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Myocardial blood supply is from the right and left coronary arteries, which run over the surface of the heart giving branches to the endocardium (the inner layer of the myocardium). Venous drainage is mostly via the coronary sinus into the right atrium, but a small proportion of blood flows directly into the ventricles through the Thebesian veins, delivering unoxygenated blood to the systemic circulation. Oxygen extraction by the tissues is dependent on consumption and delivery. Myocardial oxygen consumption is higher than in skeletal muscle (65% of arterial oxygen is extracted as compared to 25%). Therefore any increased myocardial metabolic demand must be matched by increased coronary blood flow. This is a local response, mediated by changes in coronary arterial tone, with only a small input from the autonomic nervous system.
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What occurs during the time between the first heart sound and the second sound a. systole d. a heart mur mur b. diastole e. the p wave of the ecg c. ventricular filling?
I have no idea:P
Are both sets of valves closed during the cardiac cycle?
Pulmonary and aortic valves are semilunar valves having three semilunar cusps each. these valves open with the free ends facing the vessels when the heart contracts and closes when heart relaxes thus preventing regurgitation
DNA replication occurs during which stage of the cell cycle?
The S cycle. Synthesis.
DNA replication occurs during?
DNA replication occurs during the S-phase of interphase. Also known as prophase I
When during a cell cycle does Replication occur?
The stage of the cell cycle, replication occurs is meosis The stage of the cell cycle, replication occurs is meosis The stage of the cell cycle, replication occurs is meosis The stage of the cell cycle, replication occurs is meosisDNA replication occurs during the S phase of interphase.
When does the blood flows through the coronary artery during left ventricular systole or right ventricular systole?
Neither, theoretically the two ventricles contract simultaneously. The coronary arteries begin as two holes just above the leaflets of the aortic valve. During systole the leaflets block the coronary arteries and prevent blood flow to them. It is during diastole (of both ventricles) that blood returns to the coronary vasculature.
What is s1s2?
S1 S2 are heart sounds. The S1 sound occurs at the beginning of systole (end of diastole). The S2 sound occurs at the beginning of Diastole (end of systole).
What occurs when ventricular diastole takes place?
Ventricle diastole is the period during which the ventricles are relaxing. During ventricular diastole, the pressure in the (left and right) ventricles drops from the peak that it reaches in systole. When the pressure in the left ventricle drops to below the pressure in the left atrium, the mitral(bicuspid) valve opens, causing accumulated blood from the atrium to flow into the ventricles.
Where can you find coronary circulation?
Coronary Circulations is the blood supply to the heart. The major arteries of the coronary supply are listed below. The supply to the heart is strange, in that blood only flows through its arteries during ventricular diastole (when the ventricles relax). This happens because of the Aortic valve, which stops backflow of blood from the aorta to the left ventircle. The valve is, in essence, a flap that sits over the opening to the aorta so that when the heart is relaxed the aortic blood will push againts it and hold it down, but when the veinctricla contract the flap is forced up and open to allow flow out of the ventricle. The very first arter from the aorta is the one supllying the heart (the Coronary Artery). It comes from the aorta just after the aorta come from the heart. For this reason it is blocked by the flap of skin during systole (contraction). When diastole occurs the flap is no longer pushed up so it no longer blockes the coronary supply. This is somewhat hard to explain in words and I am not aware of any way to add diagrams to this site yet but i hope this helped, or at least i hope you found it interesting. Main arteries of the heart (very abreviated): Left Coronary; Right Coronary; Right Marginal; Left Marginal; Anterior Inverventricular; Posterior Interventricular.
What occurs during the time between the first heart sound and the second sound a. systole d. a heart mur mur b. diastole e. the p wave of the ecg c. ventricular filling?
I have no idea:P
What part of the cardiac cycle is associated with the QRS complex?
The cardiac cycle refers to a complete heartbeat, including the systole and diastole. The QRS complex occurs during the depolarization of the right and left ventricles of the human heart.
How a heart attack can happen?
it's when a blood clot that blocks one of the coronary arteries occurs.
Functions of Valves operating mechanism?
The functional anatomical status of tricuspid and mitral valves is a normally open state, and the status of pulmonary and aortic valves is a normally closed state. This is their functional status when they are not actuated by the central nervous system. The specialized nervous areas of the heart of the CNS individually coordinate each side of the heart. Since the mechanism of the left heart is similar and (in normal conditions) synchronized to the right heart, I describe the mechanism of the right side of the heart having regard to its determinant role within the cardiac function. In the diastole phase, the blood flow running into the right ventricle (through normally open tricuspid valve) stimulates the sympathetic nerve fibers of the right ventricle, and the normally closed pulmonary valve stops the blood flow. In the systole phase when the transmural pressure of the right atrium and ventricle becomes equal to the transmural central venous pressure, there occurs the maximal stimulation of specialized nervous area of the right side of the heart of the central nervous system. The specialized nervous area of the CNS sends back to the right side of the heart (via parasympathetic nerve fibers) action potentials to contract the right ventricle, actuating simultaneously both closing tricuspid valve and opening pulmonary valve, and the blood is pumped into the pulmonary trunk. The return to the normally open state of the tricuspid valve takes place passively during ventricular diastole by means of chordae tendineae and papillary muscles. Similarly, in the diastole phase the pulmonary valve returns passively to its normally closed state. This occurs by means of fibrous attachments of the pulmonary valve leaflets as integrant part of the cardiac skeleton. Practically, all the structures of the pulmonary root are dynamically involved in the valvular mechanism in both systole and diastole. Moreover, all the ventricular component structures are neurally contracted during systole and return passively to their normal state during diastole. Every type of heart valve, normally open valve or normally closed valve holds a specific valvular mechanism that operates actively during systole and passively during diastole. The sinuses of Valsalva, with their morphofunctional characteristics, confer an optimal efficiency within the active and passive valvular mechanisms of the semilunar valve. The normally closed valve is a common type of valve within the circulatory system. All the valves of the blood and lymphatic vessels of the entire circulatory system except the atrioventricular valves are normally closed valves. There are only two normally open valves within the circulatory system of the body, namely, the tricuspid and mitral valves. Certainly, the valvular mechanism of the atrioventricular valve as normally open valve is anatomically and functionally more complex than the semilunar valve, this being the reason why it is morphologically so well defined compared to the subtle mechanism of the semilunar valve. The sinuses of Valsalva are essentially involved in the mechanism of autoregulation of the coronary blood flow. This occurs by means of a remarkable anatomical trick of nature, which consists in the fact that the tow coronary ostia are located within the basic functional mechanism of the aortic valve. Hence, during ventricular systole when the aortic valve actively opens, respectively, the coronary leaflets and their Valsalva sinuses actively contract, they block the coronary orifices, creating a vacuum into the coronary arteries. In the diastole phase when the right and left coronary leaflets return passively to their normally closed position, the sinuses of Valsalva unlock the coronary orifices, during which there occurs a negative pressure into the coronary arteries, serving to reduce the pressure of blood and accelerate blood flow through coronary arteries to cardiac muscle cells. The sinus of Valsalva acts like a vacuum pump during systole and diastole for regulating coronary blood flow in proportion to the heart rate.I present below some physiological considerations on the neural and mechanical mechanisms of the heart:1) The central nervous system indirectly controls the coronary autoregulatory mechanical mechanism, this occurs by means of neural mechanism of the heart;2) Coronary perfusion takes place only in the diastolic phase;3) Left ventricular end diastolic pressure (LVEDP) is a pulmonary conditioned variable. Consequently, only in normal physiological conditions the LVEDP is proportional to the RVEDP. Under improper physiological conditions or/and specific pathological conditions this ratio may be drastically changed;4) Whereas the left ventricular blood flow is dependent on the perfusion pressure, the coronary blood flow is dependent on the perfusion rate;5) The heart works based on frequency; it is essentially dependent on blood volume;6) Blood volume varies directly proportional with both the amount of metabolic end products and hepatic blood flow rate, determining blood pressure variation.
What is a condition that occurs when coronary arteries become blocked?
A heart attack
What occurs during nondijunction?
What occurs during nondisjunction
What occurs during left ventricular relaxation?
open
What occurs during ctyokinesis?
Cell plate formation occurs during cytokinesis.
