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Cardiac Cycle (Part 2 of 4)

By: Administrator, Views: 9682

Prior to atrial systole, blood has been flowing passively from the atrium into the ventricle through the open AV valve. During atrial systole the atrium contracts and tops off the volume in the ventricle with only a small amount of blood. Atrial contraction is complete before the ventricle begins...

Five phases of cardiac cycle & Atrial contraction

By: HWC, Views: 6626

1. Atrial contraction (atrial systole). 2. Isovolumetric (ventricular) contraction. 3. Ventricular ejection. 4. Isovolumetric (ventricular) relaxation. 5. Passive ventricular filling. Beginning of cardiac cycle • Prior to atrial contraction: • Atria and ventricles are relaxed....

Cardiac Cycle (Part 4 of 4)

By: Administrator, Views: 9743

Diastole and systole are two phases of the cardiac cycle. They occur as the heart beats, pumping blood through a system of blood vessels that carry blood to every part of the body. Systole occurs when the heart contracts to pump blood out, and diastole occurs when the heart relaxes after contract...

Electrical changes in the heart

By: HWC, Views: 6476

• ECG: Graph of the voltage changes that occur during the cardiac cycle. • Readings are taken by electrodes placed on the surface of the body. • Electrodes detect voltage changes caused by the electrical activity of the heart. • P wave = atrial excitation (atrial depolarization). ...

Definitions of stroke volume, preload definition & Factors influencing stroke volume

By: HWC, Views: 6460

• Stroke volume is directly correlated with cardiac output-the greater the stroke volume the greater the cardiac output. • Stroke volume represents the difference in the amount of blood between: • the volume in the ventricles at the end of diastole (end-diastolic volume EDV); • the ...

Isovolumetric VC, Ventricular ejection, Isovolumetric & Passive ventricular filling

By: HWC, Views: 6619

• Isovolumetric means that blood volume does not change. • Ventricular blood volume and cell length remain constant. • With valves closed and contraction continuing, ventricular pressure continues to rise. • Ventricular pressure rises above arterial pressure. • Increased ventr...

Hormonal regulation of blood pressure - RAA system

By: HWC, Views: 7100

■ Long-term regulation of MABP is under hormonal control. • Hormones that affect blood pressure and volume: the renin-angiotensin-aldosterone (RAA) system, antidiuretic hormone (ADM), and atrial natriuretic peptide (ANP). ■ Most important hormonal regulator of MABP. Activated by drop in...

Exercise and cardiac output & Definition of stroke volume

By: HWC, Views: 6608

▪ Cardiac output: • Maintains blood flow throughout the body. • Measure of blood volume ejected from the heart over a given time. • Determined by multiplying heart rate by stroke volume (CO = SV x HR). • Heart rate: Number of beats/min. • Stroke volume: Amount of blood eject...

Atrial natriuretic peptide (vasodilation) & Aldosterone

By: HWC, Views: 6331

• Certain situations will cause the body's stress level to rise. • increased blood pressure will stretch the atria of the heart, stimulating the secretion of atria natriuretic peptide (MP). • ANP causes muscle cells in blood vessels to relax. • Blood pressure is lowered as a result ...