The cardiovascular system delivers blood and nutrients throughout the body. The three main components of the cardiovascular system are the heart, blood vessels, and blood. Blood is what helps transfer nutrients throughout the body and keeps us alive. It must be continuously pumped through the body by the heart! Blood carries nutrients and oxygen to cells in our body.
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Heart Lesson 00:29
Heart Health Overview
What Does the Heart Do?
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.
What Are the Parts of the Heart?
The heart has four chambers — two on top and two on bottom:
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.
How Does the Heart Beat?
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.
How Can I Help Keep My Heart Healthy?
To help keep your heart healthy:
Get plenty of exercise.
Eat a nutritious diet.
Reach and keep a healthy weight.
If you smoke, quit.
Go for regular medical checkups.
Tell the doctor about any family history of heart problems.
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.