The circulatory system is made up of the heart, the lungs, blood and the vessels it travels through. Its function is to transport nutrients, gases and wastes between the cells of the body and the digestive system, respiratory system and excretory system. It also carries hormones for internal communication and co-ordination, and white blood cells for fighting disease, as well as assisting in maintaining body temperature.
Today we were learning about the heart. The heart is a huge muscle that never appears to rest. In fact it does rest – between each heart beat! It beats rhythmically, contracting two sets of chambers to act as a double pump to move blood around the body. It is about the size of a closed fist, and is protected by the ribs. The right side of the heart pumps deoxygenated (‘used’) blood through the pulmonary circuit to the lungs, where it picks up oxygen and where carbon dioxide is released. The blood is then returned to the left side of the heart, which is sufficiently muscular and powerful to pump the blood through the systemic circuit to all tissues of the body, including the kidneys for waste removal, and the liver for blood sugar regulation.
Mrs Matthews brought in some pig's hearts for us to examine and try and identify the main parts. It was a really interesting lesson!