The Heart

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The Heart
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The Heart
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The Heart consists of..

• Two pumps separated by a muscular wall (SEPTUM)
• Left and Right pump consist of two chambers-
  Atrium and Ventricle
• Total chambers in heart 4

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Atrium

• They are upper (low pressure) chambers
• Atria walls are thin when compared to ventricles
• Main functions are Collect and store blood
• Pump it into
  ventricles

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Ventricles

• They are lower (high pressure) chambers
• They generate force and pressure needed to pump
  blood around whole body
• Main functions
• - Right ventricle- blood to lungs
• - Left ventricle- blood around whole body

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Heart Structure

• Heart has 3 layers
• Pericardium
• Myocardium
• Endocardium

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PERICARDIUM

• double layered bag surrounding the heart
• contains PERICARDIAL FLUID which reduces friction
  between the layers

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MYOCARDIUM

• STRIPED CARDIAC MUSCLE TISSUE
• ATRIAL walls are thin because they only pump
  blood back into the lower chambers
• VENTRICULAR walls are thicker

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MYOCARDIUM cont

• myocardium is thicker in left ventricle than
  right
• because the left ventricle pumps blood to the
  main body mass
• whereas the right ventricle pumps blood to the
  lungs only

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ENDOCARDIUM

• the inner glistening membrane
• which reduces friction between heart muscle and
  flowing blood

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Cardiac Cycle
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Cardiac Cycle

• Represents the mechanical events of one heartbeat
• One complete cycle 0.8 seconds and is repeated
  72 times per minute
• Consists of two phases- diastole and systole

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Diastole

• relaxed heart muscle 0.5 seconds
• atria fill
• atrioventricular valves open
• blood flows into ventricles

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Systole

• contracting heart muscle 0.3 seconds
• Two types- atrial and ventrical
• ATRIAL SYSTOLE
• SA node impulse causes wave-like contraction over
  atria
• forcing blood into ventricles
• semilunar valves closed

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Ventricular systole- second phase of systole

• impulse reaches AV node and spreads to the bundle
  of His and Purkinje fibres
• a second contraction across ventricular walls
• atrioventricular valves close
• semilunar valves open
• blood pushes out into PULMONARY ARTERY

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Short term effects of exercise on heart rate
Interpretation of graph a. Anticipatory rise- due
to adrenaline b. Sharp rise- cont. release of
hormones, etc. c. Continued Heart Rate- due to
max. work loads d. Steady State- some recovery of
O2 debt e. Rapid recovery- due to fast recovery
of PC stores f. Slow recovery- clearance of
lactic acid, etc
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Short term effects of exercise on heart rate

• Differences between individuals can be due to
• Patterns of recovery
• Gender
• State of health
• HR max (approx) 220 - age

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• The End