Normal blood circulation to the brain is like a simple plumbing arrangement in a village. We call this village The Alert Village.

The Alert Village is a little town by a lake. It has several houses: the Brain house, the Right Arm house, the Left Arm house, the Guts house, Liver house, the Right Kidney house, the Left Kidney house, the Right Legs house, and the Left Legs house. The Mayor resides in the Brain house. The Mayor makes sure that the other houses are receiving electricity and water and keeps everything running smoothly.

The impure water in the lake is brought via pipes (veins) to a reservoir (right atrium), then from the reservoir is directed via a one way valve (tricuspid valve) to a pumping station (right ventricle). It is then pumped via a one way valve (pulmonary valve) to the purification station (lungs), and when it is well purified (well oxygenated), it is returned to a clean reservoir (left atrium). The water then flows via a one way valve (mitral valve) into the major pumping station (left ventricle) that pumps through a one way valve (aortic valve), into a large pipe (aorta).

The major out flowing pipe (aorta) then divides into small pipes (arteries) that supply water to houses in the village (body organs). The brain house gets it's water (blood), via the carotid pipes and the kidney house get its supply via the a pipe known as the renal artery.

The Left Ventricle pumps the blood out to reach the different parts of the body. The first amount of pumped blood goes almost simultaneously to the Right Arm House and the Front Right Side of the Brain House (Right Cerebrum). Shortly after that, the water arrives at the Left Front Side of the Brain House (Left Cerebrum). Then the flow continues down to the Left Arm House. After that it continues down a large pipe (Descending Aorta) which distributes water to all the other houses in the village.

Take a look at the Shockwave animation of the Alert Village.

Click on the "Get Shockwave" button to the left and follow the instructions to download the Shockwave Player from Macromedia.

4 Rooms of the Brain House
One very important aspect is, as you notice, the Brain House has four major rooms. Two large rooms sit in the front (Left Cerebrum and Right Cerebrum). In addition, it has two small rooms in the back (cerebellum pos and medulla).

The small Right Back Brain Room gets the water supply from a little branch (Right Vertebral Artery) which comes from the artery supplying the right arm just as it branches off. The artery supplying the small Left Back Brain Room gets its water supply from a little branch (Left Vertebral Artery) which is going to the left arm just as it branches off.

You will get to know more about the brain circulation as you learn more about the Alert Village.

Guess what? In the Alert village, the mayor controls the entire village from the Brain House. If for any reason the water supply gets cut off to the brain house, a loss of control will occur. For order to be restored the water flow should never be interrupted.

Chief Engineer, Mr. Kardi
Kardi is the chief engineer in charge of the Alert village plumbing system; he is well-trained in pipe and pump problems. If a pipe or a valve gets blocked, or an electric fault happens to any of the water pumps, you can bet that Kardi will handle it.

Kardi's expertise in electric problems is essential, since an electrical system works in coordination with the village water system. The pumps and door switches need electricity to run properly. Any electric problem will affect the functioning of the system even though the pipes may be widely open.

So one day the brain house in the Alert Village doesn't get water!
Everything was going well in the Alert Village until all of a sudden the Mayor's house (Brain house) was not getting any water. This caused the whole order in the village to collapse. The Mayor promptly contacted the chief engineer, Mr. Kardi, who went to check and make sure that there were no blockages to prevent the water from pumping. Kardi checked every part of the pipe system. When he didn't find any problems, he then checked the electrical system where he found that the main switch located at the Right Atrium reservoir was not turning on and off as it should.

Anything that may cause a decrease in blood flow to the brain may lead to fainting. The person will feel dizzy, lightheaded, and fall down. This condition is called Syncope. As you can see, this condition could come from any abnormality or fault across the heart electric (conduction system) or plumbing (heart pump, arteries or veins) system.

PART	HEART	ALERT VILLAGE WATER PUMP
Power Generating Phase	Contracting heart walls move in and out to increase the pressure of blood in a heart chamber.	A piston moves back and forth in a cylinder to increase the pressure of water.
Flow Directing Parts	Equipped with intake and outflow valves.	Equipped with intake and outflow valves.
Filling Phase	During the relaxation phase, the outflow valves (aortic and pulmonic) close, and the intake valves (mitral and tricuspid) open allowing the blood to rush in and fill the relatively empty ventricle.	On the piston's upstroke atmospheric pressure forces water into the empty space beneath the piston.
Ejecting or Emptying Phase	During the contraction phase (systole), the inflow valves (mitral and tricuspid) close and the outflow valves (aortic and pulmonic) open allowing the ventricle to empty its blood.	On the down stroke the water in the cylinder is forced to flow out via the outlet valves.