Heart || Heart Anatomy || Cardiac Cycle In Hindi || Heart Cycle || Blood Cycle

Cardiac Cycle In Hindi || Heart Cycle || Blood Cycle || Atrial Systole || Ventricular Systole Hello friends Welcome to Paramedical Education In this video i explained about #cardiaccycle #HeartCycle #Pacemaker #cardiovascularcycle #cardiac_cycle_anatomy_in_hindi #atrial_systole_in_hindi #ventricular_systole_in_hindi #cardiac_diastole_in_hindi #heart_sounds_in_hindi #stages_of_cardiac_cycle #complete_cardiac_diastole Cardiac Cycle - The pumping of the heart, or the heartbeat, is caused by alternating contractions and relaxations of the myocardium. These contractions are stimulated by electrical impulses from a natural pacemaker, the sinoatrial, or S-A, node located in the muscle of the right atrium. The SA (sinus) node represents a cluster of myocytes with pacemaker activity. Under normal circumstances, it generates electrical impulses that set the rhythm and rate of the heart. An impulse from the S-A node causes the two atria to contract, forcing blood into the ventricles. Contraction of the ventricles is controlled by impulses from the atrioventricular, or A-V, node located at the junction of the two atria. Following contraction, the ventricles relax, and pressure within them falls. Blood again flows into the atria, and an impulse from the S-A starts the cycle over again. This process is called the cardiac cycle. The period of relaxation is called diastole. The period of contraction is called systole. Diastole is the longer of the two phases so that the heart can rest between contractions. The heart has four valves that help ensure that blood only flows in one direction: Aortic valve: between the left ventricle and the aorta. Mitral valve: between the left atrium and the left ventricle. Pulmonary valve: between the right ventricle and the pulmonary artery. Tricuspid valve: between the right atrium and right ventricle. The rhythmic noises accompanying heartbeat are called heart sounds. Normally, two distinct sounds are heard through the stethoscope: a low, slightly prolonged “lub” (first sound) occurring at the beginning of ventricular contraction, or systole, and produced by closure of the mitral and tricuspid valves, and a sharper, higher-pitched “dup” (second sound), caused by closure of aortic and pulmonary valves at the end of systole. The heart rate can vary quite remarkably depending on various environmental and physiologic factors. At rest, the SA nodal myocytes depolarize at an intrinsic rate between 60 and 100 beats per minute, which is generally considered a normal heart rate. The autonomic nervous system tightly controls input into the sinus node. The autonomic fibers regulate the firing of the sinus node to initiate the start of subsequent cardiac cycles and thus, influence the heart rate. Parasympathetic input slows down the rate of action potential production, thereby decreasing the heart rate; on the other hand, sympathetic input increases the rate of action potential production, thereby increasing the heart rate. This tight, regulated control of the sinus node allows for the heart to adapt to various physiologic stressors placed on the body. For instance, the heart responds to the body’s increased oxygen demand during exercise with an increase in sympathetic input, increasing heart rate. AND- A single cycle of cardiac activity can be divided into two basic phases - diastole and systole. Diastole represents the period of time when the ventricles are relaxed (not contracting).Throughout most of this period, blood is passively flowing from the left atrium (LA) and right atrium (RA) into the left ventricle (LV) and right ventricle (RV), respectively (see figure at right). The blood flows through atrioventricular valves (mitral and tricuspid) that separate the atria from the ventricles. The RA receives venous blood from the body through the superior vena cava (SVC) and inferior vena cava (IVC). The LA receives oxygenated blood from lungs through four pulmonary veins that enter the LA. At the end of diastole, both atria contract, which propels an additional amount of blood into the ventricles. Systole represents the time during which the left and right ventricles contract and eject blood into the aorta and pulmonary artery, respectively. During systole, the aortic and pulmonic valves open to permit ejection into the aorta and pulmonary artery. The atrioventricular valves are closed during systole, therefore no blood is entering the ventricles; however, blood continues to enter the atria though the vena cava and pulmonary veins. if you have any queries regarding this video please drop your comment i would love to answer if you like the video please like, share and subscribe channel THANKS FOR WATCHING