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 The Circulatory system provides a continuous supply of nutrients and oxygen to every cell in the body. Simultaneously, it picks up carbon dioxide and other waste materials produced by the cells and carries them away for removal from the body.
Health concerns related to the circulatory system include high cholesterol or triglycerides, high blood pressure, stress, poor circulation and heart disease.
EXAMINING THE CIRCULATORY SYSTEM
In order for your body to stay alive, each of its cells must have a continuous supply of food and oxygen. At the same time, carbon dioxide and other waste materials produced by the cells must be picked up for removal from the body. The circulatory system performs these two functions.
The human heart makes the circulatory system work. A hollow, pear-shaped, muscular organ, the heart is located between the lungs in the middle of the chest. It pumps blood through the body, supplying cells and tissues with oxygen and nutrients. In order to meet your body's energy demands, your heart must beat more than 100,000 times per day.
Like all other body tissues, your heart also needs oxygen and nutrients in order to function properly. Because blood flowing through the heart is traveling too fast for the heart to absorb, the heart has its own system of vessels that supply it with oxygen and nutrients.
The heart contains four chambers: the upper chambers are called atria and the lower chambers are ventricles. Each half of your heart works as a separate pump. The right side of the heart is responsible for returning the oxygen-poor blood to the lungs to expel carbon dioxide and reoxygenate the blood. The left side receives the newly oxygenated blood from the lungs and pumps it through the entire body. Although the average adult body contains less than 1.5 gallons of blood, amazingly the heart pumps 2,000 gallons each day.
Blood vessels are small tubes that carry blood to and from all parts of the body. The human circulatory system is composed of three types of vessels that total an incredible 60,000 miles in length.
The arteries are the largest blood vessels. They carry oxygen-rich blood from the heart to the cells and tissues of the body. Because arteries transport under high pressure. They have walls that are much more elastic than veins. The arteries pulsate as a result of the force with which the heart pumps new blood into them.
The veins are smaller vessels that carry oxygen-poor blood and waste products back to the heart. This blood moves slowly due to low pressure. Veins can expand or contract to accommodate variations in blood flow. Semilunar valves are found at regular intervals throughout the veins. These force the blood to move in only one direction.
Capillaries are microscopic in size. They link the arteries and veins to the tissues of the body. The exchange of oxygen and carbon dioxide takes place across thin capillary walls.
Blood supplies oxygen and transports nutrients, waste and hormonal messengers to each of the billions of cells in the body. Blood has four main components: red blood cells, white blood cells, platelets and liquid plasma. Red blood cells carry 99 percent of the oxygen the body needs and are the most abundant cells in the body, constituting 45 percent of the blood. White blood cells comprise an important part of the body's immune system. Their main function is providing defense against infectious agents. Platelets are tiny, specialized cells that are activated whenever blood clotting or blood-vessel repair is needed. Liquid plasma carries the other 1 percent of the oxygen the body needs and also helps repair damaged blood vessels. To do this, plasma is transformed into thin strands that create a protective mesh over the damaged area.
Did You Know?
♦ Randomized, double-blind clinical studies of standardized hawthorn berry extract show positive results, appearing to increase the efficiency of nerve impulses in, and protect against oxygen deprivation of, the heart muscle.
♦ Blood is made up of 55 percent plasma and 45 percent cells.
♦ Plasma is mostly water, but it also contains proteins (albumin, immunoglobulins, clotting factors, enzymes, transport proteins), salts, lipids (cholesterol), carbohydrates (glucose) and gases (oxygen, carbon dioxide).
♦ Garlic can offer significant protection against heart disease and stroke. It has also been shown to lower high blood pressure.
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