Cardiac+Cycle

THE CARDIOVASCULAR SYSTEM AND HAEMODYNAMICS

__Blood Flow through the heart__
GENERAL FLOW OF BLOOD THROUGH THE HEART

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!__

Add Labels: Bundle of His, Purkinje fibres, papillary muscle,

__Explain__ Relative refractory period

Absolutely refractory period

Systole

Diastole



__THE CARDIAC CYCLE__



All chambers relax, atria fill up with blood : RA ........................... ;;;;;;;LA ...........................
 * __Relaxation Period / General Diastole__**

Blood runs through AV valves: __valves on right side__ __approx 100 - 105 ml__ _valves on left side into ventricles

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

EDV (End Diastolic Volume) = 130ml

AV node stimulation - AV valves forced shut as blood pushes up against it. (First sound - S1)
 * __Ventricular Systole__**

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.



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