The Cardiac Cycle

2. The defect in Caleb’s heart allows blood to mix between the two ventricular chambers. Due to this defect would you expect the blood to move from left-to-right ventricle or right-to-left ventricle during systole? Explain your answer based on blood pressure and resistance in the heart and great vessels. It goes left to right during systole. The difference is normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, and then is pumped into the lungs where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, and then is pumped out to the body through the aorta. But when an infant has ventricular septal defect it still allows oxygen-rich (red) blood to pass from the left ventricle, through the opening in the septum, and then mix with oxygen-poor (blue) blood in the right ventricle. (ROCHESTER.EDU) but instead when systole occurs the blood gets mixed because of the septum therefore heart needs to pump harder to ensure that enough blood with oxygen reaches the body.

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

The heart is divided into four chambers. The top two chambers are the atria and the bottom two chambers are the ventricles. Two of the chambers, together make up the right heart and pump blood to your lungs, where it picks up oxygen. Blood that is carrying oxygen then travels to the two chambers on the left side of your heart, which then pumps the blood to the rest of your body. The ventricles (the bottom chambers) are powerful pumping chambers, which push the blood out of the heart when they contract. The smaller and less powerful top chambers of the heart (the atria), help to fill the ventricles with blood for the next contraction. The regulation and coordinated pumping action of the heart is provided by a network of electrical connections, which deliver electrical signals to the heart

The atrial contraction is represented by the P wave. This is an upward, or positive wave of the line on the graph. The ventricular contraction is displayed by the QRS complex. The QRS

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.

When the ventricle is full, the tricuspid valve shuts. This prevents blood from flowing backward into the atria while the ventricle contracts.

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.

De-oxygenated blood enters the heart through the Superior and Inferior Vena Cava. Oxygenated blood enters the heart from the lungs via the Pulmonary veins. Both right and left Atriums fill with blood at the same time, when they are full of blood the pressure will cause the Tricuspid valve in the right Atrium and the Bicuspid valve in the left Atrium to open and allow the blood to flow to both right and left Ventricles. Each of the Atriums will contract and force any remaining blood in to the Ventricles. Each of the Ventricles will contract (Systole) and the Atriums will relax (Diastole), pressure will then close the Tricuspid and Bicuspid valves (this is the first sound of a heart beat) The Ventricles will contract opening the Semi-Lunar valves

The time taken for one cardiac cycle is 0.08sec. During the cardiac cycle, the contraction and relaxation of auricles and ventricles take place simultaneously. The right and left auricle are filled with deoxygenated and oxygenated blood respectively and the increased pressure causes contraction of auricles and pumps the blood into

The heart is made up of cardiac muscles that are striated, involuntary, and contains intercalated disks which consist of gap junctions that send electrical signals to the heart. In order for contraction to occur in the heart, action potentials have to first move through the T-tubules to the L-type calcium channels. The calcium used here is not used for contraction. From there, more calcium comes in from outside the cell and binds with ryanodine receptor which causes the actual contraction of the heart. Next, cross bridge cycling occurs and in order for contraction to end, calcium is decreased by using ATP pumps to pump the calcium to the sarcoplasmic reticulum. In the heart, the heartbeat is maintained by the pacemaker cells in the SA node. For it to maintain its heart rate, the SA node is stimulated which causes an action potential to happen. The action potential goes quickly from the top-down and it continues through the AV node. The AV node is another pacemaker in the cell but is slower than the SA node. It is also the only pathway where action potential can move from the atria to the ventricle. From the AV node, it goes to the Bundle of His which then branches

Earlier research shows that the cardiac cycle consist of two Systolic contraction and Diastolic relaxation.

A time that starts with contraction between the atria and ventricular relaxation is known as the cardiac cycle. The relaxation period also known as the diastole this occur when the chambers fills with blood. The blood will flow according to pressure. As the fluid from the vein into the left atrium the pressure gets higher and rises, initially move passively into the ventricles from the atria. As the left ventricle filled to its volume the mitral valves closes to prevent any backflow. The contraction from the left ventricle send the oxygenated blood by the aortic value to aorta as the semilunar valves closes to prevent backflow of blood into the left ventricles.

An understanding of the circulation of blood through the heart might help the reader to get an better understanding of how the different parts of the heart relate. It helps to think of all the blood vessels in the body as a huge, sophisticated railway network, where essentially all the blood in the veins throughout the body ends up in the vena cava, the railway end station. The superior vena cava receives blood from the upper part of the body, whereas the inferior vena cava receives blood from the lower part of the body. As the blood fills up in the RA, the increased pressure eventually makes the tricuspid valve shut open, allowing deoxygenated blood to enter the RV. As the deoxygenated blood flows into the RV, the pressure in front of the

Cardiac cycle - a concept that reflects the sequence of the processes taking place in a single contraction of the heart and subsequent relaxation. Each cycle includes three major stages: atrial systole, ventricular systole and diastole. The term systole is muscle contraction. There are electric systole - the electrical activity that stimulates the myocardium and causes mechanical systole - contraction of the heart muscle and a decrease in the volume of the heart chambers. The term diastole is muscle relaxation. During the cardiac cycle there is an increase and decrease in blood pressure, high blood pressure, respectively, at the time called the systolic ventricular systole and during their low diastolic - diastolic.

To keep the blood moving around the body supplying vital nutrients to cells and removing waste, a cycle of contractions (systole) and relaxations (diastole) take place, this cycle is known as the cardiac cycle. There are three stages to the cardiac cycle, all stages happen during one heartbeat (cycle) and take less than a second in total (Revisionworld.com, 2017), these different stages are pictured in figure 11.