THE CIRCULATORY SYSTEM

~ The circulatory system transports nutrients and oxygen to our cells. It is made up of:

•The heart is a muscular organ that pumps blood around the body.

•The blood collects oxygen from the alveoli and nutrients fromthe small intestine and transports them to all the cells.

•The blood vessels are the tubes through wich blood circulates.There are three types of bood vessels: arteries,veins, and capillaries.

THE BLOOD

Blood is a red liquid tissue made up of cells float in a liquid called plasma.

There are three types of blood cells:

•RED BLOOD CELLS carry oxygen.

•WHITE BLOOD CELLS remove bacteria and viruses from de blood.

•PLATELETS are small fragments of cells.

THE HEART

The heart uses rhythmic systole and diastole movements to pump the blood around the body. The systole is the movement of contraction and the diastole is the movement of relaxtiom.

Blood enters the atria through the veins and passes to the ventricles.Between the atria and ventricles, there are valves that prevent blood from flowing back to the atria.

HUMAN CIRCULATION

Human circulation is closed and double.

•HUMAN CIRCULATION IS CLOSED. In mammals the heart septum separates the two halves of the heart.

•HUMAN CIRCULATION IS DOUBLE. The blood follows two routes.

-Pulmonary circulation.The blood with carbon dioxide in it comes out of the right ventricle through the pulmonary artery

-Systemic circulation. The blood with oxygen in it leaves the left ventricle through the aorta.