
microbes in a process called phagocytosis.
Platelets
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Thrombocytes
are involved in the process of clotting
help repair slightly damaging blood
vessels.
Describe the anatomy of the heart
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The heart is an involuntary muscle with striated
muscle fibres.
The heart is surrounded by pericardium that
anchors and protects it.
Lub-dub: closing of AV Valves (lub)
closing of the semilunar valves (dub)
Describe the anatomy of the heart
Bicuspid valve (AV valve)
Tricuspid valve (AV valve)
Aortic valve (semilunar)
Pulmonary valve (semilunar)
Super vena cava
Inferior vena cava
Aorta
Pulmonary artery
Pulmonary vein
Atria
Ventricles
Septum
Pacemaker
blood flow through the heart
What prevents backflow in the heart?
How the heart works
What prevents backflow in the heart?
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Dense connective structures called valves prevent
backflow of blood into chambers by opening and
shutting when the heart contracts and relaxes.
Two lie between each atria and ventricle (the
atrioventricular valves: tricuspid on the right and
bicuspid on the left).
Both arteries coming from the heart have a semilunar
valve on them to prevent blood from flowing back into
the heart (the pulmonary semilunar valve and the aortic
semilunar valve).
Describe the difference in wall size of
the atria and ventricles
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The atria act as receiving chambers for
blood returning to the heart. They are
relatively small and thin walled, because
they only have to pump blood the
relatively small distance into the
ventricles.
The ventricles are large, because they
are responsible for propelling blood from
the heart into circulation around the
body.
Blood Vessels
• Arteries: transport oxygenated blood away
from heart.
Pulmonary artery: carry deoxygenated blood
• Veins: carry deoxygenated blood to the heart.
Pulmonary vein: carry oxygenated blood
• Capillaries: carry food & oxygen to tissues,
carry waste away.
How does the heart receive blood?
The heart has its own blood supply via the
coronary arteries. It branches off the aorta. It
also has its own set of veins.
Describe the two types of circulation
• Systemic & pulmonary
• Blood circulation in heart 1:52
• How are the two related?
Cardiac Cycle – Electrical Impulse
Cardiac Cycle video (electrical impulse)(1:38)
Cardiac Cycle – Electrical Impulse
The sinoatrial (SA) node is a small mass of specialized
muscle in the posterior wall of the right atrium. Because
automatic self-excitation of the SA node initiates each
heart beat, setting the basic pace for the heart rate, the
SA node is known as the pacemaker.
The end of the fibers of the SA node fuse with
surrounding atrial muscle fibres so that the contraction
spreads, producing atrial contraction.
Several groups of atrial muscle fibers conduct the
contraction to the atrioventricular (AV) node, which
spreads action potential throughout the rest of the heart
via specialized muscle fieres called Purkinje fibres. These
form the atrioventricular (AV) bundle OR bundle of his.
Cardiac Cycle
WHAT?!!
The heart is will beat after being separated from the
body (as seen in horror films).
The heart can actually continue to beat for a number
of hours if supplied with appropriate nutrients and
salts.
This is because the heart has it’s own specialized
conduction system and can beat independently of it’s
nerve supply.
Still beating heart
What regulates heart rate?
• SA node (pacemaker) (intrinsic control)
• Autonomic nervous system (extrinsic control)
– Sympathetic: fight or flight
epinephrine, norepinephrine underlies the fight-orflight response, directly increasing heart rate,
triggering the release of glucose from energy stores,
and increasing skeletal muscle readiness.
– Parasympathetic: feed & breed, rest & digest
What regulates heart rate?
• Indirect factors (Reading in packet)
-Stress hormones (adrenaline), thyroid
hormones
-Deep breathing, stimulants, medications
-Emotions: anxiety increase HR,
-happiness, depression lower HR
-Dehydration, temperature, altitude.
Cardiac output, stroke volume and
heart rate
• Cardiac Output = the amount of blood
pumped from the heart in one minute. This
measured in liters per minute.
• Stroke Volume = the amount of blood
pumped by each ventricle in each contraction.
• Basal Heart Rate = when heart rate is reduced
to it’s minimum. E.g. when sleeping.
Cardiac Output = Stroke Volume X HR
Discuss the differences in stroke volume
between sub-max & max exercise
• During sub-max exercise both stroke volume &
heart rate increase
• During maximal exercise only heart rate can
continue to increase because stroke volume
has already reached its max output.
Blood Pressure
• The blood pressure is the pressure of the blood
within the arteries. It is produced primarily by the
contraction of the heart muscle. It's measurement
is recorded by two numbers. (systolic & diastolic)
• Tools: stethoscope, sphygmomanometer
• Gold Standard is the Mercury Sphygmomanometer
• Karotkoff sounds:lub-dub sound
(Nickolai Korotkoff, Russian physician, 1874-1920)
How to take BP video
Blood Pressure
Systolic
• The force exerted by the blood on arterial walls
during ventricular contraction (top number)
Diastolic
• The force exerted by blood on the arterial walls
during ventricular relaxation (bottom number)
Blood Pressure
• What is the AHA recommendation for healthy
blood pressure?
Blood
Pressure
Category
Normal
Systolic
mm Hg
(upper #)
Diastolic
mm Hg (lower #)
less than 120
and
less than 80
Prehyperten
sion
120 – 139
or
80 – 89
High Blood
Pressure
(Hypertensio
n) Stage 1
140 – 159
or
90 – 99
High Blood
Pressure
(Hypertensio
n) Stage 2
160 or
higher
or
100 or higher
or
Higher than 110
Hypertensiv
e Crisis
Higher than
(Emergency
180
care needed)
Blood Pressure
AHA Recommendation
For overall health benefits to the heart, lungs and circulation, perform any
moderate- to vigorous-intensity aerobic activity using the following
guidelines:
•Get the equivalent of at least 150 minutes of moderate intensity aerobic
physical activity (2 hours and 30 minutes) each week.
•You can incorporate your weekly physical activity with 30 minutes a day on
at least 5 days a week.
•Physical activity should be performed in episodes of at least 10 minutes,
and preferably, it should be spread throughout the week.
•Include flexibility and stretching exercises.
•Include muscle strengthening activity at least 2 days each week
Discuss how BP responds to dynamic
& static exercise.
• Dynamic (moving around)
– dilation of blood vessels=increased blood flow
• Very little pressure change as a result
• Very little change in systolic number (pressure during contraction)
• Diastolic will remain the same (pressure when vessels relaxed)
• Static (stretching, holding a position)
- No blood vessel dilation
- Both systolic & diastolic increase drastically
Cardiovascular Drift
An increase of body temperature results in a
lower venous return to the heart, a small
decrease in blood volume from sweating (blood
viscosity increases). As a result of water loss
from the blood the stroke volume decreases
causing the heart rate to increase to maintain
cardiac output.
Cardiovascular Drift
– Example of cardiovascular drift
If you begin a 90 minute steady state ride on your bicycle at a
controlled intensity, your heart rate may be 145 after 10
minutes. However, as you ride and check your heart rate
every 10 minutes, you will notice a slight upward "drift". By
90 minutes, your heart rate may be 160.
Why is this happening if intensity is held constant?
As you exercise, you sweat. A portion of this lost fluid volume
comes from the plasma volume. This decrease in plasma
volume will diminish venous return and stroke volume. Heart
rate again increases to compensate and maintain constant
cardiac output. Maintaining high fluid consumption before
and during the ride will help to minimize this cardiovascular
drift, by replacing fluid volume.
Cardiovascular Drift
• Second reason: Your heart rate is controlled in large
part by the "Relative" intensity of work by the muscles.
So in a long hard ride, some of your motor units fatigue
due to glycogen depletion. Your brain compensates by
recruiting more motor units to perform the same
absolute workload. There is a parallel increase in heart
rate. Consequently, a ride that began at heart rate 150,
can end up with you exhausted and at a heart rate of
175, 2 hours later, even if speed never changed!
Compare the distribution of blood at rest and
the redistribution of blood during exercise
% Cardiac Output
• Blood distribution
• Copy graph in video
Brain Heart Muscle Skin Kidneys Stomach Intestines
Organ
Did You Know
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When one stands still for a long period of time, e.g.
when a soldier stands at attention, blood pools in
the veins. Within a few moments, pressure
increases in the capillaries (veins are not accepting
blood from them because they are dammed up with
their own), and some plasma is lost to interstitial
fluid. After a short time as much as 20% of the
blood volume can be lost from circulation in this
way. Arterial blood pressure falls and blood supply
to the brain is diminished, sometimes resulting in
fainting.
Adaptation to Exercise
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Resting heart rate decreases as a result of
aerobic training. This is due largely to an
increase in stroke volume.
Adaptation to Exercise
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Stroke volume increases due to an increased
cardiac hypertrophy (muscle size)/left ventricular
volume from aerobic training. Therefore, for every
heart beat, a trained athlete can pump more blood
from the heart to the working muscles.
Adaptation to Exercise
• Increased amount of capillaries increases
ability to distribute more oxygen and remove
more waste.
• Increased arterio-venous oxygen difference.
VO2 Max
How well your body can transport and use oxygen
during exercise
Proper Units: mL/kg/min
O2/body mass/time
• What is VO2 max? (5min)
VO2 Max
VO2 max- Hyperventilation
• A certain workload -- intensity along with duration of
exercise -- induces hyperventilation, according to
findings by "The British Journal of Sports Medicine."
This onset during exercise is caused by changes that
your body undergoes to prepare for the increase in
activity. In anticipation of exercise, your brain sends
signals to the respiratory center to increase breathing
to meet oxygen demands. In certain situations, such as
panic or accumulation of lactic acid from intense
exercise, breathing may become abnormally rapid and
hyperventilation occurs.
VO2 max- Hyperventilation
• Hyperventilation is a state of uncontrolled, rapid
breathing. The fast-paced breathing expels more
carbon dioxide from your body than usual, causing
your blood's carbon dioxide level to drop and its pH to
rise. As a result, the arteries constrict, causing feelings
of dizziness or light-headiness. Other symptoms of
hyperventilation include chest pain, numbness or
tingling in the arms, weakness and confusion.
Hyperventilation can be brought on as a result of the
changes that occur in your body during exercise.
VO2 max calculation- (Fick equation)
Can be simplified to the following equation:
VO2 max = max cardiac output x max arteriovenous difference
Where:
max cardiac output = stroke volume x heart rate
max a-vO2 difference = artery O2 conc. – veins O2 conc.
VO2 Max
•Bjorn Daehlie - Norwegian cross-country skiing - VO2 max score: 96
•Espen Harald Bjerke - Norwegian cross-country skier - VO2 max score: 96
•Greg LeMond - Professional cycling - VO2 max score: 92.5
•John Ngugi - World XC Champion distance running - VO2 max score: 85
•Steve Prefontaine - Running - VO2 max score: 84.4
•Lance Armstrong - Professional cycling - VO2 max score: 84
VO2 Max- training
What happens to our bodies as a result of VO2 increasing?
Increased stroke volume (increased cardiac output)
Decreased resting heart rate
Increase capillary density
Increased mitochondria number
As a result of the above you become:
More efficient at extracting oxygen from blood
More efficient at getting oxygen to muscles for energy production
Reduced rate of fatigue
Vo2 max- other factors
• Age
• Genetics
• Type of activity
The Heart & Body during exercise
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Response of HR & BP
Cardiac output, stroke volume
Ventricular mass & volume
Cardiovascular drift
Activity type- exercise type
Blood distribution- blood vessel response
Vo2 max