The heart and circulation

• the heart consists mainly of muscle tissues
• the heart has four chambers right atrium, right ventricle, left atrium, left ventricle
• the atriums are seperated by valves which prevent backflow of blood
• the vena cava brings in deoxygenated blood from the body the body then passes the blood from the heart to the lungs in the pulmonary artery then in the lungs the blood collects oxygen the oxygenated blood then passes from the lungs to the heart in the pulmonary vein it is then pumped to the body in the aorta.
• in the pattern of blood flow fist blood enters the left atrium and the right atrium the atrium then contracts and then the blood is forced into the ventricles the ventricles then then also contract and force blood out of the heart the valves stop the blood from flowing backwards into the atriums
• the left side of the heart has a thicker muscular wall because it pumps blood around the whole body whilst the right side only pumps blood into the lungs
• coronary arteries provide oxygen to the muscle cells in the heart the oxygen is used for respiration to provide energy for contraction
• pace maker is found in the right atrium
• an artificial pacemaker is a small electric device and it corrects irregularities in the heart
• why do humans have a double circulatory system?

  the right pumps deoxygenated blood to the lungs where it becomes oxygenated and returns back to the heart. the left pump sends the newly oxygenated around the body.