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Health Information For Teens
The heart is a pump, usually beating about 60 to 100 times per minute. With each heartbeat, the heart sends blood throughout our bodies, carrying oxygen to every cell. After delivering the oxygen, the blood returns to the heart. The heart then sends the blood to the lungs to pick up more oxygen. This cycle repeats over and over again.
The circulatory system is made up of blood vessels that carry blood away from and towards the heart. Arteries carry blood away from the heart and veins carry blood back to the heart.
The circulatory system carries oxygen, nutrients, and
to cells, and removes waste products, like carbon dioxide. These roadways travel in one direction only, to keep things going where they should.
The heart has four chambers — two on top and two on bottom:
The atria are separated from the ventricles by the atrioventricular valves:
Two valves also separate the ventricles from the large blood vessels that carry blood leaving the heart:
Two pathways come from the heart:
In pulmonary circulation:
In systemic circulation:
At each body part, a network of tiny blood vessels called capillaries connects the very small artery branches to very small veins. The capillaries have very thin walls, and through them, nutrients and oxygen are delivered to the cells. Waste products are brought into the capillaries.
Capillaries then lead into small veins. Small veins lead to larger and larger veins as the blood approaches the heart. Valves in the veins keep blood flowing in the correct direction. Two large veins that lead into the heart are the superior vena cava and inferior vena cava. (The terms superior and inferior don’t mean that one vein is better than the other, but that they’re located above and below the heart.)
Once the blood is back in the heart, it needs to re-enter the pulmonary circulation and go back to the lungs to drop off the carbon dioxide and pick up more oxygen.
The heart gets messages from the body that tell it when to pump more or less blood depending on a person’s needs. For example, when you’re sleeping, it pumps just enough to provide for the lower amounts of oxygen needed by your body at rest. But when you’re exercising, the heart pumps faster so that your muscles get more oxygen and can work harder.
How the heart beats is controlled by a system of electrical signals in the heart. The sinus (or sinoatrial) node is a small area of tissue in the wall of the right atrium. It sends out an electrical signal to start the contracting (pumping) of the heart muscle. This node is called the pacemaker of the heart because it sets the rate of the heartbeat and causes the rest of the heart to contract in its rhythm.
These electrical impulses make the atria contract first. Then the impulses travel down to the atrioventricular (or AV) node, which acts as a kind of relay station. From here, the electrical signal travels through the right and left ventricles, making them contract.
One complete heartbeat is made up of two phases:
To help keep your heart healthy:
Let the doctor know if you have any chest pain, trouble breathing, or dizzy or fainting spells; or if you feel like your heart sometimes goes really fast or skips a beat.
High blood pressure, also called hypertension, is more common in adults, but it can happen at any age. Learn what it is and how to treat it.
Atrial septal defect, or ASD, is a heart defect that some people are born with. Most ASDs are diagnosed and treated successfully with few or no complications.
Ventricular septal defect, or VSD, is a heart condition that a few teens can have. Find out what it is, how it happens, and what doctors do to correct it.
Arrhythmias are abnormal heartbeats usually caused by an electrical “short circuit” in the heart. Many are minor and not a significant health threat, but others can indicate a more serious problem.
Doctors use cardiac catheterization to gather information about the heart and blood vessels as well as treat certain heart conditions. Find out what’s involved.
When someone has coarctation of the aorta, that person’s aorta (the major blood vessel that carries blood away from the heart to the body) is narrowed at some point.
An echocardiogram (also called an echo or cardiac ultrasound) uses sound waves to create pictures of the heart. See why doctors might order this test for teens.
Cholesterol is a type of fat found in your blood. The body needs some cholesterol, but too much can be a problem. Discover more about cholesterol in this article for teens.
Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.
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