The Heart

Hiya!

Hope you're taking good care of yourself and looking after your heart! Hopefully reading this amazing blog on the heart will help to calm you if you happen to be stressed about the heart! Just to let you know the images are relatively unrelated but enjoy my failed attempts at humour in the captions. Also warning this is a very long blog so I don't suggest reading it all in one go! Happy reading!

We call our circulatory system a double-circulatory system because blood passes through the heart twice in every circuit. (De-oxygenated blood through the right side, and oxygenated blood through the left side). We hear two heartbeats due to the two halves of the circuit opening and closing the valves of the heart (don't worry we will cover this in a minute). In the first pump, blood from the body enters the right hand side of the heart and then out to the lungs in the Pulmonary circuit. In the second pump, oxygenated blood from the lungs passes through the heart and into the rest of the body in the Systematic circuit.

 (Alexandru Acea)

In the heart we have four main chambers:

• The right ventricle 
• The right atrium
• The left ventricle
• The left atrium

When blood first enters the heart from the lungs, it enters through the pulmonary vein and into the left atrium. After this, it flows into the relaxed left ventricle through a valve (which closes like a door behind it in order to prevent backflow). The oxygenated blood then passes out of the Aorta and travels around the body to transport oxygen from the blood. Along the way, the blood picks up glucose from the small intestine and collects waste products like carbon dioxide and urea and helps to transport these to the necessary recipient organs.

Not sure who to copyright this to 

Once the organs and muscles have taken in the oxygen for respiration, the blood becomes de-oxygenated (because there is little oxygen left) and the blood travels back to the heart and through the Vena Cava and into the right atrium. Just like the left atrium, the right atrium passes through into the right ventricle through a valve to prevent backflow. The blood then travels out of the lungs through the pulmonary artery to 'collect' more oxygen. And so the cycle begins again.

The left side of the heart has more muscular walls because it needs to pump high pressure blood around the whole of the body so more force is needed. The muscles in the heart contract with enough force to push blood into the arteries and around the body. 

As with every organ, the heart experiences problems. The coronary arteries supply the heart muscle with blood containing oxygen. This allows the heart muscle cells to respire and release energy. However, a built up in fatty deposits can cause the coronary artery to become blocked and blood will struggle to pass through. If it becomes blocked, there is a risk of heart attack or stroke because the heart won't recieve enough oxygen (a stroke is cause by lack of oxygen in the brain- so could be triggered by lack of oxygen in heart). We call this condition (where the coronary artery passage thins/becomes blocked) Coronary Heart Disease. There are a number or treatments and methods of prevention;

1. STENT (TREATMENT) When fatty material become deposited in the arteries, the arteries narrow. A stent is placed around and inflated balloon and guided to the affected area. The doctors then deflate and remove the balloon leaving a stent which keeps the artery open and allows blood flow to continue.
2. CORONARY BYPASS SURGERY (TREATMENT) Blocked sections of the arteries can be replaced with sections of veins from other parts of the patients body.
3. STATINS (PREVENTION) Statins are drugs that can reduce cholesterol levels and can slow down the rate of deposition of fatty materials. 

It is common that a patient can use/take a number of treatments options to ensure the condition is managed. For example, a patient can use a stent to keep an artery open whilst taking a prescription of statins to prevent a further build up on this new stent.

(Aaron Burden)

The heart is a vital but very complex organ and can develop a number of other issues. Another frequent (which is necessary to know) issue is the problem with faulty heart valves. Valves play an important role in sending the blood in the correct direction. Without them, backflow of blood would occur and blood wouldn't travel as efficiently as needed. If a valve becomes faulty, doctors can replace the valve with one of two new valves;

1. Mechanical Valves are long-lasting,artificial valves which are man-made. If a patient opts for a mechanical valve, it was last longer but the patient will have to take drugs for life to prevent blood clots.
2. Biological Valves are taken from animals such as pigs, cows or human donors. Although it has a shorter life, a biological valve doesn't need drugs to sustain.

Abnormal heart rhythm is also a problem which can be treated. A normal, undisturbed heart rate should sit as 70BPM (beats per minute) but in some people their natural pacemaker can stop working therefore their heart rate can become too slow. If the heart rate becomes too slow, not enough blood can be pumped to meet the body's demand and vital nutrients like glucose and oxygen can't reach the organ- leading to organ failure. To help people with faulty natural pacemakers, doctors can implant an artificial pacemaker to correct the heart's rhythm by sending strong electrical signals. Modern pacemakers can even match the needs of the body, e.g. pumping faster when exercising.

If a heart is severly damaged or faulty, patients can look at the option of heart transplants. This involves removing the faulty heart and replacing it with either a mechanical heart transplant or a donor heart transplant:

• Donor transplants can have long waiting lists and patients (in almost all cases) will have to take immunosuppressant drugs which stop the body's immune system from rejecting the organ. However, they have a lower risk of blood clots,and are a more natural, cheaper method of transplant.
• Mechanical transplants can lead to a higher risk of blood clots, are expensive to produce and also require advanced machinery. However, no immunosuppressant drugs are needed, no tissue match is needed and they avoid the issue of long waiting lists because they can be made to match the requirements.

The blood vessels carry the blood around the body starting from the heart. There are three main types;

• Arteries pump blood around the body away from the heart. They have thick muscular walls which allow them to stretch and also withstand high blood pressures. Their thick muscular wall is very prominent in the aorta.
• Veins have thinner muscular walls as they carry low pressure blood back to the heart. Veins are the vessels that have valves.
• Capillaries are tiny blood vessels which carry nutrients to cells in target organs and muscles. They are one cell thick which allows a short diffusion distance for the nutrients to diffuse across.