"The Pump" - The Heart

From the moment it starts beating at approximately 3 weeks after fertilization to the moment we take our last breath, the human heart beats with a powerful, rhythmic contraction, delivering goods to all areas of the human body.

Heart Facts:

• Beats approximately 72 times per minute for an adult at rest;
• Pumps 5 litres of blood in our body in less than one minute;
• The heart is located in the middle of the chest behind the sternum which acts to protect the heart;
• The heart is slightly shifted the left and becomes increasingly more angled to the left during pregnancy in females to make room for the developing fetus.

The heart itself is divided into 4 sections or chambers:

• Two Atria
• A left and right atria which are superior in location receive blood from organs and pump blood down into ventricles
• The Atria are the collecting chambers of the heart
• Two Ventricles
• The left and right ventricles are two inferior chambers which are responsible for pumping blood out of the heart to the lungs and the rest of the body;
• Each side pumps out to a specific destination;
• right ventricle - pump blood to the lungs;
• left ventricle- pump blood to the body.

"The Pipes" - The blood vessels and system

The responsibility of the the blood vessels is to carry the blood and all the important “goods” contained in it to all parts of the body. The setup of the system of vessels is such that the largest vessels (Aorta for the arteries and Vena Cava for the veins) are closest to the heart and as you travel further away they get smaller and smaller.

Three types of blood vessels:

• Arteries:
• Carry blood AWAY from the heart;
• They are the thickest because they must resist to the most pressure;
• Divide into smaller vessels called arterioles and finally into capillaries.
• Capillaries:
• Site of nutrient, waste and gas exchange between cells and vessels;
• Connect arteries to veins.
• Veins:
• Carry blood back TOWARD the heart;
• Have valves which prevent blood from flowing backwards due to gravity.

"The Liquid" - Blood

Blood is the medium to which all things, both good and bad, must be transported throughout the body. It is a liquid, made of types of cells that individually have roles and responsibilities and collectively make up approximately 7% of our body weight. There are 3 main types of cells that make up human blood:

• Red blood cells:
• Transport oxygen and carbon dioxide;
• Approximately 2 million are produced every second, in the bone marrow.
• White blood cells:
• Protect us from infection;
• The pus in wounds is formed of dead white cells;
• There are not as many of these cells.
• Platelets:
• Help clot the blood, damaged skin and damaged small blood vessels.