(a)++The+circulatory+system+and+its+components

<span style="border-bottom-color: #4f81bd; border-bottom-style: solid; border-bottom-width: 1pt; border-left-color: initial; border-left-style: none; border-left-width: medium; border-right-color: initial; border-right-style: none; border-right-width: medium; border-top-color: initial; border-top-style: none; border-top-width: medium; color: #376092; display: block; font-family: 'Times New Roman',serif; font-size: 48pt; line-height: normal; margin-bottom: 0pt; margin-left: auto; margin-right: auto; margin-top: auto; padding-bottom: 4pt; padding-left: 0in; padding-right: 0in; padding-top: 0in; text-align: justify;">The circulatory system and its components The circulatory system consists of 3 components; the heart, the blood vessels and the blood. Each component is described in terms of function, role and structure. Learn about how and where blood flow regulation happens, and the impact it has on blood pressure and heart health.

Why do we need a circulatory system?
 The circulatory system is useful to our body by bringing oxygen and nutrients to the cells in the body. It also releases carbon dioxide and other wastes which are bad for the body. It also regulates the temperature of the body, and fights against diseases - which white blood cells are responsible for. The circulatory system consist of 3 components; the heart, the blood vessels and the blood. Each component is described in terms of function, role and structure. Learn about how and where blood flow regulation happens, and the impact is has on blood pressure and heart health.   Here are the components of the circulatory system: **The Heart**

The heart is responsible for pumping blood all around your body. The heart has 4 chambers, 2 atriums and two ventricles (chambers which collect and release blood, received by the atriums). Blood enters the right atrium and passes into the right ventricle. After the right ventricle, it travels to the lungs to be oxygenated, and then back to the left atrium and into the left ventricle.



Blood Vessels
 Blood vessels are connected to the heart which surrounds the whole body and transports blood. There are 5 different types of blood vessels: the arteries, the arterioles (which are small arteries), capillaries, veins and venules (which are small veins).  They enable the exchange of water and chemicals between the blood, tissues, and the veins, which carries the blood from the capillaries back towards the heart.

**// 1. //** **// Arteries //**
 Arteries are blood vessels which carry oxygenated blood away from the heart to the cells, tissues, and organs of the body. 

====**// 2. //** **// Arterioles //** ====

Arterioles are also one of the several types of blood vessels which transport blood around the body. To be more precise, the arterioles transport blood from arteries to capillaries, they are the main regulators of blood flow and pressure. Actually, the arterioles are small arteries because as the arteries get further away from the heart, they get smaller, and when they have decreased in size to a certain point, they're called arterioles.



==== **//3.//** **//Veins//** ====

 Veins are a part of blood vessels that have a function of transporting deoxygenated blood from various parts of the body towards the heart. The veins are larger than the arteries, therefore they can transport more blood. <span style="display: block; line-height: normal; margin-bottom: 0pt; margin-left: auto; margin-right: auto; margin-top: auto; text-align: justify;"><span style="font-family: 'Times New Roman',serif;">

====<span style="color: #4f81bd; font-family: arial,helvetica,sans-serif; font-size: 12pt; font-style: normal; font-weight: normal; line-height: 18px; margin-bottom: 0pt; margin-left: 0.5in; margin-right: 0in; margin-top: 10pt; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 5px; text-indent: -0.25in;">**// 4. Venules //** ====

<span style="display: block; line-height: normal; margin-bottom: 0pt; margin-left: auto; margin-right: auto; margin-top: auto; text-align: justify;"> Venules are small blood vessels which help carry deoxygenated blood and from the capillaries to the veins. They drain blood directly from the capillaries into the veins, which then gets returned to the heart to be pumped all over the body again. ====<span style="color: #4f81bd; font-family: arial,helvetica,sans-serif; font-size: 12pt; font-style: normal; font-weight: normal; line-height: 18px; margin-bottom: 0pt; margin-left: 0.5in; margin-right: 0in; margin-top: 10pt; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 5px; text-indent: -0.25in;">**// 5. Capillaries //** ====

<span style="display: block; line-height: normal; margin-bottom: 0pt; margin-left: auto; margin-right: auto; margin-top: auto; text-align: justify;"> Capillaries are the smallest blood vessels. It is located within the tissue of the body. Capillaries are responsible for transporting blood from arteries to veins, it is also the principal connection between these two main blood vessels. <span style="font-family: 'Times New Roman',serif; line-height: 24px;">

**Blood**

<span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Blood contains red blood cells which are responsible for carrying the oxygen in the lungs and transport it to all the body cells. After delivering the oxygen cells, it gathers up the carbon dioxide and transports it back to the lungs where it is exhaled.

**Components inside blood** <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">(Erythrocytes)
 * || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Appearance (shape & size) || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Main Function || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">How their structure helps their function (job) ||
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Plasma || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">This is the liquid part of the blood || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">The plasma carries the blood cells and other components throughout the body. The plasma is made in the liver || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Since it is a liquid, it helps the red blood cells to travel and move along inside the blood vessels ||
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Red Blood cells

<span style="font-family: 'Times New Roman',Times,serif; font-size: 20px;"> || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">A red blood cell looks like a flat disc which has round edges, with a center lower than the edges (pushed inwards). An average red blood cell is about 7.2 micrometers || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">The main function of the red blood cell is to carry oxygen from the lungs to the brain, internal organs and limbs. It also exchanges the oxygen for carbon dioxide and travels back to the lungs to exchange it for more oxygen || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">The center of the red blood cells (pushed inwards) helps it to carry and transport things back and forth. The hemoglobin, which is on the outside of the cell, also helps things to be stuck onto it, which then get transported. || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">(lymphocytes)
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">White blood cells

<span style="font-family: 'Times New Roman',Times,serif;"> || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">A white blood cell has a circular shape, which is covered with “legs.” A white blood cell is actually a collection of different cells, which work together in order to attack and destroy bacteria. Lymphocytes are a certain type of white blood cell, which are an important part of the immune system. || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Lymphocytes can defend the body against infection because they can distinguish the body’s own cells from foreign ones. Once they recognize foreign materials in the body, they produce chemicals to destroy it. || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Lymphocytes have antibodies and arrange them along their membrane. An antibody is a molecule that has the ability to blind itself to molecules of a complimentary shape called antigens, and recognize them. || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">(Phagocytes) || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Phagocytes are another type of white blood cells || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Phagocytes protect the body by ingesting harmful foreign materials – such as bacteria, dead or dying cells. Phagocytes are important throughout the animal kingdom and are highly developed in vertebrates. || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">To recognize a cell, a phagocyte's receptors match the antigens on the cells from the same body. Whatever pathogen or damaged cell does not have these antigens, the phagocyte will kill it. ||
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">White blood cells
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Platelets



|| <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">latelets look like red or orange tires, or plates. When platelets are stimulated by an opening in the blood vessel wall, they change shape and become round and extend long threads. || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Platelets are blood cells which help stop bleeding. When we cut ourselves, we have broken a vessel and therefore, blood leaks out. In order to plug up the opening where the blood is leaking from, the platelets start to stick to the opening of the damaged blood vessels. As the platelets stick to the opening of the damaged vessel, they attract more platelets, fibers and other blood cells to help form a plug to seal the broken blood vessel. When the platelet plug is completely formed, the wound stops bleeding. We call our platelet plugs scabs. || <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Platelets aren’t actually cells, instead, they are circulating fragments of cells. But even though they are just fragments, they contain many structures that are critical to stop bleeding. Platelets contain proteins on their surface to allow them to stick to openings in the blood vessel wall and also stick to each other. Platelets also contain proteins similar to muscle proteins that allow them to change shape when they become sticky. ||

**Works Cited:** <span style="color: black; font-family: 'Times New Roman',Times,serif; line-height: 32px;">"Circulatory System." //Hillendale Elementary School//. Web. 21 Feb. 2011. <[]>. <span style="font-family: 'Times New Roman',Times,serif;">"Platelets." //The University of Oklahoma Health Sciences Center//. Web. 21 Feb. 2011. <[|http://www.ouhsc.edu/platelets/platelets/platelets intro.html]>.