It is important in controlling stroke volume (SV) and matching left and right cardiac output due to the intrinsic property of the cardiac muscle.
To allow atrial depolarisation, contraction, and ejection to occur before ventricular depolarisation.
Stroke volume (SV) increases due to increased end-diastolic volume (EDV).
Stroke volume (SV) decreases due to increased end-systolic volume (ESV).
Increased EDV leads to an increase in SV.
The phase of the cardiac cycle when the heart muscle contracts and pumps blood out of the chambers.
Systemic resistance (90mmHg).
Blood flow = driving pressure / resistance.
10-25mmHg.
Due to high TPR (Total Peripheral Resistance).
Stroke Volume = End diastolic volume – end systolic volume
Autorhythmic cells don't have a resting potential and instead contain a pacemaker potential.
Changes in contractility alter the rate of ventricular pressure development, affecting stroke volume.
Usually 70mL
Stroke volume changes.
The resistance to blood flow offered by all the systemic vasculature, excluding the pulmonary circulation.
Cardiac output.
Cardiac AP > SAN AP > SAN AP Control > AVN > Ventricles.
The cardiac cells are unable to respond to another stimulus, ensuring that the heart has time to rest between contractions.
The phase of the cardiac cycle when the heart muscle relaxes and allows the chambers to fill with blood.
The pressure that the ventricle must generate to eject blood into the aorta.
It decreases stroke volume.
They can be different.
Because it is unable to compensate for changes in afterload.
Locate & interpret the function of the conduction system.
Potentially increased Ca2+ sensitivity of the contractile apparatus, leading to more cross bridges formed at any given i[Ca2+].
The mitral valve quickly closes.
EDV = 120mL, ESV = 50mL
K+ channels open, allowing K+ to exit the cell.
Left ventricular end-diastolic pressure changes.
Blood continues to flow through the aorta due to the high velocity and momentum of the ejected blood.
ECG, Pressures (Atrial, Ventricular, Aortic), Ventricular volume, Heart Sounds.
Blood volume, skeletal muscle pump, respiratory pump, venous tone, and gravity.
Atrial contraction and heart rate.
From an area of high pressure/energy to an area of lower pressure/energy.
They change together.
It lasts approximately the same length as the action potential, unlike skeletal muscle.
The intrinsic property of cardiac muscle where stretching the whole heart during diastole leads to a greater force of contraction.
Ventricles fill with blood while the atrium and ventricles are relaxed.
Due to a pressure gradient where the atrial pressure is greater than the ventricular pressure.
Understand the difference in pressure & volume changes within the different chambers of the heart at different stages of the cardiac cycle.
100 beats per minute (BPM).
The blood flow to and from the lungs.
The relationship between pressure and volume during a cardiac cycle for the left ventricle.
Time (ms).
MBChB students.
No, it is not yet affiliated or endorsed.
Around 250ms.
Due to K+ leaking out.
Inward Na+ movement through voltage gated ion channels.
Due to compensatory changes in preload.
Ventricle contracting and pressure generated for ejection.
Recognise & recall the individual stages involved in the Cardiac Cycle.
Sympathetic activation increases stroke volume and decreases end-systolic volume.
The phase of contraction of cardiac muscle and ejection of blood.
The number of heart beats per minute.
Cardiac Output = Heart Rate x Stroke Volume.
The amount of blood ejected from the heart in one pump.
It is the change in electrical potential associated with the passage of an impulse along the membrane of the cardiac myocyte.
To ensure ventricles relax and fill before the next ventricular contraction.
Stroke volume (SV) increases due to decreased end-systolic volume (ESV).
ABP = Stroke Volume (SV) x Heart Rate (HR) x Total Peripheral Resistance (TPR).
To illustrate the cardiac cycle and the relationship between pressure, volume, and electrical activity in the heart.
Balancing of inward Ca2+ movement with outward K+ movement, lasting for the majority of the action potential.
Because any changes in the components of the ABP equation can affect SV.
Myocardial infarction and heart failure.
The higher pressure required for the left ventricle results in a larger left ventricular mass compared to the right ventricle.
Passively down a pressure gradient.
When Pventricular is greater than Paortic.
Explain the Frank-Starling mechanism & its effect on stroke volume.
It increases Pventricular, leading to the opening of the aortic valve.
The phase of relaxation of cardiac muscle and filling of blood.
The autonomic nervous system.
Ventricular Diastole, Ventricular Systole, Isovolumetric relaxation, Isovolumetric contraction, Rapid & passive filling, Atrial systole, Ejection.
To control the transmission of electrical impulses from the atria to the ventricles.
The sequence of events that occur in the heart during one heartbeat.
Two: pacemakers (e.g. SAN) and non-pacemakers (e.g. atria, ventricles).
Tetanus, which is sustained contraction.
The contractile unit of a muscle cell.
Pulmonary resistance (25mmHg).
Inactivation of Ca2+ channels and outward movement of K+.
80-120mmHg.
It is closed because the ventricular pressure is lower than the aortic pressure.
Be able to discuss the factors affecting preload, afterload & inotropy & how it affects stroke volume.
Inward movement of Na+ via If channels.
Both the mitral and aortic valves are closed, and the ventricle is in a closed system.
The Frank-Starling curve shifts up and left, resulting in an increase in stroke volume and left ventricular end-diastolic pressure.
The pressure exerted by circulating blood upon the walls of arteries.
The resistance that the right ventricle must overcome to pump blood through the pulmonary circulation.
Ventricular repolarisation occurs, leading to ventricular relaxation and a decrease in pressure.
The movement of blood through the heart and out the great vessels due to pressure changes generated by the muscular mechanical activity of the heart.
Preload, afterload, and inotropy.
Depolarization.
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No, it is not recommended to use these as the only revision resources.
Atrial pressures vary between 0-4mmHg on the right side and 0-10mmHg on the left side.
Ventricular pressures vary between 4-24mmHg on the right side and 4-120mmHg on the left side.
The number of cross bridges that are formed.
Ventricle relaxed (filling occurs) and majority of filling is passive.
Isovolumetric contraction and ejection.
The strength of the heart's contraction.
Heart failure decreases stroke volume and increases end-systolic volume.
The blood flow supplying all organs except the lungs.
The volume of blood the heart pumps per minute, calculated as stroke volume times heart rate.
Pressures in the heart and pressure/volume differences in the left and right sides.
By subtracting end-systolic volume (ESV) from end-diastolic volume (EDV).
It increases.
When there is a pressure/energy gradient across them.
70 cardiac cycles.
850 milliseconds.
It decreases.
PVR stands for Pulmonary Vascular Resistance. Lower pressures are required due to low PVR preventing blood accumulation in the lung and peripheral tissue.
Cardiac Output = Stroke Volume x Heart Rate
In mL/minute or L/minute
As the amount of blood (mL) ejected per beat by the left ventricle into the aorta
Atrial depolarization followed by atrial contraction.
Voltage-gated Ca2+ channels open, Ca2+ enters, and there is a further decrease in K+ conductance via L-type (long-lasting) Calcium channels.
It reduces the intrinsic heart rate to 60-80 beats per minute (BPM).
The amount of blood ejected by the left ventricle of the heart in one contraction.
