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ANATOMY OF HEART
The heart is the main organ of the cardiovascular system, a network of blood vessels that
pumps blood throughout the body. It also works with other body systems to control the
heart rate and blood pressure.
What is the heart?
The heart is a fist-sized organ that pumps blood throughout the body. It's the primary
organ of the circulatory system. The heart is located in the front of the chest. It sits
slightly behind and to the left of the sternum (breastbone). The ribcage protects the heart.
The heart is slightly on the left side of the body. It sits between the right and left lungs.
The left lung is slightly smaller to make room for the heart in the left chest. Everyone’s
heart is a slightly different size. Generally, adult hearts are about the same size as two
clenched fists, and children’s hearts are about the same size as one clenched fist. On
average, an adult’s heart weighs about 10 ounces. The heart may weigh a little more or a
little less, depending on the body size and sex.
The heart contains four main sections (chambers) made of muscle and powered by
electrical impulses. The brain and nervous system direct the heart’s function.
Function:
To move blood throughout the body
Controls the rhythm and speed of the heart rate.
Maintains the blood pressure.
The parts of the heart:
Walls.
Chambers (rooms).
Valves (doors).
Blood vessels (plumbing).
Electrical conduction system (electricity).
Heart walls
The heart walls are the muscles that contract (squeeze) and relax to send blood
throughout the body. A layer of muscular tissue called the septum divides the heart walls
into the left and right sides.
The heart walls have three layers:
Endocardium: Inner layer.
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Myocardium: Muscular middle layer.
Epicardium: Protective outer layer.
The epicardium is one layer of the pericardium. The
pericardium is a protective sac that covers the entire
heart. It produces fluid to lubricate the heart and keep
it from rubbing against other organs.
Heart chambers
The heart is divided into four chambers. You have
two chambers on the top (atrium, plural atria) and
two on the bottom (ventricles), one on each side of
the heart.
Right atrium: Two large veins deliver
oxygen-poor blood to the right atrium. The superior vena cava carries blood from
the upper body. The inferior vena cava brings blood from the lower body. Then
the right atrium pumps the blood to the right ventricle.
Right ventricle: The lower right chamber pumps the oxygen-poor blood to
the lungs through the pulmonary artery. The lungs reload blood with oxygen.
Left atrium: After the lungs fill blood with oxygen, the pulmonary veins carry
the blood to the left atrium. This upper chamber pumps the blood to the left
ventricle.
Left ventricle: The left ventricle is slightly larger than the right. It pumps
oxygen-rich blood to the rest of the body.
Heart valves
The heart valves are like doors between the heart chambers. They open and close to allow
blood to flow through.
The atrioventricular (AV) valves open between the upper and lower heart chambers.
They include:
Tricuspid valve: Door between the right atrium and right ventricle.
Mitral valve: Door between the left atrium and left ventricle.
Semilunar (SL) valves open when blood flows out of the ventricles. They include:
Aortic valve: Opens when blood flows out of the left ventricle to the aorta (artery
that carries oxygen-rich blood to the body).
Pulmonary valve: Opens when blood flows from the right ventricle to
the pulmonary arteries (the only arteries that carry oxygen-poor blood to the
lungs).
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Blood vessels
The heart pumps blood through three types of blood vessels:
Arteries carry oxygen-rich blood from the heart to the body’s tissues. The
exception is the pulmonary arteries, which go to the lungs.
Veins carry oxygen-poor blood back to the heart.
Capillaries are small blood vessels where the body exchanges oxygen-rich and
oxygen-poor blood.
The heart receives nutrients through a network of coronary arteries that run along the
heart’s surface.
Electrical conduction system
The heart’s conduction system controls the rhythm and pace of the heartbeat. It includes:
Sinoatrial (SA) node: Sends the signals that make the heart beat.
Atrioventricular (AV) node: Carries electrical signals from the heart’s upper
chambers to its lower ones.
The heart also has a network of electrical bundles and fibers. This network includes:
Left bundle branch: Sends electric impulses to the left ventricle.
Right bundle branch: Sends electric impulses to the right ventricle.
Bundle of His: Sends impulses from the AV node to the Purkinje fibers.
Purkinje fibers: Make the heart ventricles contract and pump out blood.

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ANATOMY OF HEART The heart is the main organ of the cardiovascular system, a network of blood vessels that pumps blood throughout the body. It also works with other body systems to control the heart rate and blood pressure. What is the heart? The heart is a fist-sized organ that pumps blood throughout the body. It's the primary organ of the circulatory system. The heart is located in the front of the chest. It sits slightly behind and to the left of the sternum (breastbone). The ribcage protects the heart. The heart is slightly on the left side of the body. It sits between the right and left lungs. The left lung is slightly smaller to make room for the heart in the left chest. Everyone’s heart is a slightly different size. Generally, adult hearts are about the same size as two clenched fists, and children’s hearts are about the same size as one clenched fist. On average, an adult’s heart weighs about 10 ounces. The heart may weigh a little more or a little less, depending on the body size and sex. The heart contains four main sections (chambers) made of muscle and powered by electrical impulses. The brain and nervous system direct the heart’s function. Function: • • • To move blood throughout the body Controls the rhythm and speed of the heart rate. Maintains the blood pressure. The parts of the heart: • • • • • Walls. Chambers (rooms). Valves (doors). Blood vessels (plumbing). Electrical conduction system (electricity). Heart walls The heart walls are the muscles that contract (squeeze) and relax to send blood throughout the body. A layer of muscular tissue called the septum divides the heart walls into the left and right sides. The heart walls have three layers: • Endocardium: Inner layer. 1 • • Myocardium: Muscular middle layer. Epicardium: Protective outer layer. The epicardium is one layer of the pericardium. The pericardium is a protective sac that covers the entire heart. It produces fluid to lubricate the heart and keep it from rubbing against other organs. Heart chambers The heart is divided into four chambers. You have two chambers on the top (atrium, plural atria) and two on the bottom (ventricles), one on each side of the heart. • • • • Right atrium: Two large veins deliver oxygen-poor blood to the right atrium. The superior vena cava carries blood from the upper body. The inferior vena cava brings blood from the lower body. Then the right atrium pumps the blood to the right ventricle. Right ventricle: The lower right chamber pumps the oxygen-poor blood to the lungs through the pulmonary artery. The lungs reload blood with oxygen. Left atrium: After the lungs fill blood with oxygen, the pulmonary veins carry the blood to the left atrium. This upper chamber pumps the blood to the left ventricle. Left ventricle: The left ventricle is slightly larger than the right. It pumps oxygen-rich blood to the rest of the body. Heart valves The heart valves are like doors between the heart chambers. They open and close to allow blood to flow through. The atrioventricular (AV) valves open between the upper and lower heart chambers. They include: • • Tricuspid valve: Door between the right atrium and right ventricle. Mitral valve: Door between the left atrium and left ventricle. Semilunar (SL) valves open when blood flows out of the ventricles. They include: • • Aortic valve: Opens when blood flows out of the left ventricle to the aorta (artery that carries oxygen-rich blood to the body). Pulmonary valve: Opens when blood flows from the right ventricle to the pulmonary arteries (the only arteries that carry oxygen-poor blood to the lungs). 2 Blood vessels The heart pumps blood through three types of blood vessels: • • • Arteries carry oxygen-rich blood from the heart to the body’s tissues. The exception is the pulmonary arteries, which go to the lungs. Veins carry oxygen-poor blood back to the heart. Capillaries are small blood vessels where the body exchanges oxygen-rich and oxygen-poor blood. The heart receives nutrients through a network of coronary arteries that run along the heart’s surface. Electrical conduction system The heart’s conduction system controls the rhythm and pace of the heartbeat. It includes: • • Sinoatrial (SA) node: Sends the signals that make the heart beat. Atrioventricular (AV) node: Carries electrical signals from the heart’s upper chambers to its lower ones. The heart also has a network of electrical bundles and fibers. This network includes: • • • • Left bundle branch: Sends electric impulses to the left ventricle. Right bundle branch: Sends electric impulses to the right ventricle. Bundle of His: Sends impulses from the AV node to the Purkinje fibers. Purkinje fibers: Make the heart ventricles contract and pump out blood. 3 Name: Description: ...
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