Cardiac Cycle and Heart Sounds

The period of contraction in the heart, where blood is pumped out.

The period of relaxation in the heart, where the chambers refill with blood.

The complete sequence of events in the heart, including systole and diastole.

The amount of blood pumped out by the left ventricle with each beat.

The volume of blood in the ventricle at the end of diastole (filling).

The amount of blood pumped by the heart in one minute.

The number of times the heart beats per minute.

The amount of blood left in the ventricle after contraction (ejection).

The pressure in the ventricle slightly increases due to blood flowing in from the atria during atrial contraction. This occurs just before the tricuspid valve closes.

The brief drop in left ventricular pressure that occurs immediately after the tricuspid valve closes.

The period when the ventricle contracts, causing a significant increase in pressure. All valves are closed, resulting in isovolumetric contraction, where pressure builds even though volume doesn't change.

The point during ventricular systole when all valves are closed, but pressure is increasing within the ventricle.

The peak pressure in the left ventricle, occurring just after the aortic valve opens.

The phase where the aortic valve opens, allowing blood to be ejected from the ventricle into the aorta and circulation.

The period when the ventricle relaxes and passively fills with blood. This starts after the aortic valve closes and continues until atrial systole.

The pressure increase in the ventricle due to the increased volume of blood that flows in from the atria during atrial contraction.

The first heart sound (S1) is caused by the closure of the tricuspid and mitral valves, marking the beginning of ventricular systole.

The second heart sound (S2) is caused by the closure of the aortic and pulmonary valves, marking the end of ventricular systole and the beginning of ventricular diastole.

A sharp increase in pressure within the ventricle without any change in volume. Occurs during the initial phase of ventricular contraction.

The volume of blood ejected from the left ventricle during each heartbeat.

The volume of blood remaining in the left ventricle after contraction.

The phase of the cardiac cycle where the ventricles relax and pressure decreases, but volume remains constant due to closed valves.

A visual representation of the electrical activity of the heart, displaying the depolarization and repolarization of the atria and ventricles, providing information about the heart's rhythm and function.

The first wave on an ECG, representing atrial depolarization, which precedes atrial contraction.

A complex of waves on an ECG representing ventricular depolarization, which precedes ventricular contraction.

The wave on an ECG representing ventricular repolarization, indicating the return of the ventricles to their resting state.

The period during which the ventricles are unable to be stimulated to contract again, ensuring proper heart rhythm and preventing chaotic electrical signaling.

The phase of the cardiac cycle where the atria contract and pump blood into the ventricles, increasing ventricular volume.

The pressure within the left atrium changes throughout the cardiac cycle, primarily influenced by events in the atria and ventricles.

The pressure inside the left ventricle during its contraction phase.

The volume of blood inside the left ventricle at any given moment.

The brief period during ventricular diastole when all four heart valves are closed and pressure rapidly decreases inside the ventricle.

The point at which left ventricular pressure exceeds aortic pressure, causing the aortic valve to open and blood to be ejected from the heart.

The point at which aortic pressure exceeds left ventricular pressure, causing the aortic valve to close and preventing backflow of blood.

The pressure inside the aorta during its contraction phase.

The point at which left ventricular pressure exceeds left atrial pressure, causing the tricuspid valve to open and blood to flow from the left atrium into the ventricle.

The point at which left atrial pressure exceeds left ventricular pressure, causing the tricuspid valve to close and preventing backflow of blood.

The force of contraction in the heart is determined by the length of the muscle fibers, the intrinsic ability of the muscle to contract (contractility), the amount of blood returning to the heart (venous return), and the contraction of skeletal muscles.

The Frank-Starling Law of the Heart states that the stroke volume of the heart is directly proportional to the end-diastolic volume. This means that the greater the volume of blood in the ventricle at the end of diastole, the stronger the contraction and the greater the volume of blood ejected (stroke volume).

Norepinephrine is a neurotransmitter that increases the force of contraction of the heart. This is known as a positive inotropic effect.

Any substance that affects the contractility of the heart is called an inotropic agent. Positive inotropic agents increase the force of contraction, while negative inotropic agents decrease the force.

Norepinephrine increases heart contractility by binding to beta-1 receptors, activating cAMP, increasing calcium entry and release, and enhancing the interaction between actin and myosin.

Represents the period when the atria are relaxing and filling with blood from the veins.

The sound of the closing aortic valve, which signifies the end of ventricular ejection and the beginning of ventricular diastole.

The sound of the closing mitral valve, which signifies the beginning of ventricular contraction.

The volume of blood that is in the left ventricle at the end of diastole (right before contraction).

The amount of blood that is pumped out of the heart per minute.

The rate at which the heart beats per minute.

The amount of time the ventricles spend filling with blood during each cardiac cycle.

The pressure that the ventricle has to work against to eject blood into the aorta.