Cardiovascular System

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by ksirrell
Last updated 5 years ago

Human Anatomy

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Cardiovascular System

Arteries and arterioles have a similar structures except that arterioles are smaller. Blood pressure is also similar in both the arteries and arterioles as they both carry high pressure blood. Whilst arteries are responsible for transporting blood to the body, the main function of the arterioles is to redistribute the blood and control blood pressure around organs, musscles and tissues, depending on where the blood is travelling.Blood travels from the capillaries into the venules. The venules connect to the veins which carry blood from the body back to the heart. Veins and venules also have a similar structure, with venules being smaller branches of veins. However, they have different functions. Veins transport deoxygenated blood back to the heart whereas venules collect the outflow of blood from the capillaries. They both contain valves that open to allow blood through and close to prevent the backflow of blood and both carry blood that is at a low pressure. Muscle contractions helps blood to be transported back to the heart. Veins are located within the muscles and when they contract they increase the pressure on the blood in the veins. This causes the blood to be pumped through the valves and back to the heart.The capillary's main function is to diffuse oxygen and nutrients in the blood with the carbon dioxide, produced by respiration, in the muscles. Capillaries do not contain valves and the blood travels at a low pressure. The capillaries are found throughout the body and blood flows steadily through all muscles in the body when inside them.

Blood Vessels

Cardiovascular System

Plasma transports all other elements within blood. It is mainly composed of water and is a straw coloured fluid. Red blood cells have a biconcave shape allowing them to fit into capillaries and carry more oxygen. Their main function is to caryy oxygen to tissues and carbon dioxide from tissues.Haemoglobin is a protein contained within the red blood cell and binds with oxygen. It is able to transport up to 4 molecules of oxygen. Platelets are small fragments of bone marrow cells that are scattered between blood cells. They help to prevent blood loss through the process clotting.White blood cells play a role in fighting against infection. They provide defence against bacteria, viruses and parasites. When they are activated, the body speeds up the production of white blood cells in order to fight infection.

The main function of the CV system is to deliver oxygen and nutrients to tissues within the body. Blood absorbs glucose and nutrients (from food digested in stomach) and delivers it to cells. This allows cells to abosrb oxygen. During exercise heart rate increases so that the dleivery of oxygen and nutrients to cells is also increased.The CV system removes waste products, such as carbon dioxide. This occurs during expiration. During exercise respiration rate will increase so that more carbon dioxide is removed from the body.Thermoregulation is the body's ability to maintain an internal temperature. The CV system achieves through vasodilation and vasoconstriction. Vasodilation is the dilation (widening) of blood vessels. The dilation allows more blood to flow through the vessels, causing more heat loss through the skin. This will occur during exercise in order to keep the body as cool as possible. On the other hand, vasoconstriction is the constriction (narrowing) of the vessels. This increases resistance to blood flow within vessels and therefore reduces heat loss through the skin. During exercise, vasoconstriction should not happen because the body would overheat.

The blood consists of plasma, red blood cells, white blood cells and platelets. During exercise all of these components will be transported around the body to muscles at a quicker rate.Oxygen binds with haemoglobin, in the red blood cells, and is transported around the body. The CV allows achieves this by pumping blood near the alveoli via the capillaries. Diffusion will take place in order to exchange carbon dioxide with oxygen. During exercise, breathing rate and heart rate will increase in order for the exchange of gases to hapen at a faster rate and so oxygen can be pumped to working muscles quicker.Platelets are required for the process of clotting. It is a complex process in which chemical reactions cause fibrin strands to form a net and cath red blood cells at the site of injury. Although this prevents bloodloss, DVT (deep vein thrombosis), caused by blood clotting, is very common in sports men and women because they are more likely to have a lower heart rate, causing blood to become stagnant, and are more at risk of injury.


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