Structure of the heart: The heart is at the centre of the cardiovascular system. It is a hollow muscular pump that drives blood through the arteries, which allows it to reach the working muscles and tissues. The heart is split into two halves. The right side of the heart is separated from the left by a solid wall known as the septum. This prevents any blood on the right side coming into contact with the blood on the left side. The right side of the heart sends deoxygenated blood to the lungs in order to get oxygen. The left side however sends oxygenated blood to the body.
The heart is also divided into four chambers that consist of two atria and two ventricles; the atria in the heart receives blood whilst the ventricles pump blood in the heart. The right atrium receives blood from the superior and inferior vena cavas, which allows the blood to move to the right ventricle where it is then pumped to the lungs. Following this process, the lungs re-oxygenate the blood and send it to the left atrium. Once the blood is in the left halve, it begins to move from the left atrium to the left ventricle via the bicuspid valve.
Blood is then pumped out of the left entricle to the aorta, which sends blood to the organs and muscles of the body. Atria- this is the upper chamber of the heart. They receive the blood that is either returning to your heart from either the body or the lungs. The right atrium receives deoxygenated blood from the superior and inferior vena cava. The left atrium receives oxygenated blood from the left and right pulmonary veins. Ventricles- the pumping chambers of the heart. The right ventricle pumps blood to the pulmonary circulation for the lungs and the left ventricle pumps blood to the systemic circulation for the body.
Bicuspid valve- one of the four valves in the heart. It is found between the left atrium and the left ventricle. It allows blood to flow in one direction only, from the left atrium to the left ventricle. Tricuspid valve-situated between the right atrium and the right ventricle. It allows blood to flow from the right atrium to the right ventricle. Aortic valve- found between the left ventricle the aorta, it prevents backflow from the aorta into the left ventricle. Pulmonary valve- the pulmonary is between the right ventricle and the pulmonary artery. It prevents backflow from the pulmonary artery.
Aorta- the aorta is the body’s main artery. It carries oxygenated blood to all parts of the body except the lungs. Superior vena cava- this is a vein that receives deoxygenated blood from the upper body to empty into the right atrium of the heart. Inferior vena cava- this is a vein that receives deoxygenated blood from the lower body to empty into the right atrium of the heart. Pulmonary vein- the pulmonary vein carries oxygenated blood from the lungs to the left atrium of the heart. Pulmonary artery- carries deoxygenated blood from the heart back to the lungs. It is the only artery that carries eoxygenated blood.
Blood Vessels: As the heart contracts, blood flows around the body in a complex network of vessels. Arteries, arterioles, capillaries venules and veins maintain the blood’s circulation throughout the body. Blood flowing through the arteries appears bright red due to oxygenation. As it moves through the capillaries, it drops off oxygen and picks up carbon dioxide. As a result of this, by the time it reaches the veins, it is blue. Arteries- Arteries carry blood away from the heart and with help from the pulmonary vein, they carry oxygenated blood. Arteries have two major roperties, which are elasticity and contractility.
Arteries have thick muscular walls as they carry blood at high speeds and face high levels of blood pressure. This is the reason why the artery walls are thick and more elastic and more muscular than those of other vessels. The larger arteries in the body contain a high percentage of elastic tissue that allows the to stretch and accommodate the pressure of the heart. Smaller arteries however, are more muscular in the structure of their walls. The smooth muscles within the artery walls expand or contract to regulate the blood flow of blood through their lumen.
This allows the body to control how much blood flows to different parts of the body under different circumstances. Arterioles- Arterioles are narrower arteries that branch off the ends of arteries and carry blood to capillaries. They are able to control blood distribution by changing their diameter. Arterioles do not have to deal with such high pressure, unlike arteries. This is because they face a much lower blood pressure due to their greater number and a decreased blood volume. Arterioles are however able to use smooth muscle to control and regulate blood flow and pressure.
Capillaries- Capillaries are the mallest and thinnest of the blood vessels in the body and most commonly found. They are very narrow and thin and can be found running throughout almost every tissue of the body. They also connect to arterioles on one end and venules on the other. Capillaries are a essential part of the cardiovascular system as they bathe the tissues in the body with blood and allow the diffusion of oxygen and nutrients. The walls themselves are only one cell thick, allowing nutrients, oxygen and waste products to be transferred. The number of capillaries can be increased with regular exercise.
An increase in capillary density allows a greater oxygen transport to your muscles, this improves the ability to perform intense exercise. Veins- Veins return deoxygenated blood to the heart. Because the arteries, arterioles and capillaries absorb the majority of the force from the heart’s contractions, veins have to deal with very low blood pressures. This lack of pressure enables the walls of veins to be much thinner, less elastic and less muscular. Contracting muscles push the thin walls of the veins inwards to help squeeze the blood back towards the heart.
Veins are close to the surface and can be seen under the skin. They also branch into smaller vessels called venules. They are they able to extend to the capillary network. Functions of the cardiovascular system: The main functions of the cardiovascular system are to supply oxygen to tissues and supply nutrients to tissues via the bloodstream. However I will be looking at the functions of the cardiovascular system in more depth. These include looking at; the delivery of oxygen and nutrients, the removal of waste products, thermoregulation, vasodilation, vasoconstriction.
And the function of blood, which includes looking at oxygen transport, clotting and fighting infection. Delivery of oxygen and nutrients- One key function of the cardiovascular system is to supply oxygen and nutrients to the tissues of the body via the bloodstream. The delivery of oxygen and nutrients is achieved with three elements working together. The heart pumps the blood into the blood vessels; the blood vessels then carry the blood to the body’s tissues. The blood carries in things that are dissolved in it.
An example being oxygen that is carried by the hemoglobin in the red blood cells. Removal of waste products- Another key function of the cardiovascular system is the removal of waste products. The circulatory system carries waste products from the tissues to the kidneys and the liver. It then returns carbon dioxide from the tissues to the lungs. With the removal of waste products, it allows the cardiovascular system to supply more oxygen to the muscle cells through blood meaning the muscle will be able to work for longer periods of time with tiring.
The reason why cO2 needs to be removed is because carbon dioxide sticks to the haemoglobin molecules in the red blood cells, turning it into carbixyhaemoglobin, which gets carried around the cardiovascular system, and eventually, it will be breathed out. In relation to sports, athletes such as Paula Radcliffe would need her body to be able to remove waste products quickly because her muscles will need to respire and get of the cO2, this is to allow more oxygen to go to her working muscles.
Thermoregulation- Thermoregulation is the ability to maintain body temperature within certain boundaries. If the body gets too hot, capillaries near the surface of the skin widen. Blood is then diverted to the skin where the heat can easily radiate away. This is called vasodilation. The sweat our body gets to cool ourselves down is actually water from the blood. Thermoregulation is important for all athletes as it can help to prevent muscles tears or pulls. If the muscles are warm prior to exercise, pulls and tear are less likely to occur.
Athletes must also make sure they cool down after exercise to help speed up the removal of lactic acid. This process shows how thermoregulation is a key function of the cardiovascular system for athletes. If the body gets too cold, capillaries near the surface of the skin get narrower. Blood is diverted away from the skin to limit heat loss. This is called vasoconstriction. This process causes us to stop sweating. Vasodilation- Vasodilation is the opening up of a blood vessel to allow more blood to flow through the arterioles, venules and capillaries.
An example during exercise would be when running. The leg muscle capillaries are vasodilated to allow more blood flow carrying oxygen to the muscles, allowing the muscle cells to respire and continue working for longer periods of time. Vasoconstriction- Blood vessels can temporarily shut down blood flow to tissues. This process causes a decrease in the diameter of blood vessels. Blood vessels close down in the main systems such as the igestive systems because it does not need as much blood when it is not working.
The movement of blood from the digestive system to the leg muscles ( for example) is called vascular shunting. Vascular shunt allows the redistribution of blood flow during exercise. ? Function of blood Blood has four principle constituents: plasma, red blood cells, white blood cells of which there are different types, and platelets or cells fragments. Blood has a number of functions, which include distribution, regulation and protection. It helps to maintain the body’s temperature by absorbing and distributing heat. Protective white blood cells are also transported in the blood.
Oxygen transport- When exercising, the demand for oxygen increases. Blood transports oxygen from the lungs to the parts of the body that require it. Clotting- Clotting is formed when the skin is damaged, the clot is formed by platelets in the blood. Platelets join together to become a scab to keep the blood in the vessel whilst the skin repairs itself, the scab will eventually fall off once the skin is repaired. Fighting infectionOur blood contains antibodies and white blood cells, which help defend against viruses and bacteria.
