The heart requires its own constant blood supply in order to keep beating and this is delivered through the coronary arteries. Genetic and lifestyle factors can lead to the coronary arteries becoming blocked, and an increased risk of heart disease.
The Circulatory System
Blood carries oxygen and nutrients to the body's cells, and waste products away from them. The circulatory system consists of: the heart, which is the muscular pump that keeps the blood moving, the arteries, which carry blood away from the heart, the veins, which returns blood to the heart and the capillaries, which are tiny blood vessels that are close to the body's cells.
Arteries & Veins & Capillaries
The arteries carry blood from the heart while veins return blood to it. With both, their structure is related to their function.
Blood in the arteries is under high pressure generated by the heart. The arteries have: thick outer walls and thick layers of muscle and elastic fibres.
The blood in veins is under lower pressure than the blood in arteries. The veins have: thin walls and thin layers of muscle and elastic fibres. Unlike arteries, veins have one-way valves in them to keep the blood moving in the correct direction.
The function of capillaries is to allow food and oxygen to diffuse to cells while waste is diffused from cells. Capillaries have thin walls - only one cell thick - that allow them to effectively perform their function.
Monitoring the Heart
Sometimes the heart has to work harder: for example, when it becomes clogged up with fatty deposits. One way to check how hard the heart is working is to measure your pulse rate (usually taken on the inside of your wrist); this measures the number of times your heart beats per minute. Another, more accurate way of checking how hard your heart is working is measuring blood…