Patrick Baker Biology -circulation-aneurysm

HOW DOES AN ANEURYSM HAPPEN ?

1.The heart by itself is not strong enough to move the blood some 25 thousand miles, so it needs help. Ask students to come up with ideas of what sort of help is needed to help the heart get the blood around the body. They should come up with five sources of help. Gravity works against the heart except from the shoulders up. The five things necessary to move the blood are

a. the heart is a pump
b. The smooth walls of the veins reduce friction.
c. Little hair like valves in the veins stop back flow of blood to the areas being pulled in the opposite direction by gravity.
d. The movement of blood in the veins produce a siphoning effect ,to help move the blood back to the heart.
e. The elasticity of the arteries expand with each beat of the heart to allow large quantities of blood to enter the artery. This elasticity then helps push the blood through the system when the artery goes back to normal size.

This last helper of the heart (e.) is the process that helps cause an aneurysm. An aneurysm is an artery that explodes. The artery gets a weakness and the pressure of the blood keeps working on this weakness, until their is a break.

Lab.

     PURPOSE:   Find out how the pressure of the blood causes an artery to break.
     Materials: Two ballon's ,empty thread spool.
    Procedure: Each lab partner takes a balloon, person one blows up their balloon to full size,
     person two blows up the balloon one fourth of the way , both people holds the air in the balloon.
    Person one slides their balloon over end of the spool still holding the air in the balloon. Person two
   then slides their balloon over the spool holding the air in the balloon. Person one and person two both
   release the air in their balloon to see if the air balances in the two balloon's.

     Results: List any movement of air in the two balloon's