The Phases from One Heartbeat to the Next Essay

Systolic heart failure is characterized by enlarged ventricles that are unable to fully contract to pump enough blood into circulation to adequately perfuse tissues. The enlargement in ventricles is due to an increased end-systolic volume. If the heart is not able to sufficiently pump the expected volume of blood with each contraction, which in a normal healthy heart is 50-60%, there will be a residual volume left in the heart after every pump (Heart Healthy Women, 2012). With the next period of filling, the heart will receive the same amount of blood volume from the atria combined with that residual volume from the previous contraction. This causes the ventricles to have to dilate to accommodate this increase in volume. The dilation causes the walls of the ventricles to stretch and become thin and weak. Also the myocardium, the muscle layer of the heart, will stretch and not be able to adequately make a full and forceful enough contraction to push blood from the ventricles (Lehne, 2010).

In a normal human being the heart correctly functions by the blood first entering through the right atrium from the superior and inferior vena cava. This blood flow continues through the right atrioventricular valve into the right ventricle. The right ventricle contracts forcing the pulmonary valve to open leading blood flow through the pulmonary valve and into the pulmonary trunk. Blood is then distributed from the right and left pulmonary arteries to the lungs, where carbon dioxide is unloaded and oxygen is loaded into the blood. The blood is returned from the lungs to the left

*Both sides of the heart are doing this at the same exact time and contracting/relaxing is what pumps the blood from one place to the other.

The reduced pumping can also lead to less blood being moved from the ventricle during systole. The left ventricle steadily fills with more and

As there is a hole in the wall separating the atria, the oxygenated blood from the left atrium enters the right atrium instead of the aorta. The oxygenated blood that entered the right atrium mixes with the deoxygenated

The heart goes through an auto rhythmic cycle that starts and ends in the heart. The process can be broken down into 5 main steps. First the Sinoatrial Node (SA Node) sends out a signal from its electrical system. It is commonly known as the pacemaker of the heart, if the SA Node is not working properly it will be replaced by a pacemaker to simulate the same electrical signal. The signal then travels to the Atrioventricular Node (AV Node) that is located at the top of the septum. The septum divides the left and right ventricles. If the SA Node is not working properly, the AV Node will take over and keep the heart functioning for a limited time.[5] Once the single reaches there, the atria contract and allows the blood to drop to the ventricles. The signal then travels to the Atrioventricular Bundle where it contracts the ventricles. The atrioventricular

As muscle fibers contract, they lose their ability to contract forcefully (i.e., the greatest force of muscular contraction in the ventricle occurs earlier in the contraction phase and decreases as contraction proceeds). When ventricular pressures fall below their respective attached arterial pressures, the semilunar pulmonary and aortic valves close. At the end of systole, the semilunar valves shut to prevent the backflow of blood into the ventricles.

When blood enters through the inferior and superior vena cava, into the right atrium, from the pulmonary veins into the left atrium. The right atrium contracts slightly before the left because it is first to receive the signal. During this contraction, diastole is occurring, the ventricles expand, and their pressure drops below the atria, which causes the AV valves to open and blood flows into the ventricles, causing pressure to rise and atrial pressure to fall.

The heart is a muscle that is divided into four chambers. The top of the heart has two atria while two ventricles are located on the bottom. When the heart is healthy, the heartbeat will begin in the right atrium. The right atrium will send an electrical signal across the heart spreading throughout the atria to the AV node, then to the ventricles. This electrical impulse, occurring about 60 to 100 times per minute, causes the heart to contract. Each contraction equals a single heartbeat. According to the Human Diseases and Conditions article , under some conditions, almost all heart tissue is capable of starting a heartbeat, or becoming the pacemaker. A dysrhythmia occurs when:

The pressure created in the arteries by the contraction of the left ventricle is the systolic blood pressure. After the left ventricle contracts, it begins to relax, then refills with blood from the left atria, meanwhile the pressure in the arteries falls, this is the diastolic blood pressure. In other words, during systole, cardiac muscle tissue is contracting to push blood out of the chamber; during diastole, the cardiac muscle cells relax to allow the chamber to fill with blood; systolic blood pressure is the higher number and diastolic blood pressure is the lower number.

Cardiac suction- during ventricular systole, the teninous cords pull the Av valve cusps downward, slightly expanding the atrial space. This creates a slight suction that draws blood into the atria and pulmonary veins.

The heart is divided in to four different chambers, the Atria is the upper chambers of the heart, which receive blood returning to your heart either from the body or the lungs. The right atrium receives de-oxygenated blood from the superior and inferior vena cava. The two atria are separated by a septum into the left atrium and the right. The left of which receives oxygenated blood from the left and right pulmonary veins.

During stage one the pressure in both ventricles decreases as they relax, the atrioventricular valves open slightly and blood is pumped through them due to a contraction of the atria. Blood is prevented from flowing backwards as the valves of the vena cava and pulmonary vein close. During stage two pressure in the ventricles increases

On to the right ventricle. When this contracts back pressure from the blood forces the valves to shut. When the contraction of papillary muscles holds the cords in place to stop back flow of blood in to the atria.

This is a measurement of the pressure exerted on the arteriole walls when the blood in the arterioles is at its highest pressure which is immediately after the heart has contracted. A rise in blood volume or a rise in force from the contraction rises the systolic pressure, a decrease in the arterial wall elasticity will also rise the systolic number. The opposite of these will lower the systolic number (Johnson, Taylor, 2010, p. 42).