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Important Phone Numbers. Top of the page. Topic Overview The heart is at the centre of your circulatory system, which is a network of blood vessels that delivers blood to every part of your body. How does my heart pump blood? The right side of your heart receives oxygen-poor blood from your veins and pumps it to your lungs, where it picks up oxygen and gets rid of carbon dioxide.
The left side of your heart receives oxygen-rich blood from your lungs and pumps it through your arteries to the rest of your body. How does blood flow through the heart? Blood flows through your heart and lungs in four steps: The right atrium receives oxygen-poor blood from the body and pumps it to the right ventricle through the tricuspid valve. The right ventricle pumps the oxygen-poor blood to the lungs through the pulmonary valve. The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle through the mitral valve.
The left ventricle pumps the oxygen-rich blood through the aortic valve out to the rest of the body. How does my heart maintain its normal function? To do this, your heart needs to: Regulate the timing of your heartbeat. Your heart's electrical system controls the timing of the pump. The electrical system keeps your heart beating in a regular rhythm and adjusts the rate at which it beats. When the electrical system is working properly, it maintains a normal heart rate and rhythm.
Problems with this electrical system can cause an arrhythmia, which means that your heart chambers are beating in an uncoordinated or random way or that your heart is beating too fast tachycardia or too slow bradycardia. Keep your heart muscle healthy. The four chambers of your heart are made of a special type of muscle called myocardium. It's located a little to the left of the middle of your chest, and it's about the size of your fist. There are lots of muscles all over your body — in your arms, in your legs, in your back, even in your behind.
But the heart muscle is special because of what it does. The heart sends blood around your body. The blood provides your body with the oxygen and nutrients it needs.
It also carries away waste. Your heart is sort of like a pump, or two pumps in one. The right side of your heart receives blood from the body and pumps it to the lungs. The left side of the heart does the exact opposite: It receives blood from the lungs and pumps it out to the body. How does the heart beat? Before each beat, your heart fills with blood. Then its muscle contracts to squirt the blood along.
When the heart contracts, it squeezes — try squeezing your hand into a fist. That's sort of like what your heart does so it can squirt out the blood. Your heart does this all day and all night, all the time.
The heart is one hard worker! The heart is made up of four different blood-filled areas, and each of these areas is called a chamber. There are two chambers on each side of the heart. One chamber is on the top and one chamber is on the bottom. The two chambers on top are called the atria say: AY-tree-uh.
If you're talking only about one, call it an atrium. The atria are the chambers that fill with the blood returning to the heart from the body and lungs. The heart has a left atrium and a right atrium. The two chambers on the bottom are called the ventricles say: VEN-trih-kulz.
The heart has a left ventricle and a right ventricle. Their job is to squirt out the blood to the body and lungs. Running down the middle of the heart is a thick wall of muscle called the septum say: SEP-tum.
The septum's job is to separate the left side and the right side of the heart. The atria and ventricles work as a team — the atria fill with blood, then dump it into the ventricles. The ventricles then squeeze, pumping blood out of the heart. While the ventricles are squeezing, the atria refill and get ready for the next contraction.
So when the blood gets pumped, how does it know which way to go? Well, your blood relies on four special valves inside the heart. A valve lets something in and keeps it there by closing — think of walking through a door. The door shuts behind you and keeps you from going backward. They let blood flow from the atria to the ventricles. The circumflex artery branches off from the left coronary artery to supply blood to part of the left ventricle.
The left anterior descending artery also branches from the left coronary artery and provides blood to parts of both the right and left ventricles. The right coronary artery provides blood to the right atrium and parts of both ventricles. The marginal arteries branch from the right coronary artery and provide blood to the surface of the right atrium. The posterior descending artery also branches from the right coronary artery and provides blood to the bottom of both ventricles.
After your atria pump blood into the ventricles, the valves between the atria and ventricles close to prevent backflow. At rest, your heart typically beats about 60 to 70 times per minute.
When you exercise, your heart beats faster, and your heart rate speeds up to get more oxygen to your muscles. Electrical activity. The signal begins in a group of cells, called pacemaker cells, located in the sinoatrial SA node in the right atrium. The electrical signal travels through the atria, causing them to pump blood into the ventricles. The electrical signal then moves down to a group of pacemaker cells called the atrioventricular AV node, located between the atria and the ventricles. Here the signal slows down slightly, allowing the ventricles time to finish filling with blood.
The AV node fires another signal that travels along the walls of your ventricles, causing them to contract and pump blood out of your heart.
The ventricles relax, and the heartbeat process starts all over again in the SA node. Blood pressure. Systolic pressure is the pressure when the ventricles pump blood out of the heart. The pressure on your arteries is highest during this time. Diastolic pressure is the pressure between beats, when the heart is filling with blood. The pressure on your arteries is lowest during this time. Autonomic nervous system. The parasympathetic system tells your heart to beat slower during rest.
The sympathetic system tells your heart to beat faster. Norepinephrine also signals the muscle in your heart to beat harder.
In a healthy person, the heart rate reflects a balance between these two systems. Endocrine system. These hormones include: The renin-angiotensin-aldosterone system, which can also cause the muscle cells in the heart to grow larger so they can pump harder. Vasopressin, released from the pituitary gland. Research for Your Health. Improving health with current research. Long-standing Leader in Heart Research. During this period, steady, long-term investments in heart research have led to a greater understanding of how the heart works.
These basic insights into the normal biology of the heart are essential for making biomedical discoveries that improve health for people who have heart and vascular diseases. In addition, research from the NHLBI's landmark effort, the Framingham Heart Study , has formed the basis of cardiovascular disease CVD prevention and health promotion guidelines and educational programs. The NHLBI conducted a rigorous systematic review of evidence on the effect of dietary patterns, nutrient intake, and levels and types of physical activity on reducing CVD risk in adults.
Results were incorporated into clinical guidelines for managing blood cholesterol and blood pressure in We support the development of guidelines based on up-to-date research to evaluate and manage children and adolescents' risk of heart disease, including overweight and obesity. It also educates and motivates women to take action to prevent the disease.
The Cardiothoracic Surgical Trials Network CTSN is an international clinical research enterprise that studies heart valve disease, arrhythmias, heart failure, coronary artery disease, and the complications of surgery. The CTSN's efforts extend from early translational research to the completion of six randomized clinical trials, three large observational studies, and multiple ancillary studies with more than 14, participants. Increased risk of heart disease among American Indians.
The Strong Heart Study is the largest and longest study on heart disease and its risk factors in American Indians. The study found that heart disease among American Indians has increased over the past 50 years and is now double the rate of heart disease in the general U.
Pioneered techniques to measure heart function. NHLBI-funded investigators pioneered a technique to measure electrical activity from the sinoatrial SA node, also called the pacemaker of the heart. This procedure is now used to look for problems with the SA node and to locate the SA node during surgery to avoid damaging it. Environment contributes to heart disease risk. Research from CARDIA found that living in racially segregated neighborhoods is associated with higher blood pressure among black adults, while moving away from segregated areas is associated with a decrease in blood pressure.
The heart helps controls blood pressure. NHLBI-funded researchers found that when blood pressure and the amount of blood in the body rises, the heart makes a hormone that does two things: it causes the blood vessels to widen, and it makes the kidneys remove more water from the blood so that blood pressure returns to normal.
This discovery made it possible for doctors to use the hormone as a biomarker to help diagnose patients who have heart failure. Understanding hardening of the arteries. The Atherosclerosis Risk in Communities ARIC study is investigating the causes of atherosclerosis, a disease marked by plaque buildup in the arteries, and the clinical outcomes in adults from four U.
Another goal of the study is to measure how cardiovascular risk factors, medical care, and outcomes vary by race, sex, place, and time. Advancing research for improved health.
We perform research. We fund research. The research we fund today will help improve our future health. Our Division of Cardiovascular Sciences oversees much of the research on the heart we fund, helping us to understand how the heart normally develops, functions, and repairs itself so that we can better prevent and treat heart conditions.
The Center for Translation Research and Implementation Science translates these discoveries into clinical practice. We stimulate high-impact research.
Our Trans-Omics for Precision Medicine TOPMed program includes participants who have heart conditions, such as coronary artery disease and atrial fibrillation, to help us understand how genes contribute to differences in disease severity and how patients respond to treatment. Creating heart tissue in the lab. NHLBI-funded research is exploring methods to create heart tissue that closely mimics the function, shape, and structure of the human heart, with the hope of one day using the engineered heart tissue to treat people who have heart disease.
Studying how the brain controls heart function. With support from the NHLBI, a team of scientists is looking at how the brain controls heart function. The team is studying different mechanisms from the nervous system, including hormones and other signaling molecules, with the aim of finding new treatments for high blood pressure.
Studying the balance of signaling molecules on heart health and disease. Reactive oxygen species ROS appear to contribute to heart failure and arrhythmias. But ROS are created naturally when cells make energy and are important for signaling what is happening inside of cells. Understanding how heart cells communicate with each other.
One way cells communicate across the body is by sending molecules from one cell through a channel on another cell. Researchers supported by the NHLBI are looking at a newly discovered channel on the surface of heart cells.
This channel appears to help heart cells communicate with each other to keep the heart healthy. The researchers are studying how the channel helps control blood pressure and prevent inflammation in the heart and blood vessels. NHLBI and National Cancer Institute researchers discovered how heart cells prevent damage from one network of mitochondria from spreading to the rest of the grid. Trials at the NIH Clinical Center Heart health study of members of predominately black churches This study aims to understand the health and health needs of people in predominately black churches in Washington, D.
This information will help researchers design programs to improve heart health in these communities. To participate in this study, you must be between 19 and 85 years old and attend one of the churches in the study. This study is based in Bethesda, Maryland. This study aims to improve cardiac magnetic resonance imaging MRI techniques. The clinical investigators will use new MRI methods to look at healthy people and people who have heart problems. Participants in this study must be at least 7 years old, be healthy or have cardiovascular disease, and not be pregnant.
This study is located in Bethesda, Maryland. The study is using a technique called magnetic resonance spectroscopy MRS during a cardiac magnetic resonance imaging MRI scan to determine whether energy metabolism is disrupted in heart failure and whether this contributes to poor heart function. To participate in this study, you must be at least 18 years old and either be healthy or have coronary artery disease, dilated cardiomyopathy, or left ventricular hypertrophy.
The study is located in Baltimore, Maryland. This study aims to help researchers better understand the developing heart and what controls the strength of its beats by comparing it to adult hearts. Researchers will study small pieces of the heart that are removed as a normal part of surgery or repair for children with congenital heart disease.
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