Cardiovascular System. Cardiovascular System Components Circulatory system Pulmonary system...
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Transcript of Cardiovascular System. Cardiovascular System Components Circulatory system Pulmonary system...
Cardiovascular System
Cardiovascular System Components
Circulatory system Pulmonary system
Purposes: Transport O2 to tissues and remove
waste Transport nutrients to tissues Regulation of body temperature
Circulatory System Heart
Pumps blood Arteries and arterioles
Carry blood away from heart Capillaries
Exchange nutrients with tissues Veins and venules
Carry blood toward heart
Pulmonary and Systemic Circuits Systemic Circuit
Left side of heart Pumps
oxygenated blood to body via arteries
Returns deoxygenated blood to right heart via veins
Pulmonary Circuit Right side of heart Pumps
deoxygenated blood to lungs via pulmonary arteries
Returns oxygenated blood to left heart via pulmonary veins
Cardiac Cycle Systole
Contractile phase of heart
Electrical and mechanical changes
E.g. blood pressure changes
E.g. blood volume changes
Diastole Relaxation phase
of heart Takes twice as
long as systole E.g. resting HR =
60 Systole = 0.3 s Diastole = 0.6 s
Arterial Blood Pressure Expressed as systolic/diastolic
Normal – 120/80 mmHg High – 140/90 mmHg
Systolic pressure (top number) Pressure generated during ventricular
contraction Diastolic pressure
Pressure during cardiac relaxation
Blood Pressure Pulse Pressure (PP)
Difference between systolic and diastolic
PP = systolic - diastolic Mean Arterial Pressure (MAP)
Average pressure in arteries MAP = diastolic + 1/3 (systolic –
diastolic)
Causes of High Blood Pressure
Age Race Heredity Diet Stress Inactivity
Electrical Activity of the Heart 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 Records electrical activity of the
heart P wave
Atrial depolarization QRS complex
Ventricular depolarization T wave
Ventricular repolarization
Diagnostic use of the ECG ECG abnormalities may indicate
coronary heart disease ST-segment depression may
indicate myocardial ischemia
Cardiac Output - Q 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 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 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 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 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 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 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 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 Sympathetic
control Stimulates “fight
or flight” response Speeds up heart
rate and stroke volume
Sympathetic tone > 100 bpm
Parasympathetic control Connected to
vagus nerves Slows down heart
rate Parasympathetic
tone 60 – 100 bpm
Skeletal Muscle Pump Rhythmic skeletal muscle
contractions force blood in the extremities toward the heart
One-way valves in veins prevent backflow of blood
Components of Blood Plasma
Liquid portion of blood Contains ions, proteins, hormones
Cells Red blood cells
Contain hemoglobin to carry oxygen White blood cells Platelets
Important in blood clotting Hematocrit
Percent of blood composed of cells
Oxygen Delivery During Exercise Oxygen demand by muscles during
exercise is many times greater than at rest
Increased oxygen delivery accomplished by: Increased cardiac output Redistribution of blood flow to
skeletal muscle
Changes in Cardiac Output Cardiac output increases due to:
Increase in heart rate Linear increase to max
Max HR = 220 - age Increased stroke volume
Plateau at ~40% of VO2 max
Oxygen uptake by the muscle also increases Higher arteriovenous difference
Redistribution of Blood Flow Increased blood flow to working
skeletal muscle Reduced blood flow to less active
organs Liver, kidneys, GI tract
Increased blood flow to skeletal muscle during exercise
Withdrawal of sympathetic vasoconstriction
Autoregulation Blood flow increased to meet
metabolic demands of tissue O2 tension, CO2 tension, ph,
potassium, adenosine, nitric oxide
Circulatory Responses to Exercise Heart rate and blood pressure Depend on:
Type, intensity, and duration of exercise
Environmental condition Emotional influence
Transition from rest > exercise and exercise > recovery
Rapid increase in heart rate, stroke volume, and cardiac output
Plateau in submaximal exercise Recovery depends on:
Duration and intensity of exercise Training state of subject
Incremental Exercise Heart rate and cardiac output
Increase linearly with increased work rate Reach plateau at 100% VO2 max
Systolic blood pressure Increases with increased work rate
Double product Increases linearly with exercise intensity Indicates the work of the heart Double product = heart rate x systolic blood
pressure
Arm vs Leg Exercise At the same oxygen uptake arm
work results in higher: Heart rate
Due to higher sympathetic stimulation Blood pressure
Due to vasoconstriction of large inactive muscle mass
Prolonged Exercise Cardiac output is maintained
Gradual decrease in stroke volume Gradual increase in heart rate
Cardiovascular drift 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 Relative risk of CHD increases with
age
Have a family history of CHD The more blood relatives one has
with CHD, and the younger they are (were), the higher the relative risk
Heredity influences your cardiovascular fitness
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 Males have 5-6 times the relative
risk of CHD of females
Why? Estrogen may be protective
Unalterable Risk Factors for CHD Age Family History Sex
Alterable Risk Factors Things you can do something
about…
Be fat Obesity increases CHD risk
How much fat is too much? Males - > 25% Females > 30%
Eat a high fat diet High fat foods increase plaque
within arteries and contribute to atherosclerosis
Have High Cholesterol Total cholesterol/HGH ratio above: Males – 4.5/1 Females – 4/1 Increases relative risk of CHD
Have High Blood Pressure High blood pressure forces the
heart to work harder
How high is too high?
> 140/90
Smoke 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 Type A personalities are:
High-strung Achievement-oriented Aggressive Time-conscious
Live a stressful lifestyle No one, lying on their deathbed,
has said they wished they had spent more time at the office.
Have Other Hypokinetic Diseases Diabetes Ulcers Obesity
Don’t Exercise If you get the urge to exercise, lie
down until the feeling passes.
FIT Principle for CV Fitness Frequency –
3-6x/wk Intensity – 40-85%
HR reserve
or 55-
90% max HR
Time – 20-30 min.
Field Tests of CV Fitness 12 minute run 1.5 mile run/walk Step test Bike ergometer test Rockport walk test PACER test
Telemetry 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) 6 7 very, very light 8 9 very light 10 11 fairly light 12 13 somewhat hard 14 15 hard 16 17 very hard 18 19 very, very hard