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Five phases of cardiac cycle & Atrial contraction

By: HWC, Views: 8431

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....

Electrical changes in the heart

By: HWC, Views: 8268

• 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). ...

Isovolumetric VC, Ventricular ejection, Isovolumetric & Passive ventricular filling

By: HWC, Views: 8293

• 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...

Heart sounds

By: HWC, Views: 8291

During a normal, healthy heartbeat, or what we call a cardiac cycle, the top two chambers of the heart, called the atria, contract simultaneously. Then, as they relax, the bottom two chambers, called the ventricles, contract. This explains what happens during a cardiac cycle, but what it doesn't ...

Exercise and cardiac output & Definition of stroke volume

By: HWC, Views: 8285

▪ 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...

Stroke volume

By: HWC, Views: 8306

Preload definition • Preload is the degree of stretch of cardiac muscles cells prior to contraction. • The amount of stretch is related to the end-diastolic volume[EDV]. • Increased return blood flow from the veins increases end-diastolic volume. Cardiac muscle sarcomeres stretch and ...

Definition of heart rate

By: HWC, Views: 8469

• Heart rate is determined by the rate of depolarizations of the sinoatrial (SA) node. • Cardiac output is directly proportional to heart rate, the greater the heart rate the greater the cardiac output. • Changes in heart rate are associated with exercise, stress or injury. Nervous ...

Reflex arc construction

By: HWC, Views: 8343

• Somatic reflexes are the rapid, predictable, and automatic responses of skeletal muscle to changes in stimuli. • A reflex arc is the pathway followed by the nerve impulse producing the reflex. • Reflex arcs include: • Sensory receptor • Sensory neurons • Integrating c...

Rena arc construction

By: HWC, Views: 8376

• Somatic reflexes are the rapid, predictable, and automatic responses of skeletal muscle to changes in stimuli. • A reflex arc is the pathway followed by the nerve impulse producing the reflex. • Reflex arcs include: • Sensory receptor • Sensory neurons • Integrating cen...