Transcript cardiovascular

Cardiovascular System
Cardiovascular System
Components
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Circulatory system
Pulmonary system
Purposes:
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Transport O2 to tissues and remove waste
Transport nutrients to tissues
Regulation of body temperature
Circulatory System
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Heart
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Arteries and arterioles
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Carry blood away from heart
Capillaries
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Pumps blood
Exchange nutrients with tissues
Veins and venules
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Carry blood toward heart
Pulmonary and Systemic
Circuits
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Systemic Circuit
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Left side of heart
Pumps oxygenated
blood to body via
arteries
Returns
deoxygenated blood
to right heart via
veins
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Pulmonary Circuit
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Right side of heart
Pumps deoxygenated
blood to lungs via
pulmonary arteries
Returns oxygenated
blood to left heart
via pulmonary veins
Cardiac Cycle
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Systole
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Contractile phase of
heart
Electrical and
mechanical changes
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E.g. blood pressure
changes
E.g. blood volume
changes
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Diastole
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Relaxation phase of
heart
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Takes twice as long
as systole
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E.g. resting HR =
60
Systole = 0.3 s
Diastole = 0.6 s
Arterial Blood Pressure
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Expressed as systolic/diastolic
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Systolic pressure (top number)
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Normal – 120/80 mmHg
High – 140/90 mmHg
Pressure generated during ventricular
contraction
Diastolic pressure
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Pressure during cardiac relaxation
Blood Pressure
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Pulse Pressure (PP)
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Difference between systolic and diastolic
PP = systolic - diastolic
Mean Arterial Pressure (MAP)
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Average pressure in arteries
MAP = diastolic + 1/3 (systolic – diastolic)
Causes of High Blood Pressure
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Age
Race
Heredity
Diet
Stress
Inactivity
Electrical Activity of the Heart
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Contraction of heart depends on
electrical stimulation of myocardium
Impulse is initiated on right atrium and
spreads throughout the heart
May be recorded on an ECG
Electrocardiogram
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Records electrical activity of the heart
P wave
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QRS complex
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Atrial depolarization
Ventricular depolarization
T wave
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Ventricular repolarization
Diagnostic use of the ECG
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ECG abnormalities may indicate
coronary heart disease
ST-segment depression may indicate
myocardial ischemia
Cardiac Output - Q
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Q = HR x SV or
Q = (FH) (Vs)
Where:
Q = volume of blood pumped by left
ventricle each minute (L.min)
fH = heart rate (b.min)
Vs = stroke volume (average volume of
blood pumped per each contraction
(L.b)
Cardiac Output
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Range of normal at rest is 4 – 6 L.min
During aerobic activity the increase in
cardiac output is roughly proportional to
intensity.
Max. Q is in range of 20 – 40 L.min,
depending on size, heredity, and
conditioning.
Heart Rate
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Range of normal at rest
is 50 – 100 b.m
Increases in proportion
to exercise intensity
Max. HR is 220 – age
Medications or upper
body exercise may
change normal
response
Stroke Volume
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Range of normal at rest is 60 – 100 ml.b
During exercise, SV increases quickly,
reaching max. around 40% of VO2 max.
Max. SV is 120 – 200 ml.b, depending on size,
heredity, and conditioning.
Increased SV during rhythmic aerobic
exercise is due to complete filling of ventricles
during diastole and/or complete emptying of
ventricles during systole.
Central Circulation
Maintenance
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Important for older or deconditioned adults
Moderate, continuous, rhythmic aerobic
activity encourages venous return
Strenuous activity and held muscle
contractions should be avoided
Taper or cool down should follow each activity
session to encourage venous return
Frank-Starling Law of the
Heart
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The heart will pump all the blood
returned to it by the venous system.
Central circulation must be maintained
and the veins must continuously return
blood to the heart.
Features that Encourage
Venous Return
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One-way valves in veins
Vasoconstriction of blood flow to inactive
body parts
Pumping action of skeletal muscles in arches
of feet, calves, thighs, etc.
Pressure changes in chest and abdomen
during breathing
Maintenance of blood volume by adequate
fluid replacement
Siphon action of vascular system
Features that Inhibit Venous
return
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Heat stress requiring additional blood flow to
the skin for core temp. maintenance
Dehydration from sweating or from limiting
fluid intake (dieting, making weight)
Held muscle contractions that cause blood to
pool in the extremities
A Valsalva maneuver which increases
pressure in the chest to a high level
Changing from a horizontal to a vertical
position abruptly
Autonomic Nervous System
Control of Heart Rate
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Sympathetic control
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Stimulates “fight or
flight” response
Speeds up heart rate
and stroke volume
Sympathetic tone
> 100 bpm
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Parasympathetic
control
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Connected to vagus
nerves
Slows down heart
rate
Parasympathetic
tone 60 – 100 bpm
Skeletal Muscle Pump
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Rhythmic skeletal muscle contractions
force blood in the extremities toward
the heart
One-way valves in veins prevent
backflow of blood
Components of Blood
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Plasma
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Liquid portion of blood
Contains ions, proteins, hormones
Cells
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Red blood cells
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White blood cells
Platelets
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Contain hemoglobin to carry oxygen
Important in blood clotting
Hematocrit
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Percent of blood composed of cells
Oxygen Delivery During
Exercise
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Oxygen demand by muscles during
exercise is many times greater than at
rest
Increased oxygen delivery accomplished
by:
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Increased cardiac output
Redistribution of blood flow to skeletal
muscle
Changes in Cardiac Output
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Cardiac output increases due to:
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Increase in heart rate
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Linear increase to max
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Increased stroke volume
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Max HR = 220 - age
Plateau at ~40% of VO2 max
Oxygen uptake by the muscle also
increases
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Higher arteriovenous difference
Redistribution of Blood Flow
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Increased blood flow to working skeletal
muscle
Reduced blood flow to less active
organs
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Liver, kidneys, GI tract
Increased blood flow to skeletal
muscle during exercise
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Withdrawal of sympathetic
vasoconstriction
Autoregulation
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Blood flow increased to meet metabolic
demands of tissue
O2 tension, CO2 tension, ph, potassium,
adenosine, nitric oxide
Circulatory Responses to
Exercise
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Heart rate and blood pressure
Depend on:
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Type, intensity, and duration of exercise
Environmental condition
Emotional influence
Transition from rest > exercise
and exercise > recovery
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Rapid increase in heart rate, stroke
volume, and cardiac output
Plateau in submaximal exercise
Recovery depends on:
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Duration and intensity of exercise
Training state of subject
Incremental Exercise
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Heart rate and cardiac output
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Systolic blood pressure
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Increase linearly with increased work rate
Reach plateau at 100% VO2 max
Increases with increased work rate
Double product
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Increases linearly with exercise intensity
Indicates the work of the heart
Double product = heart rate x systolic blood
pressure
Arm vs Leg Exercise
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At the same oxygen uptake arm work
results in higher:
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Heart rate
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Due to higher sympathetic stimulation
Blood pressure
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Due to vasoconstriction of large inactive muscle
mass
Prolonged Exercise
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Cardiac output is maintained
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Gradual decrease in stroke volume
Gradual increase in heart rate
Cardiovascular drift
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Due to dehydration and increased skin
blood flow (rising body temperature)
How to have a heart attack
Everyone’s doing it, so it must be
the “in” thing to do
Be Old
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Relative risk of CHD increases with age
Have a family history of CHD
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The more blood relatives one has with
CHD, and the younger they are (were),
the higher the relative risk
Heredity influences your
cardiovascular fitness
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Genetics is
important - pick
your parents
carefully
High/low responders
to training
If you do the
process, the product
will follow, within
your limitations
Be a Man
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Males have 5-6 times the relative risk of
CHD of females
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Why? Estrogen may be protective
Unalterable Risk Factors for
CHD
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Age
Family History
Sex
Alterable Risk Factors
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Things you can do something about…
Be fat
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Obesity increases CHD risk
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How much fat is too much?
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Males - > 25%
Females > 30%
Eat a high fat diet
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High fat foods increase plaque within
arteries and contribute to
atherosclerosis
Have High Cholesterol
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Total cholesterol/HGH ratio above:
Males – 4.5/1
Females – 4/1
Increases relative risk of CHD
Have High Blood Pressure
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High blood pressure forces the heart to
work harder
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How high is too high?
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> 140/90
Smoke
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Smokers are more likely to die of heart
attack than cancer
Smoking is the single most important
alterable risk factor
Be a Type A personality
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Type A personalities are:
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High-strung
Achievement-oriented
Aggressive
Time-conscious
Live a stressful lifestyle
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No one, lying on their deathbed, has
said they wished they had spent more
time at the office.
Have Other Hypokinetic
Diseases
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Diabetes
Ulcers
Obesity
Don’t Exercise
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If you get the urge to exercise, lie down
until the feeling passes.
FIT Principle for CV Fitness
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Frequency – 36x/wk
Intensity – 40-85%
HR
reserve
or
5590%
max HR
Time – 20-30 min.
Field Tests of CV Fitness
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12 minute run
1.5 mile run/walk
Step test
Bike ergometer test
Rockport walk test
PACER test
Telemetry
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HR monitors
Uses radio signals to transmit data
Useful in clinical & performance settings
Reasonably accurate
Affected by stress, excitement
Can predict energy cost b/c of linear
rel’t between HR and VO2.
Rating of Perceived Exertion
(RPE)
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very, very light
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somewhat hard
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