Faal or Kardiovaskuler

8/13/2019 Faal or Kardiovaskuler

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FISIOLOGI OLAH RAGA


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Function of Cardiorespiratory System

Transportation of O2and CO2

Transportation of nutrients/waste products

Distribution of hormones

Thermoregulation

Maintenance of blood pressure


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Role of the Heart

Moving O2from lungs to working muscle

Carry metabolism waste from tissue toexcretion organ


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Cardiac output

Cardiac output (Q) = Stroke volume (SV) Heart rate (HR) examples

rest: SV = 75 ml; HR = 60 bpm; Q = 4.5 L/min

exercise: SV = 130 ml; HR = 180 bpm; Q = 23.4L/min

Increased Cardiac Output Increase in HR & SV Enhances oxygen and fuel delivery to active

skeletal muscle and heart and speeds delivery ofcarbon dioxide


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Reflex control of cardiac output

Primary regulators

cardiovascular control center (medulla)

w/ activation of motor cortex, parallelactivation of sympathetic/parasympatheticnerves

parasympathetic inhibition predominatesat HR ~100 bpm

skeletal muscle afferents

sense mechanical and metabolicenvironment


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Reflex control of cardiac output

Secondary regulator

arterial baroreceptors

located in carotid bodies and aortic arch

respond to arterial pressure

Reset during exercise


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Cardiac Regulation

Intrinsic control

Frank-Starling Principle Ca2+influx w/ myocardial stretch

Extrinsic control

autonomic nervous system sympathetic NS (1control at HR >100 bpm)

parasympathetic NS (1control at HR


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Humoral Chemoreceptors

Pao2

Not normally involved in control

Paco2

Central PaCO2 chemoreceptors are 1stcontrol factorat rest

H+

Peripheral H

+

chemoreceptors are important factorduring high-intensity exercise


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Cardiac output affected by:

Preload end diastolic pressure (amount ofmyocardial stretch)

Afterload resistance blood encounters as itleaves ventricles

Contractility strength of cardiac contraction

Heart rate


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Factors Involved in Regulation of Cardiac Output


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Blood redistribution during exercise

Blood distribution muscles to 88% of all blood

other tissues (except brain)

Redistribution of blood to the working musclesby reducing blood flow to the kidneys,stomach, liver and intestines.

Redistribution of blood to the skin in order tomaintain body temperature.

Increased metabolic rate of working muscles


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Effect of blood redistribution

Increases skin blood flow

Helps remove heat

Decreased blood flow to kidneys

Diminished urinary output and maintenance of bloodvolume

Decreased visceral blood flow

Reduced activity in gastrointestinal tract

Vasoconstriction in the spleen

Increases blood volume

Maintenance or slight increase in brain blood flow

Increased blood flow to coronary arteries

Increased muscle blood flow


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Cardiovascular Responses to Exercise

Blood Flow to Muscles

Major portion of exercise cardiac output aredelivered to the working muscles

Rest: 4-7 ml of blood are delivered eachminute to every 100g of muscle increasessteadily until maximal

average 50-75 per 100g


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Figure 25-7: Distribution of cardiac output at rest and during exercise

Cardiovascular Response to Exercise

Copyright 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Di t ib ti f di t t t t d d i


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Distribution of cardiac output at rest and duringexercise


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Effect of exercise on blood distribution


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Increased stroke volume only up to 40%-60%of maximal capacity & then caused byreduced filling time at higher heart rate

increased volume of venous blood return increased muscle pumping of venousblood

increased breathing (thoracic pressure)

supine positions


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Increased ventrical enlargement capacity

Frank-starling law: when the ventriclestretches more, it will contract with more

force. Increased ventrical contractility

Aortic or pulmonary artery pressure


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Increased heart rate / cardiac outputAnticipatory response(increased heart ratebefore exercise)

Caused by the release of epinephrine Steady state heart rate: during steady exercise

Maximum heart rate= 220 - age


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Systolic B.P. increases with intensity

valsalva during resistance exercise

increased use of upper body musculature Diastolic B. P. does not change


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Autoregulationis triggered by low musclePO2

Cardiovascular drift: increased H.R.compensates for a decreased S.V. from a

decreased total blood volume to maintain Q.

redistribution

decreased blood plasma


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Cardiovascular drift (CVD, CVdrift)

Phenomenon where some cardiovascularresponses begin a time dependent change, or"drift" after around 10 minutes of exercise in a

warm or neutral environment.

It is characterised:decreases in MAP and SV and aparallel increase in HR.


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Cardiovascular drift (CVD, CVdrift)

It is influenced by: ambient temperature,hydration and the amount of muscle tissueactivated during exercise.

To promote coolingblood flow to the skin isincreased, resulting in a shift in fluids from bloodplasma to the skin tissuedecrease in pulmonaryarterial pressure and reduced stroke volume inthe heart.

To maintain cardiac output at reducedpressurethe heart rate must be increased.


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Increased A-V O2 difference: representing theamount of O2 extracted from the blood to beused by the muscles.

Decreased plasma volume =decreasedperformance increased blood pressure forces

water from the vascular system to theinterstitial spaces.

increased intramuscular osmotic pressureattracts fluid to the muscles.

sweating


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Increased blood viscosity

decreasing O2 transport

Decreased blood pH level


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Cardiovascular Endurance

Definition: The ability of the heart, lungs, and blood vessels to

deliver adequate amounts of oxygen to the cells to meet thedemands of prolonged physical activity.


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Oxygen Consumption VO

2

Resting 3.5 ml (one metabolic

equivalent MET) of oxygen perkilogram of body weight perminute

ml/kgBW/min

Maximal oxygen normal 25-80ml*kg-1*min-1or 7.1 to 22.9METs


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Components of Oxygen Uptake

Heart Rate

Number of times the heart beats per minute.

(220-age = MHR)

* Maximal HR drops about one b/yr starting at 12 yr

* Normal Heart rate can range from 40-200

Stroke Volume

Arterial-Venous

Oxygen Difference

Amount of blood pumped by the heart in one beat.

* 50 ml per beat (untrained) to 200ml (trained)

Amount of oxygen removed from the blood in a given tim

period. (a-vO2 difference)

VO2(l/min) = heart rate x stroke volume x a-vO2 diff

CardiacOutput


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Increased Cardiac Output

SV*HR

May increase 4X

5L/min to 20-22L/min

Stroke Volume begins toplateau at about 50-60%VO2max

Average college men:100-115 ml/beat

Average collegewomen: 25% less

Cardiovascular Drift


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Cardiac Output at Rest

Average HR 70bpm

Stroke Volume 71 ml/beat

Trained HR 50bpm

Stroke Volume 100ml/beat

Cardiac Output during Exercise

Average=5 to 20-22 L/min

Trained=5 to 35-40 L/min Equation: Trained vs. Untrained

195bpm x 113ml= 22,000ml/min

195bpm x 179ml= 35,000ml/min


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Conclusions about Cardiac Output:

Max SV is considerably larger duringrest and exercise in trained

Heart volume increase

Increased filling (preload)

Increase in venous return

Contractility increases

Frank-Starling Mechanism Can increase Cardiac Output 15-

20%


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Cardiac Output increases the greatestduring transition from rest to exercise

in trained Heart Rate increases linearly with

intensity

Untrained individuals have very littleincrease in SV from rest to exercise,

main increase in Cardiac Output is HR



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Heart Rate during exercise

HR and VO2 are linear Trained will experience a

higher level of exercise andoxygen uptake before reaching

a HR compared to untrained Oxygen uptake during

moderate exercise, HR of anathlete averages 70 bpm lower

than sedentary Maximal HR drops about one b/yr

starting at 12 yr

Normal Heart rate can range from

40-200


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A-vO2 Difference

The difference in the oxygen contentbetween arterial and venous blood

Untrained at Rest Only 5 ml of oxygen is used from the 20

ml of oxygen in each 100 ml of arterialblood that passes through capillaries

75% of bloods original oxygen load stillremains bound to hemoglobin


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Trained

Trained athletes have an increased a-vO2difference

Increase in capillaries

Increase in blood volume Shunting blood to working muscles

Increase in mitochondria density


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Opens dormant capillaries At rest, only 1 of every 30-40 capillaries is active

Opening provides the following:

Provides for a significant increase in muscleblood flow

This increase can be delivered with only aminimal increase in velocity of flow

Enhanced capillaries increases the effectivesurface for exchange between the blood andmuscle cells


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Blood Flow to Muscles Cont.

Capillaries Capillary to Fiber ratio (average 2.0 capillaries per

fibers)

Increase has been shown with training (5-20%)

Increases diffusion distance for oxygen andmetabolic substrates

Increases transit time, which prolongs thepassive exchange of gases that is essential forprolonged performance

Blood slowly travels through the capillary,gasses and metabolites diffuse from the bloodinto the muscle cell

Homeostatic Balancing of Exercise:


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Homeostatic Balancing of Exercise:Controlled Disruption

Feed forward reflexes

Anticipate demand

Heart & lungs

Protective reflexes

Stretch damage Temperature

sweating

peripheralblood flow

redistribution

Blood pressure constant

Homeostatic Balancing of Exercise:


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Homeostatic Balancing of Exercise:Controlled Disruption

Figure 25-8: Peripheral resistance and arterial blood pressure during exercise

Health Advantages of Regular Exercise:


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Health Advantages of Regular Exercise:Quality of Life

Cardiovascular disease risks: heart attack,

stroke, high BP blood pressure

LDL & triglycerides

HDL risks for diabetes

[blood [glucose]

obesity

stress association

immune function

(to a point)


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