Picture from:- www.rbch.nhs.uk3.2 Describe The Structure Of The Heart and Explain
The Cardiac Cycle
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This blog is going to discuss the structure of the heart and look at how the cardiac cycle works.In an adult our heart beats around 70 times a minute which on average is 100,000 beats a day and on average it pumps 100 millilitres of blood per beat around the body (biology reference web).
Our heart sits on the left centre of the chest and it is a lubricated sac known has the pericardium, and it consist of four chambers, the left ventricle, right ventricle, left atrium and the right atrium. Blood that is coming from the body goes through the superior vena cava which is located on the right side of the heart, this is carrying blood from the head and other parts of the body that are above the heart and also blood comes through the inferior vena cava. Blood going through the inferior vena cava is coming from parts of the body that are lower than the heart. Has the superior vena cava and the inferior vena cava enter the right atrium which is an upper chamber, they join together, the right atrium then acts as a receiving area for the blood that is entering the heart. From the right atrium the blood goes down to the lower chamber being the right ventricle, this is done via the tricuspid valve which is a one way valve. The reason it is a one way valve is because it stops the blood going back up when the ventricle contracts. From here the blood goes through the pulmonary valve, this is done when the contraction of the ventricle takes place, the pulmonary valve is also a one way valve, it then goes into the pulmonary artery that then leads the blood to the lungs. The blood that is sent to the lungs via the right side of the heart is returned to the heart by four pulmonary veins, these take the blood to the left atrium which is the other upper chamber. The blood from the left atrium then goes through the mitral valve and down to the left ventricle, the mitral valve works in the same way as the tricuspid valve as it stops the blood going back to the left atrium and the pulmonary veins when the ventricle contracts as it is also a one way valve.
When the left ventricle contracts the blood then goes through the aortic valve, which is again one way and then goes into the aorta which is the biggest artery in the body. The aorta which curves over the top of the heart as large arteries which lead of to the head, arms and upper chest.The lower part of the aorta goes through the lower part of the chest and stomach and arteries lead off from there carrying blood into the liver, spleen, intestine, kidneys and legs. The blood then goes through smaller arteries and capillaries and it then goes back to the heart through our veins. From the aorta is also two coronary arteries, these carry blood to the heart and are a part of the systemic circulation. The blood that as gone through the capillaries in the heart then goes back into the right side of the heart through veins and sits back in the right atrium.
The cardiac cycle begins when the heart is relaxed, blood that is in the veins is at an higher pressure than the atria, therefore the means the pressure is higher than that of the ventricles, this then means that blood goes from the veins to the atria and then to the ventricles. The atria is where the contraction of the heart begins, this is also known as systole. Contraction of the atria causes the an increase in pressure which pushes more blood to the ventricles, there is then a delay of around 0.1 second, after the delay the ventricles start to contract. Has the blood pressure increases and it becomes higher in the ventricle than in the atria the tricuspid and mitral valve close, however the contraction continues causing the pressure in the ventricles to build up more than in the pulmonary artery, which then causes the opening of the arterial valve letting blood flow into the arteries. Contraction in the ventricles carry's on causing the blood pressure in the pulmonary artery and the aorta to reach it's highest point, which is the systolic blood pressure rate. After this the blood pressure then falls gradually as the blood starts moving away from the heart and to the lungs, disatole occurs when the heart relaxes and blood pressure carry's on falling.
Overall the heart is a very unique structure and is a very important part of the body, in fact it is the main functioning part of the body and without it we no longer live. There are many parts of the heart even though it is only a small organ, as it is only about the size of a fist and is the shape of a pear, and it is hard to believe that it as 60,000 miles of vessels in it.
The Cardiac Cycle
-----------------------------------------------------
This blog is going to discuss the structure of the heart and look at how the cardiac cycle works.In an adult our heart beats around 70 times a minute which on average is 100,000 beats a day and on average it pumps 100 millilitres of blood per beat around the body (biology reference web).
Our heart sits on the left centre of the chest and it is a lubricated sac known has the pericardium, and it consist of four chambers, the left ventricle, right ventricle, left atrium and the right atrium. Blood that is coming from the body goes through the superior vena cava which is located on the right side of the heart, this is carrying blood from the head and other parts of the body that are above the heart and also blood comes through the inferior vena cava. Blood going through the inferior vena cava is coming from parts of the body that are lower than the heart. Has the superior vena cava and the inferior vena cava enter the right atrium which is an upper chamber, they join together, the right atrium then acts as a receiving area for the blood that is entering the heart. From the right atrium the blood goes down to the lower chamber being the right ventricle, this is done via the tricuspid valve which is a one way valve. The reason it is a one way valve is because it stops the blood going back up when the ventricle contracts. From here the blood goes through the pulmonary valve, this is done when the contraction of the ventricle takes place, the pulmonary valve is also a one way valve, it then goes into the pulmonary artery that then leads the blood to the lungs. The blood that is sent to the lungs via the right side of the heart is returned to the heart by four pulmonary veins, these take the blood to the left atrium which is the other upper chamber. The blood from the left atrium then goes through the mitral valve and down to the left ventricle, the mitral valve works in the same way as the tricuspid valve as it stops the blood going back to the left atrium and the pulmonary veins when the ventricle contracts as it is also a one way valve.
When the left ventricle contracts the blood then goes through the aortic valve, which is again one way and then goes into the aorta which is the biggest artery in the body. The aorta which curves over the top of the heart as large arteries which lead of to the head, arms and upper chest.The lower part of the aorta goes through the lower part of the chest and stomach and arteries lead off from there carrying blood into the liver, spleen, intestine, kidneys and legs. The blood then goes through smaller arteries and capillaries and it then goes back to the heart through our veins. From the aorta is also two coronary arteries, these carry blood to the heart and are a part of the systemic circulation. The blood that as gone through the capillaries in the heart then goes back into the right side of the heart through veins and sits back in the right atrium.
The cardiac cycle begins when the heart is relaxed, blood that is in the veins is at an higher pressure than the atria, therefore the means the pressure is higher than that of the ventricles, this then means that blood goes from the veins to the atria and then to the ventricles. The atria is where the contraction of the heart begins, this is also known as systole. Contraction of the atria causes the an increase in pressure which pushes more blood to the ventricles, there is then a delay of around 0.1 second, after the delay the ventricles start to contract. Has the blood pressure increases and it becomes higher in the ventricle than in the atria the tricuspid and mitral valve close, however the contraction continues causing the pressure in the ventricles to build up more than in the pulmonary artery, which then causes the opening of the arterial valve letting blood flow into the arteries. Contraction in the ventricles carry's on causing the blood pressure in the pulmonary artery and the aorta to reach it's highest point, which is the systolic blood pressure rate. After this the blood pressure then falls gradually as the blood starts moving away from the heart and to the lungs, disatole occurs when the heart relaxes and blood pressure carry's on falling.
Overall the heart is a very unique structure and is a very important part of the body, in fact it is the main functioning part of the body and without it we no longer live. There are many parts of the heart even though it is only a small organ, as it is only about the size of a fist and is the shape of a pear, and it is hard to believe that it as 60,000 miles of vessels in it.
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