ArteriesVeins
OB15 distinguish between arteries, veins and capillaries
Blood moves around us through tubes that cover our entire bodies. Some of these tubes go away from our heart and others return back to the heart. These 2 vessels are different.
We name them Arteries and Veins
It is easy to remember which one does what
Arteries go Away from the Heart
Veins go towards the Heart
talk through animation of the whole double pump system
http://www.sumanasinc.com/webcontent/animations/content/human_heart.html
The Heart acts like a Pump as so the Blood in the Arteries is under pressure, this pressure helps the blood get to all parts of the body quickly. But because of this pressure the tubes carrying the blood are also under large amounts of pressure and so the Arteries have quite thick walls.
Can you Label the two Blood Vessels?
Which one do you think is the Artery and which the Vein
Veins do not need such thick walls as the blood is being pushed into these vessels after going through the tissue.
However the blood in the veins have nothing pushing them back up to the heart, so in order to maintain the direction of the blood there are Valves in the Veins. These valves only allow blood to enter from one side, they then close until more blood wants to enter that section of the vein.
Valves in Veins at work
So how does blood get from the Arteries to the Veins ?
Capillaries
Connect arteries to veins.
Are tiny and numerous,
Allow substances to pass between the blood and body cells.
Oxygen and Glucose (food) pass into the cells ...
CO2 comes out of the cells as 1 waste product.
Very _____ walls
Capillaries are like roads coming off the motorways that allow us into the small estates (organs and tissues),
Every cell has a little road up to it, these are capillary blood vessels.