Arteries,+Capillaries+and+Veins

Blood vessels are hollow tubes that circulate your blood. During blood circulation, arteries carry blood away from the heart, capillaries connect arteries to veins and veins carry blood back to the heart.

An adult's blood vessels would be about 100,000 miles long if laid out Anatomy of a blood vessel - arteries and veins have a layer of smooth muscle around them

Arteries provide the body with fresh- oxygen rich blood from the heart and lungs They send it to the capillaries where gas exhange occurs- carbon dioxide and oxygen are let in and out Capillaries deliver waste rich blood to veins Veins send blood back to the heart and lungs



http://www.fi.edu/learn/heart/vessels/arteries.html

Arteries - have a much thicker muscle layer than veins, with more elastic fibers - the Aorta, which leaves the heart, has cardiac muscle fibers for the first few inches past the heart - have the property of elasticity- can expand easily to except blood from the heart, then contract back to their original size to squeeze blood into the veins (when the heart relaxes) - arteries maintain pressure on the blood when the heart is relaxed which keeps blood moving forward - without their elasticity, our blood pressure would be closer to 120/0 than 120/80 (normal) - when arteries get smaller, they branch into arterioles which later become capillaries



Capillaries - very thin and branching like a web- so thin that blood cells have to travel single file - exchange between the blood and the cells of the body takes place in the capillaries - blood gives up carbon dioxide and other wastes (in the kidney) and takes in oxygen - white blood cells in the capillaries leave the blood to fight infections - capillaries thicken and merge to become venules which later become veins and return to the heart - capillary walls are made up of endothelium, which is a single layer of over lapping cells -oxygen, CO2, nutrients and wastes are exchanged through the thin walls - the flow of blood in the capillaries is controlled by precapillary sphincters, located between the arterioles and capillaries - capillaries are 5-10 microns in diameter



Veins - do not have as many elastic fibers as arteries but have valves which keep blood moving the right way - if the valves don't work well blood tends to flow back into the legs due to gravity- varicose veins - venules, the smallest veins, get blood from the arteries through the arterioles and capillaries - the largest vein n the body is the vena cava - the vena cava delivers blood to the right atrium of the heart - veins range in size from 1mm. to 1.5 centimeters in diameter

http://biology.about.com/library/organs/blcircsystem6.htm

Video Script Arteries, Capillaries and Veins by Dede Bearden

This is an artery. These are arteries in the body.

Capillaries look like this. And in our bodies they spread out like this..

These are veins... These are also veins.. So are these... gross.

Everyone has arteries and capillaries, and veins but what do they do?

Well, arteries carry blood from the heart to the rest of the body. They are elastic which means they can xpand easily to except blood from the heart, then contract back to their original size to squeeze blood into the veins (when the heart relaxes). arteries maintain pressure on the blood when the heart is relaxed which keeps blood moving forward. when arteries get smaller, they branch into arterioles which later become capillaries.

Capillaries are very thin and branching. Because they are so thin, blood cells have to travel single file through them. Blood gives up carbon dioxide and other wastes (in the kidney) and takes in oxygen, in the capillaries. Capillaries thicken, become venules, which become veins, which return blood to the heart.

Veins have valves that keep blood moving in the right direction. Veins take waste-rich blood from the body back to the heart and lungs. They range in size from 1 mm. to 1.5 cm. in diameter.

The end

media type="file" key="Dedeproject.mov"