Show The human heart pumps blood to every part of your body. Learn about the different parts of the heart and watch our video about how a healthy heart works. Your heart is the pump which powers your body. It supplies blood carrying oxygen and nutrients to every cell, nerve, muscle and vital organ in your body. It sits in your chest between your lungs, slightly to the left of centre, and is protected by your rib cage. Your heart is about the size of your clenched fist and weighs about 300 grams (that's just over half a packet of butter). Watch our step-by-step video of how the heart works
What are the parts of the heart?Your heart is a bit like a house. It has: Heart wallsThe walls of your heart are made of powerful muscle tissue, which squeezes and relaxes to pump blood around your body. This muscle tissue is divided into three layers.
Heart chambers (rooms)Your heart is made up of four chambers, two on the right and two on the left. These are like the rooms of your house. The top two chambers are called the left and right atrium and the bottom two are called the left and right ventricles. They are divided by a thin wall called the septum. Heart valves (the doors between the rooms)There are four heart valves, which act like doors between the chambers of the heart. They open and close as your heart pumps. The valves only open one way. This stops blood flowing in the wrong direction between the chambers of your heart. The two valves that sit between the upper and lower chambers of the heart are called the atrioventricular, or AV valves. The tricuspid valve is the door between the right atrium and ventricle. The mitral valve is the door between the left atrium and ventricle. The other two valves are the doors out of the ventricles. They are called semilunar, or SL valves. The aortic valve is the door out of the left ventricle into the aorta. The pulmonary valve is the door out of the right ventrical into the pulmonary artery. The blood vessels (the plumbing)Blood travels between the heart and the lungs and the rest of the body, via a network of pipes called the blood vessels. There are three main types of blood vessels.
How the heart pumpsYour conduction system sends the electrical signals which trigger the heart to pump blood around the body, and to and from the lungs. Blood which has used all its oxygen is returned to the right side of the heart, via large veins called the inferior and superior vena cava. From there it is pumped to the lungs, via the pulmonary artery. Once the blood has received oxygen from the lungs, it travels through the pulmonary veins into the left side of the heart. From here it is pumped back out around the body, via the aorta. The heart's conduction system (the electrics)Your heart has its own electrical wiring system (conduction system), which keeps it beating. This conduction system includes:
The SA node sends an electrical signal that makes the upper chambers of the heart (atria) contract (squeeze). This pushes blood out of the atria and into the lower chambers of the heart (ventricles). The electrical signal passes from the atria to the AV node. From there, it passes through the bundle of His and into the right and left bundle branches. Finally, the signal travels down the Purkinje fibres, causing the ventricles to contract. This pushes blood out of your heart to your lungs and the rest of your body. How the heart pumpsYour conduction system sends the electrical signals which trigger the heart to pump blood around the body, and to and from the lungs. Blood which has used all its oxygen is returned to the right side of the heart, via large veins called the inferior and superior vena cava. From there it is pumped to the lungs, via the pulmonary artery. Once the blood has received oxygen from the lungs, it travels through the pulmonary veins into the left side of the heart. From here it is pumped back out around the body, via the aorta. The coronary arteriesThe heart has its own network of blood vessels, which supply it with the blood it needs to keep pumping. These vessels are called the coronary arteries. They branch off the body’s largest artery, the aorta, and lie on the outside of your heart. Narrowing in one of the coronary arteries can lead to angina and a blockage can cause a heart attack. Learn about heart conditions What is your pulse?The pulse you can feel, for example in your wrist or neck, is the heart pumping blood. You can measure the rate and rhythm of your heart by taking your pulse. How to take your pulse
The circulatory system (cardiovascular system) pumps blood from the heart to the lungs to get oxygen. The heart then sends oxygenated blood through arteries to the rest of the body. The veins carry oxygen-poor blood back to the heart to start the circulation process over. Your circulatory system is critical to healthy organs, muscles and tissues.
Your heart and blood vessels make up the circulatory system. The main function of the circulatory system is to provide oxygen, nutrients and hormones to muscles, tissues and organs throughout your body. Another part of the circulatory system is to remove waste from cells and organs so your body can dispose of it. Your heart pumps blood to the body through a network of arteries and veins (blood vessels). Your circulatory system can also be defined as your cardiovascular system. Cardio means heart, and vascular refers to blood vessels. The circulatory system provides blood to all the body's tissues so they can function.
The circulatory system’s function is to move blood throughout the body. This blood circulation keeps organs, muscles and tissues healthy and working to keep you alive. The circulatory system also helps your body get rid of waste products. This waste includes:
How does the circulatory system work?Your circulatory system functions with the help of blood vessels that include arteries, veins and capillaries. These blood vessels work with your heart and lungs to continuously circulate blood through your body. Here’s how:
The parts of your circulatory system are your:
What are the circulatory system circuits?Your circulatory system has three circuits. Blood circulates through your heart and through these circuits in a continuous pattern:
What are the types of blood vessels?There are three main types of blood vessels:
What are the circulatory system organs?Your heart is the only circulatory system organ. Blood goes from the heart to the lungs to get oxygen. The lungs are part of the respiratory system. Your heart then pumps oxygenated blood through arteries to the rest of the body.
Many conditions can affect the health of your circulatory system, including:
These steps can protect the health of your circulatory system:
Your body has more than 60,000 miles of blood vessels that circulate about 1.5 gallons of blood every day. What is red blood and blue blood?All blood is red. Hemoglobin, an iron-rich protein in red blood cells, mixes with oxygen to give blood its red color. Blood that’s rich in oxygen is known as red blood. Your veins carry oxygen-poor blood. This is sometimes called blue blood because your veins can look blue underneath the skin. The blood is actually red, but the low oxygen levels give veins a bluish hue. Do arteries always carry oxygenated blood?For the most part, yes. The exceptions are pulmonary arteries and veins. Pulmonary arteries carry deoxygenated blood to the lungs. Pulmonary veins return the oxygenated blood to the heart. A note from Cleveland Clinic Your circulatory system plays a critical role in keeping you alive. Blood vessels carry blood to the lungs for oxygen. Then your heart pumps oxygen-rich blood through arteries to the rest of the body. Your veins help your body get rid of waste products. Conditions like high blood pressure, high cholesterol and atherosclerosis can affect the health of your circulatory system. If you have one of these conditions, talk to your healthcare provider about steps you can take to protect your cardiovascular health.
Last reviewed by a Cleveland Clinic medical professional on 09/21/2021. References
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