The Cardio- Vascular system
The Cardio-vascular system is the heart, blood vessels and 5 litres of blood that that is moved around the body by blood vessels such as capilliaries,veins and arterys. The cardio vascular system is powered by the hearts most powerful organ the heart. On average the heart pumps 5 litres of blood at rest in only a minute. The main functions of circulatory system is to transport blood around the body, there is also other products in the blood such as oxygen and carbon dioxide which are needed by the body to function.
The heart is a strong organ which is made up of Cardiac muscle, it is contiously filling up with blood and pumping blood, its main function is to pump blood to the lungs and around the body e.g. muscles, the heart does not fatigue. It is the size of a human fist and is found below the ribs and is found on the left side of the body.
This is a labelled heart diagram, which shows the veins and arterys that carry deoxygenated blood and oxygenated blood to and from the heart, to body parts like the lungs and muscles.
Veins - are blood vessels which carry deoxygenated blood back to the heart, there is only one vein which carrys oxygenated blood and this is the pulmonary vein, The vein is made of three main parts: tunica adventitia, which is the tough outer covering, tunica media, which is the middle layer and tunica intima.
Arteries are made up of three layers, called Tunica Adventitia, Tunica Media and Tunica Intima. This represents the outer middle and inner layer. The main purpose of arteries is to move blood away from the heart.
An Arteriole is a blood vessel in the microcirculation that spreads out from an artery and leads to capillaries. The structure of the arteriole is small diameter blood vessels that have tiny branches of arteries that lead to capillaries.
The structure of the capillaries relate to the functions. They have very thin walls and a large surface area. This helps the diffusion of oxygen and carbon dioxide.
Delivery of oxygen and nutrients and removal of waste products: The CV system has many different pathways inside it such as veins, arteries and capilliaries. This allows delivery of nutrients and removal of waste productsNutrients such as glucose from digested carbohydrates are delivered to organs and muscles that need them for energy. Waste products are sent to the lungs and the urinary system to be removed from the body. The respiratory system links with the CV system to deliver oxygen to the working muscles. The pulmonary circuit pumps deoxygenated blood to the heart which is then converted into oxygenated blood (red blood).
Thermoregulation (Vasodilation and Vasoconstriction
Vasodilation - is when the blood vessels widen, this happens close to the surface of the skin, the body then feels flush and can release heat.
Vasoconstriction - is when the blood vessels narrow so less blood can flow through. Less blood = less heat. The blood vessels then direct blood deeper into the body to warm and provide nutrients for the working muscles and organs.
Function of blood (oxygen transport, clotting and fighting infection):
Transport: The blood carries many substances in it for example oxygen, nirtogen and carbon dioxide, the blood also carries waste products such as urea and water. This blood flows through the circulatory system depositing and moving products.
Clotting: When a blood vessel is injured the walls of the blood vessel contract to minimise blood loss. Platelets (small blood cells) then cover the surface and prevent bleeding. Others cells then form to make a platelet plug, all the platelets then are involved in a chemical reaction to form a fibrin clot this produces a mesh to stop bleeding.
White blood cells fight infection and platelets help repair damage and clot the blood. White Blood Cells: There a number of types of white blood cells, although the function of all of them is to help fight diases and infection They typically have a lifespan of a few days and there are only 5-10 thousand WBC's per micro-litre of blood.
Vasodilation and Vasoconstriction
Vasoconstriction is when blood vessels become smaller to keep in heat, where as Vasodilation is when blood vessels such as veins rise to the surface to release heat as the body temperature is too high, as desribed in more detail below, however vasodilation and constriction has other affects on the body such as, dilation can lead to a increase in blood pressure through out the circulatory system, and vasoconstriction can lead to a decrease in blood pressure as the temperature is dropping.
The heart in further detail:
Inside the heart there are 2 main pumps, the first is the right ventricle it recieves deoxygenated blood from the right atrium the blood is then pumped to the lungs through pulmonary arteries where it is then used for gaseous exhange. The second pump is the left ventricle it pumps oxygenated blood through the aorta to the organs of the body. The left side of the heart is thicker than the right side because the left side pumps blood to the whole body which can be very far, whereas the right side only pumps blood to the lungs.
Humans and other mammals have two-circuit circulatory systems: one circuit is for pulmonary circulation (circulation to the lungs), and the other circuit is for systemic circulation (the rest of the body). As each atrium and ventricle contract, blood is pumped into certain major blood vessels, and from there, continues through the circulatory system.