THE CARDIOVASCULAR SYSTEM
AND HAEMODYNAMICS


Blood Flow through the heart


GENERAL FLOW OF BLOOD THROUGH THE HEART

HeartBloodFlow2.jpg
Trace the Route of a drop of blood from the time it enters the Right Atrium until it leaves via the aortic arch

THE ELECTRICAL CONDUCTING SYSTEM OF THE HEART

Wikispaces doen't want to upload! DIAGRAMS!

electricheart1.jpgAdd Labels: Bundle of His, Purkinje fibres, papillary muscle,




Explain
Relative refractory period

Absolutely refractory period


Systole

Diastole



heartdepolECG_001.jpg


THE CARDIAC CYCLE


heartelectrECG2_001.jpgheartelectrECG3_001.jpg


Relaxation Period / General Diastole
All chambers relax, atria fill up with blood : RA ........................... ;;;;;;;LA ...........................

Blood runs through AV valves: valves on right side
approx 100 - 105 ml _valves on left side
into ventricles

Atrial Systole
SA node stimulation.... Atria contract - pushes more blood ( ~ 25 ml) into ventricles
Atrial Diastole - Ventricles have been relaxed up to this point

EDV (End Diastolic Volume) = ~~ 130ml

Ventricular Systole
AV node stimulation - AV valves forced shut as blood pushes up against it. (First sound - S1)

Semilunar (SL) valves in Pulmonary Trunk and Aorta still closed.

isovolumetric contraction /isometric contraction

Contraction continues - fibres shorten - space/volume decreases -

pressure increases ~ 120 mmHg

Blood forced through SL valves = ventricular ejection - 70ml

sustained contraction retains pressure during ejection -
End Systolic Volume (ESV) ~~ 60 ml
Stroke Volume = EDV - ESV = 130 ml - 60 ml = 70 ml.

Ventricular Diastole

Ventricular muscles relax . Pressure into Aorta/Pulmonary trunk decrease ~~ 100 mmHg

SL valves falls back - shuts with a bang - S2 - the second heart sound.
Heart rate & duration of one beat

Define
Stroke volume

Cardiac Output:
Calculate the Cardiac Output of a person with a heart rate of 85 and SV = 65ml

Calculate the CO of a person with a heart rate of 65 and SV = 85 ml.

Which of the two are more likely to get a heart attack at younger age? Explain your answer.


Describe the control of the heart rate under normal circumstances.

List five factors that may affect heart rate and provide a short explanation of each.


FACTORS THAT AFFECT STROKE VOLUME , BLOOD PRESSURE

Discuss four factors that may affect SV


What is regarded as normal blood pressure?
Discuss five factors that may affect blood pressure.

Use the diagram below to discuss the events that occur in the heart of a human being considered to be norma.


ECGsaPurkinje.jpg




ECG.jpg
Refer to the diagram above and answer the questions that follow:
1. What does this diagram represent?
2. Provide an explanation of each of the intervals on the graph.
3. Indicate which periods may be considered
3.1 Relative Refractory period
3.2 Absolute refractory period