The circulatory system is the transport system that makes sure everything gets to where it is needed in your body. This system carries nutrients and oxygen to the cells, carries wastes to where they can be disposed of, and distributes heat (a by-product of respiratory) throughout your body.
The circulatory system
The circulatory system consists of your heart, blood vessels and blood. The heart is the engine room of the circulatory system. It pumps continuously to keep the blood moving. The blood carries all the materials needed by the body though the blood vessels. The blood vessels are the motorways, the main roads and side streets along which the blood flows.
Blood vessels
Blood vessels
Arteries– Transport blood away from the heart. The walls of the artery are thick to withstand the high pressure of blood coming from the heart.
Veins– transports blood to the heart. The veins push blood to the heart slowly, through muscle contractions. In order to prevent the blood flowing backwards veins have valves
Â
Â
Capillaries- are very thin blood vessels to allow for gases like oxygen and carbon dioxide, wastes from cells to be moved between the blood and the cells surrounding the vessel.
Â
Â
Â
Â
Â
Â
Blood flow through the heart
The Right Atria receives DE OXYGENATED blood from the body, via the superior and inferior vena cava (main vein) , and sends it to the Right Ventricle. The Right Ventricle pumps the blood to the lungs through the pulmonary artery. OXYGENATED blood returns from the lungs through the pulmonary vein to the Left Atria of the heart. The Left Atria pumps it to the Left Ventricle. The left ventricle then pumps it to the rest of the body through the Aorta.
Â
Heartbeat
- the two atria (plural of atrium) contract, pushing blood down into the ventricles
- The ventricles contract, forcing blood out of the heart to the body and lungs
- The heart muscle relaxes and the atria fill with blood
Â
Â
Â
Â
Â
The coronary arteries supply the muscles of the heart with blood. The inner wall of healthy arteries is smooth and the blood flows easily. Plaque can build up on the inner walls of arteries. This build up of plaque narrows the arteries and reduces blood flow to the heart muscles.
Blood carries oxygen, so reduced blood flow means the oxygen supply is reduced too. A lack of oxygen to the heart muscle causes a condition called angina.
Plaque is made up of various substances that occur naturally in the blood. The substances include calcium cholesterol and fibrin ( a material involved in blood clotting).
Some scientists believe that damage to the artery wall leads to inflammation. Cholesterol, along with the other substances, move to the inflamed area to protect it.
Research into the causes of the inflammation is continuing.
Other scientists believe that too much animal fat in the diet leads to a build up of cholesterol in blood, and that this excel cholesterol is the reason that plaque builds up.
Â
Blood
Blood contains:
- Red blood cells- carries oxygen
- White blood cells- immune cells that fight disease
- Platelets
- Plasma
Â
Â