Cardiac Cycle Essay

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.

5. Which wave in an electrocardiogram represents repolarization of the ventricles? (Points : 1)       R wave

Every beat you feel you heart make is one complete cycle of blood entering the heart and exiting the heart. The heart cycle breaks down into two main contractions. Atrial contraction of the heart forces blood from the vena cava and the pulmonary veins through the atrioventricular valves and into the left and right ventricles. During ventricular contraction the tricuspid and mitral valves close and the blood is forced out of the ventricles through the semilunar valves into the aortic and pulmonic arteries. The pulmonic arteries supply blood to the lungs for oxygenation while the aortic arteries circulate the already oxygenated blood from the lungs, to the rest of the body. Diastole is the period of relaxation when the blood fills the ventricles. Systole is the period of contraction that forces the blood out of the ventricles.

The pulmonary semilunar valve is located at the junction of the right ventricle and pulmonary trunk, and has three cusps that fold within themselves. The function of this valve is to close off the right ventricle and then opens to allow deoxygenated blood to be released from the heart to the lungs through the pulmonary

The system circuit, starts via the left atrium and passing the mistral valve down into the left ventricle. The ventricle will then contract shortly after the atria have started relaxing and followed by the closing of the atrioventricular valves, so blood does not back wash into the atrium. Pressure will becoming higher in the left ventricle allowing ventricular systole 's second phase to begin by forcing blood through the aortic semi lunar valve up into the aorta so blood may reach the rest of the tissues in the body. Afterwards, the ventricles will becoming diastolic

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 heart is able to do this thanks to the specialized cardiac muscle it contains. The contraction of the heart displays excitatory- contraction coupling (EC coupling) similar to skeletal muscles except the action potential in the heart originates spontaneously at the peace maker of the heart (Silverthorn, 2013). Contraction happens when a rapid depolarization occurs due to the influx and opening of sodium voltage gated channels to raise the membrane potential toward the threshold value causing a firing of action potential. The conduction and cardiac cycle starts at a resting distol state for both ventricles and atriums and is initiated with the depolarization at the SA node (Silverthorn, 2013). This causes an action potential which moves rapidly towards the AV node where the signal gets slowed down (Silverthorn, 2013).When the signal reaches this point it causes a contraction/systole stage of the right and left atriums. This causes blood to be pumped into the ventricles through the AV valves (Silverthorn, 2013). The action potential then travels to the ventricles down the bundle branches out towards the Purkinje fibers (Silverthorn, 2013). In terms of the cardiac cycle an isovolumetric contraction occurs during the pause of the signal at the AV node allowing the AV valves to close, followed by ventricular systole where the ventricles expel blood into circulation (Silverthorn, 2013). The final stage in the cardiac cycle occurs between stimulations of action potential when the ventricles and atriums are in diastole and the chambers fill with blood once again (Silverthorn,

In this lab, the students observed the rate and rhythm and how it fluctuates when an individual is relaxed, in a seated position, and after exercising. The Heart is a hollow muscular organ that is cone shaped and it is located in the mediastinum in between the lungs (The Heart, Slide 3 2016). The heart is separated into two main divisions, the pulmonary circuit and the systemic circuit. The pulmonary circuit helps carry blood to the lungs from the heart for gas exchange and it is located in the right side of the heart. In the pulmonary circuit the heart fills with blood in the right atrium then it passes through the right atrioventricular valve which then leads to the right ventricle. Once it is in the right ventricle, the right ventricle contracts which opens the pulmonary valves. After this blood flows from the pulmonary valve to the pulmonary trunk which then distributes it into the right and left pulmonary arteries that supply the lungs where it deposits oxygenated blood.

The heart beats when all the chambers of the heart squeeze (contract). The process starts when blood collects in the upper chambers of the heart. Once the chambers are full, a group of cells called the sinoatrial node sends out an electrical signal that makes the upper chambers contract. When the chambers contract, they push the blood through the tricuspid and mitral valves into the lower chambers of the heart. Once the lower chambers have filled with blood, an electrical signal causes these chambers to contract. This pushes blood through the pulmonary and aortic valves and out of the heart.

Cardiac muscle has short branching fibers, is striated, and functions involuntary allow for the contraction of the heart to pump blood throughout the body (Castillo, 2018). The conduction system of the heart includes the Sinoatrial node, Atrioventricular node, left and right bundle branches, and Purkinje fibers and functions off of action potentials of nerve impulses. The Sinoatrial node is in the upper right atrium and is where the action potential begins and rhythm and pace of the heart is determined. The action potential will then travel to the Atrioventricular node in the lower right atrium where the impulse is delayed for a whole second so the left side of the heart can contract. After that the impulse travels to the Atrioventricular bundle, which connects the atria and ventricles. Once this is completed, the potential travels to the left and right bundle fibers that signal the septum and apex of the heart. Finally, the potential will reach the Purkinje fibers and stimulate the walls of both ventricles. This completes one cardiac cycle. A cardiac cycle is described as all the events associated with the blood flow through the heart during one complete heartbeat (McKinley, 2016). A heartbeat involves the contraction {systole} and relaxation {diastole} of the heart chambers. The most important driving force to continually move blood through the heart is the opening and closing of

The two main parts to the cycle are systole and diastole. Systole is the contraction phase of the cycle, pumping the blood, and diastole is the relaxation phase of the cycle, blood filling the chambers (Reece 921). While the blood pumps out of the heart, the arteriole blood pressure is raised; however, during the relaxation phase, the aortic valve closes thus dropping the arteriole blood pressure (Harris-Haller 243). Because of this inconsistency in blood pressure during the cardiac cycle, the mean arterial pressure compensates for these fluctuations by calculating mean values (Harris-Haller 244). An electrocardiogram is a graph that represents “the electrical activity of the heart [and] plots sequential events of excitation and recovery of a heartbeat,” and it is summarized by four main parts to the heart wave (Harris-Haller 240). The P wave shows the depolarization of the wave over the atria, the QRS complex shows the ventricle depolarization process, and the T wave shows the repolarization of the ventricles (Harris-Haller 241). Exercise can also have an impact on the blood pressure and pulse by increasing both (Moeini 431). In addition, the respiratory rate when one is exercising can often increase as well in

If the heart is compromised, it can compensate for a time by pumping harder and faster, but at a certain point, it is so over worked that it can no longer over exert the force of contraction and pump more volume out to the tissues. “The stroke volume of the heart increases in response to an increase in the volume of blood in the ventricles, before contraction (the end diastolic volume), when all other factors remain constant (Frank Starling law)” . There are four one way valves that keep the blood flowing in the correct direction throughout the body. Ther e are the mitral, tricuspid, pulmonary and aortic valve. During each beat of the heart, they open and close, allowing blood to flow through the vasculature. When the aortic valve between the left ventricle of the heart and the main artery (aorta) became stenosed, it no longer allowes the blood to pump through properly. When the left ventricle has to overcome the higher pressures (due to constriction or disfunction of the aortic valve) to force blood into the aorta. Feeding oxygen rich blood to the tissues. The extra work can cause enlargement or thickening of the heart muscle and over time, becomes weakened.

SA node: The sinoatrial node is a section of nodal tissue located in the upper wall of the right atrium. Sets the rate of contraction for the heart. Spontaneously contracts and generates nerve impulses that travel throughout the heart wall causing both

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

The right atrium contracts, the tricuspid valve opens, blood is then pumped into the right ventricle. The tricuspid valve closes itself when the right ventricle is full to stop blood from flowing back into the right atrium. (Dao, 2017)