The blood pumped by your heart provides your body with the oxygen and nutrients it needs to function. Your heart is about the size of a clenched fist, and weighs between and g. It lies in the middle of your chest, behind and slightly to the left of your breastbone. If you are of average body weight and size, your body contains about five litres of blood, all of which passes through your heart every minute or so.
However, when necessary, such as during exercise, your heart can pump up to four times that amount per minute. Your heart has a right and left side separated by a wall called the septum. There are four chambers: the left atrium and right atrium upper chambers , and the left ventricle and right ventricle lower chambers.
The right side of your heart collects blood on its return from the rest of our body. The blood entering the right side of your heart is low in oxygen. Your heart pumps the blood from the right side of your heart to your lungs so it can receive more oxygen. Once it has received oxygen, the blood returns directly to the left side of your heart, which then pumps it out again to all parts of your body through an artery called the aorta.
Blood pressure refers to the amount of force the pumping blood exerts on arterial walls. Each atrium is connected to its ventricle by a one-way valve.
The valve on the right side of the heart is called the tricuspid valve, while the valve on the left side is called the mitral valve. The familiar 'lub-dub' sound of the heartbeat is caused by the rhythmic closing of the heart valves as blood is pumped in and out of the chambers. The heart rate is regulated by a special cluster of cells situated in the right atrium, called the sinus node. This prompts the atria to contract first; then an electrical impulse is sent to a second node the atrioventricular node , which is found between the atria and the ventricles.
After a brief delay, the ventricles contract. At rest, your heart beats approximately 60 to times a minute. This page has been produced in consultation with and approved by:. A person with amyloidosis produces aggregates of insoluble protein that cannot be eliminated from the body.
Please turn on JavaScript and try again. Main Content. Important Phone Numbers. Top of the page. The right atrium receives oxygen-poor blood from the body and pumps it to the right ventricle.
The right ventricle pumps the oxygen-poor blood to the lungs. The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle.
The outer layer of the heart wall is the epicardium, the middle layer is the myocardium , and the inner layer is the endocardium. The internal cavity of the heart is divided into four chambers:.
The two atria are thin-walled chambers that receive blood from the veins. The two ventricles are thick-walled chambers that forcefully pump blood out of the heart. Differences in thickness of the heart chamber walls are due to variations in the amount of myocardium present, which reflects the amount of force each chamber is required to generate.
The right atrium receives deoxygenated blood from systemic veins; the left atrium receives oxygenated blood from the pulmonary veins. Pumps need a set of valves to keep the fluid flowing in one direction and the heart is no exception.
The heart has two types of valves that keep the blood flowing in the correct direction. The valves between the atria and ventricles are called atrioventricular valves also called cuspid valves , while those at the bases of the large vessels leaving the ventricles are called semilunar valves.
0コメント