📌𝐅𝐨𝐥𝐥𝐨𝐰 𝐨𝐧 𝐈𝐧𝐬𝐭𝐚𝐠𝐫𝐚𝐦 :- [ Ссылка ]

The cardiac cycle is the process of cardiac filling and ejection, and is often visualized with electrocardiography or jugular venous pressure readings.

Atrial systole is the activation of the atria, pumping atrial blood into the ventricles.

Isovolumetric ventricular contraction happens when the ventricles contract before the aortic and pulmonic valves open; it is the period of highest O2consumption by cardiac tissue.

Rapid ventricular ejection is the period of ventricular contraction after the aortic and pulmonic valves have opened, when the ventricles are ejecting blood into the pulmonic and systemic circulations.

Reduced ventricular ejection follows rapid ventricular ejection and results from decreased ventricular volume.This follows the length-tension relationship described by the Frank-Starling equation, where contraction strength is directly related to the load; therefore, a decreased volume would translate into a decreased load, which means less contraction strength and reduced ventricular ejection.

Isovolumetric ventricular relaxation is the period between the aortic valve closing and the mitral valve opening.

Rapid ventricular filling happens when the atrial pressure becomes slightly greater than the ventricular pressure. It starts when the mitral and tricuspid valves open.

The first heart sound (S1) is the sound of the atrioventricular (tricuspid and mitral) valves closing; it occurs at the beginning of isovolumetric ventricular contraction.

The second heart sound (S2) is the sound of the aortic and pulmonic valves closing.

Normally, the aortic valve closes before the pulmonic valve. "Splitting” of the second heart sound can occur during inspiration when negative intrathoracic pressure increases venous return, ultimately delaying closure of the pulmonic valve.

The third heart sound (S3) results from blood sloshing against the ventricular walls during the middle third of diastole.

In children and pregnant women the third heart sound may be normal. In adults it is associated with increased filling pressure from a dilated ventricle, and is considered pathological.

The fourth heart sound (S4) is a low frequency diastolic sound that occurs during the late diastolic filling phase (the atrial kick). It results from an atrial kick filling a ventricle with decreased compliance, often seen in left ventricular hypertrophy.

S4 is heard before S1. It is sometimes heard in the elderly due to a stiff ventricle. When loud, it is indicative of a pathological state, generally a hypertrophic left ventricle.

The trough is where the aortic valve closed, and the following "bump" in pressure results from aortic pressure recoil against a closed aortic valve. This bump is also known as the dicrotic wave.

#cardiaccycle #cvsphysiology #medicalphysiology #physiologyanimations #physiologylectures #physiologyvideos #physiology #medicalphysiologyvideos #cardiovascularsystem #usmle #usmlestep1 #usmlevideos #nationalexittest #nationalexitexam #mbbs #neetpg #fmge

свернуть