SCIENCE 2ND QT TEST - CIRCULATORY SYSTEM

• The heart is a pump, a muscular organ about the size of your fist and located slightly left of center in the chest.
• The heart is divided into the right and left side, which protects oxygen-rich blood from mixing with oxygen-poor blood.
• The heart and blood vessels comprise the cardiovascular system, which circulates blood and oxygen around the body.
• The heart pumps about five quarts of blood every minute and beats about one hundred thousand times in one day, which is about thirty-five million times in a year.
• Oxygen-poor blood, or blue blood, returns to the heart after circulating through the body.
• The right side of the heart, composed of the right atrium and ventricle, collects and pumps the blood to the lungs through the pulmonary arteries.
• The lungs refresh the blood with a new supply of oxygen, turning it red.
• Oxygen-rich blood, or red blood, enters the left side of the heart, composed of the left atrium and ventricle, and is pumped through the aorta to the body to supply tissues with oxygen.
• Four valves within the heart, the tricuspid, mitral, pulmonary, and aortic valves, keep the blood moving the right way.
• During systole, the ventricles contract forcing blood into the vessels going to the lungs and body, similar to ketchup being forced out of a squeeze bottle.
• The right ventricle contracts a little bit before the left ventricle does.
• During diastole, the ventricles relax and are filled with blood coming from the upper chambers, the left and right atria.
• The heart is nourished by blood vessels called coronary arteries, which extend over the surface of the heart and branch into smaller capillaries.
• The heart also has electrical wiring which keeps it beating, with electrical impulses beginning high in the right atrium and traveling through specialized pathways to the ventricles.
• The conduction system keeps the heart beating in a coordinated and normal rhythm, which in turn keeps blood circulating.
• The continuous exchange of oxygen-rich blood with oxygen-poor blood is what keeps you alive.